Improving Fatigue Performance of GFRP Composite Using Carbon Nanotubes

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Moneeb Genedy

2015-01-01

Full Text Available Glass fiber reinforced polymers (GFRP have become a preferable material for reinforcing or strengthening reinforced concrete structures due to their corrosion resistance, high strength to weight ratio, and relatively low cost compared with carbon fiber reinforced polymers (CFRP. However, the limited fatigue life of GFRP hinders their use in infrastructure applications. For instance, the low fatigue life of GFRP caused design codes to impose stringent stress limits on GFRP that rendered their use non-economic under significant cyclic loads in bridges. In this paper, we demonstrate that the fatigue life of GFRP can be significantly improved by an order of magnitude by incorporating Multi-Wall Carbon Nanotubes (MWCNTs during GFRP fabrication. GFRP coupons were fabricated and tested under static tension and cyclic tension with mean fatigue stress equal to 40% of the GFRP tensile strength. Microstructural investigations using scanning electron microscopy (SEM and Fourier Transform Infrared (FTIR spectroscopy were used for further investigation of the effect of MWCNTs on the GFRP composite. The experimental results show the 0.5 wt% and the 1.0 wt% MWCNTs were able to improve the fatigue life of GFRP by 1143% and 986%, respectively, compared with neat GFRP.

Estimation of durability of GFRP laminates under stress-corrosive environments using acoustic emission; AE wo mochiita ouryoku fushoku kankyoka deno GFRP no taikyusei hyoka

Energy Technology Data Exchange (ETDEWEB)

Fujii, Yoshimichi. [Seikow Chemical Engineering and Machinery, Ltd., Hyogo (Japan). Laboratory of Composite Materials; Nishiyabu, Kazuaki. [Osaka Prefectural College of Tehcnology, Osaka (Japan)

1999-05-15

The objective of this investigation is to estimate the creep life of glass fiber reinforced plastic (GFRP) under stress-corrosive environments using acoustic emission(AE). The laminates were fabricated using combinations of vinylester resin (R806) and random fiber mat or woven cloth. The creep tests were conducted in 5% nitric acid (HNO{sub 3}) environment. The AE depends on the loading level and the environment condition. For the creep test, the woven cloth reinforced specimens gave higher number of AE counts than the random mat reinforced specimens. The creep life decreased with increasing creep stress, whereas the rate of AE counts increased with increasing creep stress. A linear relationship was found between the creep life and the AE count rate. Using the proposed equation, a prediction of the creep life of GFRP under corrosive environments would presumably be possible. (author)

Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

Science.gov (United States)

Kim, Sang-Young; Shim, Chun Sik; Sturtevant, Caleb; Kim, Dave (Dae-Wook); Song, Ha Cheol

2014-09-01

Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

Directory of Open Access Journals (Sweden)

Kim Sang-Young

2014-09-01

Full Text Available Glass Fiber Reinforced Plastic (GFRP structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties

Mechanical properties and production quality of hand-layup and vacuum infusion processed hybrid composite materials for GFRP marine structures

Directory of Open Access Journals (Sweden)

Sang-Young Kim

2014-09-01

Full Text Available Glass Fiber Reinforced Plastic (GFRP structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties.

Monitoring Moisture Damage Propagation in GFRP Composites Using Carbon Nanoparticles

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Ahmed Al-Sabagh

2017-03-01

Full Text Available Glass fiber reinforced polymer (GFRP composites are widely used in infrastructure applications including water structures due to their relatively high durability, high strength to weight ratio, and non-corrosiveness. Here we demonstrate the potential use of carbon nanoparticles dispersed during GFRP composite fabrication to reduce water absorption of GFRP and to enable monitoring of moisture damage propagation in GFRP composites. GFRP coupons incorporating 2.0 wt % carbon nanofibers (CNFs and 2.0 wt % multi-wall carbon nanotubes (MWCNTs were fabricated in order to study the effect of moisture damage on mechanical properties of GFRP. Water absorption tests were carried out by immersing the GFRP coupons in a seawater bath at two temperatures for a time period of three months. Effects of water immersion on the mechanical properties and glass transition temperature of GFRP were investigated. Furthermore, moisture damage in GFRP was monitored by measuring the electrical conductivity of the GFRP coupons. It was shown that carbon nanoparticles can provide a means of self-sensing that enables the monitoring of moisture damage in GFRP. Despite the success of the proposed technique, it might not be able to efficiently describe moisture damage propagation in GFRP beyond a specific threshold because of the relatively high electrical conductivity of seawater. Microstructural investigations using Fourier Transform Infrared (FTIR explained the significance of seawater immersion time and temperature on the different levels of moisture damage in GFRP.

Three-Dimensional Rebar Graphene.

Science.gov (United States)

Sha, Junwei; Salvatierra, Rodrigo V; Dong, Pei; Li, Yilun; Lee, Seoung-Ki; Wang, Tuo; Zhang, Chenhao; Zhang, Jibo; Ji, Yongsung; Ajayan, Pulickel M; Lou, Jun; Zhao, Naiqin; Tour, James M

2017-03-01

Free-standing robust three-dimensional (3D) rebar graphene foams (GFs) were developed by a powder metallurgy template method with multiwalled carbon nanotubes (MWCNTs) as a reinforcing bar, sintered Ni skeletons as a template and catalyst, and sucrose as a solid carbon source. As a reinforcement and bridge between different graphene sheets and carbon shells, MWCNTs improved the thermostability, storage modulus (290.1 kPa) and conductivity (21.82 S cm -1 ) of 3D GF resulting in a high porosity and structurally stable 3D rebar GF. The 3D rebar GF can support >3150× the foam's weight with no irreversible height change, and shows only a ∼25% irreversible height change after loading >8500× the foam's weight. The 3D rebar GF also shows stable performance as a highly porous electrode in lithium ion capacitors (LICs) with an energy density of 32 Wh kg -1 . After 500 cycles of testing at a high current density of 6.50 mA cm -2 , the LIC shows 78% energy density retention. These properties indicate promising applications with 3D rebar GFs in devices requiring stable mechanical and electrochemical properties.

Fracture detection in concrete by glass fiber cloth reinforced plastics

Science.gov (United States)

Shin, Soon-Gi; Lee, Sung-Riong

2006-04-01

Two types of carbon (carbon fiber and carbon powder) and a glass cloth were used as conductive phases and a reinforcing fiber, respectively, in polymer rods. The carbon powder was used for fabricating electrically conductive carbon powder-glass fiber reinforced plastic (CP-GFRP) rods. The carbon fiber tows and the CP-GFRP rods were adhered to mortar specimens using epoxy resin and glass fiber cloth. On bending, the electrical resistance of the carbon fiber tow attached to the mortar specimen increased greatly after crack generation, and that of the CP-GFRP rod increased after the early stages of deflection in the mortar. Therefore, the CP-GFRP rod is superior to the carbon fiber tow in detecting fractures. Also, by reinforcing with a glass fiber cloth reinforced plastic, the strength of the mortar specimens became more than twice as strong as that of the unreinforced mortar.

Design and development of solid carbide step drill K34 for machining of CFRP and GFRP composite laminates

Science.gov (United States)

Rangaswamy, T.; Nagaraja, R.

2018-04-01

The Study focused on design and development of solid carbide step drill K34 to drill holes on composite materials such as Carbon Fiber Reinforced Plastic (CFRP) and Glass Fiber Reinforced Plastic (GFRP). The step drill K34 replaces step wise drilling of diameter 6.5mm and 9 mm holes that reduces the setup time, cutting speed, feed rate cost, delamination and increase the production rate. Several researchers have analyzed the effect of drilling process on various fiber reinforced plastic composites by carrying out using conventional tools and machinery. However, this process operation can lead to different kind of damages such as delamination, fiber pullout, and local cracks. To avoid the problems encountered at the time of drilling, suitable tool material and geometry is essential. This paper deals with the design and development of K34 Carbide step drill used to drill holes on CFRP and GFRP laminates. An Experimental study carried out to investigate the tool geometry, feed rate and cutting speed that avoids delamination and fiber breakage.

Strengthening Reinforced Concrete Beams with CFRP and GFRP

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Mehmet Mustafa Önal

2014-01-01

Full Text Available Concrete beams were strengthened by wrapping the shear edges of the beams twice at 45° in opposite directions by either carbon fiber reinforced polymer (CFRP or glass fiber reinforced polymer (GFRP. The study included 3 CFRP wrapped beams, 3 GFRP wrapped beams, and 3 control beams, all of which were 150 × 250 × 2200 mm and manufactured with C20 concrete and S420a structural steel at the Gazi University Technical Education Faculty labs, Turkey. Samples in molds were cured by watering in the open air for 21 days. Four-point bending tests were made on the beam test specimens and the data were collected. Data were evaluated in terms of load displacement, bearing strength, ductility, and energy consumption. In the CFRP and GFRP reinforced beams, compared to controls, 38% and 42%, respectively, strength increase was observed. In all beams, failure-flexural stress occurred in the center as expected. Most cracking was observed in the flexural region 4. A comparison of CFRP and GFRP materials reveals that GFRP enforced parts absorb more energy. Both materials yielded successful results. Thicker epoxy application in both CFRP and GFRP beams was considered to be effective in preventing break-ups.

Composite GFRP U-Shaped Footbridge

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Chróścielewski Jacek

2017-04-01

Full Text Available The paper presents proposals for the use of glass fiber reinforced polymer composites for the construction of engineering objects, known and commonly used in the shipbuilding industry. An example of a pedestrian footbridge was used in this case, which, despite the considerable thickness of the structural material, was made using infusion technology in one production cycle. The designed and produced footbridge span is durable, dynamically resistant, incombustible, easy to install and maintain, resistant to weather conditions and also aesthetically interesting. For footbridge production environmentally friendly PET foam core may be used. It may come from recycling of used plastic packages and which is produced with less energy consumption process and much less CO2 emission. The load bearing part of the structure (skin is made of polymer laminate reinforced with glass fabrics (GFRP.

Long-term performance of GFRP reinforcement : technical report.

Science.gov (United States)

2009-12-01

Significant research has been performed on glass fiber-reinforced polymer (GFRP) concrete reinforcement. : This research has shown that GFRP reinforcement exhibits high strengths, is lightweight, can decrease time of : construction, and is corrosion ...

Ground penetrating radar applied to rebar corrosion inspection

Science.gov (United States)

Eisenmann, David; Margetan, Frank; Chiou, Chien-Ping T.; Roberts, Ron; Wendt, Scott

2013-01-01

In this paper we investigate the use of ground penetrating radar (GPR) to detect corrosion-induced thinning of rebar in concrete bridge structures. We consider a simple pulse/echo amplitude-based inspection, positing that the backscattered response from a thinned rebar will be smaller than the similar response from a fully-intact rebar. Using a commercial 1600-MHz GPR system we demonstrate that, for laboratory specimens, backscattered amplitude measurements can detect a thinning loss of 50% in rebar diameter over a short length. GPR inspections on a highway bridge then identify several rebar with unexpectedly low amplitudes, possibly signaling thinning. To field a practical amplitude-based system for detecting thinned rebar, one must be able to quantify and assess the many factors that can potentially contribute to GPR signal amplitude variations. These include variability arising from the rebar itself (e.g., thinning) and from other factors (concrete properties, antenna orientation and liftoff, etc.). We report on early efforts to model the GPR instrument and the inspection process so as to assess such variability and to optimize inspections. This includes efforts to map the antenna radiation pattern, to predict how backscattered responses will vary with rebar size and location, and to assess detectability improvements via synthetic aperture focusing techniques (SAFT).

Structural Analysis of Basalt Fiber Reinforced Plastic Wind Turbine Blade

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Mengal Ali Nawaz

2014-07-01

Full Text Available In this study, Basalt fiber reinforced plastic (BFRP wind turbine blade was analyzed and compared with Glass fiber reinforced plastic blade (GFRP. Finite element analysis (FEA of blade was carried out using ANSYS. Data for FEA was obtained by using rule of mixture. The shell element in ANSYS was used to simulate the wind turbine blade and to conduct its strength analysis. The structural analysis and comparison of blade deformations proved that BFRP wind turbine blade has better strength compared to GFRP wind turbine blade.

Effect of temperature on the passivation behavior of steel rebar

Science.gov (United States)

Chen, Shan-meng; Cao, Bei; Wu, Yin-shun; Ma, Ke

2014-05-01

Steel rebar normally forms an oxide or rusty skin before it is embedded into concrete and the passivation properties of this skin will be heavily influenced by temperature. To study the effect of temperature on the passivation properties of steel rebar under different surface conditions, we conducted scanning electron microscopy (SEM) observations and electrochemical measurements, such as measurements of the free corrosion potential and polarization curves of HPB235 steel rebar. These measurements identified three kinds of surfaces: polished, oxide skin, and rusty skin. Our results show that the passivation properties of all the surface types decrease with the increase of temperature. Temperature has the greatest effect on the rusty-skin rebar and least effect on the polished steel rebar, because of cracks and crevices on the mill scale on the steel rebar's surface. The rusty-skin rebar exhibits the highest corrosion rate because crevice corrosion can accelerate the corrosion of the steel rebar, particularly at high temperature. The results also indicate that the threshold temperatures of passivation for the oxide-skin rebar and the rusty-skin rebar are 37°C and 20°C, respectively.

Kapasitas Rekatan GFRP-S pada Balok Beton Akibat Perendaman Air Laut

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Rudy Djamaluddin

2015-04-01

Full Text Available Glass Fiber Reinforced Polymer Sheet (GFRP-S is the non-corrosive material used for strengthening and has been widely used for many kinds of structures, such as buildings and structures exposed to marine environment. Its noncorrosive property is suitably purposed for the application of structures exposed to marine environment. Therefore, this study was conducted for analyzing the effect of sea water on bonding capacity of GFRP-S. Specimens were 12 concrete beams of 10 cm x 12 cm x 60 cm strengthened with GFRP-S. Three beams were not submersed in the sea while three beams were each submersed in the sea for 1 month, 3 months and 6 months, respectively. Testing was conducted on the ultimate load, the deflection, the GFRP-S strain and the concrete strain. From this study, it can be concluded that both the ultimate load and the bonding capacity of GFRP-S decreases along with the increasing of submersion period. The flexural capacity was decreased due to the decreasing of the bonding capacity of GFRP-S. The result of analysis indicates that the bonding capacity of GFRP-S decreased about 15% after submersed for 6 months in sea water.

Rebar graphene from functionalized boron nitride nanotubes.

Science.gov (United States)

Li, Yilun; Peng, Zhiwei; Larios, Eduardo; Wang, Gunuk; Lin, Jian; Yan, Zheng; Ruiz-Zepeda, Francisco; José-Yacamán, Miguel; Tour, James M

2015-01-27

The synthesis of rebar graphene on Cu substrates is described using functionalized boron nitride nanotubes (BNNTs) that were annealed or subjected to chemical vapor deposition (CVD) growth of graphene. Characterization shows that the BNNTs partially unzip and form a reinforcing bar (rebar) network within the graphene layer that enhances the mechanical strength through covalent bonds. The rebar graphene is transferrable to other substrates without polymer assistance. The optical transmittance and conductivity of the hybrid rebar graphene film was tested, and a field effect transistor was fabricated to explore its electrical properties. This method of synthesizing 2D hybrid graphene/BN structures should enable the hybridization of various 1D nanotube and 2D layered structures with enhanced mechanical properties.

Structural Analysis of Taper-Threaded Rebar Couplers

International Nuclear Information System (INIS)

Chu, Seok Jae; Kwon, Hyuk Mo; Seo, Sang Hwan

2014-01-01

A number of rebar couplers were developed by the leading companies. The information about the products is available from the company website. However, the theory on the taper-threaded coupler is not available. In this paper, the mechanics of the taper-thread was developed to understand the effect of the tightening torque. Structural analysis of our own newly developed rebar coupler was done to improve the strength of the coupler. The taper-threaded rebar coupler was analyzed. The tightening of the rebar into the coupler developed a circumferential stress in the coupler. The circumferential stress depends on the coefficient of friction as well as the tightening torque. The circumferential stress is less than the allowable stress 20 kgf/mm 2 of the material for the coefficient of friction greater than 0.1. The tightening of the rebar into the coupler and the subsequent tensioning was simulated using CATIA. Linear elastic analysis considering contact was done. The tightening of the taper-threaded rebar developed a uniform stress distribution in both standard coupler and position coupler. On the other hand, the tightening of the nut in the axial direction developed a non-uniform stress distribution. Similarly the tensioning also developed a non-uniform stress distribution

Behavior of reinforced concrete beams reinforced with GFRP bars

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D. H. Tavares

Full Text Available The use of fiber reinforced polymer (FRP bars is one of the alternatives presented in recent studies to prevent the drawbacks related to the steel reinforcement in specific reinforced concrete members. In this work, six reinforced concrete beams were submitted to four point bending tests. One beam was reinforced with CA-50 steel bars and five with glass fiber reinforced polymer (GFRP bars. The tests were carried out in the Department of Structural Engineering in São Carlos Engineering School, São Paulo University. The objective of the test program was to compare strength, reinforcement deformation, displacement, and some anchorage aspects between the GFRP-reinforced concrete beams and the steel-reinforced concrete beam. The results show that, even though four GFRP-reinforced concrete beams were designed with the same internal tension force as that with steel reinforcement, their capacity was lower than that of the steel-reinforced beam. The results also show that similar flexural capacity can be achieved for the steel- and for the GFRP-reinforced concrete beams by controlling the stiffness (reinforcement modulus of elasticity multiplied by the bar cross-sectional area - EA and the tension force of the GFRP bars.

Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

Science.gov (United States)

Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

2015-01-01

Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

Shear Strengthening of RC Deep Beam Using Externally Bonded GFRP Fabrics

Science.gov (United States)

Kumari, A.; Patel, S. S.; Nayak, A. N.

2018-06-01

This work presents the experimental investigation of RC deep beams wrapped with externally bonded Glass Fibre Reinforced Polymer (GFRP) fabrics in order to study the Load versus deflection behavior, cracking pattern, failure modes and ultimate shear strength. A total number of five deep beams have been casted, which is designed with conventional steel reinforcement as per IS: 456 (Indian standard plain and reinforced concrete—code for practice, Bureau of Indian Standards, New Delhi, 2000). The spans to depth ratio for all RC deep beams have been kept less than 2 as per the above specification. Out of five RC deep beams, one without retrofitting serves as a reference beam and the rest four have been wrapped with GFRP fabrics in multiple layers and tested with two point loading condition. The first cracking load, ultimate load and the shear contribution of GFRP to the deep beams have been observed. A critical discussion is made with respect to the enhancement of the strength, behaviour and performance of retrofitted deep beams in comparison to the deep beam without GFRP in order to explore the potential use of GFRP for strengthening the RC deep beams. Test results have demonstrated that the deep beams retrofitted with GFRP shows a slower development of the diagonal cracks and improves shear carrying capacity of the RC deep beam. A comparative study of the experimental results with the theoretical ones predicted by various researchers available in the literatures has also been presented. It is observed that the ultimate load of the beams retrofitted with GFRP fabrics increases with increase of number of GFRP layers up to a specific number of layers, i.e. 3 layers, beyond which it decreases.

Influence of specimen type and reinforcement on measured tension-tension fatigue life of unidirectional GFRP laminates

DEFF Research Database (Denmark)

Korkiakoski, Samuli; Brøndsted, Povl; Sarlin, Essi

2016-01-01

It is well known that standardised tension-tension fatigue test specimens of unidirectional (UD) glass-fibre-reinforced plastics (GFRP) laminates tend to fail at end tabs. The true fatigue life is then underestimated. The first objective of this study was to find for UD GFRP laminates a test...... specimen that fails in the gauge section. The second objective was to compare fatigue performance of two laminates, one having a newly developed UD powder-bound fabric as a reinforcement and the other having a quasi-UD stitched non-crimp fabric as a reinforcement. In the first phase, a rectangular specimen...... in accordance with the ISO 527-5 standard and two slightly different dog-bone shaped specimens were evaluated by means of finite element modelling. Subsequent comparative fatigue tests were performed for the laminates with the three specimen types. The results showed that the test specimen type has...

A study on plate anchor detailing systems of shear re-bar

International Nuclear Information System (INIS)

Tsurumaki, S.; Ujiie, K.; Nishikawa, T.; Kitayama, K.

1995-01-01

For shell walls and base slabs in reactor buildings, besides a large amount of main bars, numerous shear re-bars have been employed to resist to out-of-plane force. As a result , detailing work involving shear re-bar is extremely involved. For example, the employed re-bar anchor method differs from the ordinary methods in which, a end of shear re-bar with 135-degrees hook or with anchor plate type and another re-bar end with 90-degrees hook are used. However the structural characteristics in members using shear re-bar of the bolt-mounted anchor plate have not yet been examined. A test was performed to confirm the effects of anchor methods for shear re-bars on shearing behavior of members. This paper describes the test plan, method and results. (author). 12 figs., 7 tabs

Experimental Study on GFRP Surface Cracks Detection Using Truncated-Correlation Photothermal Coherence Tomography

Science.gov (United States)

Wang, Fei; Liu, Junyan; Mohummad, Oliullah; Wang, Yang

2018-04-01

In this paper, truncated-correlation photothermal coherence tomography (TC-PCT) was used as a nondestructive inspection technique to evaluate glass-fiber reinforced polymer (GFRP) composite surface cracks. Chirped-pulsed signal that combines linear frequency modulation and pulse excitation was proposed as an excitation signal to detect GFRP composite surface cracks. The basic principle of TC-PCT and extraction algorithm of the thermal wave signal feature was described. The comparison experiments between lock-in thermography, thermal wave radar imaging and chirped-pulsed photothermal radar for detecting GFRP artificial surface cracks were carried out. Experimental results illustrated that chirped-pulsed photothermal radar has the merits of high signal-to-noise ratio in detecting GFRP composite surface cracks. TC-PCT as a depth-resolved photothermal imaging modality was employed to enable three-dimensional visualization of GFRP composite surface cracks. The results showed that TC-PCT can effectively evaluate the cracks depth of GFRP composite.

Failure analysis of re-bars during bending operations

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Souvik Das

2014-10-01

Full Text Available Thermo-mechanical treated (TMT rebar is suitable material for reinforcing concrete structures on accounts of similarity in thermal expansion, ability to bond well with concrete and, above all the ability to shoulder most of the tensile stress acting on the structure and also steel manufacturing industry has successfully developed a corrosion-resistant variety of rebar for the construction industry. As the TMT is the finish product thus proper control of rolling parameters and water box is needed to achieve adequate property. Water box plays an important role for achieving the final structure and property of the rebars. Water box is responsible for outer rim formation and which helps to achieve the yield strength of the material. The present paper highlights failure investigation of a failed rebar during bending operations. From fractography and microstructural analysis it is confirmed that the rebar sample failed in brittle manner due to through harden martensitic structure and which indicates that there is some anomaly in water box resulting in these premature failures.

Finite element analysis of GFRP reinforced concrete pavement under static load

Science.gov (United States)

Li, Shiping; Hu, Chunhua

2018-02-01

GFRP was more corrosion resistant than traditional reinforced, it is lightweight, high strength thermal expansion coefficient is more close to the concrete and a poor conductor of electromagnetic. Therefore, the use of GFRP to replace the traditional reinforcement in concrete pavement application has excellent practical value. This paper uses ANSYS to establish delamination and reinforcement of Pavement model and analyzed response of GFRP concrete and ordinary concrete pavement structural mechanics on effects of different factors under the action of static. The results showed that under static load, pavement surface layer presented similar changes on stress of surface layer, vertical and horizontal deformation in two kinds of pavement structure, but indicators of GFRP reinforced concrete pavement were obviously better than that of ordinary concrete pavement.

An Experimental Study of Force Involved in Manual Rebar Bending Process

Science.gov (United States)

Deepu, Sasi; Vishnu, Rajendran S.; Harish, Mohan T.; Bhavani, Rao R.

2018-02-01

The work presents an experimental method of understanding the force applied during a manual rebar bending process. The study tracks the force with the variation of the angle of bend and the elapsed time from the start to the end of a complete manual rebar bending process. A sample of expert rebar bending labourers are used for conducting the experiment and the data processed to set a performance standard. If a simulator based rebar bending training can be provided for a novice, this standard can be used as a matrix to define how close a novice rebar bender is closing to the expertise.

Creep investigation of GFRP RC Beams - Part A : Literature review and experimental Study

Directory of Open Access Journals (Sweden)

masmoudi abdelmonem

2014-11-01

This paper (Part A presents a literature review and the loading history of six experimental beams reinforced with GFRP and steel bars. The results of this study revealed that Beams reinforced with GFRP are less marked with creep phenomenon.  This investigation should guide the civil engineer/designer for a better understanding creep phenomenon in GFRP reinforced concrete members.

All-Optical Photoacoustic Sensors for Steel Rebar Corrosion Monitoring

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Cong Du

2018-04-01

Full Text Available This article presents an application of an active all-optical photoacoustic sensing system with four elements for steel rebar corrosion monitoring. The sensor utilized a photoacoustic mechanism of gold nanocomposites to generate 8 MHz broadband ultrasound pulses in 0.4 mm compact space. A nanosecond 532 nm pulsed laser and 400 μm multimode fiber were employed to incite an ultrasound reaction. The fiber Bragg gratings were used as distributed ultrasound detectors. Accelerated corrosion testing was applied to four sections of a single steel rebar with four different corrosion degrees. Our results demonstrated that the mass loss of steel rebar displayed an exponential growth with ultrasound frequency shifts. The sensitivity of the sensing system was such that 0.175 MHz central frequency reduction corresponded to 0.02 g mass loss of steel rebar corrosion. It was proved that the all-optical photoacoustic sensing system can actively evaluate the corrosion of steel rebar via ultrasound spectrum. This multipoint all-optical photoacoustic method is promising for embedment into a concrete structure for distributed corrosion monitoring.

Finite Element Simulation of GFRP Reinforced Concrete Beam Externally Strengthened With CFRP Plates

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Salleh Norhafizah

2017-01-01

Full Text Available The construction technology now has become more and more advanced allowing the development of new technologies or material to replace the previous one and also solved some of the troubles confronted by construction experts. The Glass Fibre Reinforced Polymer (GFRP composite is an alternative to replace the current usage of steel as it is rust proof and stronger in terms of stiffness compared to steel. Furthermore, GFRP bars have a high strength-to-weight ratio, making them attractive as reinforcement for concrete structures. However, the tensile behavior of GFRP bars is characterized by a linear elastic stress–strain relationship up to failure and, therefore, concrete elements reinforced with GFRP reinforcement exhibit brittle failure without warning. Design codes encourage over-reinforced GFRP design since it is more progressive and leads to a less catastrophic failure with a higher degree of deformability. Moreover, because of GFRP low modulus of elasticity, GFRP reinforced concrete members exhibit larger deflections and wider cracks width than steel reinforced concrete. This aims of this paper is to developed 2D Finite Element (FE models that can accurately simulate the respond on an improvement in the deflection of GFRP reinforced concrete beam externally strengthened with CFRP plates on the tension part of beam. The prediction of flexural response according to RCCSA software was also discussed. It was observed that the predicted FE results are given similar result with the experimental measured test data. Base on this good agreement, a parametric study was the performed using the validation FE model to investigate the effect of flexural reinforcement ratio and arrangement of the beams strengthened with different regions of CFRP plates.

Durability and service life prediction of GFRP bars embedded in concrete under acid environment

Energy Technology Data Exchange (ETDEWEB)

Zhou Jikai, E-mail: jkzhou@hotmail.com [College of Civil and Transportation Engineering, Hohai University, Nanjing, Jiangsu 210098 (China); Chen Xudong, E-mail: cxdong1985@hotmail.com [College of Civil and Transportation Engineering, Hohai University, Nanjing, Jiangsu 210098 (China); Chen Shixue, E-mail: 710567525@qq.com [College of Civil and Transportation Engineering, Hohai University, Nanjing, Jiangsu 210098 (China)

2011-10-15

Highlights: > Bond strength of GFRP bars decrease with an increase in pH of acid solutions. > Bond strength of steel bars decrease with an increase in pH of acid solutions. > Durability of GFRP bars could be predicted by modified Arrhenius relation. - Abstract: In recent years, glass fiber reinforcing polymers (GFRP) has emerged as an alternative to conventional steel reinforcing bars in concrete structures. The bond behavior of GFRP bars to concrete under acidic environment is important because of increasing acid rain in China nowadays. This paper presents an experimental investigation into comparison of the durability of the bond between GFRP and steel bars to concrete under acid environment. The specimens were subject to corrosion by immersion in acid solutions with different concentration. One hundred and twenty pullout specimens were used to study the effect of different environment on bond strength of GFRP and steel bars to concrete. Experimental results showed that, For GFRP bars, at the end of 75 days of conditioning duration, maximum bond strength loss of 11%, 22%, 17.2% and 14% were observed in tap water, pH = 2, pH = 3, and pH = 4 environment, respectively. For steel bars, at the end of 75 days of conditioning duration, maximum bond strength loss of 19.6% and 12.3% were observed in pH = 2 and pH = 3 environment, respectively. The influence of solution concentration on bond strength of GFRP bars was determined using Arrhenius equation and time shift method (TSF).

Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

Science.gov (United States)

Hawileh, Rami A.; Rasheed, Hayder A.

2017-12-01

This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

Strengthing of Beams and Columns using GFRP Bars

Science.gov (United States)

Nayak, C. B.; Tade, M. K.; Thakare, S. B., Dr.

2017-08-01

Nowadays infrastructure development is raising its pace. Many reinforced high concrete and masonry buildings are constructed annually around the globe. There are large numbers of structures which deteriorate or become unsafe to use because of changes in use, changes in loading condition, change in the design configuration, inferior building material used or natural calamities. Thus repairing and retrofitting of these structures for safe usage of has a great market. There are several situations in which a civil structure would require strengthening due to lack of strength, stiffness, ductility and durability. Beams, columns may be strengthened in flexure by using GFRP in tension zone. In this present work comparative study will be made with and without GFRP circular bars in a beam and column. An experiment study will be carried out to study the change in the structural behavior of beams & columns with GFRP circular bars of different thickness, varying span to depth ratio.

Flexural Behavior of GFRP Tubes Filled with Magnetically Driven Concrete.

Science.gov (United States)

Xie, Fang; Chen, Ju; Dong, Xinlong; Feng, Bing

2018-01-08

Experimental investigation of GFRP (glass fiber reinforced polymer) tubes that were filled with magnetically driven concrete was carried out to study the flexural behavior of specimens under bending. Specimens having different cross section and lengths were tested. The test specimens were fabricated by filling magnetically driven concrete into the GFRP tubes and the concrete was vibrated using magnetic force. Specimens vibrated using vibrating tube were also tested for comparison. In addition, specimens having steel reinforcing bars and GFRP bars were both tested to study the effect of reinforcing bars on the magnetically driven concrete. The load-displacement curves, load-strain curves, failure mode, and ultimate strengths of test specimens were obtained. Design methods for the flexural stiffness of test specimens were also discussed in this study.

Effectiveness of Horizontal Rebar on Concrete Block Retaining Wall Strength

OpenAIRE

Krishpersad Manohar; Rikhi Ramkissoon

2016-01-01

The effectiveness of including a horizontal rebar compared to only a vertical rebar in concrete filled core interlocking concrete block retaining wall sections was investigated with respect to the horizontal retaining force. Experimental results for three specimens of interlocking blocks with vertical rebar and concrete filled cores showed an average horizontal retaining force of 24546 N ± 5.7% at an average wall deflection of 13.3 mm. Experimental results for three wall specimens of interloc...

Catenary Action in Rebars Crossing a Casting Joint Loaded in Shear

DEFF Research Database (Denmark)

Sørensen, Jesper Harrild; Hoang, Linh Cao; Olesen, John Forbes

2016-01-01

Reinforcement crossing a casting joint loaded in shear exhibits catenary action as the shear displacement increases. The load carrying capacity of such a joint is in practice often calculated by use of empirical methods to account for shear friction effects or by a first order plastic analysis...... if dowel action is included. The strength increase/reserve due to catenary action in the rebars is often neglected; however in some cases it may be necessary to utilize the effect in order to ensure overall structural robustness. This paper presents results of a study, where the increased shear capacity...... and theory is found when reasonable material properties are assumed....

Protection of Steel Rebar in Salt-Contaminated Cement Mortar Using Epoxy Nanocomposite Coatings

Directory of Open Access Journals (Sweden)

The Huu Nguyen

2018-01-01

Full Text Available Epoxy reinforced with two kinds of nanoparticles dealing with nano-SiO2 and nano-Fe2O3 was coated on steel rebar embedded in a chloride contaminated cement mortar. NaCl was added to the fresh Portland cement paste (at 0.3% and 0.5% by weight of cement to simulate the chloride contamination at the critical level. The effect of incorporating nanoparticles on the corrosion resistance of epoxy-coated steel rebar was investigated by linear potentiodynamic polarization and electrochemical impedance spectroscopy. For the 0.3 wt.% chloride mortars, the electrochemical monitoring of the coated steel rebars during immersion for 56 days in 0.1 M NaOH solutions suggested the beneficial role of nano-Fe2O3 particles in significantly improving the corrosion resistance of the epoxy-coated rebar. After 56 days of immersion, the nano-Fe2O3 reduced the corrosion current of epoxy-coated rebar by a factor of 7.9. When the chloride concentration in the cement mortar was 0.5 wt.%, the incorporation of nanoparticles into the epoxy matrix did not enhance the corrosion resistance of epoxy coating for the rebar. At this critical level, chloride ions initiated rebar corrosion through nanoparticles at the epoxy/rebar interface.

Creep investigation of GFRP RC Beams - Part B: a theoretical framework

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masmoudi abdelmonem

2014-11-01

Full Text Available This paper presents an analytical study about the viscoelastic time-dependent (creep behavior of pultruded GFRP elements made of polyester and E-glass fibres. Experimental results reported in Part A are firstly used for material characterization by means of empirical and phenomenological formulations.   The superposition principles by adopting the law of creep following the Eurocode 2 recommendations are also investigated. Analytical study was also conducted including creep under constant stress; successions of increasing stress superposition principle equivalent time and the return creep reloading. The results of this study revealed that Beams reinforced with GFRP are less marked with creep phenomenon.  This investigation should guide the civil engineer/designer for a better understanding creep phenomenon in GFRP reinforced concrete members.

Dowel Behavior of Rebars in Small Concrete Block for Sliding Slab Track on Railway Bridges

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Seong-Cheol Lee

2018-01-01

Full Text Available In recent years, several studies have investigated the sliding slab track for railway bridges. In the design of sliding slab tracks, one of the most important considerations is to evaluate the shear capacity of the lateral supporting concrete blocks in which dowel rebars are embedded. The predictions of the dowel behavior of rebars by existing models are considerably different. Therefore, in this study, the actual dowel behavior of the rebars embedded in a small concrete block was extensively investigated through experiments. Test variables were concrete compressive strength, dowel rebar diameter and yield strength, specimen thickness, and dowel rebar spacing. Existing model predictions were considerably different from test results. The maximum dowel force increased as concrete compressive strength and dowel rebar diameter increased, while it did not increase considerably with other test variables. Unlike in existing models, the shear slip at the maximum dowel force decreased as the dowel rebar diameter increased. Existing models significantly underestimated the maximum dowel force of the dowel rebars with small diameters and overestimated it for the dowel rebars with large diameters. This work can be useful for developing a more rational model to represent the actual dowel behavior of the rebars embedded in small concrete blocks.

Preparation and characterization of glass fibers – polymers (epoxy bars (GFRP reinforced concrete for structural applications

Directory of Open Access Journals (Sweden)

Alkjk Saeed

2016-06-01

Full Text Available The paper presents some of the results from a large experimental program undertaken at the Department of Civil Engineering of Damascus University. The project aims to study the ability to reinforce and strengthen the concrete by bars from Epoxy polymer reinforced with glass fibers (GFRP and compared with reinforce concrete by steel bars in terms of mechanical properties. Five diameters of GFRP bars, and steel bars (4mm, 6mm, 8mm, 10mm, 12mm tested on tensile strength tests. The test shown that GFRP bars need tensile strength more than steel bars. The concrete beams measuring (15cm wide × 15cm deep × and 70cm long reinforced by GFRP with 0.5 vol.% ratio, then the concrete beams reinforced by steel with 0.89 vol.% ratio. The concrete beams tested on deflection test. The test shown that beams which reinforced by GFRP has higher deflection resistance, than beams which reinforced by steel. Which give more advantage to reinforced concrete by GFRP.

Evaluation and Observation of Autogenous Healing Ability of Bond Cracks along Rebar

Directory of Open Access Journals (Sweden)

Choonghyun Kang

2014-04-01

Full Text Available Micro cracks occurring in concrete around tensile rebar is well known latent damage phenomenon. These micro cracks develop, and can be detected after reaching the surface of the concrete. Detection of these cracks before they are fully formed is preferable, but observing the whole crack structure is difficult. Another problem is repairing micro cracks under the concrete surface. The autogenous ability of bond cracks along rebar was evaluated using the air permeability test. Air permeability coefficients were measured before and after tensile loading, and experimental air permeability coefficients became larger near cracks along rebar as a result of tensile loading. Recuring for 28 days after tensile loading made the air permeability coefficients smaller, but this restriction only occurred during water recuring. Observation of crack patterns helped the understanding of change in the air permeability coefficients. Several small cracks along rebar were observed after tensile loading, and most cracks along rebar were not found after water recuring. On the other hand, the crack pattern did not change after air recuring. These results indicate that bond cracks along rebar can be closed by autogenous healing, and cause the air permeability coefficients.

Microstructural characteristics of steel rebar submitted to the process of self - tempering

International Nuclear Information System (INIS)

Barreto, M.F.O.

2014-01-01

Every day the construction industry seeks new alternatives to maximize use of the materials provided new tools for structural design of the new techniques in welding rods. In this sense, this work proposes to study the mechanical properties of steel rebar self-tempering for civil construction, choosing the bars from 6.3 to 25.4 mm in diameter for the study. The cooling process of rebar, after rolling, known as self-tempering produces a rebar with excellent mechanical properties and low cost to the plant, they put the rebar shall be composed of concentric layers with different mechanical properties among themselves. To study the influence of these layers on the mechanical behavior of rebar microstructural characterization was made by means of electron microscopy analysis of transmitted light and scanning of all samples. From the results it was found that only the bars 20 and 25mm diameter had a heat treatment for self-tempering relevant. (author)

Mechanical properties of GFRP tube confined recycled concrete under axial compression

International Nuclear Information System (INIS)

Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

2015-01-01

This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data. (paper)

Long-Term Flexural Behaviors of GFRP Reinforced Concrete Beams Exposed to Accelerated Aging Exposure Conditions

Directory of Open Access Journals (Sweden)

Yeonho Park

2014-06-01

Full Text Available This study investigates the impact of accelerated aging conditions on the long-term flexural behavior and ductility of reinforced concrete (RC members with glass fiber-reinforced polymer (GFRP bars (RC-GFRP specimen and steel bars (RC-steel specimen. A total of thirty six specimens were designed with different amounts of reinforcement with three types of reinforcing bars (i.e., helically wrapped GFRP, sand-coated surface GFRP and steel. Eighteen specimens were subjected to sustained loads and accelerated aging conditions (i.e., 47 °C and 80% relative humidity in a chamber. The flexural behavior of specimens under 300-day exposure was compared to that of the companion specimens without experiencing accelerated aging conditions. Results indicate that the accelerated aging conditions reduced flexural capacity in not only RC-steel, but also RC-GFRP specimens, with different rates of reduction. Different types of GFRP reinforcement exhibited different rates of degradation of the flexural capacity when embedded in concrete under the same exposure conditions. Several existing models were compared with experimental results for predicting the deflection and deformability index for specimens. Bischoff and Gross’s model exhibited an excellent prediction of the time-dependent deflections. Except for the deformability index proposed by Jaeger, there was no general trend related to the aging duration. This study recommends the need for further investigation on the prediction of the deformability index.

Experimental Investigation of a Self-Sensing Hybrid GFRP-Concrete Bridge Superstructure with Embedded FBG Sensors

OpenAIRE

Wang, Yanlei; Li, Yunyu; Ran, Jianghua; Cao, Mingmin

2012-01-01

A self-sensing hybrid GFRP-concrete bridge superstructure, which consists of two bridge decks and each bridge deck is comprised of four GFRP box sections combined with a thin layer of concrete in the compression zone, was developed by using eight embedded FBG sensors in the top and bottom flanges of the four GFRP box sections at midspan section of one bridge deck along longitudinal direction, respectively. The proposed self-sensing hybrid bridge superstructure was tested in 4-point loading to...

The design of an instrumented rebar for assessment of corrosion in cracked reinforced concrete

DEFF Research Database (Denmark)

Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik

2011-01-01

rebar with 17 electronically isolated corrosion sensors. Instrumented and standard rebars were cast into concrete beams and bending cracks were induced and held open using steel frames. Epoxy impregnation was used to assess and compare cracks in the concrete around the instrumented and standard rebar...... between the steel and concrete. Cracked beams with cast-in instrumented and standard rebars were ponded with a 10\\% chloride solution and the open circuit corrosion potential (OCP) of the 17 sensors was measured for up to 62 days. Measurements from the individual sensors indicate when and where active...

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

Science.gov (United States)

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

Boric Acid Corrosion of Concrete Rebar

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Yang L.

2013-07-01

Full Text Available Borated water leakage through spent fuel pools (SFPs at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure and compromise the integrity of the structure. Because corrosion rate of carbon steel in concrete in the presence of boric acid is lacking in published literature and available data are equivocal on the effect of boric acid on rebar corrosion, corrosion rate measurements were conducted in this study using several test methods. Rebar corrosion rates were measured in (i borated water flowing in a simulated concrete crack, (ii borated water flowing over a concrete surface, (iii borated water that has reacted with concrete, and (iv 2,400 ppm boric acid solutions with pH adjusted to a range of 6.0 to 7.7. The corrosion rates were measured using coupled multielectrode array sensor (CMAS and linear polarization resistance (LPR probes, both made using carbon steel. The results indicate that rebar corrosion rates are low (~1 μm/yr or lesswhen the solution pH is ~7.1 or higher. Below pH ~7.1, the corrosion rate increases with decreasing pH and can reach ~100 μm/yr in solutions with pH less than ~6.7. The threshold pH for carbon steel corrosion in borated solution is between 6.8 and 7.3.

Experimental studies on multicellular GFRP bridge deck panels ...

Indian Academy of Sciences (India)

M P MUTHURAJ

2017-11-20

Nov 20, 2017 ... design of a new bridge deck panel made of GFRP. .... cient manufacturing processes with minimal wastage. But re-use of the remaining FRP elements during manufacture ... Energy consumption for production of different.

Finite Element Simulation of Aluminium/GFRP Fibre Metal Laminate under Tensile Loading

Science.gov (United States)

Merzuki, M. N. M.; Rejab, M. R. M.; Romli, N. K.; Bachtiar, D.; Siregar, J.; Rani, M. F.; Salleh, Salwani Mohd

2018-03-01

The response of a fibre metal laminate (FML) model to the tensile loading is predicted through a computational approach. The FML consisted with layers of aluminum alloy and embedded with one layer of composite material, Glass fibre Reinforced Plastic (GFRP). The glass fibre and aluminium alloy 2024-0 was laminated by using thermoset epoxy. A compression moulding technique was used in the process of a FML fabrication. The aluminium has been roughen by a metal sanding method which to improve the bonding between the fibre and metal layer. The main objective of this paper is to determine the failure behaviour of the FML under the tensile loading. The responses on the FML under the tensile loading were numerically performed. The FML was modelled and analysed by using Abaqus/CAE 6.13 version. Based on the experimental and FE data of the tensile, the ultimate tensile stress is 120 MPa where delamination and fibre breakage happened. A numerical model was developed and agreed well with the experimental results. The laminate has an inelastic respond to increase the tensile loads which due to the plasticity of the aluminium layers.

Temperature dependency of tensile properties of GFRP composite for wind turbine blades

Energy Technology Data Exchange (ETDEWEB)

Huh, Yong Hak; Kim, Jong Il; Kim, Dong Jin; Lee, Gun Chang [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

2012-09-15

In this study, the temperature dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson's ratio of the tensile specimen manufactured from uniaxial (0 .deg.) and triaxial (0/{+-}45.deg) laminate composite plates were measured at four different testing temperatures-room temperature, -30 .deg. C, -50 .deg. C, and 60 .deg. C. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson's ratio changed slightly with a change in the testing temperature.

Temperature dependency of tensile properties of GFRP composite for wind turbine blades

International Nuclear Information System (INIS)

Huh, Yong Hak; Kim, Jong Il; Kim, Dong Jin; Lee, Gun Chang

2012-01-01

In this study, the temperature dependency of the tensile properties of a glass fiber reinforced plastic (GFRP) used in wind turbine blades was examined. The tensile strength, elastic modulus, and Poisson's ratio of the tensile specimen manufactured from uniaxial (0 .deg.) and triaxial (0/±45.deg) laminate composite plates were measured at four different testing temperatures-room temperature, -30 .deg. C, -50 .deg. C, and 60 .deg. C. It was found that the tensile strengths and elastic moduli of the uniaxial laminates were greater than those of the triaxial laminates over the testing temperature range. The tensile strength of the two laminates was significantly dependent on the testing temperature, while the dependency of the elastic modulus on the temperature was insignificant. Furthermore, it could be considered that the Poisson's ratio changed slightly with a change in the testing temperature

Properties of Reinforced Concrete Steel Rebars Exposed to High Temperatures

Directory of Open Access Journals (Sweden)

İlker Bekir Topçu

2008-01-01

Full Text Available The deterioration of the mechanical properties of yield strength and modulus of elasticity is considered as the primary element affecting the performance of steel structures under fire. In this study, hot-rolled S220 and S420 reinforcement steel rebars were subjected to high temperatures to investigate the fire performance of these materials. It is aimed to determine the remaining mechanical properties of steel rebars after elevated temperatures. Steels were subjected to 20, 100, 200, 300, 500, 800, and 950∘C temperatures for 3 hours and tensile tests were carried out. Effect of temperature on mechanical behavior of S220 and S420 were determined. All mechanical properties were reduced due to the temperature increase of the steel rebars. It is seen that mechanical properties of S420 steel was influenced more than S220 steel at elevated temperatures.

SEM in situ laboratory investigations on damage growth in GFRP composite under three-point bending tests

DEFF Research Database (Denmark)

Zhou, Hong Wei; Mishnaevsky, Leon; Brøndsted, Povl

2010-01-01

Glass fiber-reinforced polymer (GFRP) composites are widely used in low-weight constructions. SEM (scanning electron microscopy) in situ experiments of damage growth in GFRP composite under three-point bending loads are carried out. By summarizing the experimental results of three groups of samples...

Properties of Reinforced Concrete Steel Rebars Exposed to High Temperatures

OpenAIRE

Topçu, İlker Bekir; Karakurt, Cenk

2008-01-01

The deterioration of the mechanical properties of yield strength and modulus of elasticity is considered as the primary element affecting the performance of steel structures under fire. In this study, hot-rolled S220 and S420 reinforcement steel rebars were subjected to high temperatures to investigate the fire performance of these materials. It is aimed to determine the remaining mechanical properties of steel rebars after elevated temperatures. Steels were subjected to 20, 100, 200, 300, 5...

Potentialities of infrared thermography to assess damage in bonding between concrete and GFRP

Directory of Open Access Journals (Sweden)

M. M. CALDEIRA

Full Text Available This paper demonstrates the application of the active infrared thermography to detect damage in bonding between concrete and glass fiber reinforced polymer (GFRP. Specimens of concrete and mortar with GFRP externally bonded were prepared and at their interfaces were inserted polystyrene discs to simulate damages. The samples were divided into two groups. In group 1, one sample was correctly bonded by a GFRP plate to the concrete, but in the other three were inserted polystyrene discs which had different diameters to simulate damages in bonding. In group 2, all of the samples contained identical polystyrene discs at their interfaces, but the total thickness of each specimen was different, because the objective was to evaluate the ability of the camera to capture the simulated damage in depth. The experimental procedure was divided into two stages. In the first stage, four types of heating were used to heat samples of group 1: incandescent lamp, kiln, blended lamp and fan heater. Thus, it was possible to detect the damage and to observe its format and length. It was noticed that the infrared images are different depending on the heat source incident on the specimen. Therefore, group 2 was tested only for the more efficient heating (incandescent lamp. In the second stage, the infrared equipment was tested. Some of the parameters that must be inserted in the camera were varied in order to understand their influence on image formation. The results show the effectiveness of infrared thermography to assess adherence in GFRP/concrete interface. In the present work, the best results were obtained when the image is captured towards GFRP/concrete and using incandescent lamp. It was observed that the image and measured temperature suffer significant distortion when a false value was inserted for the parameter emissivity.

Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

Energy Technology Data Exchange (ETDEWEB)

Tang, W.C.; Balendran, R.V.; Nadeem, A.; Leung, H.Y. [City University of Hong Kong (China). Department of Building and Construction

2006-10-15

Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment-deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment-deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code. (author)

Simplified elastic-plastic analysis of reinforced concrete structures - design method for self-restraining stress

International Nuclear Information System (INIS)

Aihara, S.; Atsumi, K.; Ujiie, K.; Satoh, S.

1981-01-01

Self-restraining stresses generate not only moments but also axial forces. Therefore the moment and force equilibriums of cross section are considered simultaneously, in combination with other external forces. Thus, under this theory, two computer programs are prepared for. Using these programs, the design procedures which considered the reduction of self-restraining stress, become easy if the elastic design stresses, which are separated normal stresses and self-restraining stresses, are given. Numerical examples are given to illustrate the application of the simplified elastic-plastic analysis and to study its effectiveness. First this method is applied to analyze an upper shielding wall in MARK-2 type's Reactor building. The results are compared with those obtained by the elastic-plastic analysis of Finite Element Method. From this comparison it was confirmed that the method described, had adequate accuracy for re-bar design. As a second example, Mat slab of Reactor building is analyzed. The quantity of re-bars calculated by this method, comes to about two third of re-bars less than those required when self-restraining stress is considered as normal stress. Also, the self-restraining stress reduction factor is about 0.5. (orig./HP)

Degradation of glass-fiber reinforced plastics by low temperature irradiation

International Nuclear Information System (INIS)

Nishijima, S.; Nishiura, T.; Ueno, S.; Tsukazaki, Y.; Okada, T.; Okada, T.M.; Miyata, K.; Kodaka, H.

1998-01-01

Low-temperature irradiation effects of glass-fiber reinforced plastics (GFRP) have been investigated in terms of mechanical properties such as interlaminar shear strength and creep, in order to obtain the selection standard of insulating materials of superconducting magnets used for fusion reactor. It was revealed that the degradation of interlaminar shear strength was strongly dependent of characteristics of matrix and/or glass/epoxy interface. Especially, the research has been carried out towards the creep behaviour of epoxy which is the matrix of GFRP, by both experimental and simulation method. It was suggested that the synergistic effects was observed in creep test. From the molecular dynamics simulation it was found that the cage effects was the one of the main reason of the stress effects of creep behavior under irradiation. (author)

Wireless measurement of elastic and plastic deformation by a metamaterial-based sensor.

Science.gov (United States)

Ozbey, Burak; Demir, Hilmi Volkan; Kurc, Ozgur; Erturk, Vakur B; Altintas, Ayhan

2014-10-20

We report remote strain and displacement measurement during elastic and plastic deformation using a metamaterial-based wireless and passive sensor. The sensor is made of a comb-like nested split ring resonator (NSRR) probe operating in the near-field of an antenna, which functions as both the transmitter and the receiver. The NSRR probe is fixed on a standard steel reinforcing bar (rebar), and its frequency response is monitored telemetrically by a network analyzer connected to the antenna across the whole stress-strain curve. This wireless measurement includes both the elastic and plastic region deformation together for the first time, where wired technologies, like strain gauges, typically fail to capture. The experiments are further repeated in the presence of a concrete block between the antenna and the probe, and it is shown that the sensing system is capable of functioning through the concrete. The comparison of the wireless sensor measurement with those undertaken using strain gauges and extensometers reveals that the sensor is able to measure both the average strain and the relative displacement on the rebar as a result of the applied force in a considerably accurate way. The performance of the sensor is tested for different types of misalignments that can possibly occur due to the acting force. These results indicate that the metamaterial-based sensor holds great promise for its accurate, robust and wireless measurement of the elastic and plastic deformation of a rebar, providing beneficial information for remote structural health monitoring and post-earthquake damage assessment.

Development of high radiation-resistant glass fiber reinforced plastics with cyanate-based resin for superconducting magnet systems

Energy Technology Data Exchange (ETDEWEB)

Idesaki, Akira, E-mail: idesaki.akira@qst.go.jp [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Nakamoto, Tatsushi [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yoshida, Makoto [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Shimada, Akihiko [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Iio, Masami; Sasaki, Kenichi; Sugano, Michinaka [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Makida, Yasuhiro [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Ogitsu, Toru [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2016-11-15

Highlights: • GFRPs for superconducting magnet systems were developed. • Cyanate-based resins were used for GFRPs as matrices. • Radiation resistance was evaluated based on gas evolution and mechanical properties. • GFRP with bismaleimide-triazine resin exhibited excellent radiation resistance. - Abstract: Glass fiber reinforced plastics (GFRPs) with cyanate ester resin/epoxy resin, bismaleimide resin/epoxy resin, and bismaleimide-triazine resin as matrices were developed for the superconducting magnet systems used in high intensity accelerators. The radiation resistance of these GFRPs was evaluated based on their gas evolution and changes in their mechanical properties after gamma-ray irradiation with dose of 100 MGy in vacuum at ambient temperature. After irradiation, a small amount of gas was evolved from all of the GFRPs, and a slight decrease in mechanical properties was observed compared with the conventional epoxy resin-GFRP, G10. Among the GFRPs, the smallest amount of gas (6 × 10{sup −5} mol/g) was evolved from the GFRP with the bismaleimide-triazine resin, which also retained more than 88% of its flexural strength after 100 MGy irradiation; this GFRP is thus considered the most promising material for superconducting magnet systems.

Virtual reality presentation for nondestructive evaluation of rebar corrosion in concrete based on IBEM

International Nuclear Information System (INIS)

Kyung, Je Woon; Leelarkiet, V.; Ohtsu, Masayasu; Yokata, Masaru

2004-01-01

In order to evaluate the corrosion of reinforcing steel-bars (rebar) in concrete, a nondestructive evaluation by the half-cell potential method is currently applied. In this study, potentials measured on a concrete surface are compensated into those on the concrete-rebar interface by the inverse boundary element method (IBEM). Because these potentials are obtained three-dimensionally (3-D), 3-D visualization is desirable. To this end, a visualization system has been developed by using VRML (Virtual Reality Modeling Language). As an application, results of a reinforced concrete (RC) slab with corroded rebars are visualized and discussed.

Influence of SMA reinforcement on the impact resistance of GFRP ...

Indian Academy of Sciences (India)

composite laminates under different temperatures ... GFRP laminates; shape memory alloy; low velocity impact; impact resistance; SEM. ... 25 J) with the temperature range of 50–120 ... C. The fibre used as reinforcement was S-type glass fibre.

Impact properties of aluminium - glass fiber reinforced plastics sandwich panels

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Mathivanan Periasamy

2012-06-01

Full Text Available Aluminium - glass fiber reinforced plastics (GFRP sandwich panels are hybrid laminates consisting of GFRP bonded with thin aluminum sheets on either side. Such sandwich materials are increasingly used in airplane and automobile structures. Laminates with varying aluminium thickness fractions, fiber volume fractions and orientation in the layers of GFRP were fabricated by hand lay up method and evaluated for their impact performance by conducting drop weight tests under low velocity impacts. The impact energy required for initiating a crack in the outer aluminium layer as well as the energy required for perforation was recorded. The impact load-time history was also recorded to understand the failure behavior. The damage depth and the damage area were measured to evaluate the impact resistance. Optical photography and scanning electron micrographs were taken to visualize the crack and the damage zone. The bidirectional cross-ply hybrid laminate (CPHL has been found to exhibit better impact performance and damage resistance than the unidirectional hybrid laminate (UDHL. Increase in aluminium thickness fraction (Al tf and fiber volume fraction (Vf resulted in an increase in the impact energy required for cracking and perforation. On an overall basis, the sandwich panels exhibited better impact performance than the monolithic aluminium.

On the use of ground penetrating radar to detect rebar corrosion in concrete structures

Science.gov (United States)

Eisenmann, David; Margetan, Frank J.; Ellis, Shelby

2018-04-01

Two new studies are summarized in this paper. In the first, we compare recent GPR measurements on the same bridge to those obtained in 2012. The newer measurements use both the 1.6 GHz antenna used in the earlier work and an alternative higher frequency antenna (2.6 GHz). We discuss similarities and differences between the old and new results at 1.6 GHz, and also summarize the effect of the frequency change on the newer measurements. Many factors can contribute to the strength of the GPR echo seen from a given rebar, including the rebar's length, its distance from and tilt angle relative to the antenna, and the location and size of the metal-loss region. In the second section of the paper we discuss new laboratory measurements to systematically investigate these geometric effects. In 2016 we studied such effects using a simplified measurement setup where only an air layer separated the antenna from the rebar. Here we discuss similar measurements simulating rebar embedded in concrete. For our concrete "phantom" we use a layer of moist sand in between two parallel concrete blocks. When the moisture content is properly chosen, the EM properties of sand are similar to those of cured concrete. The block/sand/block sandwich then serves as a concrete-like medium in which a rebar can be inserted and readily repositioned. Results of GPR measurements using this new sandwich approach are reported and compared with those of the earlier "air layer only" measurements.

A unified bond theory, probabilistic meso-scale modeling, and experimental validation of deformed steel rebar in normal strength concrete

Science.gov (United States)

Wu, Chenglin

Bond between deformed rebar and concrete is affected by rebar deformation pattern, concrete properties, concrete confinement, and rebar-concrete interfacial properties. Two distinct groups of bond models were traditionally developed based on the dominant effects of concrete splitting and near-interface shear-off failures. Their accuracy highly depended upon the test data sets selected in analysis and calibration. In this study, a unified bond model is proposed and developed based on an analogy to the indentation problem around the rib front of deformed rebar. This mechanics-based model can take into account the combined effect of concrete splitting and interface shear-off failures, resulting in average bond strengths for all practical scenarios. To understand the fracture process associated with bond failure, a probabilistic meso-scale model of concrete is proposed and its sensitivity to interface and confinement strengths are investigated. Both the mechanical and finite element models are validated with the available test data sets and are superior to existing models in prediction of average bond strength (rib spacing-to-height ratio of deformed rebar. It can accurately predict the transition of failure modes from concrete splitting to rebar pullout and predict the effect of rebar surface characteristics as the rib spacing-to-height ratio increases. Based on the unified theory, a global bond model is proposed and developed by introducing bond-slip laws, and validated with testing of concrete beams with spliced reinforcement, achieving a load capacity prediction error of less than 26%. The optimal rebar parameters and concrete cover in structural designs can be derived from this study.

2.45 GHz Microwave Processing and Its Influence on Glass Fiber Reinforced Plastics

Science.gov (United States)

Zaremba, Swen

2018-01-01

During the production of fiber-reinforced composite materials, liquid resin is introduced into the fiber material and cured, i.e., hardened. An elevated temperature is needed for this curing. Microwave curing of composites has been investigated for some time, but it has mostly been done using small domestic or laboratory equipment. However, no investigation has been carried out using an industrial-sized chamber-microwave for glass fiber-reinforced plastic (GFRP). Here, we show that microwave curing produces laminates of the same quality as oven-cured ones. The study shows that, if the process is done right, GFRP samples can be produced with an industrial scale microwave. Even if not fully cured, microwave samples show a glass transition temperature measured with DMA (Tg-DMA) that is comparable to the Tg-DMA according to the proposed cure cycle on the data sheet. Specific microwave-cured configurations show better inter-laminar shear strength than oven specimens. The results show that microwave-based heat introduction can be a beneficial curing method for GFRP laminates. A microwave-optimized process is faster and leads to better mechanical properties. PMID:29783684

A study of the blade's material performance made of GFRP for 100kW tidal current turbine

International Nuclear Information System (INIS)

Kim, Jung Min; Chung, Hyun; Kim, Jong Sung

2009-01-01

The aim of this study is to investigate the performance of material of rotary blade which was designed for a energy system which utilizes a tide, a comparatively stable and predictable energy source. The rotary blade design for Horizontal Axis Tidal Turbine was carried out to convert an energy. And, considering seawater corrosion and material weight, Glass Fiber Reinforced Polymer (GFRP) was applied as the material of rotary blade. GFRP is a light material comparing with metal materials, while it has a sufficient stiffness, and GFRP has durability against seawater corrosion. However, it is suggested that the performance verification of material, since the material was built based on a polymer. And the performance verification of material was carried out comparing the results from experimental test and the results from finite element analysis using Nastran FX.

Non-Destructive Detection of Rebar Buried in a Reinforced Concrete Wall with Wireless Passive SAW Sensor

Science.gov (United States)

Fan, Yanping; Ji, Xiaojun; Cai, Ping; Lu, Qianhui

2013-01-01

In order to reduce the damage to the old reinforced concrete walls and work out the best construction scheme during the renovation of old buildings, it is often required to detect the position of rebar buried in concrete walls. In this paper, we propose a non-destructive method to detect the buried rebar by self-inductive sensor combined with surface acoustic wave resonator (SAWR). The proposed method has the advantages of wireless, passive and convenient operations. In our new design, the sensing element of self-inductance coil was made as a component of SAWR matching network. The distribution of rebar could be measured according to the system resonant frequency, using a signal demodulation device set. The depth of buried rebar and the deviation of output resonant frequency from inherent frequency of SAWR have an inverse relation. Finally, the validity of the method was verified in theoretical calculation and simulation.

Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

Science.gov (United States)

Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

2015-01-01

Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

An Experimental Study for Quantitative Estimation of Rebar Corrosion in Concrete Using Ground Penetrating Radar

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Md Istiaque Hasan

2016-01-01

Full Text Available Corrosion of steel rebar in reinforced concrete is one the most important durability issues in the service life of a structure. In this paper, an investigation is conducted to find out the relationship between the amount of reinforced concrete corrosion and GPR maximum positive amplitude. Accelerated corrosion was simulated in the lab by impressing direct current into steel rebar that was submerged in a 5% salt water solution. The amount of corrosion was varied in the rebars with different levels of mass loss ranging from 0% to 45%. The corroded rebars were then placed into three different oil emulsion tanks having different dielectric properties similar to concrete. The maximum amplitudes from the corroded bars were recorded. A linear relationship between the maximum positive amplitudes and the amount of corrosion in terms of percentage loss of area was observed. It was proposed that the relationship between the GPR maximum amplitude and the amount of corrosion can be used as a basis of a NDE technique of quantitative estimation of corrosion.

Pengaruh Rendaman Air Laut terhadap Kapasitas Rekatan GFRP-Sheet pada Balok Beton Bertulang

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Mufti Amir Sultan

2017-04-01

Full Text Available Construction of concrete structures that located in extreme environments are such as coastal areas will result in decreased strength or even the damage of the structures. As well know, chloride contained in sea water is responsible for strength reduction or structure failed were hence maintenance and repairs on concrete structure urgently needed. One popular method of structural improvements which under investigation is to use the material Glass Fiber Reinforced Polymer which has one of the advantages such as corrosion resistance. This research will be conducted experimental studies to investigate the flexural behavior of reinforced concrete beams with reinforcement GFRP-Sheet immersed in sea water using immersion time of 1, 3, 6 and 12 months. Test specimen consists of 11 pieces of reinforced beams with dimensions (15x20x330 cm that had been reinforced with GFRPSheet in the area of bending. The test specimen tested by providing a static load until it reaches the power limit, to record data during the test strain gauge mounted on the surface of the specimen and the GFRP-Sheet to collect the strain value. The result of analysis indicates the bonding capacity of GFRP Sheet decreases about 11.04% after immersed for 12 months in sea water.

Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

International Nuclear Information System (INIS)

Simescu, Florica; Idrissi, Hassane

2008-01-01

We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 . After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

Effect of zinc phosphate chemical conversion coating on corrosion behaviour of mild steel in alkaline medium: protection of rebars in reinforced concrete

Directory of Open Access Journals (Sweden)

Florica Simescu and Hassane Idrissi

2008-01-01

Full Text Available We outline the ability of zinc phosphate coatings, obtained by chemical conversion, to protect mild steel rebars against localized corrosion, generated by chloride ions in alkaline media. The corrosion resistance of coated steel, in comparison with uncoated rebars and coated and uncoated steel rebars embedded in mortar, were evaluated by open-circuit potential, potentiodynamic polarization, cronoamperometry and electrochemical impedance spectroscopy. The coated surfaces were characterized by x-ray diffraction and scanning electron microscopy. First, coated mild steel rebars were studied in an alkaline solution with and without chloride simulating a concrete pore solution. The results showed that the slow dissolution of the coating generates hydroxyapatite Ca10(PO46(OH2. After a long immersion, the coating became dense and provided an effective corrosion resistance compared with the mild steel rebar. Secondly, the coated and uncoated steel rebars embedded in mortar and immersed in chloride solution showed no corrosion or deterioration of the coated steel. Corrosion rate is considerably lowered by this phosphate coating.

Modal parameter identification of all-GFRP composite cable-stayed footbridge in Denmark

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Górski Piotr

2017-01-01

Full Text Available The aim of this paper is to investigate of dynamic characteristics of cable-stayed Fiberline Bridge in Kolding, Denmark, made entirely of Glass Fiber Reinforced Polymer (GFRP composite. During examination based on in situ free-decay measurements and using accelerometers under human jumping the primary five natural frequencies, corresponding mode shapes and damping ratios of the footbridge were identified. The Peak Picking (PP and Frequency Domain Decomposition (FDD approaches were applied to identify the natural frequencies and mode shapes. The corresponding damping ratios were extracted by a linear regression on the extremes of modal decays. The estimated damping ratios were compared with published data for selected footbridges made of various conventional materials. The obtained experimental results provide a relevant data regarding the dynamic response prediction or structural health monitoring of all-GFRP composite footbridges.

Bonding capacity of the GFRP-S on strengthened RC beams after sea water immersion

Science.gov (United States)

Sultan, Mufti Amir; Djamaluddin, Rudy

2017-11-01

Construction of concrete structures that located in extreme environments are such as coastal areas will result in decreased strength or even the damage of the structures. As well know, chloride contained in sea water is responsible for strength reduction or structure fail were hence maintenance and repairs on concrete structure urgently needed. One popular method of structural improvements which under investigation is to use the material Glass Fibre Reinforced Polymer which has one of the advantages such as corrosion resistance. This research will be conducted experimental studies to investigate the bonding capacity behavior of reinforced concrete beams with reinforcement GFRP-S immersed in sea water using immersion time of one month, three months, six months and twelve months. Test specimen consists of 12 pieces of reinforced concrete beams with dimensions (150x200x3000) mm that had been reinforced with GFRP-S in the area of bending, the beam without immersion (B0), immersion one month (B1), three months (B3), six months (B6) and twelve months (B12). Test specimen were cured for 28 days before the application of the GFRP sheet. Test specimen B1, B3, B6 and B12 that have been immersed in sea water pool with a immersion time each 1, 3, 6 and 12 months. The test specimen without immersion test by providing a static load until it reaches the failure, to record data during the test strain gauge mounted on the surface of the specimen and the GFRP to collect the strain value. From the research it obvious that there is a decrease bonding capacity on specimens immersed for one month, three months, six months and twelve months against the test object without immersion of 8.85%; 8.89%; 9.33% and 11.04%.

The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

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Abdulaziz M Jarkas

2010-07-01

Full Text Available  Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

Directory of Open Access Journals (Sweden)

Abdulaziz M Jarkas

2010-06-01

Full Text Available Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

Directory of Open Access Journals (Sweden)

Abdulaziz M Jarkas

2010-06-01

Full Text Available  Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting its rebar fixing efficiency. To achieve this objective, a large volume of fixing productivity data was collected and analysed using the categorical interaction - regression method. As a result, the main and interaction effects of rebar diameter; reinforcement quantity; slab geometry; and reinforcement layer location are determined. The findings show a significant influence of these factors on the fixing operation, which can be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the tangible consequences of designers‟ decisions on labour productivity

Numerical assessment of non-uniform corrosion scenarios of rebar ...

Indian Academy of Sciences (India)

Corrosion of embedded rebars is a classical deterioration mechanism that remains as one of the most significant problems limiting the service life of concrete structures exposed to chloride-laden environments. The primary objective of this study is to propose and verify a numerical framework that can efficiently quantify ...

Splice performance evaluation of enamel-coated rebar for structural safety.

Science.gov (United States)

2014-07-01

This report summarizes the findings and results from an experimental study of vitreous enamel coating effects on the bond : strength between deformed rebar and normal strength concrete. A total of 24 beam splice specimens were tested under four-point...

Improvement of the mode II interface fracture toughness of glass fiber reinforced plastics/aluminum laminates through vapor grown carbon fiber interleaves.

Science.gov (United States)

Ning, Huiming; Li, Yuan; Hu, Ning; Cao, Yanping; Yan, Cheng; Azuma, Takesi; Peng, Xianghe; Wu, Liangke; Li, Jinhua; Li, Leilei

2014-06-01

The effects of acid treatment, vapor grown carbon fiber (VGCF) interlayer and the angle, i.e., 0° and 90°, between the rolling stripes of an aluminum (Al) plate and the fiber direction of glass fiber reinforced plastics (GFRP) on the mode II interlaminar mechanical properties of GFRP/Al laminates were investigated. The experimental results of an end notched flexure test demonstrate that the acid treatment and the proper addition of VGCF can effectively improve the critical load and mode II fracture toughness of GFRP/Al laminates. The specimens with acid treatment and 10 g m -2 VGCF addition possess the highest mode II fracture toughness, i.e., 269% and 385% increases in the 0° and 90° specimens, respectively compared to those corresponding pristine ones. Due to the induced anisotropy by the rolling stripes on the aluminum plate, the 90° specimens possess 15.3%-73.6% higher mode II fracture toughness compared to the 0° specimens. The improvement mechanisms were explored by the observation of crack propagation path and fracture surface with optical, laser scanning and scanning electron microscopies. Moreover, finite element analyses were carried out based on the cohesive zone model to verify the experimental fracture toughness and to predict the interface shear strength between the aluminum plates and GFRP laminates.

Crack identification for reinforced concrete using PZT based smart rebar active sensing diagnostic network

Science.gov (United States)

Song, N. N.; Wu, F.

2016-04-01

An active sensing diagnostic system using PZT based smart rebar for SHM of RC structure has been currently under investigation. Previous test results showed that the system could detect the de-bond of concrete from reinforcement, and the diagnostic signals were increased exponentially with the de-bonding size. Previous study also showed that the smart rebar could function well like regular reinforcement to undertake tension stresses. In this study, a smart rebar network has been used to detect the crack damage of concrete based on guided waves. Experimental test has been carried out for the study. In the test, concrete beams with 2 reinforcements have been built. 8 sets of PZT elements were mounted onto the reinforcement bars in an optimized way to form an active sensing diagnostic system. A 90 kHz 5-cycle Hanning-windowed tone burst was used as input. Multiple cracks have been generated on the concrete structures. Through the guided bulk waves propagating in the structures from actuators and sensors mounted from different bars, crack damage could be detected clearly. Cases for both single and multiple cracks were tested. Different crack depths from the surface and different crack numbers have been studied. Test result shows that the amplitude of sensor output signals is deceased linearly with a propagating crack, and is decreased exponentially with increased crack numbers. From the study, the active sensing diagnostic system using PZT based smart rebar network shows a promising way to provide concrete crack damage information through the "talk" among sensors.

Experimental and Numerical Analysis of Damage in Woven GFRP Composites Under Large-deflection Bending

Science.gov (United States)

Ullah, Himayat; Harland, Andy R.; Silberschmidt, Vadim V.

2012-10-01

Textile-reinforced composites such as glass fibre-reinforced polymer (GFRP) used in sports products can be exposed to different in-service conditions such as large bending deformation and multiple impacts. Such loading conditions cause high local stresses and strains, which result in multiple modes of damage and fracture in composite laminates due to their inherent heterogeneity and non-trivial microstructure. In this paper, various damage modes in GFRP laminates are studied using experimental material characterisation, non-destructive micro-structural damage evaluation and numerical simulations. Experimental tests are carried out to characterise the behaviour of these materials under large-deflection bending. To obtain in-plane shear properties of laminates, tensile tests are performed using a full-field strain-measurement digital image correlation technique. X-ray micro computed tomography (Micro CT) is used to investigate internal material damage modes - delamination and cracking. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus to study the deformation behaviour and damage in GFRP. In these models, multiple layers of bilinear cohesive-zone elements are employed to study the onset and progression of inter-ply delamination and intra-ply fabric fracture of composite laminate, based on the X-ray Micro CT study. The developed numerical models are capable to simulate these features with their mechanisms as well as subsequent mode coupling observed in tests and Micro CT scanning. The obtained results of simulations are in agreement with experimental data.

Experimental Assessment on the Flexural Bonding Performance of Concrete Beam with GFRP Reinforcing Bar under Repeated Loading

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Minkwan Ju

2015-01-01

Full Text Available This study intends to investigate the flexural bond performance of glass fiber-reinforced polymer (GFRP reinforcing bar under repeated loading. The flexural bond tests reinforced with GFRP reinforcing bars were carried out according to the BS EN 12269-1 (2000 specification. The bond test consisted of three loading schemes: static, monotonic, and variable-amplitude loading to simulate ambient loading conditions. The empirical bond length based on the static test was 225 mm, whereas it was 317 mm according to ACI 440 1R-03. Each bond stress on the rib is released and bonding force is enhanced as the bond length is increased. Appropriate level of bond length may be recommended with this energy-based analysis. For the monotonic loading test, the bond strengths at pullout failure after 2,000,000 cycles were 10.4 MPa and 6.5 MPa, respectively: 63–70% of the values from the static loading test. The variable loading test indicated that the linear cumulative damage theory on GFRP bonding may not be appropriate for estimating the fatigue limit when subjected to variable-amplitude loading.

The effect of nylon nanofibers on the dynamic behaviour and the delamination resistance of GFRP composites

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Garcia Cristobal

2018-01-01

Full Text Available Vibrations are responsible for a considerable number of accidents in aircrafts, bridges and other civil engineering structures. Therefore, there is a need to reduce the vibrations on structures made of composite materials. Delamination is a particularly dangerous failure mode for composite materials because delaminated composites can lose up to 60% of their strength and stiffness and still remain unchanged. One of the methods to suppress vibrations and preventing delamination is to incorporate nanofibers into the composite laminates. The aim of the present work is to investigate how nylon nanofibers affect the dynamic behaviour and delamination resistance of glass fibre reinforced polymer (GFRP composites. Experiments and numerical simulations using finite element modelling (FEM analysis are used to estimate the natural frequencies, the damping ratio and inter-laminar strength in GFRP composites with and without nylon nanofibers. It is found that the natural frequencies of the nylon nano-modified composites do not change significantly as compared to the traditional composites. However, nano-modified composites demonstrated a considerable increase in damping ratio and inter-laminar shear strength due to the incorporation of nylon nanofibers. This work contributes to the knowledge about the mechanical and dynamic properties of glass fibre reinforced polymer (GFRP composites with nylon nanofibers.

EFFECT OF GAMMA RAY IRRADIATION ON INTERLAMINAR SHEAR STRENGTH OF GLASS FIBER REINFORCED PLASTICS AT 77 K

International Nuclear Information System (INIS)

Nishimura, A.; Nishijima, S.; Izumi, Y.

2008-01-01

It is known that an organic material is damaged by gamma ray irradiation, and the strength after irradiation has dependence on the gamma ray dose. These issues are important not only to make global understanding of electric insulating performance of glass fiber reinforced plastics (GFRP) under irradiation condition but also to develop new insulation materials. This paper presents the dependence of fracture mode and interlaminar shear strength (ILSS) on the material and the gamma ray irradiation effect on the fracture mode and the ILSS. 6 mm radius loading nose and supports were used to prompt ILS fracture for a short beam test. A 2.5 mm thick small specimen machined out of a 13 mm thick G-10CR GFRP plate (sliced specimen) showed lower ILSS and translaminar shear (TLS) fracture, although the same size specimen prepared from a 2.5 mm G-10CR GFRP plate (non-sliced specimen) showed ILS fracture and the higher ILSS. Both type of specimens showed the degradation of ILSS after gamma ray irradiation. The fracture mode of the non-sliced specimen changed from ILS to TLS fracture and no bending fracture was observed. The resistance to shear deformation of glass cloth/epoxy laminate structure would be damaged by the irradiation

Cement content influence in rebar corrosion in carbonated mortars

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Américo, P. O.

2003-12-01

Full Text Available The cement hydration products protect the concrete rebars of the reinforced concrete due to the production of Ca(OH₂, NaOH, and KOH that, upon dissolving in the concrete s aqueous phase, generate a pH above 12.5. However, reinforced concrete structures are exposed to pollutant gases, such as, CO₂ which upon penetrating the concrete, reacts with the alkaline components, consequently reducing the pH of the aqueous phase causing the loss of passivity by the rebar and as a consequence its corrosion when there is the presence of humidity and oxygen. The objective of the current paper is the analysis of the alkaline reserve influence, measured by the cement content, in the corrosion of rebars employing the polarization resistance technique for determining the corrosion intensity. Results for corrosion intensity of rebars embedded in prismatic mortar test specimens are produced with three cement content levels, with equal water/cement ratio. Cylindrical test specimens were also used for verification of the capillary absorption and the porosity by means of mercury porosymetry The results show that the initiation period is shorter and the corrosion intensity of the rebars is higher when the cement content is lower However, there is also an alteration in the microstructure upon altering the cement content, and far this reason one cannot conclude that the alkaline reserve alone is responsible for these results.

Los productos de hidratación del cemento protegen las armaduras embebidas en el hormigón debido a la gran cantidad de Ca(OH₂, NaOH y KOH disueltos en la fase acuosa del hormigón que proporcionan un pH mayor que 12,5. Sin embargo, las estructuras de hormigón armado están expuestas a los gases contaminantes como el CO₂, que al penetrar en el hormigón reacciona con los compuestos alcalinos, se reduce el pH de la fase acuosa y provocan la despasivación de la armadura. Posteriormente, si hay

Reliability Analysis of Cooling Towers: Influence of Rebars Corrosion on Failure

International Nuclear Information System (INIS)

Sudret, Bruno; Pendola, Maurice

2002-01-01

Natural-draught cooling towers are used in nuclear power plants as heat exchangers. These structures are submitted to environmental loads such as wind and thermal gradients that are stochastic in nature. A probabilistic framework has been developed by EDF (Electricite de France) for assessing the durability of such structures. In this paper, the corrosion of the rebars due to concrete carbonation and the corresponding weakening of the reinforced concrete sections is considered. Due to the presence of time in the definition of the limit state function associated with the loss of serviceability of the cooling tower, time-variant reliability analysis has to be used. A novel approach is proposed to take into account the random 'initiation time', which corresponds to the time necessary for the carbonation to attain the rebars. Results are given in terms of the probability of failure of the structure over its life time. (authors)

Coated steel rebar for enhanced concrete-steel bond strength and corrosion resistance.

Science.gov (United States)

2010-10-01

This report summarizes the findings and recommendations on the use of enamel coating in reinforced concrete structures both for bond strength and : corrosion resistance of steel rebar. Extensive laboratory tests were conducted to characterize the pro...

A Review of Natural Joint Systems and Numerical Investigation of Bio-Inspired GFRP-to-Steel Joints

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Evangelos I. Avgoulas

2016-07-01

Full Text Available There are a great variety of joint types used in nature which can inspire engineering joints. In order to design such biomimetic joints, it is at first important to understand how biological joints work. A comprehensive literature review, considering natural joints from a mechanical point of view, was undertaken. This was used to develop a taxonomy based on the different methods/functions that nature successfully uses to attach dissimilar tissues. One of the key methods that nature uses to join dissimilar materials is a transitional zone of stiffness at the insertion site. This method was used to propose bio-inspired solutions with a transitional zone of stiffness at the joint site for several glass fibre reinforced plastic (GFRP to steel adhesively bonded joint configurations. The transition zone was used to reduce the material stiffness mismatch of the joint parts. A numerical finite element model was used to identify the optimum variation in material stiffness that minimises potential failure of the joint. The best bio-inspired joints showed a 118% increase of joint strength compared to the standard joints.

A Study on Load Carrying Capacity of Fly Ash Based Polymer Concrete Columns Strengthened Using Double Layer GFRP Wrapping

Directory of Open Access Journals (Sweden)

S. Nagan

2014-01-01

Full Text Available This paper investigates the suitability of glass fiber reinforced polymer (GFRP sheets in strengthening of fly ash based polymer members under compression. Experimental results revealed that load carrying capacity of the confined columns increases with GFRP sheets wrapping. Altogether 18 specimens of M30 and G30 grade short columns were fabricated. The G30 specimens were prepared separately in 8 molarity and 12 molarity of sodium hydroxide concentration. Twelve specimens for low calcium fly ash based reinforced polymer concrete and six specimens of ordinary Portland cement reinforced concrete were cast. Three specimens from each molarity fly ash based reinforced polymer concrete and ordinary Portland cement reinforced concrete were wrapped with double layer of GFRP sheets. The load carrying capacity of fly ash based polymer concrete was tested and compared with control specimens. The results show increase in load carrying capacity and ductility index for all strengthened elements. The maximum increase in load carrying capacity was 68.53% and is observed in strengthened G30 specimens.

Performance evaluation of concrete bridge decks reinforced with MMFX and SSC rebars.

Science.gov (United States)

2006-01-01

This report investigates the performance of bridge decks reinforced with stainless steel clad (SSC) and micro-composite multistructural formable steel (MMFX) rebars. The two-span Galloway Road Bridge on route CR5218 over North Elkhorn Creek in Scott ...

Analytical model of asymmetrical Mixed-Mode Bending test of adhesively bonded GFRP joint

Czech Academy of Sciences Publication Activity Database

Ševčík, Martin; Hutař, Pavel; Vassilopoulos, Anastasios P.; Shahverdi, M.

2015-01-01

Roč. 9, č. 34 (2015), s. 237-246 ISSN 1971-8993 R&D Projects: GA MŠk(CZ) EE2.3.30.0063; GA ČR GA15-09347S Institutional support: RVO:68081723 Keywords : GFRP materials * Mixed-Mode bending * Fiber bridging * Analytical model Subject RIV: JL - Materials Fatigue, Friction Mechanics

Residual Tensile Strength and Bond Properties of GFRP Bars after Exposure to Elevated Temperatures

Directory of Open Access Journals (Sweden)

Devon S. Ellis

2018-02-01

Full Text Available The use of fiber reinforced polymer (FRP bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated temperatures (due to fire, there is little published information available on their post-fire residual load capacity. This paper reports residual tensile strength, modulus of elasticity, and bond strength (to concrete of glass fiber reinforced polymer (GFRP bars after exposure to elevated temperatures of up to 400 °C and subsequent cooling to an ambient temperature. The results showed that the residual strength generally decreases with increasing temperature exposure. However, as much as 83% of the original tensile strength and 27% of the original bond strength was retained after the specimens were heated to 400 °C and then cooled to ambient temperature. The residual bond strength is a critical parameter in post-fire strength assessments of GFRP-reinforced concrete members.

Residual Tensile Strength and Bond Properties of GFRP Bars after Exposure to Elevated Temperatures.

Science.gov (United States)

Ellis, Devon S; Tabatabai, Habib; Nabizadeh, Azam

2018-02-27

The use of fiber reinforced polymer (FRP) bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated temperatures (due to fire), there is little published information available on their post-fire residual load capacity. This paper reports residual tensile strength, modulus of elasticity, and bond strength (to concrete) of glass fiber reinforced polymer (GFRP) bars after exposure to elevated temperatures of up to 400 °C and subsequent cooling to an ambient temperature. The results showed that the residual strength generally decreases with increasing temperature exposure. However, as much as 83% of the original tensile strength and 27% of the original bond strength was retained after the specimens were heated to 400 °C and then cooled to ambient temperature. The residual bond strength is a critical parameter in post-fire strength assessments of GFRP-reinforced concrete members.

Quantitative sensing of corroded steel rebar embedded in cement mortar specimens using ultrasonic testing

Science.gov (United States)

Owusu Twumasi, Jones; Le, Viet; Tang, Qixiang; Yu, Tzuyang

2016-04-01

Corrosion of steel reinforcing bars (rebars) is the primary cause for the deterioration of reinforced concrete structures. Traditional corrosion monitoring methods such as half-cell potential and linear polarization resistance can only detect the presence of corrosion but cannot quantify it. This study presents an experimental investigation of quantifying degree of corrosion of steel rebar inside cement mortar specimens using ultrasonic testing (UT). A UT device with two 54 kHz transducers was used to measure ultrasonic pulse velocity (UPV) of cement mortar, uncorroded and corroded reinforced cement mortar specimens, utilizing the direct transmission method. The results obtained from the study show that UPV decreases linearly with increase in degree of corrosion and corrosion-induced cracks (surface cracks). With respect to quantifying the degree of corrosion, a model was developed by simultaneously fitting UPV and surface crack width measurements to a two-parameter linear model. The proposed model can be used for predicting the degree of corrosion of steel rebar embedded in cement mortar under similar conditions used in this study up to 3.03%. Furthermore, the modeling approach can be applied to corroded reinforced concrete specimens with additional modification. The findings from this study show that UT has the potential of quantifying the degree of corrosion inside reinforced cement mortar specimens.

Durability study of neat/nanophased GFRP composites subjected to different environmental conditioning

International Nuclear Information System (INIS)

Zainuddin, S.; Hosur, M.V.; Zhou, Y.; Kumar, Ashok; Jeelani, S.

2010-01-01

Experimental investigations on the durability of E-glass/nanoclay-epoxy composites are reported. SC-15 epoxy system was modified using 1-2 wt.% of nanoclay. Extent of clay platelet exfoliation in epoxy was evaluated using X-ray diffraction (XRD). Glass fiber reinforced plastic (GFRP) composite panels were fabricated using modified epoxy and exposed to four different conditions, i.e. hot (elevated temperature-dry, wet: 60 and 80 deg. C) and cold (subzero-dry, wet) for 15, 45 and 90 days. Weight change due to conditioning, quasi-static flexure and micrographic characterization were studied on the conditioned samples. Room temperature samples were also tested for baseline consideration. XRD results showed exfoliation of clay platelets in nanoclay-epoxy samples with decrease in peak intensity and increase in interplanar spacing. Samples subjected to hot-wet conditions showed higher percentage weight gain with a maximum of 4.25% in neat and 3.1% in 2 wt.% samples. Flexural tests results showed degradation with increasing time. Maximum degradation were observed for hot-wet (80 deg. C) for 90 days neat samples, i.e. 22.6% and 29.8% reduction in flexural strength and stiffness, respectively. However, less degradation was noticed for nanophased composites under similar conditions. Scanning electron microscopy (SEM) results of failed samples showed better interfacial bonding in nanophased composites.

An Experimental Evaluation of Mechanical Properties of Hybrid Reinforcements

Science.gov (United States)

Sai Kumar, A.; Ganesan, G.; Karthikeyan, K.

2017-07-01

This paper presents the mechanical properties of unidirectional hybrid reinforcements formed from continuous fibres impregnated with a fibre binding material which are used for reinforcing the concrete. Recently FRP (Fibre Reinforced Polymer) manufacturers and suppliers have been increased all over the world because of the superior performance of FRP products in the construction industry. Its non-corrosive nature has turned the attention of many researchers to make several studies on different type of FRP products. Through a vast research, several standards also have been formulated. In this regard a new combination of FRP materials is tried in this paper and its properties have been derived. Carbon fibre and glass fibres fuse in this study to form a new hybrid rebar. The design properties such as tensile strength, tensile modulus, and compressive strength have been studied as per ASTM standards and it has been identified that the Hybrid rebar show a superior performance in comparison with GFRP (Glass FRP) and Steel rebars. This extraordinary performance of hybrid composite material increases the extensive engineering applications such as transport industry, aeronautics, naval, automotive industries.

Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types.

Science.gov (United States)

Kim, JunHee; You, Young-Chan

2015-03-03

A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs) reinforced with grid-type glass-fiber-reinforced polymer (GFRP) shear connectors. Two kinds of insulation-expanded polystyrene (EPS) and extruded polystyrene (XPS) with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

Method and device for detecting impact events on a security barrier which includes a hollow rebar allowing insertion and removal of an optical fiber

Science.gov (United States)

Pies, Ross E.

2016-03-29

A method and device for the detection of impact events on a security barrier. A hollow rebar is farmed within a security barrier, whereby the hollow rebar is completely surrounded by the security barrier. An optical fiber passes through the interior of the hollow rebar. An optical transmitter and an optical receiver are both optically connected to the optical fiber and connected to optical electronics. The optical electronics are configured to provide notification upon the detection of an impact event at the security barrier based on the detection of disturbances within the optical fiber.

Effect of Fly-Ash on Corrosion Resistance Characteristics of Rebar Embedded in Recycled Aggregate Concrete

Science.gov (United States)

Revathi, Purushothaman; Nikesh, P.

2018-04-01

In the frame of an extended research programme dealing with the utilization of recycled aggregate in concrete, the corrosion resistance characteristics of rebars embedded in recycled aggregate concrete is studied. Totally five series of concrete mixtures were prepared with fly-ash as replacement for cement in the levels of 10-30% by weight of cement. Corrosion studies by 90 days ponding test, linear polarization test and impressed voltage tests were carried out, in order to investigate whether corrosion behaviour of the rebars has improved due to the replacement of cement with fly-ash. Results showed that the replacement of cement with fly-ash in the range of 20-30% improves the corrosion resistance characteristics of recycled aggregate concrete.

Initiation and propagation of rebar corrosion in carbonated and cracked concrete

International Nuclear Information System (INIS)

Ghantous, Rita-Maria

2016-01-01

This thesis aims to study the carbonation-induced corrosion initiation and propagation in cracked concrete under different conditions. It is performed in the framework of concrete ageing management of cooling towers of Electricity of France (EDF) nuclear power plants. Indeed some of them can be affected by cracks which may promote the carbonation of the concrete surrounding the cracks and induce a rapid reinforcement corrosion initiation in the carbonated area. Firstly, cracks representative of those encountered in the cooling towers concrete are reproduced on laboratory specimens using the three point bending test. Three crack openings are obtained (100 μm, 300 μm and 500 μm). Cracked specimens are thereafter exposed to accelerated carbonation for two aims. First for the acceleration of the concrete neutralization phase which ensure the suitable thermodynamic conditions for active corrosion initiation. Second, for the estimation of the length of the mechanically damaged steel/binder interface supposed to be comparable to the carbonated length along the rebar on both sides of the crack. It is found that carbonation at 50% CO_2 is not suitable here because it overestimated the damaged zone length, maybe due to enhanced carbonation shrinkage. The second part aims to investigate the corrosion initiation and propagation phases while varying several parameters. For this purpose, cracked and carbonated specimens are subjected to corrosion under different exposure conditions. Specimens showing different crack widths and different types of binder are corroded in a reference test in which 30 minutes of rain occurs each 3 days at 20 C. Additionally, some corrosion tests are realized under raining/drying cycles for 3 minutes rain, other at 40 C and other in natural environmental conditions. Moreover, some cracked specimens are exposed in different orientations with respect to rain. Furthermore, specimens with different bars locations are prepared in order to investigate

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

Science.gov (United States)

Ren, Zhenhua; Zeng, Xiantao; Liu, Hanlong; Zhou, Fengjun

2013-03-01

The application of fiber reinforced plastic (FRP), including carbon FRP and glass FRP, for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement (EBR) and near-surface mounted (NSM) strengthening techniques. This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods, including externally-bonded and near-surface mounted FRP, to study the strain coordination of the FRP and steel rebar of the RC beam. Since there is relative slipping between the RC beam and the FRP, the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis; that is, the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height ( h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of the FRP and steel rebar satisfies the equation: ɛ FRP= βɛ steel, and the value of β is equal to 1.1-1.3 according to the test results.

Data of the properties of rebar steel brands in Lagos, Nigerian market used in reinforced concrete applications.

Science.gov (United States)

Joshua, Opeyemi; Olusola, Kolapo O; Oyeyemi, Kehinde D; Ogunde, Ayodeji O; Amusan, Lekan M; Nduka, David O; Abuka-Joshua, Joyce

2018-04-01

The data presented herein are compilations of the research summary of "Assessment of the Quality of Steel Reinforcement Bars Available in Nigerian Market" (Joshua et al., 2013) [1]. This data article provides information on the properties and cost of steel rebars used in reinforced concrete in Lagos, Nigeria. The data is based on the properties of 12 mm rebar brands which are the most used steel diameter in construction and they include actual diameters, yield strengths, ultimate strengths, ultimate/yield strength ratio, ductility and the cost of each brand. This data also contains the limiting standard properties of the highlighted properties in this data.

The Effect of superficial cracks of the concrete on the behavior and corrosion rate of steel rebars in Persian Golf (Booshehr)

International Nuclear Information System (INIS)

Afshar, A.; Rajabi, A.

2001-01-01

The presence of superficial cracks in concrete increases the diffusion of destructive agents into concrete and the corrosion of rebars will take place. In the present work, the effects of cracks width on the behavior and corrosion rate of steel rebars in the concrete containing cements type I and II at Persian Gulf water have been studied. The results show that the corrosion rate of steel rebars in the concrete with cracks width less than 0.4 mm is negligible, but with increasing the cracks width to 0.7 mm, the corrosion rate increase rapidly. Also, the corrosion gate of gebars in the concrete containing cement type I is more than that of cement type II. The visual inspection of the surface area of gebars shows that the corroded area is 6-7 times of the crack width and length

Evaluation method for corrosion level of rebar in RC with electrical impedance measurement

Science.gov (United States)

Sasamoto, Akira

2018-04-01

The author reported that the impedance measurement using the 4-terminal method on the RC surface for diagnosing corrosion of internal rebar. The difference between the maximum value at 0.01 Hz and the minimum value around 10 Hz indicates the corrosion level of rebar in that report. This is successive report on a signal processing method for estimating the corrosion level by the measured impedance data to obtain more high accuracy. In the dielectric, a graph of frequency and dielectric constant (Cole-Cole plot diagram by KS Cole and RH Cole article of 1941) draws a shape of circle if the dielectric is independent of frequency but it draws a shape of ellipse in reality due to frequency dependency. Havriliak and Negami have also presented Havriliak-Negami model which introduced parameter into dielectric constant equation which deforms Cole-Cole plot diagram and showed that acquired dielectric data of polymer materials fit to this model with proper parameters. In this report, we first consider electric model connected with resistance and capacitance as a rough model of RC concrete. If the capacitance in this model circuit has some loss of dielectric, it is stated that graph in impedance plot is expected to take as similar deformation in the dielectric Cole-Cole plot. Then a numerical optimization computer code for obtaining parameters in the Cole-Cole plot diagram and Havriliak-Negami model is constructed, and the correlation between the deformation parameter of each model and corrosion is shown by this code. These results are feasibility study for diagnosis of corrosion level of rebar by associated parameters to a shape of impedance graph.

Approach to the effect of concrete resistivity in the corrosion of rebars in concrete

Directory of Open Access Journals (Sweden)

Andrade, C.

1987-09-01

Full Text Available The concrete resistivity has been considered as a factor which affects the corrosion rate of the rebars. Untill now the only relation found has been stablished between potentials and resistivity for steel embedded in Chloride contaminated concrete. In this paper a comparison between corrosion rate of rebars, determined from Polarization Resistance method, and Electrical Resistance data measured through the electronic compensation of the ohmic drop are given. The results of i_corr and R_ohm has been measured for rebars embedded in mortar made with three different types of cement. The specimens were submited to an accelerated carbonation. The relation between i_corr and R_ohm is quite similar in all the cases and suggests that the concrete electrical resistivity may be a controling factor of the corrosion rate of the rebars.

La resistividad del hormigón se ha venido considerando como uno de los factores que afectan a la velocidad de corrosión de las armaduras, aunque, hasta ahora, la única relación encontrada ha sido la establecida entre los potenciales y la resistividad para acero embebido en hormigón contaminado por cloruros. En este trabajo se establecen comparaciones entre velocidad de corrosión de las armaduras, medida a través del método de determinación de la Resistencia de Polarización, y los datos de resistencia eléctrica medidos a través de la compensación de caída óhmica. Los resultados de i_corr y R_ohm se han medido en armaduras embebidas en mortero fabricado con tres tipos de cemento a los que se ha sometido a un proceso de carbonatación acelerada. La relación entre i_corr y R_ohm es muy similar en todos los casos y sugiere que la resistencia del hormigón puede actuar como un factor controlante de la velocidad de corrosión de las armaduras.

Analytical modeling of mixed-Mode bending behavior of asymmetric adhesively bonded pultruded GFRP joints

Czech Academy of Sciences Publication Activity Database

Ševčík, Martin; Shahverdi, M.; Hutař, Pavel; Vassilopoulos, Anastasios P.

2015-01-01

Roč. 147, OCT (2015), s. 228-242 ISSN 0013-7944 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068; GA MŠk(CZ) EE2.3.30.0063 Institutional support: RVO:68081723 Keywords : Mixed-Mode delamination * Asymmetric joint * Adhesively bonded joint * Failure criterion * Analytical prediction * GFRP Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.024, year: 2015

High-performance GFRP materials with glass fibre prepregs; Hochleistungs-Faserverbundwerkstoffe aus UD-Gelegeprepregs

Energy Technology Data Exchange (ETDEWEB)

Prause, J.P. [Schichtstoff-Technik, Arnsberg (Germany); Schroeder, K.F. [Wissenschaftliche Verlagsanstalt, Mettmann (Germany)

1999-07-01

The US 3M Company is the producer of the 'Scotchply' glass fibre prepreg which results in materials that can withstand higher dynamic loads than conventional glass fibre reinforced plastics. The new materials are used, e.g., for leaf spring construction. The fatigue characteristics of GFRP leaf springs were discussed at the DGM 'Verbundwerkstoffe und Werkstoffverbunde' conference at Kaiserslauter in September 1997. This contribution presents tools for the engineer for calculation of leaf springs in consideration of the expected loads. [German] Bereits frueher konnte nachgewiesen werden, dass mit Glasgarngelegen verstaerkte Kunststoffe dynamisch hoeher beansprucht werden koennen als gleichartige Konstruktionen mit Glasgewebeverstaerkung. Dieser Vorteil wird in der industriellen Praxis genutzt, um den breiten Einsatzbereich von Blattfedern aus Stahl durch solche aus Faserverbundwerkstoffen zu erweitern. Mit Glasfasern verstaerkte Kunststoffe (GFK) sind seit Jahren Stand der Technik. Die Verarbeitung als Gelegeprepreg hat sich oekonomisch und oekologisch als eine guenstige Technologie bewaehrt. Die Prepregs werden im Wickelverfahren in die endgueltige Form gebracht oder zu Platten verpresst, aus denen die gewuenschten Werkstuecke mechanisch herausgearbeitet werden. Eine ideale Ausnutzung aller in UD-Gelegen vorgegebenen Eigenschaften ist die Form der Blattfeder. Werkstoff und Geometrie koennen optimal an die Belastung angepasst werden. Ueber die Ermuedungsfestigkeit von GFK-Blattfedern wurde waehrend der Vortragstagung der DGM 'Verbundwerkstoffe und Werkstoffverbunde' im September 1997 in Kaiserslautern eingehend berichtet. Mit dieser Veroeffentlichung soll dem Ingenieur eine Hilfe gegeben werden, solche Blattfedern entsprechend der spaeteren Beanspruchung zu berechnen. (orig.)

Earthquake resistance of cracked concrete embedded with large size rebars (D43 and D57) in nuclear containment

Energy Technology Data Exchange (ETDEWEB)

Kan, Y-C. [Chaoyang Univ. of Tech., Taichung, Taiwan (China); Pei, K-C. [Inst. of Nuclear Energy Research, Taiwan (China)

2014-07-01

The bond behavior of varying size re-bar (D19, D32, D43 and D57) embedded in concrete, under cyclic load in a pullout test, were investigated through a series of experiments and monitored in real-time by acoustic emission (AE) herein. Parallel tests of specimens with an existing crack were also conducted to observe the behavior of cracked concrete subject to cyclic load. The detailed acoustics information can be used for analyzing and comparing the effects of concrete with varying size re-bar. The results provide useful in formation in evaluating the safety of NPP RC structure subjected to cyclic load. (author)

Breakdown tests of glass fibre reinforced polymers (GFRP) as part of improved lightning protection of wind turbine blades

DEFF Research Database (Denmark)

Madsen, Søren Find; Holbøll, Joachim; Henriksen, Mogens

2004-01-01

the test methods and the results are evaluated. The different results are compared with respect to the GFRP materials' overall thicknesses, thickness of laminates and thickness of coatings. Finally, some general conclusions and different statements on how to manufacture specimens with minimum likelihood...

Numerical Study on Deflection Behaviour of Concrete Beams Reinforced with GFRP Bars

Science.gov (United States)

Mohamed, Osama A.; Khattab, Rania; Hawat, Waddah Al

2017-10-01

Fiber-Reinforced Polymer (FRP) bars are gaining popularity as sustainable alternatives to conventional reinforcing steel bars in reinforced concrete applications. The production of FRP bars has lower environmental impact compared to steel reinforcing bars. In addition, the non-corroding FRP materials can potentially decrease the cost or need for maintenance of reinforced concrete structural elements, especially in harsh environmental conditions that can impact both concrete and reinforcement. FRP bars offer additional favourable properties including high tensile strength and low unit weight. However, the mechanical properties of FRP bars can lead to large crack widths and deflections. The objective of this study is to investigate the deflection behaviour of concrete beams reinforced with Glass FRP (GFRP) bars as a longitudinal main reinforcement. Six concrete beams reinforced with GFRP bars were modelled using the finite element computer program ANSYS. The main variable considered in the study is the reinforcement ratio. The deflection equations in current North American codes including ACI 440.1R-06, ACI 440.1R-15 and CSA S806-12 are used to compute deflections, and these are compared to numerical results. It was concluded in this paper that deflections predicted by ACI 440.1R-06 equations are lower than the numerical analysis results while ACI 440.1R-15 is in agreement with numerical analysis with tendency to be conservative. The values of deflections estimated by CSA S806-12 formulas are consistent with results of numerical analysis.

Effect of GFRP spacer on local deformation of large superconductor in coil pack

International Nuclear Information System (INIS)

Nishimura, Arata; Tamura, Hitoshi; Mito, Toshiyuki; Yamamoto, Junya

1994-01-01

Design and construction of the Large Helical Device (LHD) are in progress at the National Institute for Fusion Science (NIFS) in Japan. The LHD has superconducting poloidal and helical coils, and many efforts have been undertaken to develop these large superconductors. When designing a large superconducting magnet, the mechanical behavior of the wound structure becomes a very important factor since the apparent rigidity affects the design of a coil support structure and the superconducting coil needs to endure the large electro-magnetic force it creates. Also, non-linear mechanical behavior should yield the instability of the magnet. In this paper, local deformation in a large conductor caused by GFRP spacers and epoxy adhesives was investigated after compressive rigidity testing. The epoxy adhesive used for attaching the GFRP spacers to the superconductor changed shape from an almost square sheet into a lens-like sheet during deformation, and a dent appeared on the surface of the superconductor. Three-dimensional FEM analysis showed that a compressive stress in the vertical direction of the loading axis existed in the adhesive plane. This stress component makes the adhesive lens-like and it results in the dent created during the compressive testing. This local deformation should yield a part of the permanent deformation observed after the compressive load cycle at 4.2 K

Microstructural characteristics of steel rebar submitted to the process of self - tempering; Caracterizacao microestrutural de superficies e interfaces de vergalhoes de aco auto-revenidos utilizando Microscopia Eletronica de Varredura (MEV) e analise quimica

Energy Technology Data Exchange (ETDEWEB)

Barreto, M.F.O., E-mail: matheusfob@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), MG (Brazil)

2014-07-01

Every day the construction industry seeks new alternatives to maximize use of the materials provided new tools for structural design of the new techniques in welding rods. In this sense, this work proposes to study the mechanical properties of steel rebar self-tempering for civil construction, choosing the bars from 6.3 to 25.4 mm in diameter for the study. The cooling process of rebar, after rolling, known as self-tempering produces a rebar with excellent mechanical properties and low cost to the plant, they put the rebar shall be composed of concentric layers with different mechanical properties among themselves. To study the influence of these layers on the mechanical behavior of rebar microstructural characterization was made by means of electron microscopy analysis of transmitted light and scanning of all samples. From the results it was found that only the bars 20 and 25mm diameter had a heat treatment for self-tempering relevant. (author)

Durability evaluation method on rebar corrosion of reinforced concrete

International Nuclear Information System (INIS)

Kitsutaka, Yoshinori

2013-01-01

In this paper, method on the durability evaluation in nuclear power plant concrete structures was investigated. In view of the importance of evaluating the degree of deterioration of reinforced concrete structures, relationships should be formulated among the number of years elapsed, t, the amount of action of a deteriorative factor, F, the degree of material deterioration, D, and the performance of the structure, P. Evaluation by PDFt diagrams combining these relationships may be effective. A detailed procedure of durability evaluation for a reinforced concrete structure using PDFt concept is presented for the deterioration of rebar corrosion caused by neutralization and penetration of salinity by referring to the recent papers. (author)

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

Science.gov (United States)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

Reinforcement of Bolted Timber Joints Using GFRP Sheets in Poplar and Pine Woods

Directory of Open Access Journals (Sweden)

Mehrab Madhoushi

2013-01-01

Full Text Available Failure in timber structures occurs mainly in crucial points such as joints areas. Therefore, the idea of using composite sheets in timber joints has been intro-duced as a method in order to increase the strength and ductility behaviour of timber joints. This research aims to study the behaviour of bolted joints in poplar and pine woods, which are reinforced by two types of GFRP sheets. A single shear bolted joint consisted of 3 timber members whose length and width were 30 cm in length and 5 cm in width. The thickness of each member was 4 cm for internal part and 2 cm for external part. The employed steel bolt was 10 cm in length and 1 cm in diameter. In this respect, one layer of GFRP sheet was used to be bonded to timber members by using epoxy resin and left between the clamps for 24 hours. They were then kept at room temperature for three weeks. Also the effect of adding a wood veneer on the reinforced joints was investigated. The tensile strength of the reinforced and control samples (un-reinforced joints was measured according to ASTM D5652-92 standard. The results show that the reinforced samples have higher tensile strength compared to that of reinforced joints, although it is not statistically signifcant. Also, two types of sheets infuence the joint behaviour as the reinforced joints display more ductility behaviour.

Boundary element inverse analysis for rebar corrosion detection: Study on the 2004 tsunami-affected structure in Aceh

Directory of Open Access Journals (Sweden)

S. Fonna

2018-06-01

Full Text Available Evaluation of rebar/reinforcing-steel corrosion for the 2004 tsunami-affected reinforced concrete (RC buildings in Aceh was conducted using half-cell potential mapping technique. However, the results only show qualitative meaning as corrosion risk rather than the corrosion itself, such as the size and location of corrosion. In this study, boundary element inverse analysis was proposed to be performed to detect rebar corrosion of the 2004 tsunami-affected structure in Aceh, using several electrical potential measurement data on the concrete surface. One RC structure in Peukan Bada, an area heavily damaged by the tsunami, was selected for the study. In 2004 the structure was submerged more than 5 m by the tsunami. Boundary element inverse analysis was developed by combining the boundary element method (BEM and particle swarm optimization (PSO. The corrosion was detected by evaluating measured and calculated electrical potential data. The measured and calculated electrical potential on the concrete surface was obtained by using a half-cell potential meter and by performing BEM, respectively. The solution candidates were evaluated by employing PSO. Simulation results show that boundary element inverse analysis successfully detected the size and location of corrosion for the case study. Compared with the actual corrosion, the error of simulation result was less than 5%. Hence, it shows that boundary element inverse analysis is very promising for further development to detect rebar corrosion. Keywords: Inverse analysis, Boundary element method, PSO, Corrosion, Reinforced concrete

Elasto-plastic hardening models adjustment to ferritic, austenitic and austenoferritic Rebar; Ajuste de los aceros corrugados ferríticos, austeníticos y austenoferríticos a los modelos de endurecimiento elastoplástico por deformación

Energy Technology Data Exchange (ETDEWEB)

Hortigóna, B.; Gallardo, J.M.; Nieto-García, E.J.; López, J.A.

2017-09-01

The elastoplastic behaviour of steel used for structural member fabrication has received attention to facilitate a mechanical-resistant design. New Zealand and South African standards have adopted various theoretical approaches to describe such behaviour in stainless steels. With respect to the building industry, describing the tensile behaviour of steel rebar used to produce reinforced concrete structures is of interest. Differences compared with the homogenous material described in the above mentioned standards and related literatures are discussed in this paper. Specifically, the presence of ribs and the TEMPCORE® technology used to produce carbon steel rebar may alter the elastoplastic model. Carbon steel rebar is shown to fit a Hollomon model giving hardening exponent values on the order of 0.17. Austenitic stainless steel rebar behaviour is better described using a modified Rasmussen model with a free fitted exponent of 6. Duplex stainless steel shows a poor fit to any previous model. [Spanish] Uno de los principales factores tenidos en cuenta en la fabricación de aceros estructurales es su comportamiento durante la fase elastoplástica o de endurecimiento por deformación. Normas neozelandesas y sudafricanas plantean diversas aproximaciones teóricas para describir dicho comportamiento en el caso de los aceros inoxidables. En el campo de la construcción resulta de interés la descripción del comportamiento tenso-deformacional de los aceros corrugados utilizados en las estructuras de hormigón armado. En este artículo se discuten los modelos planteados en las normas citadas anteriormente así como los existentes en la literatura tanto para los aceros corrugados inoxidables como para los aceros al carbono fabricados mediante el proceso denominado TEMPCORE® Los aceros TEMPCORE® analizados arrojan un valor del exponente de endurecimiento por deformación según el modelo de Hollomon de 0.17. Los aceros inoxidables austeníticos se ajustan mejor al modelo

Estudio experimental de la adherencia entre laminados de GFRP y el hormigón

OpenAIRE

Albiol Ibáñez, José Ramón

2016-01-01

[EN] At present, hybrid structures in flexural elements are being gradually incorporated in the field of civil and building structures. The low weight and high durability of these structures make use viable. Hybrid structures are usually composed of polymeric materials reinforced with glass or carbon fibers (GFRP or CFRP) in structural shapes of any type of section, in I, in box, trough-shaped, as elements working in tension, and the concrete in the compressed head of the resistant section. D...

Preparation, mechanical, and in vitro properties of glass fiber-reinforced polycarbonate composites for orthodontic application.

Science.gov (United States)

Tanimoto, Yasuhiro; Inami, Toshihiro; Yamaguchi, Masaru; Nishiyama, Norihiro; Kasai, Kazutaka

2015-05-01

Generally, orthodontic treatment uses metallic wires made from stainless steel, cobalt-chromium-nickel alloy, β-titanium alloy, and nickel-titanium (Ni-Ti) alloy. However, these wires are not esthetically pleasing and may induce allergic or toxic reactions. To correct these issues, in the present study we developed glass-fiber-reinforced plastic (GFRP) orthodontic wires made from polycarbonate and E-glass fiber by using pultrusion. After fabricating these GFRP round wires with a diameter of 0.45 mm (0.018 inch), we examined their mechanical and in vitro properties. To investigate how the glass-fiber diameter affected their physical properties, we prepared GFRP wires of varying diameters (7 and 13 µm). Both the GFRP with 13-µm fibers (GFRP-13) and GFRP with 7 µm fibers (GFRP-7) were more transparent than the metallic orthodontic wires. Flexural strengths of GFRP-13 and GFRP-7 were 690.3 ± 99.2 and 938.1 ± 95.0 MPa, respectively; flexural moduli of GFRP-13 and GFRP-7 were 25.4 ± 4.9 and 34.7 ± 7.7 GPa, respectively. These flexural properties of the GFRP wires were nearly equivalent to those of available Ni-Ti wires. GFRP-7 had better flexural properties than GFRP-13, indicating that the flexural properties of GFRP increase with decreasing fiber diameter. Using thermocycling, we found no significant change in the flexural properties of the GFRPs after 600 or 1,200 cycles. Using a cytotoxicity detection kit, we found that the glass fiber and polycarbonate components comprising the GFRP were not cytotoxic within the limitations of this study. We expect this metal-free GFRP wire composed of polycarbonate and glass fiber to be useful as an esthetically pleasing alternative to current metallic orthodontic wire. © 2014 Wiley Periodicals, Inc.

GFRP seismic strengthening and structural heath monitoring of Portage Creek Bridge concrete columns

International Nuclear Information System (INIS)

Huffman, S.; Bagchi, A.; Mufti, A.; Neale, K.; Sargent, D.; Rivera, E.

2006-01-01

Located in Victoria British Columbia (BC), Canada, the Portage Creek Bridge is a 124m long, three-span structure with a reinforced concrete piers and abutments on H piles. The bridge was designed prior to the introduction of current bridge seismic design codes and construction practices. Therefore it was not designed to resist the earthquake forces as required by today's standards. The bridge is on a route classified as a Municipal Disaster Route scheduled to be retrofitted to prevent collapse during a design seismic event, with a return period of 475 years (i.e., an event with 105 probability of exceedance in 50 years). Conventional materials and methods were used to retrofit most of the bridge. The dynamic analysis of the bridge predicted the two tall columns of Pier No. 1 will form plastic hinges under an earthquake resulting an additional shear to the short columns of Pier No. 2. A non-liner static pushover analysis indicated the short columns will not be able to form plastic hinges prior to failure in shear. The innovative solution of Fiber Reinforced Polymer wraps (FRPs) was chosen to strengthen the short columns for shear without increasing the moment capacity. The FRP wraps and the bridge were instrumented as one of 36 demonstration projects across Canada sponsored by ISIS (Intelligent Sensing for Innovative Structure) Canada, federally funded Network of Centers of Excellence, to access the performance of FRP and the use of FOS (Fiber Optic Sensors) for Structural Health Monitoring (SHM). The two columns of the bridge pier were strengthened with GFRP (Glass Fiber Reinforced Polymer) wraps with eight bi-directional rosette type strain gauges and four long gauge fiber optic sensors attached to the outer layer of the wraps. In addition, two 3-D Crossbow accelerometers are installed on the pier cap above the columns and a traffic web-cam mounted above the deck at the pier location. The data is collected through high sped internet line to an interactive web page

Evaluation of the cryogenic mechanical properties of the insulation material for ITER Feeder superconducting joint

Science.gov (United States)

Wu, Zhixiong; Huang, Rongjin; Huang, ChuanJun; Yang, Yanfang; Huang, Xiongyi; Li, Laifeng

2017-12-01

The Glass-fiber reinforced plastic (GFRP) fabricated by the vacuum bag process was selected as the high voltage electrical insulation and mechanical support for the superconducting joints and the current leads for the ITER Feeder system. To evaluate the cryogenic mechanical properties of the GFRP, the mechanical properties such as the short beam strength (SBS), the tensile strength and the fatigue fracture strength after 30,000 cycles, were measured at 77K in this study. The results demonstrated that the GFRP met the design requirements of ITER.

Interface enhancement of glass fiber reinforced vinyl ester composites with flame-synthesized carbon nanotubes and its enhancing mechanism.

Science.gov (United States)

Liao, Lingmin; Wang, Xiao; Fang, Pengfei; Liew, Kim Meow; Pan, Chunxu

2011-02-01

Interface enhancement with carbon nanotubes (CNTs) provides a promising approach for improving shock strength and toughness of glass fiber reinforced plastic (GFRP) composites. The effects of incorporating flame-synthesized CNTs (F-CNTs) into GFRP were studied, including on hand lay-up preparation, microstructural characterization, mechanical properties, fracture morphologies, and theoretical calculation. The experimental results showed that: (1) the impact strength of the GFRP modified by F-CNTs increased by more than 15% over that of the GFRP modified by CNTs from chemical vapor deposition; and (2) with the F-CNT enhancement, no interfacial debonding was observed at the interface between the fiber and resin matrix on the GFRP fracture surface, which indicated strong adhesive strength between them. The theoretical calculation revealed that the intrinsic characteristics of the F-CNTs, including lower crystallinity with a large number of defects and chemical functional groups on the surface, promoted their surface activity and dispersibility at the interface, which improved the interfacial bond strength of GFRP.

The Effects of Buildability Factors on Rebar Fixing Labour Productivity of Beamless Slabs

OpenAIRE

Jarkas, Abdulaziz M

2010-01-01

 Buildability is an important factor affecting labour productivity. Nevertheless, a thorough search of the literature revealed a dearth of research into its effects on in situ reinforced concrete construction, especially at the activity levels. Since rebar fixing is an integral trade of this type of construction material, and beamless slabs are amongst the major encountered activities on construction sites, the objective of this research is to explore the buildability factors affecting i...

Glass Fiber Reinforced Polymer (GFRP Bars for Enhancing the Flexural Performance of RC Beams Using Side-NSM Technique

Directory of Open Access Journals (Sweden)

Md. Akter Hosen

2017-05-01

Full Text Available Reinforced concrete (RC structures require strengthening for numerous factors, such as increased load, modification of the structural systems, structural upgrade or errors in the design and construction stages. The side near-surface mounted (SNSM strengthening technique with glass fiber-reinforced polymer (GFRP bars is a relatively new emerging technique for enhancing the flexural capacities of existing RC elements. Nine RC rectangular beams were flexurally strengthened with this technique and tested under four-point bending loads until failure. The main goal of this study is to optimize the structural capacity of the RC beams by varying the amount of strengthening reinforcement and bond length. The experimental test results showed that strengthening with SNSM GFRP bars significantly enhanced the flexural responses of the specimens compared with the control specimen. The first cracking and ultimate loads, energy absorption capacities, ductility and stiffness were remarkably enhanced by the SNSM technique. It was also confirmed that the bond length of the strengthened reinforcement greatly influences the energy absorption capacities, ductility and stiffness. The effect of the bond length on these properties is more significant compared to the amount of strengthening reinforcement.

Preliminary study of dose equivalent evaluation for residents in radioactivity contaminated rebar buildings

International Nuclear Information System (INIS)

Chen, W.L.; Liao, C.C.; Wang, M.T.; Chen, F. D.

1998-01-01

It has recently been found that several resident and office buildings in Taiwan were constructed with 60 Co-contaminated reinforcing steel bar (rebar). Both governmental officials and the residents of such buildings have been concerned about this finding. In order to respond to the situation, the government has adopted a number of remedial measures, including full-scale radiation survey, dose evaluation and physical examinations of residents. This article presents three methods for evaluating the dose equivalents of the residents living in the contaminated rebar buildings by means of γ-ray survey, necklace-type thermoluminescence dosimeters (TLDs) and the human lymphocyte chromosome aberration analyses. The results reveal that the dose evaluation by γ-ray survey is rather conservative. Generally for the residents whose annual dose equivalents are greater than 5 mSv (0.5 rem) by γ-ray survey, the dose equivalents from necklace-type TLDs are only within the range of 20 to 50% of the evaluated values mentioned above. For chromosome analyses, at least 500 lymphocyte cells were scored and analyzed for each resident. Most of the chromosome analysis data show that the dose equivalents received by residents are lower than the detection limit of the method (100 mSv) and quite different from the estimated dose obtained from either γ-ray survey or necklace-type TLD measurements

Determination of mechanical properties of some glass fiber reinforced plastics suitable to Wind Turbine Blade construction

Science.gov (United States)

Steigmann, R.; Savin, A.; Goanta, V.; Barsanescu, P. D.; Leitoiu, B.; Iftimie, N.; Stanciu, M. D.; Curtu, I.

2016-08-01

The control of wind turbine's components is very rigorous, while the tower and gearbox have more possibility for revision and repairing, the rotor blades, once they are deteriorated, the defects can rapidly propagate, producing failure, and the damages can affect large regions around the wind turbine. This paper presents the test results, performed on glass fiber reinforced plastics (GFRP) suitable to construction of wind turbine blades (WTB). The Young modulus, shear modulus, Poisson's ratio, ultimate stress have been determined using tensile and shear tests. Using Dynamical Mechanical Analysis (DMA), the activation energy for transitions that appear in polyester matrix as well as the complex elastic modulus can be determined, function of temperature.

PERFORMANCE OF RC AND FRC WALL PANELS REINFORCED WITH MILD STEEL AND GFRP COMPOSITES IN BLAST EVENTS

Energy Technology Data Exchange (ETDEWEB)

Timothy Garfield; William D. Richins; Thomas K. Larson; Chris P. Pantelides; James E. Blakeley

2011-06-01

The structural integrity of reinforced concrete structures in blast events is important for critical facilities. This paper presents experimental data generated for calibrating detailed finite element models that predict the performance of reinforced concrete wall panels with a wide range of construction details under blast loading. The test specimens were 1.2 m square wall panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consists of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bar reinforcement (Type A); FRC panels without additional reinforcement (Type B); FRC panels with steel bar reinforcement (Type C); NWC panels with glass fiber reinforced polymer (GFRP) bar reinforcement (Type D); and NWC panels reinforced with steel bar reinforcement and external bidirectional GFRP overlays on both faces (Type E). An additional three Type C panels were used as control specimens (CON). Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. The panels were instrumented with strain gauges, and accelerometers; in addition, pressure sensors and high speed videos were employed during the blast events. Panel types C and E had the best performance, whereas panel type B did not perform well. Preliminary dynamic simulations show crack patterns similar to the experimental results.

Structural performance of circular columns confined by recycled GFRP stirrups and exposed to severe conditions

Directory of Open Access Journals (Sweden)

Mohamed S. Sayed

2012-08-01

Full Text Available Since 1980, Egyptian government investment has been directed to the infrastructure projects. Water supply and water drainage networks are among those projects which are very costly; therefore they are designed with a life span of about one hundred years. There is a new trend toward the use of durable and maintenance free systems. The “GFRP” pipes are one of the economic solutions if the project life span is taken into consideration. A number of investors currently produce the “GFRP” pipes in the Egyptian market and although they follow the latest technologies in their production lines, they still suffer 2–5% deficiency of their produced pipes which consequently regarded as rejected pipes. This percentage has a negative impact on the environmental and economical issues. This research is a trial to investigate the behavior of circular columns confined by GFRP stirrups and exposed to severe conditions. A number of waste pipes were randomly selected and sliced to be used as circular column transverse reinforcement. An experimental program consisting of ten short circular columns was designed to study the effect of corrosion, high degrees of temperature, and sulfate attack on the structural behavior of the axially loaded short circular columns. The experimental results showed that columns laterally reinforced by GFRP slices have a comparable behavior to conventionally reinforced concrete columns especially for those columns exposed to corrosion and sulfate attack.

Rebar corrosion due to carbonation in structural reinforced concretes for near-surface LLW repositories: A critical failure mechanism

Energy Technology Data Exchange (ETDEWEB)

Torok, J

1995-03-01

The concrete roof of a near-surface radioactive waste repository is the principle protection against water infiltration and intrusion. The following potential roof failure mechanism is examined: carbon dioxide generated by the biodegradation of organic materials in the repository initiates corrosion of reinforcing steel embedded in the concrete roof. Because the bottom surface of the roof is mostly under tension, it is susceptible to cracking. The migration path for carbon dioxide is through cracks in the concrete between the bottom of the roof and the reinforcing bars. Carbonate corrosion of the reinforcing bars may result in concrete spalling, more extensive rebar corrosion and ultimately structural failure. Attention is brought to this failure mechanism because it has generally been overlooked in repository performance assessments. Literature relevant to the above failure is reviewed. Prerequisites for rebar corrosion are the presence of carbon dioxide and oxygen in the repository gas, high relative humidity and through-cracks in the concrete. High carbon dioxide concentrations and relative humidity are expected in the repository. The oxygen concentration in the repository is expected to be very low, and that is expected to minimize rebar corrosion rates. Cracks are likely to form in locations with high tensile stresses. Healing of the cracks could be a mitigating factor, but based on our analysis, it can not be relied on. To minimize the potential of this failure mechanism occurring with the Intrusion Resistant Underground Structure (IRUS), Canada`s proposed near-surface repository, carbon dioxide from the repository gas will be absorbed by the reactive, porous concrete placed between the waste and the roof. (author). 4 refs.

Rebar corrosion due to carbonation in structural reinforced concretes for near-surface LLW repositories: A critical failure mechanism

International Nuclear Information System (INIS)

Torok, J.

1995-03-01

The concrete roof of a near-surface radioactive waste repository is the principle protection against water infiltration and intrusion. The following potential roof failure mechanism is examined: carbon dioxide generated by the biodegradation of organic materials in the repository initiates corrosion of reinforcing steel embedded in the concrete roof. Because the bottom surface of the roof is mostly under tension, it is susceptible to cracking. The migration path for carbon dioxide is through cracks in the concrete between the bottom of the roof and the reinforcing bars. Carbonate corrosion of the reinforcing bars may result in concrete spalling, more extensive rebar corrosion and ultimately structural failure. Attention is brought to this failure mechanism because it has generally been overlooked in repository performance assessments. Literature relevant to the above failure is reviewed. Prerequisites for rebar corrosion are the presence of carbon dioxide and oxygen in the repository gas, high relative humidity and through-cracks in the concrete. High carbon dioxide concentrations and relative humidity are expected in the repository. The oxygen concentration in the repository is expected to be very low, and that is expected to minimize rebar corrosion rates. Cracks are likely to form in locations with high tensile stresses. Healing of the cracks could be a mitigating factor, but based on our analysis, it can not be relied on. To minimize the potential of this failure mechanism occurring with the Intrusion Resistant Underground Structure (IRUS), Canada's proposed near-surface repository, carbon dioxide from the repository gas will be absorbed by the reactive, porous concrete placed between the waste and the roof. (author). 4 refs

The Effect of Slamming Impact on Out-of-Autoclave Cured Prepregs of GFRP Composite Panels for Hulls

OpenAIRE

Suárez, J.C.; Townsend, P.; Sanz, E.; Ulzurrum, I. Diez de; Pinilla, P.

2016-01-01

This paper proposes a methodology that employs an experimental apparatus that reproduces, in pre-impregnated and cured out-of-autoclave Glass Fiber Reinforced Polymer (GFRP) panels, the phenomenon of slamming or impact on the bottom of a high-speed boat during planing. The pressure limits in the simulation are defined by employing a finite element model (FEM) that evaluates the forces applied by the cam that hits the panels in the apparatus via microdeformations obtained in the simulation. Th...

New recycling approaches for thermoset polymeric composite wastes – an experimental study on polyester based concrete materials filled with fibre reinforced plastic recyclates

OpenAIRE

Ribeiro, M. C. S.; Fiúza, António; Meira Castro, A C; Dinis, M. L.; Silva, Francisco J. G.; Meixedo, João Paulo

2011-01-01

In this study, a new waste management solution for thermoset glass fibre reinforced polymer (GFRP) based products was assessed. Mechanical recycling approach, with reduction of GFRP waste to powdered and fibrous materials was applied, and the prospective added-value of obtained recyclates was experimentally investigated as raw material for polyester based mortars. Different GFRP waste admixed mortar formulations were analyzed varying the content, between 4% up to 12% in we...

Criterion for matrix cracking in glass fiber reinforced cross-ply laminates. GFRP chokko sekisoban ni okeru matrix kiretsu no hattatsu kijun

Energy Technology Data Exchange (ETDEWEB)

Motoki, S.; Fukuda, T. (Osaka City Univ., Osaka (Japan). Faculty of Engineering); Tanaka, M. (Kobe City College of Technology, Kobe (Japan))

1992-05-15

In this research, with regard to GFRP cross-ply laminates, which were the most basic lamination composition, the factors governing the progress of matrix cracks at the 90{degree} layer were studied, in particular the criterion for not depending on the thickness of the 90{degree} layer was examined. For the experiment concerning the above, GFRP prepreg was laminated and three kinds of cross-ply laminates were made for use. A quasistatic tensile load was applied to these specimens and a load-displacement curve was measured, and at the same time, the matrix crack numbers generated in the 90{degree} layer were counted. As a result, it was found that the maximum value of the vertical stress in the loading direction of 90{degree} layer did not depend on the lamination composition, hence could become the criterion for the crack progress. Also it was found that in case when this stress surpassed a certain threshold value, cracks were formed, but in case when it was smaller than the threshold value, no crack was formed. 12 refs., 14 figs.

Compressive damage mechanism of GFRP composites under off-axis loading: Experimental and numerical investigations

DEFF Research Database (Denmark)

Zhou, H.W.; Li, H.Y.; Gui, L.L.

2013-01-01

the angle between the fiber direction and the loading vector goes from 0° to 45° (by 2.3–2.6 times), and then slightly increases (when the angle approaches 80–90°). At the low angles between the fiber and the loading vector, fiber buckling and kinking are the main mechanisms of fiber failure....... With increasing the angle between the fiber and applied loading, failure of glass fibers is mainly controlled by shear cracking. For the computational analysis of the damage mechanisms, 3D multifiber unit cell models of GFRP composites and X-FEM approach to the fracture modeling were used. The computational...

Effects of sea water environment on glass fiber reinforced plastic materials used for marine civil engineering constructions

International Nuclear Information System (INIS)

Garcia-Espinel, J.D.; Castro-Fresno, D.; Parbole Gayo, P.; Ballester-Muñoz, F.

2015-01-01

Highlights: • Seawater environment over composite material that are suitable for civil applications. • Seawater intake is linked to tensile and flexural strength degradation in GFC. • Fatigue performance of glass composites is similar in seawater environment than in air. - Abstract: Glass fiber composites (GFRP) are common in civil engineering projects, but not in marine structures. One reason is that seawater effects degrade GFRP composites mechanical properties and interlaminar shear strength (ILSS). Here, influence of seawater environment is studied to determine the best composite materials for marine civil engineer applications, studying the influence of several factors in their mechanical properties. This is to determine safety factors to use in the design of structural calculations for marine applications. Glass/epoxy composites are the safest materials to use in marine civil structures as mechanical properties degradation becomes stabilized after moisture saturation level. UV and water cyclic analysis must be done to determine affection to transversal strength. Only vinylester GFRP has problems with biodegradation. GFRP fatigue performance is not influenced by seawater environment

Detection of rebars in concrete using advanced ultrasonic pulse compression techniques.

Science.gov (United States)

Laureti, S; Ricci, M; Mohamed, M N I B; Senni, L; Davis, L A J; Hutchins, D A

2018-04-01

A pulse compression technique has been developed for the non-destructive testing of concrete samples. Scattering of signals from aggregate has historically been a problem in such measurements. Here, it is shown that a combination of piezocomposite transducers, pulse compression and post processing can lead to good images of a reinforcement bar at a cover depth of 55 mm. This has been achieved using a combination of wide bandwidth operation over the 150-450 kHz range, and processing based on measuring the cumulative energy scattered back to the receiver. Results are presented in the form of images of a 20 mm rebar embedded within a sample containing 10 mm aggregate. Copyright © 2017 Elsevier B.V. All rights reserved.

Strengthening and repairing of damaged concrete beams

International Nuclear Information System (INIS)

Mahmoud, M.K.; Ebrahiem, G.T.A.; Hassanein, S.A.

2005-01-01

The main part in this investigation is concerned with the advanced techniques of retrofitting damaged reinforced concrete (RC) beams. Glass fiber reinforced plastics (GFRP) were employed for this purpose. The aim of this paper is to investigate the advantage of using glass fiber .reinforced plastics (GFRP) to retrofit and repair damaged reinforced concrete beams. In this investigation, concrete beam specimens were preloaded up to the 60%, 70% arid 80% of their ultimate load capacity. The damaged beams were then repaired with one layer of FRP composite wraps and re-tested. Plastic reinforced by glass fibers 20% fiber volume fractions and with various fiber arrangement unidirectional, bi-directional and chopped were also considered. Four points bending test was adopted. The bending tests were performed on fourteen RC beams in addition to a two control, all of them were (225 30 15) cm in dimensions, and with a typical reinforcement details. Test results were indicative of the merit of using GFRP, as the ultimate loads were almost restored and the modes of failure were of ductile nature. Even more an increase in the ultimate bearing capacity was recorded for some of the retrofitted beams. The effects of the previously mentioned parameters on the cracking pattern and failure mode were reported and thoroughly discussed

Seismic damage sensing of bridge structures with TRIP reinforcement steel bars

Science.gov (United States)

Adachi, Yukio; Unjoh, Shigeki

2001-07-01

Intelligent reinforced concrete structures with transformation-induced-plasticity (TRIP) steel rebars that have self-diagnosis function are proposed. TRIP steel is special steel with Fe-Cr based formulation. It undergoes a permanent change in crystal structure in proportion to peak strain. This changes from non-magnetic to magnetic steel. By using the TRIP steel rebars, the seismic damage level of reinforced concrete structures can be easily recognized by measuring the residual magnetic level of the TRIP rebars, that is directly related to the peak strain during a seismic event. This information will be most helpful for repairing the damaged structures. In this paper, the feasibility of the proposed intelligent reinforced concrete structure for seismic damage sensing is experimentally studied. The relation among the damage level, peak strain of rebars, and residual magnetic level of rebars of reinforced concrete beams implemented with TRIP steel bars was experimentally studied. As the result of this study, this intelligent structure can diagnose accumulated strain/damage anticipated during seismic event.

Long Term Corrosion Experiment of Steel Rebar in Fly Ash-Based Geopolymer Concrete in NaCl Solution

OpenAIRE

Asmara, Y. P.; Siregar, J. P.; Tezara, C.; Nurlisa, Wan; Jamiluddin, J.

2016-01-01

This research focuses on an experimental investigation to identify the effects of fly ash on the electrochemical process of concrete during the curing time. A rebar was analysed using potentiostat to measure the rest potential, polarization diagram, and corrosion rate. Water-to-cement ratio and amount of fly ash were varied. After being cured for 24 hours at a temperature of 65°C, the samples were immersed in 3.5% of NaCl solution for 365 days for electrochemical measurement. Measurements of ...

Effects of reinforcement ratio and arrangement on the structural behavior of a nuclear building under aircraft impact

International Nuclear Information System (INIS)

Thai, Duc-Kien; Kim, Seung-Eock; Lee, Hyuk-Kee

2014-01-01

Highlights: • Numerical analysis of RC nuclear building model under aircraft impact was conducted. • The analysis result shows similar behavior as compared to the Riera function. • The effects of reinforcement ratio and arrangement were enumerated. • The appropriate number of layer of longitudinal rebar was recommended. - Abstract: This study presents the effectiveness of the rebar ratio and the arrangement of reinforced concrete (RC) structures on the structural behavior of nuclear buildings under aircraft impact using a finite element (FE) approach. A simplified model of a fictitious nuclear building using RC structures was fully modeled. The aircraft model of a Boeing 767-400 was used for impact simulation and was developed and verified with a conventional impact force–time history curve. The IRIS Punching test was used to validate the damage prediction capabilities of the RC wall under impact loading. With regard to the different rebar ratios and rebar arrangements of a nuclear RC building, the structural behavior of a building under aircraft impact was investigated. The structural behavior investigated included plastic deformation, displacement, energy dissipation, perforation/penetration depth and scabbing area. The results showed that the rebar ratio has a significant effect on withstanding aircraft impact and reducing local damage. With four layers of rebar, the RC wall absorbed and dissipated the impact energy more than once with only two layers of rebar for the same rebar ratio

Large scale distribution monitoring of FRP-OF based on BOTDR technique for infrastructures

Science.gov (United States)

Zhou, Zhi; He, Jianping; Yan, Kai; Ou, Jinping

2007-04-01

BOTDA(R) sensing technique is considered as one of the most practical solution for large-sized structures as the instrument. However, there is still a big obstacle to apply BOTDA(R) in large-scale area due to the high cost and the reliability problem of sensing head which is associated to the sensor installation and survival. In this paper, we report a novel low-cost and high reliable BOTDA(R) sensing head using FRP(Fiber Reinforced Polymer)-bare optical fiber rebar, named BOTDA(R)-FRP-OF. We investigated the surface bonding and its mechanical strength by SEM and intensity experiments. Considering the strain difference between OF and host matrix which may result in measurement error, the strain transfer from host to OF have been theoretically studied. Furthermore, GFRP-OFs sensing properties of strain and temperature at different gauge length were tested under different spatial and readout resolution using commercial BOTDA. Dual FRP-OFs temperature compensation method has also been proposed and analyzed. And finally, BOTDA(R)-OFs have been applied in Tiyu west road civil structure at Guangzhou and Daqing Highway. This novel FRP-OF rebar shows both high strengthen and good sensing properties, which can be used in long-term SHM for civil infrastructures.

Interfacial degradation of organic composite material by irradiation in reactor

Energy Technology Data Exchange (ETDEWEB)

Nishijima, Shigehiro; Nishiura, Tetsuya; Okada, Toichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research

1996-04-01

Glass fiber reinforced plastics (GFRP) with many kinds of matrix resins were made of E glass treated with silane as the reinforced material. Degradation of shearing strength of GFRP irradiated at low temperature was determined. It was clear from the results of comparing the degradation process with the fractured surface that the degradation was very affected by the radiation resistance of the bonded part between resin and coupling agents. It means that we had to be careful in the choice of interfacial treatments and epoxy matrices corresponded to it. (S.Y.)

Recycling of Reinforced Plastics

Science.gov (United States)

Adams, R. D.; Collins, Andrew; Cooper, Duncan; Wingfield-Digby, Mark; Watts-Farmer, Archibald; Laurence, Anna; Patel, Kayur; Stevens, Mark; Watkins, Rhodri

2014-02-01

This work has shown is that it is possible to recycle continuous and short fibre reinforced thermosetting resins while keeping almost the whole of the original material, both fibres and matrix, within the recyclate. By splitting, crushing hot or cold, and hot forming, it is possible to create a recyclable material, which we designate a Remat, which can then be used to remanufacture other shapes, examples of plates and tubes being demonstrated. Not only can remanufacturing be done, but it has been shown that over 50 % of the original mechanical properties, such as the E modulus, tensile strength, and interlaminar shear strength, can be retained. Four different forms of composite were investigated, a random mat Glass Fibre Reinforced Plastic (GFRP) bathroom component and boat hull, woven glass and carbon fibre cloth impregnated with an epoxy resin, and unidirectional carbon fibre pre-preg. One of the main factors found to affect composite recyclability was the type of resin matrix used in the composite. Thermoset resins tested were shown to have a temperature range around the Glass Transition Temperature (Tg) where they exhibit ductile behaviour, hence aiding reforming of the material. The high-grade carbon fibre prepreg was found to be less easy to recycle than the woven of random fibre laminates. One method of remanufacturing was by heating the Remat to above its glass transition temperature, bending it to shape, and then cooling it. However, unless precautions are taken, the geometric form may revert. This does not happen with the crushed material.

Quantitative estimation on delaying of onset of corrosion of rebar in surface treated concrete using sealers

Directory of Open Access Journals (Sweden)

A. Sivasankar

2013-12-01

Full Text Available Surface treatment on the concrete surface using sealers reduces the rate of permeability of chloride and moisture through the concrete. The delaying of onset of corrosion is evaluated for surface treated and untreated concrete using electrochemical techniques. After conducting rapid chloride permeability test (RCPT, using Nernst–Plank equation, the diffusion coefficient of chloride (Deff is calculated. Substituting threshold chloride concentration of rebar (Cth from cyclic polarization test in the ficks second law, the time to initiation of corrosion (Ti is arrived. From the results it is found that the treated concrete with alkyltrialkoxy silane sealer delays the onset of corrosion by four times than that of untreated concrete.

Identification of corrosion in reinforcement rebars by using the GPR

Directory of Open Access Journals (Sweden)

Mechbal Z.

2014-01-01

Full Text Available Considering the problem of corroded steel reinforcements buried in concrete members, a methodology based on ground penetrating radar was proposed for the identification of the corrosion affected zone. The method uses post-processing of radargram as obtained from a classic B-scan realized by the electromagnetic radar, when working with adequate high frequencies that are usually used for inspection of reinforced concrete structures. The radar displays are in general complex and not easy to interpret. However, significant information can be extracted from the obtained images to make a reliable report after the inspection. In this context, a correlation formula was proposed previously to estimate the perimeter of a reinforcement bar which is embedded in a concrete massif by using the radargram traces. This formula was employed in the present work in order to estimate the corroded zone perimeter. The obtained results have shown that it provides good prediction of the deterioration extent. Clear contrast of traces was noticed also while modifying the depth of the corrosion affected zone. However, to obtain the depth of the corroded segment of the rebar, further developments concerning image processing of a radargram are required.

Effect of Calcium Nitrate and Sodium Nitrite on the Rebar Corrosion of Medium Carbon Steel in Seawater and Cassava Fluid

OpenAIRE

Adamu, M; Umoru, LE; Ige, OO

2014-01-01

Inhibitors are regularly used as one of the principal prevention and control techniques in reinforcement corrosion. Hence this study investigates the effect of calcium nitrate and sodium nitrite inhibitors on the rebar corrosion of medium carbon steel in seawater and cassava fluid with a view to determining inhibitive potentials of the different inhibitors in the two media. Gravimetric and voltametric techniques were employed in this study and a total of forty-five corrosion coupons of differ...

Wear and friction behaviour of soft particles filled random direction short GFRP composites

International Nuclear Information System (INIS)

Srivastava, V.K.; Wahne, S.

2007-01-01

The random direction short E-glass fibre reinforced epoxy resin composites filled with the particles of mica and tricalcium phosphate (TCP) were prepared by hand lay-up method. The wear and friction behaviour of random direction short E-glass fibre reinforced epoxy resin (GFRP) composites sliding against AISI-1045 steel in a pin-on-disc configuration were evaluated on a TR-20LE wear and friction tester. The microhardness, density, tensile strength and compressive strength of the filled and unfilled mica as well as TCP particles were determined. The morphology of the worn surfaces of the unfilled and filled random E-glass fibre composites and the transfer films were analyzed with the scanning electron microscope. It was found that the particles as the fillers contributed significantly to improve the mechanical properties and wear resistance of the E-glass fibre. This was because the particulates as the fillers contributed to enhance the bonding strength between the fibre and the epoxy resin. Moreover, the wear and friction properties of the random E-glass fibre composites were reduced by increasing filler weight of particles

Analytical model of cracking due to rebar corrosion expansion in concrete considering the structure internal force

Science.gov (United States)

Lin, Xiangyue; Peng, Minli; Lei, Fengming; Tan, Jiangxian; Shi, Huacheng

2017-12-01

Based on the assumptions of uniform corrosion and linear elastic expansion, an analytical model of cracking due to rebar corrosion expansion in concrete was established, which is able to consider the structure internal force. And then, by means of the complex variable function theory and series expansion technology established by Muskhelishvili, the corresponding stress component functions of concrete around the reinforcement were obtained. Also, a comparative analysis was conducted between the numerical simulation model and present model in this paper. The results show that the calculation results of both methods were consistent with each other, and the numerical deviation was less than 10%, proving that the analytical model established in this paper is reliable.

Improving the Wear Resistance of Moulds for the Injection of Glass Fibre–Reinforced Plastics Using PVD Coatings: A Comparative Study

Directory of Open Access Journals (Sweden)

Francisco Silva

2017-02-01

Full Text Available It is well known that injection of glass fibre–reinforced plastics (GFRP causes abrasive wear in moulds’ cavities and runners. Physical vapour deposition (PVD coatings are intensively used to improve the wear resistance of different tools, also being one of the most promising ways to increase the moulds’ lifespan, mainly when used with plastics strongly reinforced with glass fibres. This work compares four different thin, hard coatings obtained using the PVD magnetron sputtering process: TiAlN, TiAlSiN, CrN/TiAlCrSiN and CrN/CrCN/DLC. The first two are monolayer coatings while the last ones are nanostructured and consist of multilayer systems. In order to carry out the corresponding tribological characterization, two different approaches were selected: A laboratorial method, using micro-abrasion wear tests based on a ball-cratering configuration, and an industrial mode, analysing the wear resistance of the coated samples when inserted in a plastic injection mould. As expected, the wear phenomena are not equivalent and the results between micro-abrasion and industrial tests are not similar due to the different means used to promote the abrasion. The best wear resistance performance in the laboratorial wear tests was attained by the TiAlN monolayer coating while the best performance in the industrial wear tests was obtained by the CrN/TiAlCrSiN nanostructured multilayer coating.

Evaluate of the Effects of Drilling with Varying Spindle Speed Using Different Thickness of GFRP on the Damage Factor

Directory of Open Access Journals (Sweden)

Keong Woo Tze

2014-07-01

Full Text Available Composite have been widely used in industries which such as aircraft structural components, electric and electronics components, aerospace, and oil and gas fields due to their superior mechanical properties. Among machining process, drilling can be considered as one of the most important process in final machining of composite. In this research, vacuum assisted resin infusion method is use in fabricating the glass fiber reinforcement polymer samples, where different thickness of GFRP were used in the drilling process with different spindle speed. The results show that the temperature influences the damage factor of the drilling. Higher spindle speed will generate higher temperature that softens the matrix thus generating lower damage factor. The suitable drill bit temperature is between 150-200°C

Finite Element Modeling of GFRP-Reinforced Concrete Interior Slab-Column Connections Subjected to Moment Transfer

Directory of Open Access Journals (Sweden)

Ahmed Gouda

2015-10-01

Full Text Available A finite element model (FEM was constructed using specialized three-dimensional (3D software to investigate the punching shear behavior of interior slab-column connections subjected to a moment-to-shear ratio of 0.15 m. The FEM was then verified against the experimental results of full-scale interior slab-column connections reinforced with glass fiber reinforcement polymer (GFRP bars previously tested by the authors. The FEM results showed that the constructed model was able to predict the behavior of the slabs with reasonable accuracy. Afterward, the verified model was used to conduct a parametric study to investigate the effects of reinforcement ratio, perimeter-to-depth ratio, and column aspect ratio on the punching shear behavior of such connections. The test results showed that increasing the tested parameters enhanced the overall behavior of the connections in terms of decreasing deflections and reinforcement strain and increasing the ultimate capacity. In addition, the obtained punching shear stresses of the connections were compared to the predictions of the Canadian standard and the American guideline for FRP-reinforced concrete structures.

Application of wire beam electrode technique to investigate initiation and propagation of rebar corrosion

International Nuclear Information System (INIS)

Shi, Wei; Dong, Ze Hua; Kong, De Jie; Guo, Xing Peng

2013-01-01

Multi-electrode technique named as wire beam electrode (WBE) was used to study pitting corrosion of rebar under concrete cover. When WBE embedded mortar sample was immersed in NaCl solution, uneven distributions of galvanic current and open circuit potential (OCP) on the WBE were observed due to the initiation of pitting corrosion. The following oxygen depletion in mortar facilitated the negative shift of the OCP and the smoothing of the current and potential distributions. Wetting–drying cycle experiments showed that corrosion products instead of oxygen in wet mortar specimen sustained the propagation of pitting corrosion due to Fe (III) taking part in cathodic depolarization during oxygen-deficient wet period, which was confirmed by micro-Raman spectroscopy. In addition, new pitting corrosion occurred mainly near the corrosion products, leading to preferentially horizontal propagation of rust layer on the WBE. A localized corrosion factor was further presented to quantify the localised corrosion based on galvanic current maps

Application of wire beam electrode technique to investigate initiation and propagation of rebar corrosion

Energy Technology Data Exchange (ETDEWEB)

Shi, Wei; Dong, Ze Hua, E-mail: zehua.dong@gmail.com; Kong, De Jie; Guo, Xing Peng

2013-06-15

Multi-electrode technique named as wire beam electrode (WBE) was used to study pitting corrosion of rebar under concrete cover. When WBE embedded mortar sample was immersed in NaCl solution, uneven distributions of galvanic current and open circuit potential (OCP) on the WBE were observed due to the initiation of pitting corrosion. The following oxygen depletion in mortar facilitated the negative shift of the OCP and the smoothing of the current and potential distributions. Wetting–drying cycle experiments showed that corrosion products instead of oxygen in wet mortar specimen sustained the propagation of pitting corrosion due to Fe (III) taking part in cathodic depolarization during oxygen-deficient wet period, which was confirmed by micro-Raman spectroscopy. In addition, new pitting corrosion occurred mainly near the corrosion products, leading to preferentially horizontal propagation of rust layer on the WBE. A localized corrosion factor was further presented to quantify the localised corrosion based on galvanic current maps.

The characteristics of acoustic emission signal under composite destruction on GFRP gas cylinder

International Nuclear Information System (INIS)

Jee, Hyun Sup; Lee, Jong O; Ju, No Hoe; So, Cheal Ho; Lee, Jong Kyu

2013-01-01

This study is investigation of the characteristics for acoustic emission signal generated by destruction on glass fiber bundles and specimen that was machined composite materials surrounding the outside of GFRP cylinder. The Amplitude of acoustic emission signal gets bigger as the cutting angle of knife increases. Accordingly, the number of hits in destruction of composite materials specimen have more in longitudinal direction (longitudinal direction to the glass fiber) than in hoop direction (horizontal direction to the glass fiber) while the amplitude of signals were bigger in hoop direction than longitudinal direction. It was found out that the amplitude of the glass fiber breakage is more than 40 dB and that the amplitude of signal for matrix crack was less than 40 dB because matrix crack signal was not observed when threshold value is 40 dB and matrix crack signal suddenly appeared when threshold value is 32 dB. The slope of the amplitude is related to the acoustic emission source and the slope of the amplitude of the horizontal and vertical directions are 0.16 and 0.08. In particular, The slope of the amplitude of longitudinal direction breakage appear similar to the glass fiber breakage and therefore Acoustic emission source of longitudinal direction breakage is estimated the glass fiber breakage.

Effect of fabrication processes on mechanical properties of glass fiber reinforced polymer composites for 49 meter (160 foot) recreational yachts

Science.gov (United States)

Kim, Dave (dea-wook); Hennigan, Daniel John; Beavers, Kevin Daniel

2010-03-01

Polymer composite materialsoffer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet) in length. In order to construct even larger hull structures, higher quality composites with a lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic(GFRP) composites is presented. Fabrication techniques used in this study are hand lay-up (HL), vacuum infusion (VI), and hybrid (HL+VI) processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented during composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results

Retrofit of hollow concrete masonry infilled steel frames using glass fiber reinforced plastic laminates

Science.gov (United States)

Hakam, Zeyad Hamed-Ramzy

2000-11-01

This study focuses on the retrofit of hollow concrete masonry infilled steel frames subjected to in-plane lateral loads using glass fiber reinforced plastic (GFRP) laminates that are epoxy-bonded to the exterior faces of the infill walls. An extensive experimental investigation using one-third scale modeling was conducted and consisted of two phases. In the first phase, 64 assemblages, half of which were retrofitted, were tested under various combined in-plane loading conditions similar to those which different regions of a typical infill wall are subjected to. In the second phase, one bare and four masonry-infilled steel frames representative of a typical single-story, single-bay panel were tested under diagonal loading to study the overall behavior and the infill-frame interaction. The relative infill-to-frame stiffness was varied as a test parameter by using two different steel frame sections. The laminates altered the failure modes of the masonry assemblages and reduced the variability and anisotropic nature of the masonry. For the prisms which failed due to shear and/or mortar joint slip, significant strength increases were observed. For those exhibiting compression failure modes, a marginal increase in strength resulted. Retrofitting the infilled frames resulted in an average increase in initial stiffness of two-fold compared to the unretrofitted infilled frames, and seemed independent of the relative infill-to-frame stiffness. However, the increase in the load-carrying capacity of the retrofitted frames compared to the unretrofitted counterparts was higher for those with the larger relative infill-to-frame stiffness parameter. Unlike the unretrofitted infill walls, the retrofitted panels demonstrated almost identical failure modes that were characterized as "strictly comer crushing" in the vicinity of the loaded comers whereas no signs of distress were evident throughout the remainder of the infill. The laminates also maintained the structural integrity of

Experimental Investigation on Strengthening of Bolted Connections in Transmission/Communication Towers

Science.gov (United States)

Balagopal, R.; Prasad Rao, N.; Rokade, R. P.; Umesha, P. K.

2018-02-01

Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.

Experimental Investigation on Strengthening of Bolted Connections in Transmission/Communication Towers

Science.gov (United States)

Balagopal, R.; Prasad Rao, N.; Rokade, R. P.; Umesha, P. K.

2018-06-01

Due to increase in demand for power supply and increase in bandwidth for communication industry, the existing transmission line (TL) and communication towers needs to be strengthened. The strengthening of existing tower is economical rather than installation of new towers due to constraints in acquisition of land. The size of conductors have to be increased or additional number of antenna needs to be installed in existing TL/communication tower respectively. The compression and tension capacity of members in the existing towers have to be increased to sustain the additional loads due to wind and self-weight of these components. The tension capacity enhancement of existing angle sections in live line condition without power shut-down is a challenging task. In the present study, the use of Glass Fiber Reinforced Plastic (GFRP) plate/angle sections is explored to strengthen existing bolted connections in TL/communication towers. Experimental investigation conducted at component level on strengthening of existing two types of single cover steel butt joint, one made of steel plate and another joint made of steel angle sections respectively. First series of experiment conducted on strengthening the connection using GFRP plate/cleat angle sections. The second series of strengthening experiment is conducted using steel plate/angle sections to replace GFRP sections. The load sharing behaviour of strengthened GFRP and steel section is compared and suitable recommendations are given.

Nonlinear failure analysis of a reinforced concrete containment under internal pressure

International Nuclear Information System (INIS)

Sharma, S.; Wang, Y.K.; Reich, M.

1984-01-01

A detailed nonlinear finite element model is used to investigate the failure response of the Indian Point containment building under severe accident pressures. Refined material models are used to describe the complex stress-strain behavior of the liner and rebar steels, the plain concrete and the reinforced concrete. Structural geometry of the containment is idealized by eight layers of axisymmetric finite elements through the wall thickness in order to closely model the actual placement of the rebars. Soil stiffness under the containment base mat is modeled by a series of nonlinear spring elements. Numerical results presented in the paper describe cracking and plastic deformation (in compression) of the concrete, yielding of the liner and rebar steels and eventual loss of the load carrying capacity of the containment. The results are compared with available data from the previous studies for this containment. 8 references, 9 figures

Bond slip and crack development in FRC and regular concrete specimens longitudinally reinforced with FRP or steel under tension loading

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor

2012-01-01

tensile loading using high definition image analysis in two unique test setups. Two different types of cementitious materials, conventional concrete and highly ductile Engineered Cementitious Composite (ECC), and two types of reinforcement bars, regular steel and Glass Fiber Reinforcement Polymer (GFRP......The governing mechanism in the structural response of reinforced concrete members in tension is the interaction between structural reinforcement and the surrounding concrete matrix. The composite response and the mechanical integrations of reinforced cementitious members were investigated during......), were tested. It was found that the ductile ECC in contrast to regular brittle concrete decreases crack widths significantly which effectively results in decreased bond slip between the reinforcement and surrounding matrix. Furthermore the use of elastic GFRP in comparison to elastic/plastic steel...

Effect of electric field in the characterization of pultruded GFRP boron-free composite insulator for the extra high voltage by the ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, Hissae; Silva Junior, Edmilson Jose; Shinohara, Armando Hideki [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Xavier, Gustavo Jose Vasconcelos [CHESF, Recife, PE (Brazil); Costa, Edson Guedes [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Lott Neto, Henrique Batista Duffles Teixeira; Britto, Paulo Roberto Ranzan; Fontan, Marcio A.B. [Sistema de Transmissao do Nordeste S.A., Recife, PE (Brazil)

2016-07-01

Full text: The pultruded boron-free glass fiber reinforced polymer (GFRP) composite has been widely used material for the electrical insulators in the high, extra and ultra high voltage overhead lines worldwide. In terms of design, the composite insulator has a highly complex geometry and large size. Aging of materials begin as soon as the insulators start their operation due to the strong electric field, mechanical load due to the weight of conductor cables, environment, corona discharge, generation of acids, and as a result, GFRP can fail mechanically by the stress corrosion crack (SCC) and electrical breakdown known as flashover. In order to mitigate the mechanical and electrical failures, the insulators in the field are frequently monitored by visual inspection, infrared thermography, UV detection, variation of measurement of distribution of electric field variation. However, new technologies for characterization and inspection of the composite insulator in the field are required for reliable operation. Imaging characterization using ionizing radiation (X-ray or g-ray) is an interesting technique, however, it can reduce drastically breakdown voltage due to the Townsend discharge, which free electrons are accelerated by an electric field, collide with gas molecules of air, and free additional electrons resulting in an avalanche multiplication that allows an electrical conduction through the air. In this study, in order to evaluate the potential application of ionization radiation for characterization of composite insulator under electric field, testing were conducted in high voltage laboratory by applying voltages up to 640 kV and varying radiation area of the composite insulator. As a result, even though there was an occurrence of flame on Imaging Plate (IP) detector case when it was located near the phase, corona discharge, but no breakdown discharge (flashover) occurred and high quality imaging of radiography could be obtained when X-ray source was employed

Fabrication of a smart air intake structure using shape memory alloy wire embedded composite

International Nuclear Information System (INIS)

Jung, Beom-Seok; Kim, Min-Saeng; Kim, Ji-Soo; Kim, Yun-Mi; Lee, Woo-Yong; Ahn, Sung-Hoon

2010-01-01

Shape memory alloys (SMAs) have been actively studied in many fields utilizing their high energy density. Applying SMA wire-embedded composite to aerospace structures, such as air intake of jet engines and guided missiles, is attracting significant attention because it could generate a comparatively large actuating force. In this research, a scaled structure of SMA wire-embedded composite was fabricated for the air intake of aircraft. The structure was composed of several prestrained Nitinol (Ni-Ti) SMA wires embedded in intersection -shape glass fabric reinforced plastic (GFRP), and it was cured at room temperature for 72 h. The SMA wire-embedded GFRP could be actuated by applying electric current through the embedded SMA wires. The activation angle generated from the composite structure was large enough to make a smart air intake structure.

Effect of fabrication processes on mechanical properties of glass fiber reinforced polymer composites for 49 meter (160 foot recreational yachts

Directory of Open Access Journals (Sweden)

Dave (Dae-Wook Kim

2010-03-01

Full Text Available Polymer composite materials offer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet in length. In order to construct even larger hull structures, higher quality composites with lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic (GFRP composites is presented. Fabrication techniques investigated during this study are hand lay-up (HL, vacuum infusion (VI, and hybrid (HL + VI processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented during composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results.

Proyecto de una torre de perforación con perfiles pultrusionados de GFRP

Directory of Open Access Journals (Sweden)

Recuero Fornies, Alfonso

2001-02-01

Full Text Available The goal of this project was to design a removable and reusable structure (derrick built with pultrusion profiles of GFRP (Glass Fiber Reinforced Polymers. These profiles have better physical and mechanical properties than those commonly used for these structures, such as steel or concrete profiles. A methodology for drilling an oil field is described in this document. The structure has been worked out by computer program. An economical study with a comparison between the structure designed with common materials and with composites is included. An application to different situations where steel design could not be possible is also shown.El proyecto presenta el diseño de una estructura desmontable y reutilizable para la realización de sondeos de petróleo .La estructura ha sido proyectada con perfiles pultrusionados de material compuesto avanzado ya que presentan unas cualidades, tanto físicas como mecánicas, superiores a la de los materiales convencionales. El empleo de estos materiales ha sido justificado desde el punto de vista técnico y económico. A lo largo del artículo se describen las operaciones requeridas en la explotación por sondeos, así como el planteamiento seguido en el cálculo estructural mediante un programa que tiene por objeto el análisis matricial de estructuras de barras. Al final del mismo se hacen una serie de reflexiones sobre las tendencias futuras de estos materiales.

Load Testing of GFRP Composite U-Shape Footbridge

Science.gov (United States)

Pyrzowski, Łukasz; Miśkiewicz, Mikołaj; Chróścielewski, Jacek; Wilde, Krzysztof

2017-10-01

The paper presents the scope of load tests carried out on an innovative shell composite footbridge. The tested footbridge was manufactured in one production cycle and has no components made from materials other than GFRP laminates and PET foam. The load tests, performed on a 14-m long structure, were the final stage of a research program in the Fobridge project carried out in cooperation with: Gdańsk University of Technology (leader), Military University of Technology in Warsaw, and ROMA Co. Ltd.; and co-financed by NCBR. The aim of the tests was to confirm whether the complex U-shape sandwich structure behaves correctly. The design and technological processes involved in constructing this innovative footbridge required the solving of many problems: absence of standards for design of composite footbridges, lack of standardized material data, lack of guidelines for calculation and evaluation of material strength, and no guidelines for infusion of large, thick sandwich elements. Obtaining answers during the design process demanded extensive experimental tests, development of material models, validation of models, updating parameters and extensive numerical parametric studies. The technological aspects of infusion were tested in numerous trials involving the selection of material parameters and control of the infusion parameters. All scientific validation tests were successfully completed and market assessment showed that the proposed product has potential applications; it can be used for overcoming obstacles in rural areas and cities, as well as in regions affected by natural disasters. Load testing included static and dynamic tests. During the former, the span was examined at 117 independent measurement points. The footbridge was loaded with concrete slabs in different configurations. Their total weight ranged from 140 kN up to 202 kN. The applied load at the most heavily loaded structural points caused an effect from 89% to 120%, compared to the load specified by

Fracture Behaviours in Compression-loaded Triangular Corrugated Core Sandwich Panels

Directory of Open Access Journals (Sweden)

Zaid N.Z.M.

2016-01-01

Full Text Available The failure modes occurring in sandwich panels based on the corrugations of aluminium alloy, carbon fibre-reinforced plastic (CFRP and glass fibre-reinforced plastic (GFRP are analysed in this work. The fracture behaviour of these sandwich panels under compressive stresses is determined through a series of uniform lateral compression performed on samples with different cell wall thicknesses. Compression test on the corrugated-core sandwich panels were conducted using an Instron series 4505 testing machine. The post-failure examinations of the corrugated-core in different cell wall thickness were conducted using optical microscope. Load-displacement graphs of aluminium alloy, GFRP and CFRP specimens were plotted to show progressive damage development with five unit cells. Four modes of failure were described in the results: buckling, hinges, delamination and debonding. Each of these failure modes may dominate under different cell wall thickness or loading condition, and they may act in combination. The results indicate that thicker composites corrugated-core panels tend can recover more stress and retain more stiffness. This analysis provides a valuable insight into the mechanical behaviour of corrugated-core sandwich panels for use in lightweight engineering applications.

Numerical simulation of impact tests on reinforced concrete beams

International Nuclear Information System (INIS)

Jiang, Hua; Wang, Xiaowo; He, Shuanhai

2012-01-01

Highlights: ► Predictions using advanced concrete model compare well with the impact test results. ► Several important behavior of concrete is discussed. ► Two mesh ways incorporating rebar into concrete mesh is also discussed. ► Gives a example of using EPDC model and references to develop new constitutive models. -- Abstract: This paper focuses on numerical simulation of impact tests of reinforced concrete (RC) beams by the LS-DYNA finite element (FE) code. In the FE model, the elasto-plastic damage cap (EPDC) model, which is based on continuum damage mechanics in combination with plasticity theory, is used for concrete, and the reinforcement is assumed to be elasto-plastic. The numerical results compares well with the experimental values reported in the literature, in terms of impact force history, mid-span deflection history and crack patterns of RC beams. By comparing the numerical and experimental results, several important behavior of concrete material is investigated, which includes: damage variable to describe the strain softening section of stress–strain curve; the cap surface to describe the plastic volume change; the shape of the meridian and deviatoric plane to describe the yield surface as well as two methods of incorporating rebar into concrete mesh. This study gives a good example of using EPDC model and can be utilized for the development new constitutive models for concrete in future.

Plastic

International Nuclear Information System (INIS)

Jeong Gi Hyeon

1987-04-01

This book deals with plastic, which includes introduction for plastic, chemistry of high polymers, polymerization, speciality and structure of a high molecule property of plastic, molding, thermosetting plastic, such as polyethylene, polyether, polyamide and polyvinyl acetyl, thermal plastic like phenolic resins, xylene resins, melamine resin, epoxy resin, alkyd resin and poly urethan resin, new plastic like ionomer and PPS resin, synthetic laminated tape and synthetic wood, mixed materials in plastic, reprocessing of waste plastic, polymer blend, test method for plastic materials and auxiliary materials of plastic.

Long Term Corrosion Experiment of Steel Rebar in Fly Ash-Based Geopolymer Concrete in NaCl Solution

Directory of Open Access Journals (Sweden)

Y. P. Asmara

2016-01-01

Full Text Available This research focuses on an experimental investigation to identify the effects of fly ash on the electrochemical process of concrete during the curing time. A rebar was analysed using potentiostat to measure the rest potential, polarization diagram, and corrosion rate. Water-to-cement ratio and amount of fly ash were varied. After being cured for 24 hours at a temperature of 65°C, the samples were immersed in 3.5% of NaCl solution for 365 days for electrochemical measurement. Measurements of the half-cell potential and corrosion current density indicated that the fly ash has significant effects on corrosion behaviour of concrete. Although fly ash tends to create passivity on anodic current, it increases corrosion rate. The corrosion potential of this concrete mixture decreases compared to concrete without fly ash. From the result, it can be summarized that concrete mixture with 70% of OPC (Ordinary Portland Cement and 30% fly ash has shown the best corrosion resistance.

GREEN PLASTIC: A NEW PLASTIC FOR PACKAGING

OpenAIRE

Mr. Pankaj Kumar*, Sonia

2016-01-01

This paper gives a brief idea about a new type of plastic called as bio-plastic or green plastic. Plastic is used as a packaging material for various products, but this plastic is made up of non renewable raw materials. There are various disadvantages of using conventional plastic like littering, CO2 production, non-degradable in nature etc. To overcome these problems a new type of plastic is discovered called bio-plastic or green plastic. Bio-plastic is made from renewable resources and also...

Study on evolution of disposal environment due to alteration of cement. Commission work report

International Nuclear Information System (INIS)

Iriya, K.; Kubo, H.; Kato, T.; Fujita, H.

2001-02-01

The study shows effects on performance of the engineered and geological barriers due to alteration of cement including low alkalinity cement. Alteration test of bentonite and crystalline rock was carried out by low alkalinity cement pore water. Leaching of super plasticizer was investigated modeled for the latest period of alteration of cement. Planning a experiment for corrosion of re-bar in low alkalinity cement was carried out. Application of the cement for shotcrete was investigated. The results described below are obtained. 1. Almost of montmorillonite was solved in Na-K-Ca mixed solution. No alteration was observed in low alkalinity cement. The similar results were obtained for crystalline rock. 2. It is noted that main part of super plasticizer wasn't leachate even in the latest period of leaching of cement. Increment of leaching of super plasticizer wasn't observed corresponding to leaching of cement hydrates. 3. Accelerating test for corrosion of re-bar in low alkalinity cement was proposed. 4. It was demonstrated that low alkalinity cement was applicable for shotcrete. 5. pH of pore water of cement with highly pozzolanic materials isn't significantly decreased in high temperature. 6. Predictable alteration of barriers due to alteration of cement were pointed out including interaction of bentonite and rock. (author)

Study on evolution of disposal environment due to alteration of cement. Summary report. Commission work report

International Nuclear Information System (INIS)

Iriya, K.; Kubo, H.; Kato, T.; Fujita, H.

2001-02-01

The study shows effects on performance of the engineered and geological barriers due to alteration of cement including low alkalinity cement. Alteration test of bentonite and crystalline rock was carried out by low alkalinity cement pore water. Leaching of super plasticizer was investigated modeled for the latest period of alteration of cement. Planning a experiment for corrosion of re-bar in low alkalinity cement was carried out. Application of the cement for shotcrete was investigated. The results described below are obtained. 1. Almost of montmorillonite was solved in Na-K-Ca mixed solution. No alteration was observed in low alkalinity cement. The similar results were obtained for crystalline rock. 2. It is noted that main part of super plasticizer wasn't leachated even in the latest period of leaching of cement. Increment of leaching of super plasticizer wasn't observed corresponding to leaching of cement hydrates. 3. Accelerating test for corrosion of re-bar in low alkalinity cement was proposed. 4. It was demonstrated that low alkalinity cement was applicable for shotcrete. 5. pH of pore water of cement with highly pozzolanic materials isn't significantly decreased in high temperature. 6. Predictable alteration of barriers due to alteration of cement were pointed out including interaction of bentonite and rock. (author)

The carbon fibre market and uses for composite wind blades

Energy Technology Data Exchange (ETDEWEB)

Lowe, J R [Tenax Fibers Gmbh and Co. KG, Wuppertal (Germany)

1996-09-01

Due to its excellent fatigue properties, low weight and high stiffness, carbon fibre reinforced plastic (CFRP) is the ideal material to use for the manufacture of wind blades. The present use of CFRP in the wind energy sector however is very low in comparison to glass fibre reinforced plastic (GFRP) materials. The main reason for this low use of CFRP is cost since at present times carbon fibre is valued ten times as much as glass fibre. This paper introduces carbon fibre as an alternative material to glass and examines the use of CFRP components in other high fatigue applications. (au)

Characterization of Fibre-Direction Dependent Damping of Glass-Fibre Composites at Low Temperatures and Low Frequencies

DEFF Research Database (Denmark)

Kliem, Mathias; Høgsberg, Jan Becker; Dannemann, Martin

2016-01-01

This paper deals with the characterization of the fibre-direction dependent damping capability of glass fibre reinforced plastics (GFRP) to be used in electrical power transmission pylons. A fibre-direction dependent damping analysis of unidirectional (UD) GFRP samples was carried out using...... a Dynamic Mechanical Analysis (DMA) for five different fibre orientations (0˚ | 30˚ | 45˚ | 60˚ and 90˚) and two different matrix systems (epoxy and a vinyl ester resin). Based on the dynamic characteristics the damping performance of the various composite materials was studied at three temperatures (-10˚C......, 0˚C and 10˚C) and three vibration frequencies (1 Hz, 10 Hz and 30 Hz). It was observed that the loss factor of Glass Fibre Reinforced Vinyl-Ester (GF-VE) was in general slightly higher compared to the Glass Fibre Reinforced Epoxy (GF-EP). The loss factor increased slightly with temperature, while...

Damage detection in wind turbine blades using acoustic techniques

Energy Technology Data Exchange (ETDEWEB)

Juengert, A., E-mail: anne.juengert@mpa.uni-stuttgart.de [Univ. of Stuttgart, Materialpruefungsanstalt Stuttgart, Stuttgart (Germany)

2013-05-15

Facing climate change, the use of renewable energy gains importance. The wind energy sector grows very fast. Bigger and more powerful wind turbines will be built in the coming decades and the safety and reliability of the turbines will become more important. Wind turbine blades have to be inspected at regular intervals, because they are highly stressed during operation and a blade breakdown can cause big economic damages. The turbine blades consist of fiber reinforced plastics (GFRP/CFRP) and sandwich areas containing wood or plastic foam. The blades are manufactured as two halves and glued together afterwards. Typical damages are delaminations within the GFRP or the sandwich and missing adhesive or deficient bond at the bonding surfaces. The regular inspections of wind turbine blades are performed manually by experts and are limited to visual appraisals and simple tapping tests. To improve the inspections of wind turbine blades non-destructive testing techniques using acoustic waves are being developed. To detect delaminations within the laminates of the turbine blade, a local resonance spectroscopy was used. To detect missing bond areas from the outside of the blade the impulse-echo-technique was applied. This paper is an updated reprint of an article published on ndt.net in 2008. (author)

Damage detection in wind turbine blades using acoustic techniques

International Nuclear Information System (INIS)

Juengert, A.

2013-01-01

Facing climate change, the use of renewable energy gains importance. The wind energy sector grows very fast. Bigger and more powerful wind turbines will be built in the coming decades and the safety and reliability of the turbines will become more important. Wind turbine blades have to be inspected at regular intervals, because they are highly stressed during operation and a blade breakdown can cause big economic damages. The turbine blades consist of fiber reinforced plastics (GFRP/CFRP) and sandwich areas containing wood or plastic foam. The blades are manufactured as two halves and glued together afterwards. Typical damages are delaminations within the GFRP or the sandwich and missing adhesive or deficient bond at the bonding surfaces. The regular inspections of wind turbine blades are performed manually by experts and are limited to visual appraisals and simple tapping tests. To improve the inspections of wind turbine blades non-destructive testing techniques using acoustic waves are being developed. To detect delaminations within the laminates of the turbine blade, a local resonance spectroscopy was used. To detect missing bond areas from the outside of the blade the impulse-echo-technique was applied. This paper is an updated reprint of an article published on ndt.net in 2008. (author)

Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

Science.gov (United States)

Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

2016-01-01

In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete. PMID:27618054

Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

Directory of Open Access Journals (Sweden)

Yunze Xu

2016-09-01

Full Text Available In this paper, a new kind of carbon steel (CS and stainless steel (SS galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER method and zero resistance ammeter (ZRA technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete.

Evaluation of Shear Tie Connectors for Use in Insulated Concrete Sandwich Panels

Science.gov (United States)

2009-12-01

stainless steel, galvanized carbon steel, carbon fiber reinforced polymers (CFRP), glass fiber reinforced polymer (GFRP), and basalt fiber reinforced polymer...Glass Fiber Reinforced Polymer (GFRP) Delta Tie produced by Dayton Superior; • (B) THERMOMASS® composite GFRP pins; • (C) THERMOMASS® non-composite...GFRP pins; • (D) Altus Group CFRP Grid; • (E) Universal Building products GFRP Teplo Tie; and • (F) Universal Building products Basalt FRP

Corrosion behaviour of steel rebars embedded in a concrete designed for the construction of an intermediate-level radioactive waste disposal facility

Directory of Open Access Journals (Sweden)

Schulz F.M.

2013-07-01

Full Text Available The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on an instrumented reinforced concrete prototype specifically designed for this purpose, to study the behaviour of an intermediate level radioactive waste disposal facility from the rebar corrosion point of view. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

Numerical Analysis of Carbon Fiber Reinforced Plastic (CFRP Shear Walls and Steel Strips under Cyclic Loads Using Finite Element Method

Directory of Open Access Journals (Sweden)

N. Askarizadeh

2017-12-01

Full Text Available Reinforced concrete shear walls are the main elements of resistance against lateral loads in reinforced concrete structures. These walls should not only provide sufficient resistance but also provide sufficient ductility in order to avoid brittle fracture, particularly under strong seismic loads. However, many reinforced concrete shear walls need to be stabilized and reinforced due to various reasons such as changes in requirements of seismic regulations, weaknesses in design and execution, passage of time, damaging environmental factors, patch of rebar in plastic hinges and in some cases failures and weaknesses caused by previous earthquakes or explosion loads. Recently, Fiber Reinforced Polymer (FRP components have been extensively and successfully used in seismic improvement. This study reinforces FRP reinforced concrete shear walls and steel strips. CFRP and steel strips are evaluated by different yield and ultimate strength. Numerical and experimental studies are done on walls with scale 1/2. These walls are exposed to cyclic loading. Hysteresis curves of force, drift and strain of FRP strips are reviewed in order to compare results of numerical work and laboratory results. Both numerical and laboratory results show that CFRP and steel strips increase resistance, capacity and ductility of the structure.

Development of a vacuum leak test method for large-scale superconducting magnet test facilities

International Nuclear Information System (INIS)

Kawano, Katsumi; Hamada, Kazuya; Okuno, Kiyoshi; Kato, Takashi

2006-01-01

Japan Atomic Energy Agency (JAEA) has developed leak detection technology for liquid helium temperature experiments in large-scale superconducting magnet test facilities. In JAEA, a cryosorption pump that uses an absorbent cooled by liquid nitrogen with a conventional helium leak detector, is used to detect helium gas that is leaking from pressurized welded joints of pipes and valves in a vacuum chamber. The cryosorption pump plays the role of decreasing aerial components, such as water, nitrogen and oxygen, to increase the sensitivity of helium leak detection. The established detection sensitivity for helium leak testing is 10 -10 to 10 -9 Pam 3 /s. A total of 850 welded and mechanical joints inside the cryogenic test facility for the ITER Central Solenoid Model Coil (CSMC) experiments have been tested. In the test facility, 73 units of glass fiber-reinforced plastic (GFRP) insulation break are used. The amount of helium permeation through the GFRP was recorded during helium leak testing. To distinguish helium leaks from insulation-break permeation, the helium permeation characteristic of the GFRP part was measured as a function of the time of helium charging. Helium permeation was absorbed at 6 h after helium charging, and the detected permeation is around 10 -7 Pam 3 /s. Using the helium leak test method developed, CSMC experiments have been successfully completed. (author)

Shear Strengthening of RC Beams Using Sprayed Glass Fiber Reinforced Polymer

Directory of Open Access Journals (Sweden)

Sayed Mohamad Soleimani

2012-01-01

Full Text Available The effectiveness of externally bonded sprayed glass fiber reinforced polymer (Sprayed GFRP in shear strengthening of RC beams under quasi-static loading is investigated. Different techniques were utilized to enhance the bond between concrete and Sprayed GFRP, involving the use of through bolts and nuts paired with concrete surface preparation through sandblasting and through the use of a pneumatic chisel prior to Sprayed GFRP application. It was found that roughening the concrete surface using a pneumatic chisel and using through bolts and nuts were the most effective techniques. Also, Sprayed GFRP applied on 3 sides (U-shaped was found to be more effective than 2-sided Sprayed GFRP in shear strengthening. Sprayed GFRP increased the shear load-carrying capacity and energy absorption capacities of RC beams. It was found that the load-carrying capacity of strengthened RC beams was related to an effective strain of applied Sprayed GFRP. This strain was related to Sprayed GFRP configuration and the technique used to enhance the concrete-FRP bond. Finally, an equation was proposed to calculate the contribution of Sprayed GFRP in the shear strength of an RC beam.

Plasticity theory

CERN Document Server

Lubliner, Jacob

2008-01-01

The aim of Plasticity Theory is to provide a comprehensive introduction to the contemporary state of knowledge in basic plasticity theory and to its applications. It treats several areas not commonly found between the covers of a single book: the physics of plasticity, constitutive theory, dynamic plasticity, large-deformation plasticity, and numerical methods, in addition to a representative survey of problems treated by classical methods, such as elastic-plastic problems, plane plastic flow, and limit analysis; the problem discussed come from areas of interest to mechanical, structural, and

New Trends for Reinforced Concrete Structures: Some Results of Exploratory Studies

Directory of Open Access Journals (Sweden)

Ricardo N. F. Carmo

2017-10-01

Full Text Available Today, the concrete sector is being pushed to innovate in order to better address current challenges with higher competitiveness and more sustainable solutions. Different research studies have been conducted all over the world in which novel approaches and paths were proposed. It is important to spread information to define new strategies for the future of this industry. The enhancement of concrete properties and the impact of these changes in structural design are some of the topics analysed in those studies. This paper presents four experimental studies conducted by the authors where different types of concrete and structural members were tested. The common goal of these studies was to develop innovative solutions with high performance and low environmental impact. The scope of the first study was the structural behaviour of members produced with lightweight aggregate concrete (LWAC. Results of several beams, ties, and slabs are herein presented and analysed. The advantage of using glass fibre–reinforced polymer (GFRP rebars was addressed in a second study, and main results obtained with this type of rebar are also herein presented. Recent advances in nanotechnology led to the development of concretes incorporating nanoparticles into the binder matrix. Typically, these nanoparticles have a diameter of 10–300 nanometers and are added to the mixture to reduce the porosity and increase the density of the binder matrix, improving the mechanical properties and durability. To analyse their influence on steel-to-concrete bonding and on the shear and flexural behaviour of the beams was the main goal of the third study herein described. Finally, a new concept to produce reinforced concrete members with high durability using a special concrete cover, which was the goal of the fourth study, is also herein presented.

ENVIRONMENTAL AND ECONOMIC ASPECTS OF ANTICORROSION PROTECTION BY HOT-DIP GALVANIZED METHOD REBARS IN CONCRETE

Directory of Open Access Journals (Sweden)

Hegyi Andreea

2015-05-01

Full Text Available The implementation of the sustainable development concept is nowadays a key issue in almost all human activities. For the constructions domain an European strategy has already been elaborated. Among its goals are also the use of long lasting materials and the reduction of repair costs. This paper presents an interdisciplinary study concerning the efficiency of the use of hot-dip galvanized rebar for concrete structures. Experimental results about corrosion kinetics of coated and usual steel reinforcement embedded in concrete, subjected to chlorine ions attack, are analyzed. Electrochemical methods as chronoamperometry and linear polarization have been used. Corrosion potential values recorded for galvanized steel embedded in concrete indicate an uncertain corrosion activation process up to a rate of 2.5 % calcium chloride relative to concrete. For rates of 5% CaCl2 and more the corrosion process is activated. For unprotected steel bars embedded in concrete the corrosion activation process started at all calcium chloride studied rates and higher corrosion potential values has been registered than for the hot-dip galvanized ones, at the same rates. Economical assessments have been done using entire lifetime cost analysis of the reinforced concrete structures. Despite that the hotdip galvanization is a rather expansive procedure, when taking into account the whole expected life span, the use of zinc coating proves to be efficient both from structural and financial approaches.

Testing and modeling dowel and catenary action in rebars crossing shear joints in RC

DEFF Research Database (Denmark)

Sørensen, Jesper Harrild; Hoang, Linh Cao; Olesen, John Forbes

2017-01-01

presents a simple, second order plasticity model to describe the non-linear regime of the load-displacement relationship. In the model, kinematic relations and the normality condition of plastic theory are utilized to establish a unique link between the imposed shear displacement and combinations of moment...

Magical Engineering Plastic

Energy Technology Data Exchange (ETDEWEB)

Kim, Gwang Ung

1988-01-15

This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

Magical Engineering Plastic

International Nuclear Information System (INIS)

Kim, Gwang Ung

1988-01-01

This book introduces engineering plastic about advantage of engineering plastic, plastic material from processing method, plastic shock, plastic until now, background of making of engineering plastic, wonderful engineering plastic science such as a high molecule and molecule, classification of high molecule, difference between metal and high molecule, heat and high molecule materials, and property of surface, engineering plastic of dream like from linseed oil to aramid, small dictionary of engineering plastic.

International policies to reduce plastic marine pollution from single-use plastics (plastic bags and microbeads): A review.

Science.gov (United States)

Xanthos, Dirk; Walker, Tony R

2017-05-15

Marine plastic pollution has been a growing concern for decades. Single-use plastics (plastic bags and microbeads) are a significant source of this pollution. Although research outlining environmental, social, and economic impacts of marine plastic pollution is growing, few studies have examined policy and legislative tools to reduce plastic pollution, particularly single-use plastics (plastic bags and microbeads). This paper reviews current international market-based strategies and policies to reduce plastic bags and microbeads. While policies to reduce microbeads began in 2014, interventions for plastic bags began much earlier in 1991. However, few studies have documented or measured the effectiveness of these reduction strategies. Recommendations to further reduce single-use plastic marine pollution include: (i) research to evaluate effectiveness of bans and levies to ensure policies are having positive impacts on marine environments; and (ii) education and outreach to reduce consumption of plastic bags and microbeads at source. Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental Investigation on the Durability of Glass Fiber-Reinforced Polymer Composites Containing Nanocomposite

Directory of Open Access Journals (Sweden)

Weiwen Li

2013-01-01

Full Text Available Nanoclay layers incorporated into polymer/clay nanocomposites can inhibit the harmful penetration of water and chemicals into the material, and thus the durability of glass fiber-reinforced polymer (GFRP composites should be enhanced by using polymer/clay nanocomposite as the matrix material. In this study, 1.5 wt% vinyl ester (VE/organoclay and 2 wt% epoxy (EP/organoclay nanocomposites were prepared by an in situ polymerization method. The dispersion states of clay in the nanocomposites were studied by performing XRD analysis. GFRP composites were then fabricated with the prepared 1.5 wt% VE/clay and 2.0 wt% EP/clay nanocomposites to investigate the effects of a nanocomposite matrix on the durability of GFRP composites. The durability of the two kinds of GFRP composites was characterized by monitoring tensile properties following degradation of GFRP specimens aged in water and alkaline solution at 60°C, and SEM was employed to study fracture behaviors of aged GFRP composites under tension. The results show that tensile properties of the two types of GFRP composites with and without clay degrade significantly with aging time. However, the GFRP composites with nanoclay show a lower degradation rate compared with those without nanoclay, supporting the aforementioned hypothesis. And the modification of EP/GFRP enhanced the durability more effectively.

Seismic Performance of a Corroded Reinforce Concrete Frame Structure Using Pushover Method

Directory of Open Access Journals (Sweden)

Meng Zhang

2018-01-01

Full Text Available SAP2000 software was used to build the finite element model of a six-storey-three-span reinforced concrete (RC frame structure. The numerical simulation of the seismic performance of the RC frame structure incorporating different levels of rebar corrosion was conducted using pushover analysis method. The degradation characteristics of the seismic performance of the corroded structure under severe earthquake were also analyzed. The results show that the seismic performance of the RC frame decreased significantly due to corrosion of the longitudinal rebars. And the interstory drift ratios increase dramatically with the increasing of the corrosion rate. At the same time, the formation and development of plastic hinges (beam hinges or column hinges will accelerate, which leads to a more aggravated deformation of the structure under rare earthquake action, resulting in a negative effect to the seismic bearing capacity of the structure.

Mechanical interaction between concrete and structural reinforcement in the tension stiffening process

DEFF Research Database (Denmark)

Lárusson, Lárus Helgi; Fischer, Gregor; Jönsson, Jeppe

2011-01-01

as Engineered Cementitious Composite (ECC), have been combined with steel and glass fiber reinforced polymer (GFRP) reinforcement to contrast the effects of brittle and ductile cement matrices as well as elastic/plastic and elastic reinforcement on the tension stiffening process. Particular focus...... investigated using an image-based deformation measurement and analysis system. This allowed for detailed view of surface deformations and the implications on the resulting response of the member in tension. In this study, conventional concrete and a ductile, strain hardening cement composite, known...

Plastic Surgery

Science.gov (United States)

... Staying Safe Videos for Educators Search English Español Plastic Surgery KidsHealth / For Teens / Plastic Surgery What's in ... her forehead lightened with a laser? What Is Plastic Surgery? Just because the name includes the word " ...

Rhéologie des bétons fluides à hautes performances : relations entre formulations, propriétés rhéologiques, physico-chimie et propriétés mécaniques

OpenAIRE

Yammine , Joumana

2007-01-01

The High Performance Concrete, from high to low plastic consistency, develops high long term mechanical resistances. Nevertheless, it presents the disadvantage of a very hard filling in dense steel reinforcements rebars like in the Millau's viaduct piles, which constitute a framework of barriers for the concrete casting by vibration. To guarantee a total filling in the framework, the self compacting concretes are the issue and are adopted respecting mechanical performances and durability main...

Plastic dosimeter

International Nuclear Information System (INIS)

Nagai, Shiro; Matsuda, Kohji.

1988-01-01

The report outlines major features and applications of plastic dosimeters. Some plastic dosimeters, including the CTA and PVC types, detect the response of the plastic material itself to radiations while others, such as pigment-added plastic dosimeters, contain additives as radiation detecting material. Most of these dosimeters make use of color centers produced in the dosimeter by radiations. The PMMA dosimeter is widely used in the field of radiation sterilization of food, feed and medical apparatus. The blue cellophane dosimeter is easy to handle if calibrated appropriately. The rad-color dosimeter serves to determine whether products have been irradiated appropriately. The CTA dosimeter has better damp proofing properties than the blue cellophane type. The pigment-added plastic dosimeter consists of a resin such as nylon, CTA or PVC that contains a dye. Some other plastic dosimeters are also described briefly. Though having many advantages, these plastic dosimeter have disadvantages as well. Some of their major disadvantages, including fading as well as large dependence on dose, temperature, humidity and anviroment, are discussed. (Nogami, K.)

plastic waste recycling

African Journals Online (AJOL)

Dr Ahmed

incinerators is increasing around the world. Discarded plastic products ... Agency (EPA) estimated that the amount of plastics throw away is. 50 % greater in the ... The waste plastics were identified using the Society of the Plastic. Industry (SPI) ...

Direct liquefaction of plastics and coprocessing of coal with plastics

Energy Technology Data Exchange (ETDEWEB)

Huffman, G.P.; Feng, Z.; Mahajan, V. [Univ. of Kentucky, Lexington, KY (United States)

1995-12-31

The objectives of this work were to optimize reaction conditions for the direct liquefaction of waste plastics and the coprocessing of coal with waste plastics. In previous work, the direct liquefaction of medium and high density polyethylene (PE), polypropylene (PPE), poly(ethylene terephthalate) (PET), and a mixed plastic waste, and the coliquefaction of these plastics with coals of three different ranks was studied. The results established that a solid acid catalyst (HZSM-5 zeolite) was highly active for the liquefaction of the plastics alone, typically giving oil yields of 80-95% and total conversions of 90-100% at temperatures of 430-450 {degrees}C. In the coliquefaction experiments, 50:50 mixtures of plastic and coal were used with a tetralin solvent (tetralin:solid = 3:2). Using approximately 1% of the HZSM-5 catalyst and a nanoscale iron catalyst, oil yields of 50-70% and total conversion of 80-90% were typical. In the current year, further investigations were conducted of the liquefaction of PE, PPE, and a commingled waste plastic obtained from the American Plastics Council (APC), and the coprocessing of PE, PPE and the APC plastic with Black Thunder subbituminous coal. Several different catalysts were used in these studies.

Recycling of Plastic

DEFF Research Database (Denmark)

Christensen, Thomas Højlund; Fruergaard, Thilde

2011-01-01

Plastic is produced from fossil oil. Plastic is used for many different products. Some plastic products like, for example, wrapping foil, bags and disposable containers for food and beverage have very short lifetimes and thus constitute a major fraction of most waste. Other plastic products like...

Plastic value chains

DEFF Research Database (Denmark)

Baxter, John; Wahlstrom, Margareta; Zu Castell-Rüdenhausen, Malin

2014-01-01

Optimizing plastic value chains is regarded as an important measure in order to increase recycling of plastics in an efficient way. This can also lead to improved awareness of the hazardous substances contained in plastic waste, and how to avoid that these substances are recycled. As an example......, plastics from WEEE is chosen as a Nordic case study. The project aims to propose a number of improvements for this value chain together with representatives from Nordic stakeholders. Based on the experiences made, a guide for other plastic value chains shall be developed....

Our plastic age.

Science.gov (United States)

Thompson, Richard C; Swan, Shanna H; Moore, Charles J; vom Saal, Frederick S

2009-07-27

Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation.

Our plastic age

Science.gov (United States)

Thompson, Richard C.; Swan, Shanna H.; Moore, Charles J.; vom Saal, Frederick S.

2009-01-01

Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste plastic, the effects of plastic debris on wildlife and concerns for human health that arise from the production, usage and disposal of plastics. Finally, we consider some possible solutions to these problems together with the research and policy priorities necessary for their implementation. PMID:19528049

Impact of Bio-Based Plastics on Current Recycling of Plastics

Directory of Open Access Journals (Sweden)

Luc Alaerts

2018-05-01

Full Text Available Bio-based plastics are increasingly appearing in a range of consumption products, and after use they often end up in technical recycling chains. Bio-based plastics are different from fossil-based ones and could disturb the current recycling of plastics and hence inhibit the closure of plastic cycles, which is undesirable given the current focus on a transition towards a circular economy. In this paper, this risk has been assessed via three elaborated case studies using data and information retrieved through an extended literature search. No overall risks were revealed for bio-based plastics as a group; rather, every bio-based plastic is to be considered as a potential separate source of contamination in current recycling practices. For PLA (polylactic acid, a severe incompatibility with PET (polyethylene terephthalate recycling is known; hence, future risks are assessed by measuring amounts of PLA ending up in PET waste streams. For PHA (polyhydroxy alkanoate there is no risk currently, but it will be crucial to monitor future application development. For PEF (polyethylene furanoate, a particular approach for contamination-related issues has been included in the upcoming market introduction. With respect to developing policy, it is important that any introduction of novel plastics is well guided from a system perspective and with a particular eye on incompatibilities with current and upcoming practices in the recycling of plastics.

Plastic condoms.

Science.gov (United States)

1968-01-01

Only simple equipment, simple technology and low initial capital investment are needed in their manufacture. The condoms can be made by people who were previously unskilled or only semi-skilled workers. Plastic condoms differ from those made of latex rubber in that the nature of the plastic film allows unlimited shelf-life. Also, the plastic has a higher degree of lubricity than latex rubber; if there is a demand for extra lubrication in a particular market, this can be provided. Because the plastic is inert, these condoms need not be packaged in hermetically sealed containers. All these attributes make it possible to put these condoms on the distributors' shelves in developing countries competitively with rubber condoms. The shape of the plastic condom is based on that of the lamb caecum, which has long been used as luxury-type condom. The plastic condom is made from plastic film (ethylene ethyl acrilate) of 0.001 inch (0.0254 mm.) thickness. In addition, a rubber ring is provided and sealed into the base of the condom for retention during coitus. The advantage of the plastic condom design and the equipment on which it is made is that production can be carried out either in labour-intensive economy or with varying degrees of mechanization and automation. The uniform, finished condom if made using previously untrained workers. Training of workers can be done in a matter of hours on the two machines which are needed to produce and test the condoms. The plastic film is provided on a double wound roll, and condom blanks are prepared by means of a heat-sealing die on the stamping machine. The rubber rings are united to the condom blanks on an assembly machine, which consists of a mandrel and heat-sealing equipment to seal the rubber ring to the base of the condom. Built into the assembly machine is a simple air-testing apparatus that can detect the smallest pinhole flaw in a condom. The manufacturing process is completed by unravelling the condom from the assembly

Biodegradability of plastics.

Science.gov (United States)

Tokiwa, Yutaka; Calabia, Buenaventurada P; Ugwu, Charles U; Aiba, Seiichi

2009-08-26

Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

Characterization of plastic blends made from mixed plastics waste of different sources.

Science.gov (United States)

Turku, Irina; Kärki, Timo; Rinne, Kimmo; Puurtinen, Ari

2017-02-01

This paper studies the recyclability of construction and household plastic waste collected from local landfills. Samples were processed from mixed plastic waste by injection moulding. In addition, blends of pure plastics, polypropylene and polyethylene were processed as a reference set. Reference samples with known plastic ratio were used as the calibration set for quantitative analysis of plastic fractions in recycled blends. The samples were tested for the tensile properties; scanning electron microscope-energy-dispersive X-ray spectroscopy was used for elemental analysis of the blend surfaces and Fourier transform infrared (FTIR) analysis was used for the quantification of plastics contents.

Effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure

Directory of Open Access Journals (Sweden)

Zaid N.Z.M.

2017-01-01

Full Text Available Sandwich structure is an attractive alternative that increasingly used in the transportation and aerospace industry. Corrugated-core with trapezoidal shape allows enhancing the damage resistance to the sandwich structure, but on the other hand, it changes the structural response of the sandwich structure. The aim of this paper is to study the effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure under compression loading. The corrugated-core specimen was fabricated using press technique, following the shape of trapezoidal shape. Two different materials were used in the study, glass fibre reinforced plastic (GFRP and carbon fibre reinforced plastic (CFRP. The result shows that the mechanical properties of the core in compression loading are sensitive to the variation of a number of unit cells and the core thickness.

The Prevalence of Cosmetic Facial Plastic Procedures among Facial Plastic Surgeons.

Science.gov (United States)

Moayer, Roxana; Sand, Jordan P; Han, Albert; Nabili, Vishad; Keller, Gregory S

2018-04-01

This is the first study to report on the prevalence of cosmetic facial plastic surgery use among facial plastic surgeons. The aim of this study is to determine the frequency with which facial plastic surgeons have cosmetic procedures themselves. A secondary aim is to determine whether trends in usage of cosmetic facial procedures among facial plastic surgeons are similar to that of nonsurgeons. The study design was an anonymous, five-question, Internet survey distributed via email set in a single academic institution. Board-certified members of the American Academy of Facial Plastic and Reconstructive Surgery (AAFPRS) were included in this study. Self-reported history of cosmetic facial plastic surgery or minimally invasive procedures were recorded. The survey also queried participants for demographic data. A total of 216 members of the AAFPRS responded to the questionnaire. Ninety percent of respondents were male ( n  = 192) and 10.3% were female ( n  = 22). Thirty-three percent of respondents were aged 31 to 40 years ( n  = 70), 25% were aged 41 to 50 years ( n  = 53), 21.4% were aged 51 to 60 years ( n  = 46), and 20.5% were older than 60 years ( n  = 44). Thirty-six percent of respondents had a surgical cosmetic facial procedure and 75% has at least one minimally invasive cosmetic facial procedure. Facial plastic surgeons are frequent users of cosmetic facial plastic surgery. This finding may be due to access, knowledge base, values, or attitudes. By better understanding surgeon attitudes toward facial plastic surgery, we can improve communication with patients and delivery of care. This study is a first step in understanding use of facial plastic procedures among facial plastic surgeons. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Recycling of plastic waste: Presence of phthalates in plastics from households and industry.

Science.gov (United States)

Pivnenko, K; Eriksen, M K; Martín-Fernández, J A; Eriksson, E; Astrup, T F

2016-08-01

Plastics recycling has the potential to substitute virgin plastics partially as a source of raw materials in plastic product manufacturing. Plastic as a material may contain a variety of chemicals, some potentially hazardous. Phthalates, for instance, are a group of chemicals produced in large volumes and are commonly used as plasticisers in plastics manufacturing. Potential impacts on human health require restricted use in selected applications and a need for the closer monitoring of potential sources of human exposure. Although the presence of phthalates in a variety of plastics has been recognised, the influence of plastic recycling on phthalate content has been hypothesised but not well documented. In the present work we analysed selected phthalates (DMP, DEP, DPP, DiBP, DBP, BBzP, DEHP, DCHP and DnOP) in samples of waste plastics as well as recycled and virgin plastics. DBP, DiBP and DEHP had the highest frequency of detection in the samples analysed, with 360μg/g, 460μg/g and 2700μg/g as the maximum measured concentrations, respectively. Among other, statistical analysis of the analytical results suggested that phthalates were potentially added in the later stages of plastic product manufacturing (labelling, gluing, etc.) and were not removed following recycling of household waste plastics. Furthermore, DEHP was identified as a potential indicator for phthalate contamination of plastics. Close monitoring of plastics intended for phthalates-sensitive applications is recommended if recycled plastics are to be used as raw material in production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recycling of plastic waste: Presence of phthalates in plastics from households and industry

DEFF Research Database (Denmark)

Pivnenko, Kostyantyn; Eriksen, Marie Kampmann; Martín-Fernández, J. A.

2016-01-01

Plastics recycling has the potential to substitute virgin plastics partially as a source of raw materials in plastic product manufacturing. Plastic as a material may contain a variety of chemicals, some potentially hazardous. Phthalates, for instance, are a group of chemicals produced in large...... recognised, the influence of plastic recycling on phthalate content has been hypothesised but not well documented. In the present work we analysed selected phthalates (DMP, DEP, DPP, DiBP, DBP, BBzP, DEHP, DCHP and DnOP) in samples of waste plastics as well as recycled and virgin plastics. DBP, DiBP and DEHP...

Biodegradability of Plastics

Directory of Open Access Journals (Sweden)

Yutaka Tokiwa

2009-08-01

Full Text Available Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.. In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.

Elastic-plastic behaviour of thick-walled containers considering plastic compressibility

International Nuclear Information System (INIS)

Betten, J.; Frosch, H.G.

1983-01-01

In this paper the elastic-plastic behaviour of thick-walled pressure vessels with internal and external pressure is studied. To describe the mechanical behaviour of isotropic, plastic compressible materials we use a plastic potential which is a single-valued function of the principle stresses. For cylinders and spheres an analytic expression for the computation of stresses and residual stresses is specified. Afterwards the strains are calculated by using the finite difference method. Some examples will high-light the influence of the plastic compressibility on the behaviour of pressure vessels. (orig.) [de

Mechanically equivalent elastic-plastic deformations and the problem of plastic spin

Directory of Open Access Journals (Sweden)

Steigmann David J.

2011-01-01

Full Text Available The problem of plastic spin is phrased in terms of a notion of mechanical equivalence among local intermediate configurations of an elastic/ plastic crystalline solid. This idea is used to show that, without further qualification, the plastic spin may be suppressed at the constitutive level. However, the spin is closely tied to an underlying undistorted crystal lattice which, once specified, eliminates the freedom afforded by mechanical equivalence. As a practical matter a constitutive specification of plastic spin is therefore required. Suppression of plastic spin thus emerges as merely one such specification among many. Restrictions on these are derived in the case of rate-independent response.

Plastics and health risks.

Science.gov (United States)

Halden, Rolf U

2010-01-01

By 2010, the worldwide annual production of plastics will surpass 300 million tons. Plastics are indispensable materials in modern society, and many products manufactured from plastics are a boon to public health (e.g., disposable syringes, intravenous bags). However, plastics also pose health risks. Of principal concern are endocrine-disrupting properties, as triggered for example by bisphenol A and di-(2-ethylhexyl) phthalate (DEHP). Opinions on the safety of plastics vary widely, and despite more than five decades of research, scientific consensus on product safety is still elusive. This literature review summarizes information from more than 120 peer-reviewed publications on health effects of plastics and plasticizers in lab animals and humans. It examines problematic exposures of susceptible populations and also briefly summarizes adverse environmental impacts from plastic pollution. Ongoing efforts to steer human society toward resource conservation and sustainable consumption are discussed, including the concept of the 5 Rs--i.e., reduce, reuse, recycle, rethink, restrain--for minimizing pre- and postnatal exposures to potentially harmful components of plastics.

Recycling of plastic waste: Presence of phthalates in plastics from households and industry

DEFF Research Database (Denmark)

Pivnenko, Kostyantyn; Eriksen, Marie Kampmann; Martín-Fernández, J. A.

2016-01-01

recognised, the influence of plastic recycling on phthalate content has been hypothesised but not well documented. In the present work we analysed selected phthalates (DMP, DEP, DPP, DiBP, DBP, BBzP, DEHP, DCHP and DnOP) in samples of waste plastics as well as recycled and virgin plastics. DBP, DiBP and DEHP...... product manufacturing (labelling, gluing, etc.) and were not removed following recycling of household waste plastics. Furthermore, DEHP was identified as a potential indicator for phthalate contamination of plastics. Close monitoring of plastics intended for phthalates-sensitive applications...

Challenges in plastics recycling

DEFF Research Database (Denmark)

Pivnenko, Kostyantyn; Jakobsen, L. G.; Eriksen, Marie Kampmann

2015-01-01

Recycling of waste plastics still remains a challenging area in the waste management sector. The current and potential goals proposed on EU or regional levels are difficult to achieve, and even to partially fullfil them the improvements in collection and sorting should be considerable. A study...... was undertaken to investigate the factors affecting quality in plastics recycling. The preliminary results showed factors primarily influencing quality of plastics recycling to be polymer cross contamination, presence of additives, non-polymer impurities, and polymer degradation. Deprivation of plastics quality......, with respect to recycling, has been shown to happen throughout the plastics value chain, but steps where improvements may happen have been preliminary identified. Example of Cr in plastic samples analysed showed potential spreading and accumulation of chemicals ending up in the waste plastics. In order...

Individual differences in behavioural plasticities.

Science.gov (United States)

Stamps, Judy A

2016-05-01

Interest in individual differences in animal behavioural plasticities has surged in recent years, but research in this area has been hampered by semantic confusion as different investigators use the same terms (e.g. plasticity, flexibility, responsiveness) to refer to different phenomena. The first goal of this review is to suggest a framework for categorizing the many different types of behavioural plasticities, describe examples of each, and indicate why using reversibility as a criterion for categorizing behavioural plasticities is problematic. This framework is then used to address a number of timely questions about individual differences in behavioural plasticities. One set of questions concerns the experimental designs that can be used to study individual differences in various types of behavioural plasticities. Although within-individual designs are the default option for empirical studies of many types of behavioural plasticities, in some situations (e.g. when experience at an early age affects the behaviour expressed at subsequent ages), 'replicate individual' designs can provide useful insights into individual differences in behavioural plasticities. To date, researchers using within-individual and replicate individual designs have documented individual differences in all of the major categories of behavioural plasticities described herein. Another important question is whether and how different types of behavioural plasticities are related to one another. Currently there is empirical evidence that many behavioural plasticities [e.g. contextual plasticity, learning rates, IIV (intra-individual variability), endogenous plasticities, ontogenetic plasticities) can themselves vary as a function of experiences earlier in life, that is, many types of behavioural plasticity are themselves developmentally plastic. These findings support the assumption that differences among individuals in prior experiences may contribute to individual differences in behavioural

Durability of wood plastic composites manufactured from recycled plastic

Directory of Open Access Journals (Sweden)

Irina Turku

2018-03-01

Full Text Available The influence of accelerated weathering, xenon-arc light and freeze-thaw cycling on wood plastic composites extruded from a recycled plastic was studied. The results showed that, in general, weathering had a stronger impact on samples made from plastic waste compared to a sample made from virgin material. After weathering, the mechanical properties, tensile and flexural, were reduced by 2–30%, depending on the plastic source. Wettability of the samples was shown to play a significant role in their stability. Chemical analysis with infrared spectroscopy and surface observation with a scan electron microscope confirmed the mechanical test results. Incorporation of carbon black retained the properties during weathering, reducing the wettability of the sample, diminishing the change of mechanical properties, and improving color stability. Keywords: Environmental science, Mechanical engineering, Materials science

Phenotypic plasticity, costs of phenotypes, and costs of plasticity

DEFF Research Database (Denmark)

Callahan, Hilary S; Maughan, Heather; Steiner, Uli

2008-01-01

Why are some traits constitutive and others inducible? The term costs often appears in work addressing this issue but may be ambiguously defined. This review distinguishes two conceptually distinct types of costs: phenotypic costs and plasticity costs. Phenotypic costs are assessed from patterns...... of covariation, typically between a focal trait and a separate trait relevant to fitness. Plasticity costs, separable from phenotypic costs, are gauged by comparing the fitness of genotypes with equivalent phenotypes within two environments but differing in plasticity and fitness. Subtleties associated with both...... types of costs are illustrated by a body of work addressing predator-induced plasticity. Such subtleties, and potential interplay between the two types of costs, have also been addressed, often in studies involving genetic model organisms. In some instances, investigators have pinpointed the mechanistic...

Plastic waste as a resource. Strategies for reduction and utilization of plastic waste

OpenAIRE

Pasqual i Camprubí, Gemma

2010-01-01

Plastic materials have experienced a spectacular rate of growth in recent decades, consequently, production of plastics, and likewise their consumption, has increased markedly since 1950. Moreover, they are lightweight and durable, as well as can be moulded into a variety of products that can be manufactured in many different types of plastic and in a wide range of applications. Inevitably, continually increasing amounts of used plastic are originating daily, resulting in a plastic waste prob...

Thermal degradation and plasticizing mechanism of poly(vinyl chloride) plasticized with a novel cardanol derived plasticizer

Science.gov (United States)

Chen, J.; Nie, X. A.; Jiang, J. C.; Zhou, Y. H.

2018-01-01

A natural plasticizer cardanol derivatives glycidyl ether (CGE) was synthesized and employed as a plasticizer for the poly(vinyl chloride). The effect of CGE on thermal degradation of PVC films and its plasticizing mechanism were firstly reported. The molecular structure of CGE was characterized with Fourier transform infrared spectroscopy (FTIR). Thermal properties, degradation properties and compatibility of the PVC films were investigated by Differential scanning calorimeter analysis (DSC), Thermogravimetric analysis (TGA) and FTIR, respectively. Compared with the commercial plasticizers dioctylphthalate (DOP), CGE can endow PVC film with a decrease of 4.31 °C in glass transition temperature (Tg), an increase of 24.01 °C and 25.53 °C in 10% weight loss (T 10) and 50% weight loss (T 50) respectively, and a higher activetion energy of thermal degradation (Ea ).

Mixed plastics recycling technology

CERN Document Server

Hegberg, Bruce

1995-01-01

Presents an overview of mixed plastics recycling technology. In addition, it characterizes mixed plastics wastes and describes collection methods, costs, and markets for reprocessed plastics products.

Sub-nanosecond plastic scintillators

International Nuclear Information System (INIS)

Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

1977-01-01

Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

Sub-nanosecond plastic scintillators

International Nuclear Information System (INIS)

Lyons, P.B.; Caldwell, S.E.; Hocker, L.P.; Crandall, D.G.; Zagarino, P.A.; Cheng, J.; Tirsell, G.; Hurlbut, C.R.

1976-01-01

Quenched plastic scintillators have been developed that yield much faster short decay components and greatly reduced long decay components compared to conventional plastic scintillators. The plastics are produced through the addition of selected quench agents to NE111 plastic scintillator that result in reduced total light output. Eight different agents have been studied. Benzophenone and piperidine are two of the most effective quench agents. Data are presented both for short and long decay components. The plastics are expected to make significant contributions in areas of plasma diagnostics

Time between plastic displacements of elasto-plastic oscillators subject to Gaussian white noise

DEFF Research Database (Denmark)

Tarp-Johansen, Niels Jacob; Ditlevsen, Ove Dalager

2001-01-01

A one degree of freedom elasto-plastic oscillator subject to stationary Gaussian white noise has a plastic displacement response process of intermittent character. During shorter or longer time intervals the oscillator vibrates within the elastic domain without undergoing any plastic displacements...... between the clumps of plastic displacements. This is needed for a complete description of the plastic displacement process. A quite accurate fast simulation procedure is presented based on an amplitude model to determine the short waiting times in the transient regime of the elastic vibrations existing...

[Application of biodegradable plastic film to reduce plastic film residual pollution in Chinese agriculture].

Science.gov (United States)

Yan, Changrong; He, Wenqing; Xue, Yinghao; Liu, Enke; Liu, Qin

2016-06-25

Plastic film has become an important agriculture production material in recent years. Over the past three decades, the amount and application area of plastic film have increased steadily, and in 2014, which are 1.4 million tons and more than 180 million hm² respectively. It plays a key role for ensuring the supply of agricultural goods in China. Meanwhile, plastic film residual pollution becomes more and more serious, and in some regions, the amount of plastic film residues has reached over 250 kg/hm². In part of the Northwest region, soil structure of farmland has been destroyed by plastic film residues and then crop growth and farming operations were suppressed. It is recognized as a good choice to replace plastic film with biodegradable plastic film, an effective measure to solve the plastic film residue pollution. Now, it is in a critical stage of study and assessment of biodegradable plastic film in China and fortunately some biodegradable plastic films show effects in the production of potatoes, peanuts and tobacco. Overall, a series of challenges has still been faced by the biodegradable plastic film, mainly including improving the quality of biodegradable plastic products, such as tensile strength, flexibility, improving the controllability of rupture and degradation, enhancing the ability of increasing soil temperature and preserving soil moisture, and to satisfy the demand of crops production with mulching. In addition, it is essential to reduce the cost of the biodegradable film and promote the application of biodegradable film on large-scale. With the development of biodegradable plastic technology and agricultural production environment, the application of the biodegradable film will have a good future.

Plastic fish

CERN Multimedia

Antonella Del Rosso

2015-01-01

In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness.   Artwork by Wolfgang Trettnak. Packaging materials, consumer goods (shoes, kids’ toys, etc.), leftovers from fishing and aquaculture activities… our oceans and beaches are full of plastic litter. Most of the debris from beaches is plastic bottles. “PET bottles have high durability and stability,” explains Wolfgang Trettnak, a chemist by education and artist from Austria, who gave a lecture on this topic organised by the Staff Association at CERN on 26 May. “PET degrades very slowly and the estimated lifetime of a bottle is 450 years.” In addition to the beach litter accumulated from human use, rivers bring several ki...

Plastics in the Marine Environment.

Science.gov (United States)

Law, Kara Lavender

2017-01-03

Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence-albeit limited-of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

Plastics in the Marine Environment

Science.gov (United States)

Law, Kara Lavender

2017-01-01

Plastics contamination in the marine environment was first reported nearly 50 years ago, less than two decades after the rise of commercial plastics production, when less than 50 million metric tons were produced per year. In 2014, global plastics production surpassed 300 million metric tons per year. Plastic debris has been detected worldwide in all major marine habitats, in sizes from microns to meters. In response, concerns about risks to marine wildlife upon exposure to the varied forms of plastic debris have increased, stimulating new research into the extent and consequences of plastics contamination in the marine environment. Here, I present a framework to evaluate the current understanding of the sources, distribution, fate, and impacts of marine plastics. Despite remaining knowledge gaps in mass budgeting and challenges in investigating ecological impacts, the increasing evidence of the ubiquity of plastics contamination in the marine environment, the continued rapid growth in plastics production, and the evidence—albeit limited—of demonstrated impacts to marine wildlife support immediate implementation of source-reducing measures to decrease the potential risks of plastics in the marine ecosystem.

Selection of polychlorinated plastics in plastic waste by X-ray fluorescence method

International Nuclear Information System (INIS)

Kumasaki, H.; Shinozaki, Y.

1979-01-01

The X-ray fluorescence method using a small source of 55 Fe was examined and found to be applicable for the selection of polychlorinated plastics from plastic waste in model areas in Tokyo designated for investigating their content in the waste. The weight ratios of soft and hard polychlorinated plastics to the total plastic waste estimated by this method were found to be 15.6% and 0.29% respectively. These values agree well with the results obtained with the Beilstein method. (author)

Toxicological Threats of Plastic

Science.gov (United States)

Plastics pose both physical (e.g., entanglement, gastrointestinal blockage, reef destruction) and chemical threats (e.g., bioaccumulation of the chemical ingredients of plastic or toxic chemicals sorbed to plastics) to wildlife and the marine ecosystem.

Plasticity and beyond microstructures, crystal-plasticity and phase transitions

CERN Document Server

Hackl, Klaus

2014-01-01

The book presents the latest findings in experimental plasticity, crystal plasticity, phase transitions, advanced mathematical modeling of finite plasticity and multi-scale modeling. The associated algorithmic treatment is mainly based on finite element formulations for standard (local approach) as well as for non-standard (non-local approach) continua and for pure macroscopic as well as for directly coupled two-scale boundary value problems. Applications in the area of material design/processing are covered, ranging from grain boundary effects in polycrystals and phase transitions to deep-drawing of multiphase steels by directly taking into account random microstructures.

Vegetative and reproductive evaluation of hot peppers under different plastic mulches in poly/plastic tunnel

International Nuclear Information System (INIS)

Iqbal, Q.; Amjad, M.; Ahmad, R.

2009-01-01

Since the beginning of civilization, the man has developed technologies to increase the efficiency of food production. The use of plastic mulch in commercial vegetable production is one of these traditional techniques that have been used for centuries. Studies were conducted to assess the efficacy of plastic mulch on growth and yield of two hot pepper hybrids, viz. Sky Red and Maha in poly/plastic tunnel. The treatments were black plastic mulch, clear plastic mulch and bare soil as control. Both hot pepper hybrids mulched with black plastic showed significantly better vegetative growth (plant height, leaf area etc) and fruit yield. Clear plastic mulch significantly increased soil temperature and reduced the number of days to first flower than black plastic mulch and bare soil. However, fruit yield was higher by 39.56 and 36.49% respectively in both hybrids when they were grown on black and clear plastic mulch as compared to bare soil. Overall results indicated that the use of plastic mulch is an ideal option to maximize hot pepper productivity as well as to extend their production season in poly/plastic tunnels. (author)

Interaction between vegetable oil based plasticizer molecules and polyvinyl chloride, and their plasticization effect

Science.gov (United States)

Haryono, Agus; Triwulandari, Evi; Jiang, Pingping

2017-01-01

Plasticizer molecules are low molecular weight compounds that are widely used in polymer industries especially in polyvinyl chloride (PVC) resin. As an additive in PVC resin, the important role of plasticizer molecules is to improve the flexibility and processability of PVC by lowering the glass transition temperature (Tg). However, the commercial plasticizer like di(2-ethylhexyl)phthalate (DEHP) is known to cause liver cancer, at least in laboratory rats. DEHP can leach out from PVC into blood, certain drug solutions and fatty foods, which has been detected in the bloodstream of patients undergoing transfusion. Vegetable oil based plasticizers have some attractive properties such as non-toxic, bio-degradable, good heat and light stability, renewable resources, and environmentally friendly. Here we discussed the main results and development of vegetable oil based plasticizer, and especially palm oil based plasticizer. The interaction between plasticizer and polymer was discussed from the properties of the plasticized polymeric material.

Handbook of Plastic Welding

DEFF Research Database (Denmark)

Islam, Aminul

The purpose of this document is to summarize the information about the laser welding of plastic. Laser welding is a matured process nevertheless laser welding of micro dimensional plastic parts is still a big challenge. This report collects the latest information about the laser welding of plastic...... materials and provides an extensive knowhow on the industrial plastic welding process. The objectives of the report include: - Provide the general knowhow of laser welding for the beginners - Summarize the state-of-the-art information on the laser welding of plastics - Find the technological limits in terms...... of design, materials and process - Find the best technology, process and machines adaptive to Sonion’s components - Provide the skills to Sonion’s Design Engineers for successful design of the of the plastic components suitable for the laser welding The ultimate goal of this report is to serve...

Abiotic degradation of plastic films

Science.gov (United States)

Ángeles-López, Y. G.; Gutiérrez-Mayen, A. M.; Velasco-Pérez, M.; Beltrán-Villavicencio, M.; Vázquez-Morillas, A.; Cano-Blanco, M.

2017-01-01

Degradable plastics have been promoted as an option to mitigate the environmental impacts of plastic waste. However, there is no certainty about its degradability under different environmental conditions. The effect of accelerated weathering (AW), natural weathering (NW) and thermal oxidation (TO) on different plastics (high density polyethylene, HDPE; oxodegradable high density polyethylene, HDPE-oxo; compostable plastic, Ecovio ® metalized polypropylene, PP; and oxodegradable metalized polypropylene, PP-oxo) was studied. Plastics films were exposed to AW per 110 hours; to NW per 90 days; and to TO per 30 days. Plastic films exposed to AW and NW showed a general loss on mechanical properties. The highest reduction in elongation at break on AW occurred to HDPE-oxo (from 400.4% to 20.9%) and was higher than 90% for HDPE, HDPE-oxo, Ecovio ® and PP-oxo in NW. No substantial evidence of degradation was found on plastics exposed to TO. Oxo-plastics showed higher degradation rates than their conventional counterparts, and the compostable plastic was resistant to degradation in the studied abiotic conditions. This study shows that degradation of plastics in real life conditions will vary depending in both, their composition and the environment.

Plasticity characteristic obtained by indentation

International Nuclear Information System (INIS)

Mil'man, Yu.V.; Chugunova, S.I.; Goncharova, I.V.

2011-01-01

Methods for determination plasticity characteristic δH in the measurement of hardness and nanohardness are considered. Parameter δH characterizes the plasticity of a material by the part of plastic deformation in the total elastic-plastic deformation. The value of δH is defined for metals with different types of crystal lattice, covalent and partially covalent crystals, intermetallics, metallic glasses and quasicrystals. It is discussed the dependence of the plasticity characteristic δH on structural factors and temperature. Parameter δH allows to analyze and compare the plasticity of materials which are brittle at standard mechanical tests. The combination of hardness H, as the strength characteristic, and the plasticity characteristic δH makes possible the better characterization of mechanical behavior of materials than only the hardness H. The examples of plasticity characteristic δH application are represented.

Experiments with elasto-plastic oscillator

DEFF Research Database (Denmark)

Randrup-thomsen, Søren; Ditlevsen, Ove Dalager

1996-01-01

Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...

Experiments with elasto-plastic oscillator

DEFF Research Database (Denmark)

Randrup-Thomsen, S.; Ditlevsen, Ove Dalager

1999-01-01

Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...

ENVIRONMENTAL ISSUE-PLASTIC

OpenAIRE

Sunita Shakle

2017-01-01

Polythene is the most common plastic, the annual global production is approximately 60 million tones, and its primary use is in packing. Plastic bags pollute soil and waters and kill thousands of marine generalize plastic bags are not biodegradable they clog water ways, spoil the land scape and end up in landfills. Where they may take 1000 year or more to break down into ever smaller particals that continue to pollution the soil and water.

Nano-Ceramic Coated Plastics

Science.gov (United States)

Cho, Junghyun

2013-01-01

Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (nano-ceramic coatings (TiO2, ZnO) on plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

Performance and Characterization of Shear Ties for Use in Insulated Precast Concrete Sandwich Wall Panels

Science.gov (United States)

2010-11-01

stainless 14 steel, galvanized carbon steel, carbon- fiber -reinforced polymer (CFRP), glass- fiber -reinforced polymer 15 (GFRP), and basalt - fiber ...CFRP Grid, (E) Universal Building Products GFRP Teplo Tie, and (F) Universal Building Products 6 Basalt FRP RockBar. Traditional steel connections...1.6 E Universal Building Products TeploTie GFRP Tie 10 mm dia. x 150 mm F RockBar Basalt FRP Bar 7 in. x 5/16 in. G TSA Manufacturing C-Clip

Elastic-plastic analysis of AS4/PEEK composite laminate using a one-parameter plasticity model

Science.gov (United States)

Sun, C. T.; Yoon, K. J.

1992-01-01

A one-parameter plasticity model was shown to adequately describe the plastic deformation of AS4/PEEK (APC-2) unidirectional thermoplastic composite. This model was verified further for unidirectional and laminated composite panels with and without a hole. The elastic-plastic stress-strain relations of coupon specimens were measured and compared with those predicted by the finite element analysis using the one-parameter plasticity model. The results show that the one-parameter plasticity model is suitable for the analysis of elastic-plastic deformation of AS4/PEEK composite laminates.

Performance of molded plastic scintillators

International Nuclear Information System (INIS)

Gen, N.S.; Leman, V.E.; Solomonov, V.M.

1989-01-01

The performance of molded plastic scintillators is studied. The plastic scintillators studied were formed by transfer molding and intrusion from a scintillation composition consisting of polystyrene and a standard system of luminescent additives: 2 mass % of paraterphenyl + 0.06 mass % 1,4-di-/2-[5-phenyloxazoyly]/benzene and a plasticizer. The combined effect of mechanical load and temperature was studied. The effect of radiation on molded plastic scintillators was studied using gamma radiation from a 60 Co source. The studies show that the main operating characteristics of molded plastic scintillators are on a par with those of polymerized plastic scintillators. At the same time, molded plastic scintillators are superior in thermal stability at temperatures below the glass transition temperature and with respect to their working temperature range

Plastic food packaging and health

Directory of Open Access Journals (Sweden)

Raika Durusoy

2011-02-01

Full Text Available Plastics have a wide usage in our daily lives. One of their uses is for food packaging and food containers. The aim of this review is to introduce different types of chemicals that can leach from food packaging plastics into foods and cause human exposure and to mention their effects on health. The types of plastics were reviewed under the 13 headings in Turkish Codex Alimentarius and plastics recycling symbols were provided to enable the recognition of the type of plastic when applicable. Chemicals used during the production and that can cause health risks are investigated under the heading of the relevant type of plastic. The most important chemicals from plastic food packaging that can cause toxicity are styrene, 1,3-butadiene, melamine, formaldehyde, acrylamide, di-2-ethylhexyl phthalate, di-2-ethylhexyl adipate, vinyl chloride and bisphenol A. These chemicals have endocrine disrupting, carcinogenic and/or development disrupting effects. These chemicals may leach into foods depending on the chemical properties of the plastic or food, temperature during packaging, processing and storage, exposure to UV and duration of storage. Contact with fatty/oily or acidic foods, heating of the food inside the container, or drinking hot drinks from plastic cups, use of old and scratched plastics and some detergents increase the risk of leaching. The use of plastic containers and packaging for food and beveradges should be avoided whenever possible and when necessary, less harmful types of plastic should be preferred. [TAF Prev Med Bull 2011; 10(1.000: 87-96

Our plastic age

OpenAIRE

Thompson, Richard C.; Swan, Shanna H.; Moore, Charles J.; vom Saal, Frederick S.

2009-01-01

Within the last few decades, plastics have revolutionized our daily lives. Globally we use in excess of 260 million tonnes of plastic per annum, accounting for approximately 8 per cent of world oil production. In this Theme Issue of Philosophical Transactions of the Royal Society, we describe current and future trends in usage, together with the many benefits that plastics bring to society. At the same time, we examine the environmental consequences resulting from the accumulation of waste pl...

A Conservative Formulation for Plasticity

Science.gov (United States)

1992-01-01

concepts that apply to a broad class of macroscopic models: plastic deformation and plastic flow rule. CONSERVATIVE PLASTICITY 469 3a. Plastic Defrrnation...temperature. We illustrate these concepts with a model that has been used to describe high strain-rate plastic flow in metals [11, 31, 32]. In the case...JOURDREN, AND P. VEYSSEYRE. Un Modele ttyperelastique- Plastique Euldrien Applicable aux Grandes Dtformations: Que/ques R~sultats 1-D. preprint, 1991. 2. P

Wood-plastic combination

International Nuclear Information System (INIS)

Schaudy, R.

1978-02-01

A review on wood-plastic combinations is given including the production (wood and plastic component, radiation hardening, curing), the obtained properties, present applications and prospects for the future of these materials. (author)

Plastic deformation and contact area of an elastic-plastic contact of ellipsoid bodies after unloading

NARCIS (Netherlands)

Jamari, Jamari; Schipper, Dirk J.

2007-01-01

This paper presents theoretical and experimental results of the residual or plastic deformation and the plastic contact area of an elastic–plastic contact of ellipsoid bodies after unloading. There are three regime responses of the deformation and contact area: elastic, elastic–plastic and fully

Effect of Cr on the passive film formation mechanism of steel rebar in saturated calcium hydroxide solution

Energy Technology Data Exchange (ETDEWEB)

Liu, Ming; Cheng, Xuequn [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China); Li, Xiaogang, E-mail: lixiaogang@ustb.edu.cn [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China); Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, Zhejiang (China); Pan, Yue; Li, Jun [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China)

2016-12-15

Highlights: • Cr inhibits the formation of passive film at the beginning of its formation. • Cr promotes the formation of a denser and more compact passive film. • The passive film thickness presents a slight increase as the content of Cr goes up. - Abstract: Passive films grow on the surface of Cr-modified steels subjected to saturated Ca(OH){sub 2} solution. Electrochemical techniques, such as measurement of open circuit potentials, polarization curves, and electrochemical impedance spectroscopy combined with X-ray photoelectron spectrometer and auger electron spectroscopy, were applied to study the influence of low Cr content on the passive film formation mechanism of steel rebar in saturated Ca(OH){sub 2} solution. Results show that Cr inhibits the formation of passive film at the beginning of its formation. Corrosion current density decreases and polarization resistance increases with the extension of the immersion time. A stable passive film takes at least three days to form. The passive film resistance of HRB400 carbon steel is higher than that of Cr-modified steels in the early stage of immersion (<72 h). The polarization resistance of Cr-modified steel is larger after a stable passive film is formed (>72 h), and Cr promotes the formation of a denser and more compact passive film. The stable passive film is primarily made up of iron oxides with a thickness of 5–6 nm. Cr are involved in the formation of passive films, thereby resulting in a film that consists of an inner layer that contains Cr–Fe oxides and an outer layer that contains Fe oxides, whose thickness presents a slight increase as the content of Cr increases.

Synaptic Plasticity and Nociception

Institute of Scientific and Technical Information of China (English)

ChenJianguo

2004-01-01

Synaptic plasticity is one of the fields that progresses rapidly and has a lot of success in neuroscience. The two major types of synaptie plasticity: long-term potentiation ( LTP and long-term depression (LTD are thought to be the cellular mochanisms of learning and memory. Recently, accumulating evidence suggests that, besides serving as a cellular model for learning and memory, the synaptic plasticity involves in other physiological or pathophysiological processes, such as the perception of pain and the regulation of cardiovascular system. This minireview will focus on the relationship between synaptic plasticity and nociception.

Synthesis of biodegradable plastic from tapioca with N-Isopropylacrylamid and chitosan using glycerol as plasticizer

Science.gov (United States)

Syaubari; Safwani, S.; Riza, M.

2018-04-01

One of natural polymers that can be used as raw material in the manufacture of biodegradable plastic is tapioca and chitosan. The addition of other compounds such as glycerol as plasticizer is to improve the characteristics of the plastic that already produced. N- Isopropylacrylamid (NIPAm) is an organic compound that can be synthesized into a polymer or polymer grafting which also biodegradable too. This research aims tostudy the synthesis of biodegradable plastics from tapioca with the addition of chitosan, NIPAm, poly(NIPAm) and analyze the characteristics of biodegradable plastics that already produced. This research was done in three stages, there are (1) polymerization NIPAm, (2) the grafting of chitosan-poly NIPAm and (3) the synthesis of biodegradable plastics from starch mixture with variation of addition chitosan, NIPAm, poly(NIPAm), chitosan-graft-poly(NIPAm) and also variations of glycerol as plasticizer. The results of this research is a thin sheet of plastic which is will get analyzed for the characteristics of functional groups, mechanical, morphological and its biodegradability. FTIR spectra showed the grafting process with the new group formation of CO single-bond at 850 cm-1. Plastic with the addition of NIPAm and 1 ml glycerol has the highest tensile strength value about 31.1 MPa. Plastic with poly(NIPAm) and 4 ml glycerol produces the highest elongation value about 153.72%. Plastic with Chitosan-graft-poly(NIPAm) with 1 ml glycerol has the longest biodegradation because of the small mass-loss for six weeks which is about 6.6%.

New perspectives in plastic biodegradation.

Science.gov (United States)

Sivan, Alex

2011-06-01

During the past 50 years new plastic materials, in various applications, have gradually replaced the traditional metal, wood, leather materials. Ironically, the most preferred property of plastics--durability--exerts also the major environmental threat. Recycling has practically failed to provide a safe solution for disposal of plastic waste (only 5% out of 1 trillion plastic bags, annually produced in the US alone, are being recycled). Since the most utilized plastic is polyethylene (PE; ca. 140 million tons/year), any reduction in the accumulation of PE waste alone would have a major impact on the overall reduction of the plastic waste in the environment. Since PE is considered to be practically inert, efforts were made to isolate unique microorganisms capable of utilizing synthetic polymers. Recent data showed that biodegradation of plastic waste with selected microbial strains became a viable solution. Copyright © 2011 Elsevier Ltd. All rights reserved.

Thermal test of the insulation structure for LH 2 tank by using the large experimental apparatus

Science.gov (United States)

Kamiya, S.; Onishi, K.; Konshima, N.; Nishigaki, K.

Conceptual designs of large mass LH 2 (liquid hydrogen) storage systems, whose capacity is 50,000 m3, have been studied in the Japanese hydrogen project, World Energy Network (WE-NET) [K. Fukuda, in: WE-NET Hydrogen Energy Symposium, 1999, P1-P41]. This study has concluded that their thermal insulation structures for the huge LH 2 tanks should be developed. Their actual insulation structures comprise not only the insulation material but also reinforced members and joints. To evaluate their thermal performance correctly, a large test specimen including reinforced members and joints will be necessary. After verifying the thermal performance of a developed large experimental apparatus [S. Kamiya, Cryogenics 40 (1) (2000) 35] for measuring the thermal conductance of various insulation structures, we tested two specimens, a vacuum multilayer insulation (MLI) with a glass fiber reinforced plastic (GFRP) support and a vacuum solid insulation (microtherm ®) with joints. The thermal background test for verifying the thermal design of the experimental apparatus showed that the background heat leak is 0.1 W, small enough to satisfy apparatus performance requirement. The thermal conductance measurements of specimens also showed that thermal heat fluxes of MLI with a GFRP support and microtherm ® are 8 and 5.4 W/m2, respectively.

Avalanches and plastic flow in crystal plasticity: an overview

Science.gov (United States)

Papanikolaou, Stefanos; Cui, Yinan; Ghoniem, Nasr

2018-01-01

Crystal plasticity is mediated through dislocations, which form knotted configurations in a complex energy landscape. Once they disentangle and move, they may also be impeded by permanent obstacles with finite energy barriers or frustrating long-range interactions. The outcome of such complexity is the emergence of dislocation avalanches as the basic mechanism of plastic flow in solids at the nanoscale. While the deformation behavior of bulk materials appears smooth, a predictive model should clearly be based upon the character of these dislocation avalanches and their associated strain bursts. We provide here a comprehensive overview of experimental observations, theoretical models and computational approaches that have been developed to unravel the multiple aspects of dislocation avalanche physics and the phenomena leading to strain bursts in crystal plasticity.

A bamboo braced frame system for tropical climates

Directory of Open Access Journals (Sweden)

Echeverria, J.

2014-12-01

Full Text Available A low-cost housing system was developed for use in tropical countries, specifically Haiti, with the aims of minimizing environmental impact (including carbon emissions, maximizing use of local and preferably recycled materials, and using local labor. The housing system integrates low-strength concrete blocks (made using recycled concrete aggregate, an innovative seismically-resistant bamboo frame, earthen plasters, bamboo trusses, and metal deck roofs. The bamboo frame relies on flexural yielding of a short rebar dowel to provide ductile performance at a controlled strength level. The plinth walls below the frame and short rebar dowel protects the bamboo from moisture. The top of a plastic soda bottle is used to protect the rebar from moisture and to seal the base of the bamboo culm, allowing mortar to be introduced into the culm above. This paper focuses on the experimental and analytical results of the flexural yielding of the rebar dowel to establish the structural design of this critical component of the system for resisting wind and seismic loads.En este artículo se presenta un sistema de construcción de viviendas de bajo coste para países tropicales en los cuales existe riesgo sísmico. Los objetivos de este trabajo son generar bajo impacto medioambiental (incluyendo las emisiones de carbono, empleo de materiales locales, preferiblemente reciclados, y mano de obra local. Para esta construcción se han empleado bloques de hormigón de baja resistencia (con agregado reciclado junto con un innovador sistema de pórticos de bambú, botellas de plástico, vigas de bambú y cubiertas de chapa. El comportamiento dúctil de la estructura se garantiza introduciendo una barra de acero en la base del pórtico de bambú. Para proteger el bambú de la humedad, el pórtico se monta sobre un zócalo. Los resultados experimentales y analíticos obtenidos se utilizan para el diseño estructural del sistema frente a cargas de viento y sísmicas.

Melting the Plastic Ceiling: Overcoming Obstacles to Foster Leadership in Women Plastic Surgeons.

Science.gov (United States)

Silva, Amanda K; Preminger, Aviva; Slezak, Sheri; Phillips, Linda G; Johnson, Debra J

2016-09-01

The underrepresentation of women leaders in plastic surgery echoes a phenomenon throughout society. The importance of female leadership is presented, and barriers to gender equality in plastic surgery, both intrinsic and extrinsic, are discussed. Strategies for fostering women in leadership on an individual level and for the specialty of plastic surgery are presented.

The electrical characteristics of solid insulators for 154 kV class HTS transformer

International Nuclear Information System (INIS)

Cheon, H.G.; Choi, J.H.; Pang, M.S.; Kim, W.J.; Kim, S.H.

2011-01-01

HTS transformer, without any loss of insulation lifetime due to the reduction in terms of size and weight, can increase the overload capacity, and have some benefits such as the improvement in efficiency, minimization of environmental pollution, and convenient spatial arrangement, which contribute a lot to electric power system operation. However, for practical insulation design of the HTS transformer, it is necessary to establish the research on electrical properties LN 2 as well as solid insulators. These solid insulators have been used as main insulations for HTS transformer. In this paper, we discussed breakdown and V-t characteristics of glass fiber reinforced plastics (GFRP) and pressboard in LN 2 .

Some Limitations in the Use of Plastic and Dyed Plastic Dosimeters

DEFF Research Database (Denmark)

Miller, Arne; Bjergbakke, Erling; McLaughlin, W. L.

1975-01-01

Several practical plastic and dyed plastic dosimeters were examined under irradiation conditions similar to those used for radiation processing of materials. Cellulose triacetate, polymethyl methacrylate, polyvinyl chloride, dyed polymethyl methacrylate, dyed Cellophane and dyed Nylon were given...

Plastic Fishes

CERN Multimedia

Trettnak, Wolfgang

2015-01-01

In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness. The slideshow below gives you a taste of the artworks by Wolfgang Trettnak and Margarita Cimadevila.

Plasticity resembling spike-timing dependent synaptic plasticity: the evidence in human cortex

Directory of Open Access Journals (Sweden)

Florian Müller-Dahlhaus

2010-07-01

Full Text Available Spike-timing dependent plasticity (STDP has been studied extensively in a variety of animal models during the past decade but whether it can be studied at the systems level of the human cortex has been a matter of debate. Only recently newly developed non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS have made it possible to induce and assess timing dependent plasticity in conscious human subjects. This review will present a critical synopsis of these experiments, which suggest that several of the principal characteristics and molecular mechanisms of TMS-induced plasticity correspond to those of STDP as studied at a cellular level. TMS combined with a second phasic stimulation modality can induce bidirectional long-lasting changes in the excitability of the stimulated cortex, whose polarity depends on the order of the associated stimulus-evoked events within a critical time window of tens of milliseconds. Pharmacological evidence suggests an NMDA receptor mediated form of synaptic plasticity. Studies in human motor cortex demonstrated that motor learning significantly modulates TMS-induced timing dependent plasticity, and, conversely, may be modulated bidirectionally by prior TMS-induced plasticity, providing circumstantial evidence that long-term potentiation-like mechanisms may be involved in motor learning. In summary, convergent evidence is being accumulated for the contention that it is now possible to induce STDP-like changes in the intact human central nervous system by means of TMS to study and interfere with synaptic plasticity in neural circuits in the context of behaviour such as learning and memory.

Plastic and Non-plastic Debris Ingestion in Three Gull Species Feeding in an Urban Landfill Environment.

Science.gov (United States)

Seif, S; Provencher, J F; Avery-Gomm, S; Daoust, P-Y; Mallory, M L; Smith, P A

2018-04-01

Plastic debris is recognized as a widespread, common and problematic environmental pollutant. An important consequence of this pollution is the ingestion of plastic debris by wildlife. Assessing the degree to which different species ingest plastics, and the potential effects of these plastics on their health are important research needs for understanding the impacts of plastic pollution. We examined debris (plastic and other types) ingestion in three sympatric overwintering gull species (Herring gulls Larus smithsonianus, Great Black-backed Gulls Larus marinus, and Iceland Gulls Larus glaucoides) to understand how debris ingestion differs among species, age classes and sexes in gulls. We also assessed how plastic burdens were associated with body condition to investigate how gulls may be affected by debris ingestion. There were no differences among the species, age classes or sexes in the incidence of debris ingestion (plastic or otherwise), the mass or number of debris pieces ingested. We found no correlation between ingested plastics burdens and individual condition. Gulls ingested plastic debris, but also showed high levels of other debris types as well, including metal, glass and building materials, including a metal piece of debris found within an abscess in the stomach. Thus, when the health effects of debris ingestion on gulls, and other species that ingest debris, is of interest, either from a physical or chemical perspective, it may be necessary to consider all debris types and not just plastic burdens as is often currently done for seabirds.

Education on the Business of Plastic Surgery During Training: A Survey of Plastic Surgery Residents.

Science.gov (United States)

Ovadia, Steven A; Gishen, Kriya; Desai, Urmen; Garcia, Alejandro M; Thaller, Seth R

2018-06-01

Entrepreneurial skills are important for physicians, especially plastic surgeons. Nevertheless, these skills are not typically emphasized during residency training. Evaluate the extent of business training at plastic surgery residency programs as well as means of enhancing business training. A 6-question online survey was sent to plastic surgery program directors for distribution to plastic surgery residents. Responses from residents at the PGY2 level and above were included for analysis. Tables were prepared to present survey results. Hundred and sixty-six residents including 147 PGY2 and above residents responded to our survey. Only 43.5% reported inclusion of business training in their plastic surgery residency. A majority of residents reported they do not expect on graduation to be prepared for the business aspects of plastic surgery. Additionally, a majority of residents feel establishment of a formal lecture series on the business of plastic surgery would be beneficial. Results from our survey indicate limited training at plastic surgery programs in necessary business skills. Plastic surgery residency programs should consider incorporating or enhancing elements of business training in their curriculum. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Beam Test for Evaluating Applicabillity of High - Strength Reinforcement in Structure of Nuclear Facility

International Nuclear Information System (INIS)

Yim, Sangjun; Lee, Byungsoo; Bang, Changjoon

2014-01-01

The high-strength rebar which has high yield strength can reduce the amount of rebar in concrete and widen its spacing so that it has better workability and higher economic benefits for the structure. However, the maximum yield strength of rebar is limited to 420MPa in the design criteria for structure of nuclear facility in Korea and USA. Korea Hydro and Nuclear Power is progressing research to revise the limitation in the yield strength of rebar, which is suggested in the criteria of KEPIC and ACI, in order to apply 550 MPa high-strength rebar for the construction of a nuclear facility. This study is to review the applicability of high strength rebar in structure of a nuclear facility through a model beam test. After reviewing the shear capacity and reinforcement yield to assess the applicability of high-strength reinforcement in the structure of a nuclear facility, we make the following conclusions. When using high shear reinforcement with wider spacing, it has a similar shear capacity to normal reinforcement with narrower spacing. This means better workability and economic benefits can be achieved by widening the rebar spacing without brittle fracture in the elements. For future plans, the results of this test and supplementary test will be submitted to ACI349 committee as backup data to revise the standard for yield strength of high-strength rebar

Beam Test for Evaluating Applicabillity of High - Strength Reinforcement in Structure of Nuclear Facility

Energy Technology Data Exchange (ETDEWEB)

Yim, Sangjun; Lee, Byungsoo; Bang, Changjoon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

2014-05-15

The high-strength rebar which has high yield strength can reduce the amount of rebar in concrete and widen its spacing so that it has better workability and higher economic benefits for the structure. However, the maximum yield strength of rebar is limited to 420MPa in the design criteria for structure of nuclear facility in Korea and USA. Korea Hydro and Nuclear Power is progressing research to revise the limitation in the yield strength of rebar, which is suggested in the criteria of KEPIC and ACI, in order to apply 550 MPa high-strength rebar for the construction of a nuclear facility. This study is to review the applicability of high strength rebar in structure of a nuclear facility through a model beam test. After reviewing the shear capacity and reinforcement yield to assess the applicability of high-strength reinforcement in the structure of a nuclear facility, we make the following conclusions. When using high shear reinforcement with wider spacing, it has a similar shear capacity to normal reinforcement with narrower spacing. This means better workability and economic benefits can be achieved by widening the rebar spacing without brittle fracture in the elements. For future plans, the results of this test and supplementary test will be submitted to ACI349 committee as backup data to revise the standard for yield strength of high-strength rebar.

The effects of plastic waves on the numerical convergence of the viscous-plastic and elastic-viscous-plastic sea-ice models

Science.gov (United States)

Williams, James; Tremblay, L. Bruno; Lemieux, Jean-François

2017-07-01

The plastic wave speed is derived from the linearized 1-D version of the widely used viscous-plastic (VP) and elastic-viscous-plastic (EVP) sea-ice models. Courant-Friedrichs-Lewy (CFL) conditions are derived using the propagation speed of the wave. 1-D numerical experiments of the VP, EVP and EVP* models successfully recreate a reference solution when the CFL conditions are satisfied, in agreement with the theory presented. The IMplicit-EXplicit (IMEX) method is shown to effectively alleviate the plastic wave CFL constraint on the timestep in the implicitly solved VP model in both 1-D and 2-D. In 2-D, the EVP and EVP* models show first order error in the simulated velocity field when the plastic wave is not resolved. EVP simulations are performed with various advective timestep, number of subcycles, and elastic-wave damping timescales. It is found that increasing the number of subcycles beyond that needed to resolve the elastic wave does not improve the quality of the solution. It is found that reducing the elastic wave damping timescale reduces the spatial extent of first order errors cause by the unresolved plastic wave. Reducing the advective timestep so that the plastic wave is resolved also reduces the velocity error in terms of magnitude and spatial extent. However, the parameter set required for convergence to within the error bars of satellite (RGPS) deformation fields is impractical for use in climate model simulations. The behavior of the EVP* method is analogous to that of the EVP method except that it is not possible to reduce the damping timescale with α = β.

Coliquefaction of coal, tar sand bitumen and plastic (interaction among coal, bitumen and plastic); Sekitan/tar sand bitumen/plastic no kyoekika ni okeru kyozon busshitsu no eikyo

Energy Technology Data Exchange (ETDEWEB)

Yamaguchi, H.; Okuyama, Y.; Matsubara, K. [NKK Corp., Tokyo (Japan); Kamo, T.; Sato, Y. [National Institute for Resources and Environment, Tsukuba (Japan)

1996-10-28

For the improvement of economy, coliquefaction of coal, tar sand bitumen and plastic was performed under low hydrogen pressure, to investigate the influence of interaction among these on the liquefaction characteristics. For comparison, coliquefaction was also performed under the hydrogen pressure same as the NEDOL process. In addition, for clarifying its reaction mechanism, coliquefaction of dibenzyl and plastic was performed as a model experiment, to illustrate the distribution of products and composition of oil, and to discuss the interaction between dibenzyl and various plastics, and between various plastics. Under direct coal liquefaction conditions, coprocessing of Tanito Harum coal, Athabasca tar sand and plastic was carried out under low hydrogen pressure with an autoclave. The observed value of oil yield was higher than the calculated value based on the values from separate liquefaction of coal and plastic, which suggested the interaction between coal and the mixed plastic. The results of coliquefaction of coal, tar sand bitumen and plastic could be explained from the obtained oil yield and its composition by the coliquefaction of dibenzyl and plastic. 2 refs., 3 tabs.

A review of plastic waste biodegradation.

Science.gov (United States)

Zheng, Ying; Yanful, Ernest K; Bassi, Amarjeet S

2005-01-01

With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

Recycling of plastics

Energy Technology Data Exchange (ETDEWEB)

Kaminsky, W; Menzel, J; Sinn, H

1976-01-01

Considering the shortage of raw materials and environmental pollution, the recycling of plastic waste is a very important topic. Pilot plants for research in Funabashi Japan, Franklin (Ohio) U.S.A., and the R 80-process of Krauss Maffei, W. Germany, have demonstrated the possibility of reclaiming plastics from refuse. Old tires and waste from the plastic producing and manufacturing industries are readily available. The pyrolysis of plastic yields gaseous and liquid products, and the exploitation of this cracking reaction has been demonstrated by pilot plants in Japan and Great Britain. Further laboratory scale experiments are taking place in W. Germany. In continuous fluidized beds and in molten salts, polyethylene, polypropylene, polyvinylchloride, polystyrene and rubber are pyrolysed and better than 98 percent conversion is obtained. Up to 40 percent of the feed can be obtained as aromatic compounds, and a pilot plant is under construction. As a first step PVC-containing material can be almost quantitatively dehydrochlorinated.

Plastics and environment

International Nuclear Information System (INIS)

Avenas, P.

1996-01-01

Synthetic organic polymers, such as plastics, PVC, polyamides etc are considered less ecological than natural materials such as wood. Other artificial materials such as metals, glass or biodegradable plastics have also a better image than petroleum products. This short paper demonstrates that the manufacturing or the transport of every material uses energy and that the complete energy balance sheet of a plastic bottle, for instance, is more favourable than the one of a glass bottle. Plastic materials are also easily valorized and recycled and part of the energy spent during manufacturing can be recovered during incineration for district heating. During the life-cycle of such a synthetic material, the same petroleum quantity can be used twice which leads to less negative effects on the environment. Finally, the paper focusses on the problem of biodegradable materials which are not degradable when buried under several meters of wastes and which are a nuisance to recycling. (J.S.)

Stem cell plasticity.

Science.gov (United States)

Lakshmipathy, Uma; Verfaillie, Catherine

2005-01-01

The central dogma in stem cell biology has been that cells isolated from a particular tissue can renew and differentiate into lineages of the tissue it resides in. Several studies have challenged this idea by demonstrating that tissue specific cell have considerable plasticity and can cross-lineage restriction boundary and give rise to cell types of other lineages. However, the lack of a clear definition for plasticity has led to confusion with several reports failing to demonstrate that a single cell can indeed differentiate into multiple lineages at significant levels. Further, differences between results obtained in different labs has cast doubt on some results and several studies still await independent confirmation. In this review, we critically evaluate studies that report stem cell plasticity using three rigid criteria to define stem cell plasticity; differentiation of a single cell into multiple cell lineages, functionality of differentiated cells in vitro and in vivo, robust and persistent engraft of transplanted cells.

Cross-Linked Amylose Bio-Plastic: A Transgenic-Based Compostable Plastic Alternative

Directory of Open Access Journals (Sweden)

Domenico Sagnelli

2017-09-01

Full Text Available Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO, an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi© plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material.

Cross-Linked Amylose Bio-Plastic: A Transgenic-Based Compostable Plastic Alternative

Science.gov (United States)

Sagnelli, Domenico; Kemmer, Gerdi Christine; Holse, Mette; Hebelstrup, Kim H.; Bao, Jinsong; Stelte, Wolfgang; Bjerre, Anne-Belinda; Blennow, Andreas

2017-01-01

Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO), an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi© plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material. PMID:28973963

Cross-Linked Amylose Bio-Plastic: A Transgenic-Based Compostable Plastic Alternative.

Science.gov (United States)

Sagnelli, Domenico; Hooshmand, Kourosh; Kemmer, Gerdi Christine; Kirkensgaard, Jacob J K; Mortensen, Kell; Giosafatto, Concetta Valeria L; Holse, Mette; Hebelstrup, Kim H; Bao, Jinsong; Stelte, Wolfgang; Bjerre, Anne-Belinda; Blennow, Andreas

2017-09-30

Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO), an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi © plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material.

Plastics and beaches: A degrading relationship

International Nuclear Information System (INIS)

Corcoran, Patricia L.; Biesinger, Mark C.; Grifi, Meriem

2009-01-01

Plastic debris in Earth's oceans presents a serious environmental issue because breakdown by chemical weathering and mechanical erosion is minimal at sea. Following deposition on beaches, plastic materials are exposed to UV radiation and physical processes controlled by wind, current, wave and tide action. Plastic particles from Kauai's beaches were sampled to determine relationships between composition, surface textures, and plastics degradation. SEM images indicated that beach plastics feature both mechanically eroded and chemically weathered surface textures. Granular oxidation textures were concentrated along mechanically weakened fractures and along the margins of the more rounded plastic particles. Particles with oxidation textures also produced the most intense peaks in the lower wavenumber region of FTIR spectra. The textural results suggest that plastic debris is particularly conducive to both chemical and mechanical breakdown in beach environments, which cannot be said for plastics in other natural settings on Earth

Art and Plastic Surgery.

Science.gov (United States)

Fernandes, Julio Wilson; Metka, Susanne

2016-04-01

The roots of science and art of plastic surgery are very antique. Anatomy, drawing, painting, and sculpting have been very important to the surgery and medicine development over the centuries. Artistic skills besides shape, volume, and lines perception can be a practical aid to the plastic surgeons' daily work. An overview about the interactions between art and plastic surgery is presented, with a few applications to rhinoplasty, cleft lip, and other reconstructive plastic surgeries. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Plastics recycling: challenges and opportunities.

Science.gov (United States)

Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

2009-07-27

Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3-4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

Plastics recycling: challenges and opportunities

Science.gov (United States)

Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

2009-01-01

Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3–4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it

Plastic pollutants in water environment

OpenAIRE

Mrowiec Bożena

2017-01-01

Nowadays, wide applications of plastics result in plastic waste being present in the water environment in a wide variety of sizes. Plastic wastes are in water mainly as microplastics (the size range of 1 nm to < 5 mm). Microplastics have been recognized as an emerging threat, as well as ecotoxicological and ecological risk for water ecosystems. In this review are presented some of the physicochemical properties of plastic materials that determine their toxic effect on the aquatic environment....

DEVELOPMENT OF PLASTIC SURGERY.

Science.gov (United States)

Pećanac, Marija Đ

2015-01-01

Plastic surgery is a medical specialty dealing with corrections of defects, improvements in appearance and restoration of lost function. Ancient times. The first recorded account of reconstructive plastic surgery was found in ancient Indian Sanskrit texts, which described reconstructive surgeries of the nose and ears. In ancient Greece and Rome, many medicine men performed simple plastic cosmetic surgeries to repair damaged parts of the body caused by war mutilation, punishment or humiliation. In the Middle Ages, the development of all medical braches, including plastic surgery was hindered. New age. The interest in surgical reconstruction of mutilated body parts was renewed in the XVIII century by a great number of enthusiastic and charismatic surgeons, who mastered surgical disciplines and became true artists that created new forms. Modern era. In the XX century, plastic surgery developed as a modern branch in medicine including many types of reconstructive surgery, hand, head and neck surgery, microsurgery and replantation, treatment of burns and their sequelae, and esthetic surgery. Contemporary and future plastic surgery will continue to evolve and improve with regenerative medicine and tissue engineering resulting in a lot of benefits to be gained by patients in reconstruction after body trauma, oncology amputation, and for congenital disfigurement and dysfunction.

A work criterion for plastic collapse

International Nuclear Information System (INIS)

Muscat, Martin; Mackenzie, Donald; Hamilton, Robert

2003-01-01

A new criterion for evaluating limit and plastic loads in pressure vessel design by analysis is presented. The proposed criterion is based on the plastic work dissipated in the structure as loading progresses and may be used for structures subject to a single load or a combination of multiple loads. Example analyses show that limit and plastic loads given by the plastic work criterion are robust and consistent. The limit and plastic loads are determined purely by the inelastic response of the structure and are not influenced by the initial elastic response: a problem with some established plastic criteria

A Coupled Plastic Damage Model for Concrete considering the Effect of Damage on Plastic Flow

OpenAIRE

Zhou, Feng; Cheng, Guangxu

2015-01-01

A coupled plastic damage model with two damage scalars is proposed to describe the nonlinear features of concrete. The constitutive formulations are developed by assuming that damage can be represented effectively in the material compliance tensor. Damage evolution law and plastic damage coupling are described using the framework of irreversible thermodynamics. The plasticity part is developed without using the effective stress concept. A plastic yield function based on the true stress is ado...

Effect of Different Fillers on Adhesive Wear Properties of Glass Fiber Reinforced Polyester Composites

Directory of Open Access Journals (Sweden)

E. Feyzullahoğlu

2017-12-01

Full Text Available Polymeric composites are used for different aims as substitute of traditional materials such as metals; due to their improved strength at small specific weight. The fiber reinforced polymer (FRP composite material consists of polymeric matrix and reinforcing material. Polymeric materials are commonly reinforced with synthetic fibers such as glass and carbon. The glass fiber reinforced polyester (GFRP composites are used with different filler materials. The aim of this study is to investigate the effects of different filler materials on adhesive wear behavior of GFRP. In this experimental study; polymetilmetacrilat (PMMA, Glass beads (GB and Glass sand (GS were used as filling material in GFRP composite samples. The adhesive wear behaviors of samples were carried out using ball on disc type tribometer. The friction force and coefficient of friction were measured during the test. The volume loss and wear rate values of samples were calculated according to test results. Barcol hardness values of samples were measured. The densities of samples were measured. Results show that the wear resistance of GB filled GFRP composite samples was much more than non-filled and PMMA filled GFRP composite samples.

The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

Science.gov (United States)

Tarigan, Johannes; Meka, Randi; Nursyamsi

2018-03-01

Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

Plastic solid waste utilization technologies: A Review

Science.gov (United States)

Awasthi, Arun Kumar; Shivashankar, Murugesh; Majumder, Suman

2017-11-01

Plastics are used in more number of applications in worldwide and it becomes essential part of our daily life. In Indian cities and villages people use the plastics in buying vegetable as a carry bag, drinking water bottle, use of plastic furniture in home, plastics objects uses in kitchen, plastic drums in packing and storage of the different chemicals for industrial use, use plastic utensils in home and many more uses. After usage of plastics it will become part of waste garbage and create pollution due to presence of toxic chemicals and it will be spread diseases and give birth to uncontrolled issues in social society. In current scenario consumption of plastic waste increasing day by day and it is very difficult to manage the plastic waste. There are limited methodologies available for reutilization of plastic waste again. Such examples are recycling, landfill, incineration, gasification and hydrogenation. In this paper we will review the existing methodologies of utilization of plastic waste in current scenario

Plastic Pollution from Ships

OpenAIRE

Čulin, Jelena; Bielić, Toni

2016-01-01

The environmental impact of shipping on marine environment includes discharge of garbage. Plastic litter is of particular concern due to abundance, resistance to degradation and detrimental effect on marine biota. According to recently published studies, a further research is required to assess human health risk. Monitoring data indicate that despite banning plastic disposal at sea, shipping is still a source of plastic pollution. Some of the measures to combat the problem are discussed.

Practical solution of plastic deformation problems in elastic-plastic range

Science.gov (United States)

Mendelson, A; Manson, S

1957-01-01

A practical method for solving plastic deformation problems in the elastic-plastic range is presented. The method is one of successive approximations and is illustrated by four examples which include a flat plate with temperature distribution across the width, a thin shell with axial temperature distribution, a solid cylinder with radial temperature distribution, and a rotating disk with radial temperature distribution.

Extruding plastic scintillator at Fermilab

International Nuclear Information System (INIS)

Pla-Dalmau, Anna; Bross, Alain D.; Rykalin, Viktor V.

2003-01-01

An understanding of the costs involved in the production of plastic scintillators and the development of a less expensive material have become necessary with the prospects of building very large plastic scintillation detectors. Several factors contribute to the high cost of plastic scintillating sheets, but the principal reason is the labor-intensive nature of the manufacturing process. In order to significantly lower the costs, the current casting procedures had to be abandoned. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. This concept was tested and high quality extruded plastic scintillator was produced. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. This paper will discuss the characteristics of extruded plastic scintillator and its raw materials, the different manufacturing techniques and the current R andD program at Fermilab

Applications and societal benefits of plastics.

Science.gov (United States)

Andrady, Anthony L; Neal, Mike A

2009-07-27

This article explains the history, from 1600 BC to 2008, of materials that are today termed 'plastics'. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years.

Plastic pollutants in water environment

Directory of Open Access Journals (Sweden)

Mrowiec Bożena

2017-12-01

Full Text Available Nowadays, wide applications of plastics result in plastic waste being present in the water environment in a wide variety of sizes. Plastic wastes are in water mainly as microplastics (the size range of 1 nm to < 5 mm. Microplastics have been recognized as an emerging threat, as well as ecotoxicological and ecological risk for water ecosystems. In this review are presented some of the physicochemical properties of plastic materials that determine their toxic effect on the aquatic environment. Wastewater treatment plants (WWTPs are mentioned as one of main sources of microplastics introduced into fresh water, and rivers are the pathways for the transportation of the pollutants to seas and oceans. But, effluents from tertiary wastewater treatment facilities can contain only minimally microplastic loads. The issue of discharge reduction of plastic pollutants into water environment needs activities in the scope of efficient wastewater treatment, waste disposal, recycling of plastic materials, education and public involvement.

Track treeing mechanism and plastic zone in solid Part 1: Initial development of plastic zone

International Nuclear Information System (INIS)

Li Boyang

2008-01-01

After neutron exposure and chemical etching in advance, latent tracks of recoil nucleon develop into pits on CR39 surface. During electrochemical etching, plastic zone is formed at top of pits. Some pits develop into tree cracks in the initial stage of plastic zone development. Physical and mathematical model of crack and plastic zone is proposed; parameter of development free path of plastic zone is presented. Based on integration of elementary theories the stress analysis is build up; based on analyses of measured parameters, a set of common relations between parameters is obtained. Integrate parameter analysis and stress analysis, depth of plastic zone development, law and phenomenon in experimental data can be interpreted completely

Accumulation of plastic-derived chemicals in tissues of seabirds ingesting marine plastics.

Science.gov (United States)

Tanaka, Kosuke; Takada, Hideshige; Yamashita, Rei; Mizukawa, Kaoruko; Fukuwaka, Masa-aki; Watanuki, Yutaka

2013-04-15

We analyzed polybrominated diphenyl ethers (PBDEs) in abdominal adipose of oceanic seabirds (short-tailed shearwaters, Puffinus tenuirostris) collected in northern North Pacific Ocean. In 3 of 12 birds, we detected higher-brominated congeners (viz., BDE209 and BDE183), which are not present in the natural prey (pelagic fish) of the birds. The same compounds were present in plastic found in the stomachs of the 3 birds. These data suggested the transfer of plastic-derived chemicals from ingested plastics to the tissues of marine-based organisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis.

Science.gov (United States)

Pflieger, Marilyne; Makorič, Petra; Kovač Viršek, Manca; Koren, Špela

2017-07-01

Plastic resin pellets, categorized as microplastics (≤5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Computational strain gradient crystal plasticity

DEFF Research Database (Denmark)

Niordson, Christian Frithiof; Kysar, Jeffrey W.

2014-01-01

A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

Imaging brain plasticity after trauma

Institute of Scientific and Technical Information of China (English)

Zhifeng Kou; Armin Iraji

2014-01-01

The brain is highly plastic after stroke or epilepsy;however, there is a paucity of brain plasticity investigation after traumatic brain injury (TBI). This mini review summarizes the most recent evidence of brain plasticity in human TBI patients from the perspective of advanced magnetic resonance imaging. Similar to other forms of acquired brain injury, TBI patients also demonstrat-ed both structural reorganization as well as functional compensation by the recruitment of other brain regions. However, the large scale brain network alterations after TBI are still unknown, and the ifeld is still short of proper means on how to guide the choice of TBI rehabilitation or treat-ment plan to promote brain plasticity. The authors also point out the new direction of brain plas-ticity investigation.

Recycled Glass Fiber Reinforced Polymer Composites Incorporated in Mortar for Improved Mechanical Performance

Science.gov (United States)

2017-12-11

Glass fiber reinforced polymer (GFRP) recycled from retired wind turbines was implemented in mortar as a volumetric replacement of sand during the two phases of this study. In Phase I, the mechanically refined GFRP particle sizes were sieved for four...

Constraints on the evolution of phenotypic plasticity

DEFF Research Database (Denmark)

Murren, Courtney J; Auld, Josh R.; Callahan, Hilary S

2015-01-01

Phenotypic plasticity is ubiquitous and generally regarded as a key mechanism for enabling organisms to survive in the face of environmental change. Because no organism is infinitely or ideally plastic, theory suggests that there must be limits (for example, the lack of ability to produce...... an optimal trait) to the evolution of phenotypic plasticity, or that plasticity may have inherent significant costs. Yet numerous experimental studies have not detected widespread costs. Explicitly differentiating plasticity costs from phenotype costs, we re-evaluate fundamental questions of the limits...... to the evolution of plasticity and of generalists vs specialists. We advocate for the view that relaxed selection and variable selection intensities are likely more important constraints to the evolution of plasticity than the costs of plasticity. Some forms of plasticity, such as learning, may be inherently...

Recycling of packing plastics

International Nuclear Information System (INIS)

Gintenreiter-Koegl, S.

2001-05-01

The ordinance on the avoidance of packaging waste was a serious intervention in the public and private waste management in Austria. Above all the high expenses for an overall packaging waste collection and the recycling of packaging plastics were criticized. The landfill ordinance comes into force in 2004 and this means another major change in the Austrian waste management system. In the course of this change the overall collection and the recycling and recovery of waste streams, especially of the high caloric plastics waste, have to be discussed again. The goal of this work was on the one hand to develop and adapt the hydrocracking process for the recovery of mixed plastics waste and to show a possible application in Austria. On the other hand the work shows the technical, ecological and economical conditions for packaging plastics recycling and recovery in order to find optimum applications for the processes and to examine their contribution to a sustainable development. A hydrocracking test plant for the processing of mixed plastic wastes was built and had been running for about three years. The tests were carried out successfully and the suitability of the technology for the recovery of packaging plastics could be shown. Results show at least a 35 % yield of fuel. The hydrocracking technology is quite common in the oil industries and therefore an integration on a refinery site is suggested. (author)

The characteristics of ultra-high performance concrete and cracking behavior of reinforced concrete tensile specimens

Directory of Open Access Journals (Sweden)

H.A. Rahdar

2016-09-01

Full Text Available The tensile behavior of concrete depends on some factors such as member dimensions, reinforcement ratio, diameter of rebar, strength and elasticity modulus of material. In this research the experimental method is used to examine the characteristics and the behavior of ultra-high performance concrete on the tensile behavior of concrete members reinforced by steel rebar. The results show that increasing the rebar cover on diameter rebar ratio (C/d increases the initial stiffening before the cracking stage in concrete. Also, by increasing of reinforcement ratio the cracking space decreased.

Influence of preliminary plastic deformation on plasticity characteristics and structure of armco-iron

International Nuclear Information System (INIS)

Vergazov, A.N.; Rybin, V.V.; Meshkov, Yu.Ya.; Moskvina, V.A.; Serditova, T.N.

1990-01-01

Effect of preliminary plastic deformation (PPD) by drawing on the maximum plasticity characteristics (critical rupture strain) ε c , general δ and uniform δ p relative elongation and on the structure of armco-iron in a wide range of PPD degree change (e=0-4.6) is studied. It is ascertained that with e growth the metal plastic properties at T test =77 and 293 K change in a different way. In particular, the critical strain ε c increases monotonously at 77 K and reduces at 293 K. It is shown that all changes of mechanical characteristics observed with e increase are conditioned by the development of fragmentation process in armco-iron. The data obtained are discussed from the veiwpoint of the developed plastic deformation physics concepts

Plastic accumulation in the Mediterranean sea.

Directory of Open Access Journals (Sweden)

Andrés Cózar

Full Text Available Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2, as well as its frequency of occurrence (100% of the sites sampled, are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region.

Plastic Accumulation in the Mediterranean Sea

KAUST Repository

Có zar, André s; Sanz-Martí n, Marina; Martí , Elisa; Gonzá lez-Gordillo, J. Ignacio; Ubeda, Bá rbara; Gá lvez, José Á .; Irigoien, Xabier; Duarte, Carlos M.

2015-01-01

Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region.

Nano-plastics in the aquatic environment.

Science.gov (United States)

Mattsson, K; Hansson, L-A; Cedervall, T

2015-10-01

The amount of plastics released to the environment in modern days has increased substantially since the development of modern plastics in the early 1900s. As a result, concerns have been raised by the public about the impact of plastics on nature and on, specifically, aquatic wildlife. Lately, much attention has been paid to macro- and micro-sized plastics and their impact on aquatic organisms. However, micro-sized plastics degrade subsequently into nano-sizes whereas nano-sized particles may be released directly into nature. Such particles have a different impact on aquatic organisms than larger pieces of plastic due to their small size, high surface curvature, and large surface area. This review describes the possible sources of nano-sized plastic, its distribution and behavior in nature, the impact of nano-sized plastic on the well-being of aquatic organisms, and the difference of impact between nano- and micro-sized particles. We also identify research areas which urgently need more attention and suggest experimental methods to obtain useful data.

Integrating Hebbian and homeostatic plasticity: introduction.

Science.gov (United States)

Fox, Kevin; Stryker, Michael

2017-03-05

Hebbian plasticity is widely considered to be the mechanism by which information can be coded and retained in neurons in the brain. Homeostatic plasticity moves the neuron back towards its original state following a perturbation, including perturbations produced by Hebbian plasticity. How then does homeostatic plasticity avoid erasing the Hebbian coded information? To understand how plasticity works in the brain, and therefore to understand learning, memory, sensory adaptation, development and recovery from injury, requires development of a theory of plasticity that integrates both forms of plasticity into a whole. In April 2016, a group of computational and experimental neuroscientists met in London at a discussion meeting hosted by the Royal Society to identify the critical questions in the field and to frame the research agenda for the next steps. Here, we provide a brief introduction to the papers arising from the meeting and highlight some of the themes to have emerged from the discussions.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'. © 2017 The Author(s).

Plastic Accumulation in the Mediterranean Sea

KAUST Repository

Cózar, Andrés

2015-04-01

Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region.

Plastic accumulation in the Mediterranean sea.

Science.gov (United States)

Cózar, Andrés; Sanz-Martín, Marina; Martí, Elisa; González-Gordillo, J Ignacio; Ubeda, Bárbara; Gálvez, José Á; Irigoien, Xabier; Duarte, Carlos M

2015-01-01

Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region.

Plastic Accumulation in the Mediterranean Sea

Science.gov (United States)

Cózar, Andrés; Sanz-Martín, Marina; Martí, Elisa; González-Gordillo, J. Ignacio; Ubeda, Bárbara; Gálvez, José Á.; Irigoien, Xabier; Duarte, Carlos M.

2015-01-01

Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region. PMID:25831129

Americium behaviour in plastic vessels

Energy Technology Data Exchange (ETDEWEB)

Legarda, F.; Herranz, M. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Idoeta, R., E-mail: raquel.idoeta@ehu.e [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain); Abelairas, A. [Departamento de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria de Bilbao, Universidad del Pais Vasco (UPV/EHU), Alameda de Urquijo s/n, 48013 Bilbao (Spain)

2010-07-15

The adsorption of {sup 241}Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of {sup 241}Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of {sup 241}Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

Americium behaviour in plastic vessels

International Nuclear Information System (INIS)

Legarda, F.; Herranz, M.; Idoeta, R.; Abelairas, A.

2010-01-01

The adsorption of 241 Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of 241 Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of 241 Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification.

Sustainable reverse logistics for household plastic waste

NARCIS (Netherlands)

Bing, X.

2014-01-01

Summary of the thesis titled “Sustainable Reverse Logistics for Household Plastic Waste”

PhD Candidate: Xiaoyun Bing

Recycled plastic can be used in the manufacturing of plastic products to reduce the use of virgin plastics material. The cost of recycled plastics is usually lower

Size effects in crystal plasticity

DEFF Research Database (Denmark)

Borg, Ulrik

2007-01-01

Numerical analyses of plasticity size effects have been carried out for different problems using a developed strain gradient crystal plasticiy theory. The theory employs higher order stresses as work conjugates to slip gradients and uses higher order boundary conditions. Problems on localization...... of plastic flow in a single crystal, grain boundary effects in a bicrystal, and grain size effects in a polycrystal are studied. Single crystals containing micro-scale voids have also been analyzed at different loading conditions with focus on the stress and deformation fields around the voids, on void...... growth and interaction between neighboring voids, and on a comparison between the developed strain gradient crystal plasticity theory and a discrete dislocation plasticity theory. Furthermore, voids and rigid inclusions in isotropic materials have been studied using a strain gradient plasticity theory...

Multi-Objective Structural Optimization Design of Horizontal-Axis Wind Turbine Blades Using the Non-Dominated Sorting Genetic Algorithm II and Finite Element Method

Directory of Open Access Journals (Sweden)

Jie Zhu

2014-02-01

Full Text Available A multi-objective optimization method for the structural design of horizontal-axis wind turbine (HAWT blades is presented. The main goal is to minimize the weight and cost of the blade which uses glass fiber reinforced plastic (GFRP coupled with carbon fiber reinforced plastic (CFRP materials. The number and the location of layers in the spar cap, the width of the spar cap and the position of the shear webs are employed as the design variables, while the strain limit, blade/tower clearance limit and vibration limit are taken into account as the constraint conditions. The optimization of the design of a commercial 1.5 MW HAWT blade is carried out by combining FEM analysis and a multi-objective evolutionary algorithm under ultimate (extreme flap-wise load and edge-wise load conditions. The best solutions are described and the comparison of the obtained results with the original design is performed to prove the efficiency and applicability of the method.

SYNTHESIS AND CHARACTERIZATION OF BIODEGRDABLE PLASTIC FROM CASAVA STARCH AND ALOE VERA EXTRACT WITH GLYCEROL PLASTICIZER

Directory of Open Access Journals (Sweden)

Mery Apriyani

2016-05-01

Full Text Available Synthesis and characterizations of Biodegradable Plastic made of Cassava Waste Starch, glycerol, acetic acid and Aloe vera extract has done. The aims of this research are to study the influence of addition of aloe vera extract in plastics mechanics properties, water vapor transmission rate and biodegradation. There are five main steps in this research, extraction of aloe vera, cassava starch preparation from cassava waste, preparations, characterization and biodegradability study of biodegradable plastic. The addition variations of aloe vera extract that used in this research are 0.01; 0.03; 0.05; 0.07 and 0.14 grams. Results showed that the addition of aloe Vera tends to increased biodegrable plastic thickness to 0.01 mm and elongation to 32.07%. However, biodegradable plastic tensile strength tends to decreased to 23.95 Mpa. Optimum tensile strength is 3.90 Mpa and elongation is 34.43%. Optimum water vapor transmission rate is 2.40 g/m2hours. Biodegradation study of biodegradable plastic showed that addition of aloe vera extract doesn’t significantly influence in plastic degradations.

Lifetime Prediction of Nano-Silica based Glass Fibre/Epoxy composite by Time Temperature Superposition Principle

Science.gov (United States)

Anand, Abhijeet; Banerjee, Poulami; Prusty, Rajesh Kumar; Ray, Bankin Chandra

2018-03-01

The incorporation of nano fillers in Fibre reinforced polymer (FRP) composites has been a source of experimentation for researchers. Addition of nano fillers has been found to improve mechanical, thermal as well as electrical properties of Glass fibre reinforced polymer (GFRP) composites. The in-plane mechanical properties of GFRP composite are mainly controlled by fibers and therefore exhibit good values. However, composite exhibits poor through-thickness properties, in which the matrix and interface are the dominant factors. Therefore, it is conducive to modify the matrix through dispersion of nano fillers. Creep is defined as the plastic deformation experienced by a material for a temperature at constant stress over a prolonged period of time. Determination of Master Curve using time-temperature superposition principle is conducive for predicting the lifetime of materials involved in naval and structural applications. This is because such materials remain in service for a prolonged time period before failure which is difficult to be kept marked. However, the failure analysis can be extrapolated from its behaviour in a shorter time at an elevated temperature as is done in master creep analysis. The present research work dealt with time-temperature analysis of 0.1% SiO2-based GFRP composites fabricated through hand-layup method. Composition of 0.1% for SiO2nano fillers with respect to the weight of the fibers was observed to provide optimized flexural properties. Time and temperature dependence of flexural properties of GFRP composites with and without nano SiO2 was determined by conducting 3-point bend flexural creep tests over a range of temperature. Stepwise isothermal creep tests from room temperature (30°C) to the glass transition temperature Tg (120°C) were performed with an alternative creep/relaxation period of 1 hour at each temperature. A constant stress of 40MPa was applied during the creep tests. The time-temperature superposition principle was

Utilization of new materials in prestressed concrete. Shin zairyo no puresutoresuto concrete eno tekiyo

Energy Technology Data Exchange (ETDEWEB)

Imai, Y. (Taisei Corp., Tokyo (Japan)); Kato, H. (Building Research Inst., Tokyo (Japan)); Mutsuyoshi, H. (Saitama Univ., Urawa (Japan). Faculty of Engineering)

1994-03-31

In this session for the new materials, almost all of them were the presentation on the fiber reinforced plastics (FRP). Based on these facts, the topics of new materials about PC centered around FRP, and consequently it was found that how it was expected as the new materials and how it is being watched with keen interest. Even in FRP, the presentations on the carbon fiber reinforced plastics (CFRP) and aramid fiber reinforced plastics (AFRP) were a little bit more than those on the glass fiber reinforced plastics (GFRP), and therefore they were felt to be predominant. Although the ones about a fundamental study on the material characters of FRP held approximately 70%, as a content, there were 6 presentations on the design and execution of the actual bridges in which FRP was used for the PC take-up materials and the oblique cable of cable-stayed bridges, consequently it was found that FRP did not stay at a study stage, and was already shifting to the actual application stage. However, at the current situation, there were many of experimental ones like the small scale bridges in the golf courses, and furthermore it can not be said that a guideline for the design and execution is sufficiently established. 2 figs.

Americium behaviour in plastic vessels.

Science.gov (United States)

Legarda, F; Herranz, M; Idoeta, R; Abelairas, A

2010-01-01

The adsorption of (241)Am dissolved in water in different plastic storage vessels was determined. Three different plastics were investigated with natural and distilled waters and the retention of (241)Am by these plastics was studied. The same was done by varying vessel agitation time, vessel agitation speed, surface/volume ratio of water in the vessels and water pH. Adsorptions were measured to be between 0% and 70%. The adsorption of (241)Am is minimized with no water agitation, with PET or PVC plastics, and by water acidification. Copyright 2009 Elsevier Ltd. All rights reserved.

Plastics control paraffin buildup

Energy Technology Data Exchange (ETDEWEB)

1965-06-01

Paraffin buildup in producing oil wells has been virtually eliminated by the use of plastic-coated sucker rods. The payout of the plasticing process is generally reached in less than a year, and the paraffin buildup may be inhibited for 10 yr or longer. Most of the plants applying plastic coatings to sucker rods are now fully automated, though a few still offer the hand-sprayed coating that some operators prefer. The several steps involved are described. The ideal plastic for the job is resistant to chemicals at high and low temperatures, flexible, has good adhesion, abrasion resistance, impact resistance, and a smooth glossy finish. The phenol aldehyde and epoxy resins presently offered by the industry fulfill these specifications very well; the multicoating and multibaking techniques improve their performance. Due to wide variations in the severity of the paraffin problem from one oil field to another, there is no general rule to estimate the possible savings from using plastic-coated sucker rods. The process, however, does appear to do a remarkable job in controlling paraffin buildup wherever it is a problem in producing oil by pump.

Plastics: Friend or foe?

Directory of Open Access Journals (Sweden)

O P Gupta

2018-01-01

Full Text Available Plastics has been playing a very significant role in our life. Being light weight, inexpensive and heving good insulating properties it is being used in all aspects of life, from clothes to contact lenses and from mobile phones to automobiles as well as in medical equipments, However it is not biodegradable, and while degrading to fragments it gets converted in to microplastics and nanoplastics The plastic waste is being recognized as an environmental hazard, since these micr- and nanoplastics find way from landfills to water and foods, It is said that we are not only using, but we are eating, drinking and even braething the plastics. These microplastics in body release certain hazardous chemicals and found to be disrupting functions of certain endocrine organs. Whether the rising prevalence of Diabetes, thyroid disorders or infirtility etc., are realated to the plastics?

Motor cortical plasticity in Parkinson's disease.

Science.gov (United States)

Udupa, Kaviraja; Chen, Robert

2013-09-04

In Parkinson's disease (PD), there are alterations of the basal ganglia (BG) thalamocortical networks, primarily due to degeneration of nigrostriatal dopaminergic neurons. These changes in subcortical networks lead to plastic changes in primary motor cortex (M1), which mediates cortical motor output and is a potential target for treatment of PD. Studies investigating the motor cortical plasticity using non-invasive transcranial magnetic stimulation (TMS) have found altered plasticity in PD, but there are inconsistencies among these studies. This is likely because plasticity depends on many factors such as the extent of dopaminergic loss and disease severity, response to dopaminergic replacement therapies, development of l-DOPA-induced dyskinesias (LID), the plasticity protocol used, medication, and stimulation status in patients treated with deep brain stimulation (DBS). The influences of LID and DBS on BG and M1 plasticity have been explored in animal models and in PD patients. In addition, many other factors such age, genetic factors (e.g., brain derived neurotropic factor and other neurotransmitters or receptors polymorphism), emotional state, time of the day, physical fitness have been documented to play role in the extent of plasticity induced by TMS in human studies. In this review, we summarize the studies that investigated M1 plasticity in PD and demonstrate how these afore-mentioned factors affect motor cortical plasticity in PD. We conclude that it is important to consider the clinical, demographic, and technical factors that influence various plasticity protocols while developing these protocols as diagnostic or prognostic tools in PD. We also discuss how the modulation of cortical excitability and the plasticity with these non-invasive brain stimulation techniques facilitate the understanding of the pathophysiology of PD and help design potential therapeutic possibilities in this disorder.

Process for remediation of plastic waste

Science.gov (United States)

Pol, Vilas G [Westmont, IL; Thiyagarajan, Pappannan [Germantown, MD

2012-04-10

A single step process for degrading plastic waste by converting the plastic waste into carbonaceous products via thermal decomposition of the plastic waste by placing the plastic waste into a reactor, heating the plastic waste under an inert or air atmosphere until the temperature of 700.degree. C. is achieved, allowing the reactor to cool down, and recovering the resulting decomposition products therefrom. The decomposition products that this process yields are carbonaceous materials, and more specifically egg-shaped and spherical-shaped solid carbons. Additionally, in the presence of a transition metal compound, this thermal decomposition process produces multi-walled carbon nanotubes.

Effect of fabric structure and polymer matrix on flexural strength, interlaminar shear stress, and energy dissipation of glass fiber-reinforced polymer composites

Science.gov (United States)

We report the effect of glass fiber structure and the epoxy polymer system on the flexural strength, interlaminar shear stress (ILSS), and energy absorption properties of glass fiber-reinforced polymer (GFRP) composites. Four different GFRP composites were fabricated from two glass fiber textiles of...

DESIGNERS’ KNOWLEDGE IN PLASTICS

DEFF Research Database (Denmark)

Eriksen, Kaare

2013-01-01

The Industrial designers’ knowledge in plastics materials and manufacturing principles of polymer products is very important for the innovative strength of the industry, according to a group of Danish plastics manufacturers, design students and practicing industrial designers. These three groups ...

Study on mechanical properties of fly ash impregnated glass fiber reinforced polymer composites using mixture design analysis

International Nuclear Information System (INIS)

Satheesh Raja, R.; Manisekar, K.; Manikandan, V.

2014-01-01

Highlights: • FRP with and without fly ash filler were prepared. • Mechanical properties of composites were analyzed. • Mixture Design Method was used to model the system. • Experimental and mathematical model results were compared. - Abstract: This paper describes the mechanical behavior of fly ash impregnated E-glass fiber reinforced polymer composite (GFRP). Initially the proportion of fiber and resin were optimized from the analysis of the mechanical properties of the GFRP. It is observed that the 30 wt% of E-glass in the GFRP without filler material yields better results. Then, based on the optimized value of resin content, the varying percentage of E-glass and fly ash was added to fabricate the hybrid composites. Results obtained in this study were mathematically evaluated using Mixture Design Method. Predictions show that 10 wt% addition of fly ash with fiber improves the mechanical properties of the composites. The fly ash impregnated GFRP yields significant improvement in mechanical strength compared to the GFRP without filler material. The surface morphologies of the fractured specimens were characterized using Scanning Electron Microscope (SEM). The chemical composition and surface morphology of the fly ash is analyzed by using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscope

Grain Interactions in Crystal Plasticity

International Nuclear Information System (INIS)

Boyle, K.P.; Curtin, W.A.

2005-01-01

The plastic response of a sheet metal is governed by the collective response of the underlying grains. Intragranular plasticity depends on intrinsic variables such as crystallographic orientation and on extrinsic variables such as grain interactions; however, the role of the latter is not well understood. A finite element crystal plasticity formulation is used to investigate the importance of grain interactions on intragranular plastic deformation in initially untextured polycrystalline aggregates. A statistical analysis reveals that grain interactions are of equal (or more) importance for determining the average intragranular deviations from the applied strain as compared to the orientation of the grain itself. Furthermore, the influence of the surrounding grains is found to extend past nearest neighbor interactions. It is concluded that the stochastic nature of the mesoscale environment must be considered for a proper understanding of the plastic response of sheet metals at the grain-scale

Degradation of oxo-biodegradable plastic by Pleurotus ostreatus.

Science.gov (United States)

da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Nunes, Mateus Dias; da Silva, Marliane de Cássia Soares; Kasuya, Maria Catarina Megumi

2013-01-01

Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate.

Degradation of oxo-biodegradable plastic by Pleurotus ostreatus.

Directory of Open Access Journals (Sweden)

José Maria Rodrigues da Luz

Full Text Available Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate.

Degradation of Oxo-Biodegradable Plastic by Pleurotus ostreatus

Science.gov (United States)

da Luz, José Maria Rodrigues; Paes, Sirlaine Albino; Nunes, Mateus Dias; da Silva, Marliane de Cássia Soares; Kasuya, Maria Catarina Megumi

2013-01-01

Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate. PMID:23967057

Desorption modeling of hydrophobic organic chemicals from plastic sheets using experimentally determined diffusion coefficients in plastics.

Science.gov (United States)

Lee, Hwang; Byun, Da-Eun; Kim, Ju Min; Kwon, Jung-Hwan

2018-01-01

To evaluate rate of migration from plastic debris, desorption of model hydrophobic organic chemicals (HOCs) from polyethylene (PE)/polypropylene (PP) films to water was measured using PE/PP films homogeneously loaded with the HOCs. The HOCs fractions remaining in the PE/PP films were compared with those predicted using a model characterized by the mass transfer Biot number. The experimental data agreed with the model simulation, indicating that HOCs desorption from plastic particles can generally be described by the model. For hexachlorocyclohexanes with lower plastic-water partition coefficients, desorption was dominated by diffusion in the plastic film, whereas desorption of chlorinated benzenes with higher partition coefficients was determined by diffusion in the aqueous boundary layer. Evaluation of the fraction of HOCs remaining in plastic films with respect to film thickness and desorption time showed that the partition coefficient between plastic and water is the most important parameter influencing the desorption half-life. Copyright © 2017 Elsevier Ltd. All rights reserved.

Liquid crystal displays with plastic substrates

Science.gov (United States)

Lueder, Ernst H.

1998-04-01

Plastic substrates for the cells of displays exhibit only 1/6 of the weight of glass substrates; they are virtually unbreakable; their flexibility allows the designer to give them a shape suppressing reflections, to realize a display board on a curved surface or meeting the requirements for an appealing styling; displays with plastics are thinner which provides a wider viewing angle. These features render them attractive for displays in portable systems such as mobile phones, pagers, smart cards, personal digital assistants (PDAs) and portable computers. Reflective displays are especially attractive as they don't need a back light. The most important requirements are the protection of plastics against gas permeation and chemical agents, the prevention of layers on plastics to crack or peel off when the plastic is bent and the development of low temperature thin film processes because the plastics, as a rule, only tolerate temperatures below 150 degrees Celsius. Bistable reflective FLC- and PSCT-displays with plastic substrates will be introduced. Special sputtered SiO2-orientation layers preserve the displayed information even if pressure or torsion is applied. MIM-addressed PDLC-displays require additional Al- or Ti-layers which provide the necessary ductility. Sputtered or PECVD-generated TFTs can be fabricated on plastics at temperatures below 150 degrees Celsius.

PLASTIC ANALYSIS OF STEEL FRAME STRUCTURE

Directory of Open Access Journals (Sweden)

M. Rogac

2013-05-01

Full Text Available This paper presents the plastic analysis of steel frame structure loaded by gravity loads. By applying the cinematic theorem of ultimate analysis, the ultimate load for the case of elastic - ideally plastic material is calculated. The identical structure was treated in the computer program SAP2000 where the zone of material reinforcement in the plastic area was covered. Keywords: Steel frame structure, plastic analysis, ultimate gravity load, material reinforcement.

Water Vapor Permeation in Plastics

Energy Technology Data Exchange (ETDEWEB)

Keller, Paul E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kouzes, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-01-01

Polyvinyl toluene (PVT) and polystyrene (PS) (referred to as “plastic scintillator”) are used for gamma ray detectors. A significant decrease in radiation detection performance has been observed in some PVT-based gamma-ray detectors in systems in outdoor environments as they age. Recent studies have revealed that plastic scintillator can undergo an environmentally related material degradation that adversely affects gamma ray detection performance under certain conditions and histories. A significant decrease in sensitivity has been seen in some gamma-ray detectors in some systems as they age. The degradation of sensitivity of plastic scintillator over time is due to a variety of factors, and the term “aging” is used to encompass all factors. Some plastic scintillator samples show no aging effects (no significant change in sensitivity over more than 10 years), while others show severe aging (significant change in sensitivity in less than 5 years). Aging effects arise from weather (variations in heat and humidity), chemical exposure, mechanical stress, light exposure, and loss of volatile components. The damage produced by these various causes can be cumulative, causing observable damage to increase over time. Damage may be reversible up to some point, but becomes permanent under some conditions. The objective of this report is to document the phenomenon of permeability of plastic scintillator to water vapor and to derive the relationship between time, temperature, humidity and degree of water penetration in plastic. Several conclusions are documented about the properties of water permeability of plastic scintillator.

The plasticity of clays

Science.gov (United States)

Group, F.F.

1905-01-01

(1) Sand injures plasticity little at first because the grains are suspended in a plastic mass. It is only when grains are abundant enough to come in contact with their neighbors, that the effect becomes serious, and then both strength and amount of possible flow are injured. (2) Certain rare organic colloids increase the plasticity by rendering the water viscous. (3) Fineness also tends to increase plasticity. (4) Plane surfaces (plates) increase the amount of possible flow. They also give a chance for lubrication by thinner films, thus increasing the friction of film, and the strength of the whole mass. The action of plates is thus twofold ; but fineness may be carried to such an extent as to break up plate-like grains into angular fragments. The beneficial effects of plates are also decreased by the fact that each is so closely surrounded by others in the mass. (5) Molecular attraction is twofold in increasing plasticity. As the attraction increases, the coherence and strength of the mass increase, and the amount of possible deformation before crumbling also increases. Fineness increases this action by requiring more water. Colloids and crystalloids in solution may also increase the attraction. It is thus seen to be more active than any other single factor.

Plastic debris in the coastal environment: The invincible threat? Abundance of buried plastic debris on Malaysian beaches.

Science.gov (United States)

Fauziah, S H; Liyana, I A; Agamuthu, P

2015-09-01

Studies on marine debris have gained worldwide attention since many types of debris have found their way into the food chain of higher organisms. Thus, it is crucial that more focus is given to this area in order to curb contaminations in sea food. This study was conducted to quantify plastic debris buried in sand at selected beaches in Malaysia. Marine debris was identified according to size range and distribution, and this information was related to preventive actions to improve marine waste issues. For the purpose of this study, comparison of plastic waste abundance between a recreational beach and fish-landing beaches was also carried out, since the different beach types represent different activities that produce debris. Six beaches along the Malaysian coastline were selected for this study. The plastic types in this study were related to the functions of the beach. While recreational beaches have abundant quantities of plastic film, foamed plastic including polystyrene, and plastic fragment, fish-landing beaches accumulated line and foamed plastic. A total of 2542 pieces (265.30 g m(-2)) of small plastic debris were collected from all six beaches, with the highest number from Kuala Terengganu, at 879 items m(-2) on Seberang Takir Beach, followed by Batu Burok Beach with 780 items m(-2). Findings from studies of Malaysian beaches have provided a clearer understanding of the distribution of plastic debris. This demonstrates that commitments and actions, such as practices of the 'reduce, reuse, recycle' (3R) approach, supporting public awareness programmes and beach clean-up activities, are essential in order to reduce and prevent plastic debris pollution. © The Author(s) 2015.

Review of the partitioning of chemicals into different plastics: Consequences for the risk assessment of marine plastic debris

International Nuclear Information System (INIS)

O'Connor, Isabel A.; Golsteijn, Laura; Hendriks, A. Jan

2016-01-01

Marine plastic debris are found worldwide in oceans and coastal areas. They degrade only slowly and contain chemicals added during manufacture or absorbed from the seawater. Therefore, they can pose a long-lasting contaminant source and potentially transfer chemicals to marine organisms when ingested. In order to assess their risk, the contaminant concentration in the plastics needs to be estimated and differences understood. We collected from literature plastic water partition coefficients of various organic chemicals for seven plastic types: polydimethylsiloxane (PDMS), high-density, low-density and ultra-high molecular weight polyethylene (LDPE, HDPE, UHMWPE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). Most data was available for PDMS (1060) and LDPE (220), but much less for the remaining plastics (73). Where possible, regression models were developed and the partitioning was compared between the different plastic types. The partitioning of chemicals follows the order of LDPE ≈ HDPE ≥ PP > PVC ≈ PS. Data describing the impact of weathering are urgently needed. - Highlights: • Comparison of organic chemicals partitioning into seven plastic types • Linear correlation between plastic-water partition coefficient K pw and K ow • More data is needed for polypropylene, polystyrene and polyvinyl chloride. • In all plastic types, most K pw were similar to/smaller than the corresponding K ow .

Plasticity of pressure-sensitive materials

CERN Document Server

Ochsner, Andreas

2014-01-01

Classical plasticity theory of metals is independent of the hydrostatic pressure. However, if the metal contains voids or pores or if the structure is composed of cells, this classical assumption is no more valid and the influence of the hydrostatic pressure must be incorporated in the constitutive description. Looking at the microlevel, metal plasticity is connected with the uniform planes of atoms organized with long-range order. Planes may slip past each other along their close-packed directions. The result is a permanent change of shape within the crystal and plastic deformation. The presence of dislocations increases the likelihood of planes slipping. Nowadays, the theory of pressure sensitive plasticity is successfully applied to many other important classes of materials (polymers, concrete, bones etc.) even if the phenomena on the micro-level are different to classical plasticity of metals. The theoretical background of this phenomenological approach based on observations on the macro-level is describe...

Seabirds, gyres and global trends in plastic pollution

International Nuclear Information System (INIS)

Franeker, Jan A. van; Law, Kara Lavender

2015-01-01

Fulmars are effective biological indicators of the abundance of floating plastic marine debris. Long-term data reveal high plastic abundance in the southern North Sea, gradually decreasing to the north at increasing distance from population centres, with lowest levels in high-arctic waters. Since the 1980s, pre-production plastic pellets in North Sea fulmars have decreased by ∼75%, while user plastics varied without a strong overall change. Similar trends were found in net-collected floating plastic debris in the North Atlantic subtropical gyre, with a ∼75% decrease in plastic pellets and no obvious trend in user plastic. The decreases in pellets suggest that changes in litter input are rapidly visible in the environment not only close to presumed sources, but also far from land. Floating plastic debris is rapidly “lost” from the ocean surface to other as-yet undetermined sinks in the marine environment. - Highlights: • Seabirds are effective biological monitors of floating plastic marine debris. • Plastics in fulmar stomachs and in the North Atlantic gyre show similar trends. • Pre-production plastic pellets show strong decreases in fulmars and in the gyre. • These data show that floating plastics rapidly disappear from the ocean surface. - Long term studies give evidence that reduced input of plastic debris into the ocean becomes rapidly visible. Floating plastics disappear to as-yet undetermined sinks

Plastic zonder olie : lesmodule voor nieuwe scheikunde

OpenAIRE

Langejan, B.; Klein Douwel, C.; Horst, ter, J.J.; Tijdink, K.; Marle, van, N.; Klaasen, P.; Coolen, R.; Assenbergh, van, P.; Sijbers, J.P.J.; Mast, A.

2013-01-01

Lesmodule voor nieuwe scheikunde voor leerlingen uit 5 en 6 vwo. Bioplastics worden gemaakt uit natuurlijke grondstoffen. Als ze de synthetische plastics vervangen kan de voorraad aardolie ontzien worden. Omdat veel bioplastics afbreekbaar zijn, kan ook de berg plastic afval krimpen. Maar zijn bioplastics in staat om ons de reguliere plastics te doen vergeten? Hoe maken we bioplastics met dezelfde veelzijdige eigenschappen als plastic? Waar komen de uiteenlopende eigenschappen van plastics ei...

Elimination of Plastic Polymers in Natural Environments

OpenAIRE

Ramirez-Ekner, Sofia; Bidstrup, Marie Juliane Svea; Brusen, Nicklas Hald; Rugaard-Morgan, Zsa-Zsa Sophie Oona Ophelia

2017-01-01

Plastic production and consumption continues to rise and subsequently plastic waste continues to accumulates in natural environments, causing harm to ecosystems.The aim of this paper was to come up with a way to utilize organisms, that have been identified to produce plastic degrading enzymes, as a waste disposal technology. This review includes accounts of plastic production rates, the occurrence of plastic in natural environments and the current waste management systems to create an underst...

The evolution of age-dependent plasticity

NARCIS (Netherlands)

Fischer, Barbara; van Doorn, G. Sander; Dieckmann, Ulf; Taborsky, Barbara

2014-01-01

When organisms encounter environments that are heterogeneous in time, phenotypic plasticity is often favored by selection. The degree of such plasticity can vary during an organism''s lifetime, but the factors promoting differential plastic responses at different ages or life stages remain poorly

Biodegradability of Plastics: Challenges and Misconceptions.

Science.gov (United States)

Kubowicz, Stephan; Booth, Andy M

2017-11-07

Plastics are one of the most widely used materials and, in most cases, they are designed to have long life times. Thus, plastics contain a complex blend of stabilizers that prevent them from degrading too quickly. Unfortunately, many of the most advantageous properties of plastics such as their chemical, physical and biological inertness and durability present challenges when plastic is released into the environment. Common plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) are extremely persistent in the environment, where they undergo very slow fragmentation (projected to take centuries) into small particles through photo-, physical, and biological degradation processes 1 . The fragmentation of the material into increasingly smaller pieces is an unavoidable stage of the degradation process. Ultimately, plastic materials degrade to micron-sized particles (microplastics), which are persistent in the environment and present a potential source of harm for organisms.

Synaptic plasticity in drug reward circuitry.

Science.gov (United States)

Winder, Danny G; Egli, Regula E; Schramm, Nicole L; Matthews, Robert T

2002-11-01

Drug addiction is a major public health issue worldwide. The persistence of drug craving coupled with the known recruitment of learning and memory centers in the brain has led investigators to hypothesize that the alterations in glutamatergic synaptic efficacy brought on by synaptic plasticity may play key roles in the addiction process. Here we review the present literature, examining the properties of synaptic plasticity within drug reward circuitry, and the effects that drugs of abuse have on these forms of plasticity. Interestingly, multiple forms of synaptic plasticity can be induced at glutamatergic synapses within the dorsal striatum, its ventral extension the nucleus accumbens, and the ventral tegmental area, and at least some of these forms of plasticity are regulated by behaviorally meaningful administration of cocaine and/or amphetamine. Thus, the present data suggest that regulation of synaptic plasticity in reward circuits is a tractable candidate mechanism underlying aspects of addiction.

Pregnancy and the Plastic Surgery Resident.

Science.gov (United States)

Garza, Rebecca M; Weston, Jane S; Furnas, Heather J

2017-01-01

Combining pregnancy with plastic surgery residency has historically been difficult. Two decades ago, 36 percent of plastic surgery program directors surveyed actively discouraged pregnancy among residents, and 33 percent of women plastic surgeons suffered from infertility. Most alarmingly, 26 percent of plastic surgery trainees had had an elective abortion during residency. With increasing numbers of women training in plastic surgery, this historical lack of support for pregnancy deserves further attention. To explore the current accommodations made for the pregnant plastic surgery resident, an electronic survey was sent to 88 plastic surgery program directors in the United States. Fifty-four responded, for a response rate of 61.36 percent. On average, a director trained a total of 7.91 women among 17.28 residents trained over 8.19 years. Of the women residents, 1.43 were pregnant during a director's tenure, with 1.35 of those residents taking maternity leave. An average 1.75 male residents took paternity leave. Approximately one-third of programs had a formal maternity/paternity leave policy (36.54 percent) which, in most cases, was limited to defining allowed weeks of leave, time required to fulfill program requirements, and remuneration during leave. This survey of plastic surgery directors is a first step in defining the challenges training programs face in supporting the pregnant resident. Directors provided comments describing their challenges accommodating an absent resident in a small program and complying with the American Board of Plastic Surgery's required weeks of training per year. A discussion of these challenges is followed by suggested solutions.

Functional nanostructures on injection molded plastic

DEFF Research Database (Denmark)

Johansson, Alicia Charlotte; Søgaard, Emil; Andersen, Nis Korsgaard

Nanotechnology can be used to make inexpensive plastic parts with functional surfaces. The plastic parts can be molded using a standard injection molding process. The nanostructures are directly transferred from the surface of the molding tool to the surface of the molded plastic part during...

7 CFR 58.326 - Plastic cream.

Science.gov (United States)

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Plastic cream. 58.326 Section 58.326 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Material § 58.326 Plastic cream. To produce plastic cream eligible for official certification, the quality...

Environment friendly solutions of plastics waste management

International Nuclear Information System (INIS)

Pirzada, F.N.; Riffat, T.; Pirzada, M.D.S.

1997-01-01

The use of plastics is growing worldwide. Consequently, the volume of plastic waste is also increasing. Presently, more than 100 million tons per year of plastic is being produced globally. In U.S. alone more than 10 million tons of plastic is being dumped in landfills as waste, where it can persist for decades. This has resulted in exhausting old landfills. Public awareness on environment is also making it difficult to find new sites for landfills. This has led to increased emphasis on treatment and recycling of plastic wastes. Volume reduction of plastic waste has some unique problems. They arise from the intrinsic chemical inertness of polymeric materials and toxic nature of their degradation byproducts. The paper reviews the present state of plastic waste management including land filling, incineration and recycling technologies. The technical problems associated with each of these processes have been discussed. There is also brief description of ongoing R and D for finding improved methods of plastic waste handling with their promises and problems. The role of tougher legislation in developing better recycling methods and degradable plastics has also been evaluated. The claims made by the proponents of degradable polymers have also been critically reviewed. (authors)

Modeling plasticity by non-continuous deformation

Science.gov (United States)

Ben-Shmuel, Yaron; Altus, Eli

2017-10-01

Plasticity and failure theories are still subjects of intense research. Engineering constitutive models on the macroscale which are based on micro characteristics are very much in need. This study is motivated by the observation that continuum assumptions in plasticity in which neighbour material elements are inseparable at all-time are physically impossible, since local detachments, slips and neighbour switching must operate, i.e. non-continuous deformation. Material microstructure is modelled herein by a set of point elements (particles) interacting with their neighbours. Each particle can detach from and/or attach with its neighbours during deformation. Simulations on two- dimensional configurations subjected to uniaxial compression cycle are conducted. Stochastic heterogeneity is controlled by a single "disorder" parameter. It was found that (a) macro response resembles typical elasto-plastic behaviour; (b) plastic energy is proportional to the number of detachments; (c) residual plastic strain is proportional to the number of attachments, and (d) volume is preserved, which is consistent with macro plastic deformation. Rigid body displacements of local groups of elements are also observed. Higher disorder decreases the macro elastic moduli and increases plastic energy. Evolution of anisotropic effects is obtained with no additional parameters.

Plastic debris in the open ocean

KAUST Repository

Cozar, Andres

2014-06-30

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

Plastic debris in the open ocean.

Science.gov (United States)

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J Ignacio; Irigoien, Xabier; Ubeda, Bárbara; Hernández-León, Santiago; Palma, Alvaro T; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L; Duarte, Carlos M

2014-07-15

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

Plastic debris in the open ocean

Science.gov (United States)

Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

2014-01-01

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean. PMID:24982135

Plastic Accumulation in the Mediterranean Sea

OpenAIRE

C?zar, Andr?s; Sanz-Mart?n, Marina; Mart?, Elisa; Gonz?lez-Gordillo, J. Ignacio; Ubeda, B?rbara; G?lvez, Jos? ?.; Irigoien, Xabier; Duarte, Carlos M.

2015-01-01

Copyright: © 2015 Cózar et al. Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by ...

21 CFR 872.5470 - Orthodontic plastic bracket.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Orthodontic plastic bracket. 872.5470 Section 872...) MEDICAL DEVICES DENTAL DEVICES Therapeutic Devices § 872.5470 Orthodontic plastic bracket. (a) Identification. An orthodontic plastic bracket is a plastic device intended to be bonded to a tooth to apply...

Plastic photochromic eyewear: a status report

Science.gov (United States)

Crano, John C.; Elias, Richard C.

1991-12-01

An estimated 10 million pairs of photochromic prescription lenses were dispensed in the United States in 1989, essentially all based on a silver halide system suspended in an inorganic glass. A significant trend within the ophthalmic industry has been the growth of light-weight plastic lenses. In the United States market, the percentage of prescription eyewear made of plastic is now greater than 70%. With this increasing market penetration of plastic lenses, the desire for an acceptable plastic photochromic lens has also increased. As with any commercial product, in order to achieve consumer acceptance there exist several technical requirements for a plastic photochromic lens. These include the light transmission and color of the lens in both the unactivated and activated states, the speeds of darkening and fading, and the fatigue resistance or lifetime of the photochromic system. These requirements will be defined along with approaches to achieving them. The properties of the commercially available plastic photochromic lenses will be compared with the defined requirements.

Study on reinforced concrete high-rise building using prefabricated beam-column joints. Part 3. ; Basic anchorage behaviors of longitudinal bars of beams. Hahsirater dot hari setsugobu PC ka koho (PG connection koho) wo mochiita RC koso tatemono no kaihatsu. 3. ; Hari shukin no kisoteki teichaku seijo

Energy Technology Data Exchange (ETDEWEB)

SEkine, M.; Yoshioka, K.; Eto, H. (Obayashi Corp., Tokyo (Japan))

1991-08-10

Pull-out tests were carried out to examine basic anchorage behaviors of through holes for beam re-bars by using a PG connection method, in which columns and beam-column joints with through holes for beam re-bars in the reinforced concrete framed construction are precast simultaneously. Specimens made by the PG connection method showed better anchorage behaviors than specimens made by the conventional anchorage method. In case of anchorage width of 80cm and concrete strength of about 350kgf/cm{sup 2}, it was recognized that large slipping of re-bars did not occur under allowable bond stress when the interval between re-bars was not less than 15cm and covering depth to the core of re-bars was not less than 8cm. Concerning a specimen which did not show splitting bond failure because of lateral compressive stress, bond stress of re-bars when large slipping occurred was 1.5 times or more in comparison with the allowable bond stress. Since this specimen held high slipping rigidity even after increase of slipping, its anchoring stress increased by 32-57% compared with a specimen without lateral compressive stress. 4 refs., 7 figs., 3 tabs.

49 CFR 192.375 - Service lines: Plastic.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Plastic. 192.375 Section 192.375... § 192.375 Service lines: Plastic. (a) Each plastic service line outside a building must be installed... terminate above ground level and outside the building, if— (i) The above ground level part of the plastic...

[From the French Society of Plastic and Reconstructive Surgery to the French Society of Plastic Reconstructive and Aesthetic Surgery].

Science.gov (United States)

Glicenstein, J

2004-04-01

(The) 3rd December 1952, 11 surgeons and other specialists found the French Society of Plastic and Reconstructive Surgery (SFCPR) which was officially published on (the) 28 September 1953. The first congress was during October 1953 and the first president as Maurice Aubry. The first secretary was Daniel Morel Fatio. The symposiums were after about three of four times each year and the thematic subjects were initially according the reconstructive surgery. The review "Annales de chirurgie plastique" was free in 1956. The members of the Society were about 30 initially, but their plastic surgery in the big hospitals at Paris and other big towns in France. The "specialty" of plastic surgery was created in 1971. On "syndicate", one French board of plastic reconstructive and aesthetic surgery, the increasing of departments of plastic surgery were the front of increasing of the plastic surgery in French and of the number of the French Society of Plastic Reconstructive surgery (580 in 2003). The French Society organized the International Congress of Plastic Surgery in 1975. The society SFCPR became the French Society of plastic reconstruction and Aesthetic Surgery (SFCPRE) in 1983 and the "logo" (front view) was in the 1994 SOF.CPRE.

Percutaneous Augmented Peripheral Osteoplasty in Long Bones of Oncologic Patients for Pain Reduction and Prevention of Impeding Pathologic Fracture: The Rebar Concept

International Nuclear Information System (INIS)

Kelekis, A.; Filippiadis, D.; Anselmetti, G.; Brountzos, E.; Mavrogenis, A.; Papagelopoulos, P.; Kelekis, N.; Martin, J.-B.

2016-01-01

PurposeTo evaluate clinical efficacy/safety of augmented peripheral osteoplasty in oncologic patients with long-term follow-up.Materials and MethodsPercutaneous augmented peripheral osteoplasty was performed in 12 patients suffering from symptomatic lesions of long bones. Under extensive local sterility measures, anesthesiology care, and fluoroscopic guidance, direct access to lesion was obtained and coaxially a metallic mesh consisting of 25–50 medical grade stainless steel micro-needles (22 G, 2–6 cm length) was inserted. PMMA for vertebroplasty was finally injected under fluoroscopic control. CT assessed implant position 24-h post-treatment.ResultsClinical evaluation included immediate and delayed follow-up studies of patient’s general condition, NVS pain score, and neurological status. Imaging assessed implant’s long-term stability. Mean follow-up was 16.17 ± 10.93 months (range 2–36 months). Comparing patients’ scores prior (8.33 ± 1.67 NVS units) and post (1.42 ± 1.62 NVS units) augmented peripheral osteoplasty, there was a mean decrease of 6.92 ± 1.51 NVS units. Overall mobility improved in 12/12 patients. No complication was observed.ConclusionPercutaneous augmented peripheral osteoplasty (rebar concept) for symptomatic malignant lesions in long bones seems to be a possible new technique for bone stabilization. This combination seems to provide necessary stability against shearing forces applied in long bones during weight bearing

Percutaneous Augmented Peripheral Osteoplasty in Long Bones of Oncologic Patients for Pain Reduction and Prevention of Impeding Pathologic Fracture: The Rebar Concept

Energy Technology Data Exchange (ETDEWEB)

Kelekis, A., E-mail: akelekis@med.uoa.gr; Filippiadis, D., E-mail: dfilippiadis@yahoo.gr [University General Hospital “ATTIKON”, 2nd Radiology Department (Greece); Anselmetti, G., E-mail: gc.anselmetti@fastwebnet.it [GVM Care and Research Maria Pia Hospital (Italy); Brountzos, E., E-mail: ebrountz@med.uoa.gr [University General Hospital “ATTIKON”, 2nd Radiology Department (Greece); Mavrogenis, A., E-mail: afm@otenet.gr; Papagelopoulos, P., E-mail: pjp@hol.gr [University General Hospital “ATTIKON”, A Orthopedic Clinic (Greece); Kelekis, N., E-mail: kelnik@med.uoa.gr [University General Hospital “ATTIKON”, 2nd Radiology Department (Greece); Martin, J.-B., E-mail: jbmartin@cird.ch [Centre Imaginerie Rive Droite & Gauche (Switzerland)

2016-01-15

PurposeTo evaluate clinical efficacy/safety of augmented peripheral osteoplasty in oncologic patients with long-term follow-up.Materials and MethodsPercutaneous augmented peripheral osteoplasty was performed in 12 patients suffering from symptomatic lesions of long bones. Under extensive local sterility measures, anesthesiology care, and fluoroscopic guidance, direct access to lesion was obtained and coaxially a metallic mesh consisting of 25–50 medical grade stainless steel micro-needles (22 G, 2–6 cm length) was inserted. PMMA for vertebroplasty was finally injected under fluoroscopic control. CT assessed implant position 24-h post-treatment.ResultsClinical evaluation included immediate and delayed follow-up studies of patient’s general condition, NVS pain score, and neurological status. Imaging assessed implant’s long-term stability. Mean follow-up was 16.17 ± 10.93 months (range 2–36 months). Comparing patients’ scores prior (8.33 ± 1.67 NVS units) and post (1.42 ± 1.62 NVS units) augmented peripheral osteoplasty, there was a mean decrease of 6.92 ± 1.51 NVS units. Overall mobility improved in 12/12 patients. No complication was observed.ConclusionPercutaneous augmented peripheral osteoplasty (rebar concept) for symptomatic malignant lesions in long bones seems to be a possible new technique for bone stabilization. This combination seems to provide necessary stability against shearing forces applied in long bones during weight bearing.

Plastic ingestion by Flesh-footed Shearwaters (Puffinus carneipes): Implications for fledgling body condition and the accumulation of plastic-derived chemicals

International Nuclear Information System (INIS)

Lavers, Jennifer L.; Bond, Alexander L.; Hutton, Ian

2014-01-01

To provide much needed quantitative data on the lethal and sublethal effects of plastic pollution on marine wildlife, we sampled breast feathers and stomach contents from Flesh-footed Shearwater (Puffinus carneipes) fledglings in eastern Australia. Birds with high levels of ingested plastic exhibited reduced body condition and increased contaminant load (p < 0.05). More than 60% of fledglings exceed international targets for plastic ingestion by seabirds, with 16% of fledglings failing these targets after a single feeding (range: 0.13–3.21 g of plastic/feeding). As top predators, seabirds are considered sentinels of the marine environment. The amount of plastic ingested and corresponding damage to Flesh-footed Shearwater fledglings is the highest reported for any marine vertebrate, suggesting the condition of the Australian marine environment is poor. These findings help explain the ongoing decline of this species and are worrying in light of increasing levels of plastic pollution in our oceans. - Highlights: • Proportion of the shearwater population ingesting plastic increased over four years. • Shearwater body condition is negatively influenced by the amount of ingested plastic. • Shearwater contaminant load is positively related to the amount of ingested plastic. • Many chicks exceed international targets for ingested plastic after a single feeding. • Plastic ingestion in this study is the highest reported for any marine vertebrate. - Flesh-footed Shearwaters ingest large quantities of marine plastic, which is correlated with poor body condition and increased concentrations of trace metals such as chromium

Effect of waste plastic as modifier on thermal stability and degradation kinetics of bitumen/waste plastics blend

Energy Technology Data Exchange (ETDEWEB)

Naskar, M. [Rubber Technology Centre, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India); Chaki, T.K., E-mail: tapan@rtc.iitkgp.ernet.in [Rubber Technology Centre, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India); Reddy, K.S. [Department of Civil Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India)

2010-09-20

Different modified bituminous binders are used in pavement construction for improved durability and for enhanced performance in resisting cracking and permanent deformation of bituminous layers. Waste plastics, whose disposal is a matter of concern, have been used successfully for modifying bitumen. This paper reports the thermogravimetric studies conducted on waste plastic modified bituminous binders. Modified bituminous binders prepared using different plastic contents (0-7 wt% by weight of bitumen) were investigated. The activation energies were determined from thermogravimetric analysis (TGA) data using Kissinger and the Flynn-Wall-Ozawa methods, which do not require knowledge of the reaction mechanism. Modified bitumen (WPMB5) with 5 wt% plastic was found to have the highest thermal stability compared to other binders investigated. Differential scanning calorimetry (DSC) studies were carried out to find crystalline melting temperature and fusion enthalpy. Rheological parameters of modified binders prepared with different plastic contents also suggest that the 5 wt% plastic content is expected to yield optimal performance.

Effect of waste plastic as modifier on thermal stability and degradation kinetics of bitumen/waste plastics blend

International Nuclear Information System (INIS)

Naskar, M.; Chaki, T.K.; Reddy, K.S.

2010-01-01

Different modified bituminous binders are used in pavement construction for improved durability and for enhanced performance in resisting cracking and permanent deformation of bituminous layers. Waste plastics, whose disposal is a matter of concern, have been used successfully for modifying bitumen. This paper reports the thermogravimetric studies conducted on waste plastic modified bituminous binders. Modified bituminous binders prepared using different plastic contents (0-7 wt% by weight of bitumen) were investigated. The activation energies were determined from thermogravimetric analysis (TGA) data using Kissinger and the Flynn-Wall-Ozawa methods, which do not require knowledge of the reaction mechanism. Modified bitumen (WPMB5) with 5 wt% plastic was found to have the highest thermal stability compared to other binders investigated. Differential scanning calorimetry (DSC) studies were carried out to find crystalline melting temperature and fusion enthalpy. Rheological parameters of modified binders prepared with different plastic contents also suggest that the 5 wt% plastic content is expected to yield optimal performance.

Neuronal cytoskeleton in synaptic plasticity and regeneration.

Science.gov (United States)

Gordon-Weeks, Phillip R; Fournier, Alyson E

2014-04-01

During development, dynamic changes in the axonal growth cone and dendrite are necessary for exploratory movements underlying initial axo-dendritic contact and ultimately the formation of a functional synapse. In the adult central nervous system, an impressive degree of plasticity is retained through morphological and molecular rearrangements in the pre- and post-synaptic compartments that underlie the strengthening or weakening of synaptic pathways. Plasticity is regulated by the interplay of permissive and inhibitory extracellular cues, which signal through receptors at the synapse to regulate the closure of critical periods of developmental plasticity as well as by acute changes in plasticity in response to experience and activity in the adult. The molecular underpinnings of synaptic plasticity are actively studied and it is clear that the cytoskeleton is a key substrate for many cues that affect plasticity. Many of the cues that restrict synaptic plasticity exhibit residual activity in the injured adult CNS and restrict regenerative growth by targeting the cytoskeleton. Here, we review some of the latest insights into how cytoskeletal remodeling affects neuronal plasticity and discuss how the cytoskeleton is being targeted in an effort to promote plasticity and repair following traumatic injury in the central nervous system. © 2013 International Society for Neurochemistry.

Mechanisms of GABAergic Homeostatic Plasticity

Directory of Open Access Journals (Sweden)

Peter Wenner

2011-01-01

Full Text Available Homeostatic plasticity ensures that appropriate levels of activity are maintained through compensatory adjustments in synaptic strength and cellular excitability. For instance, excitatory glutamatergic synapses are strengthened following activity blockade and weakened following increases in spiking activity. This form of plasticity has been described in a wide array of networks at several different stages of development, but most work and reviews have focussed on the excitatory inputs of excitatory neurons. Here we review homeostatic plasticity of GABAergic neurons and their synaptic connections. We propose a simplistic model for homeostatic plasticity of GABAergic components of the circuitry (GABAergic synapses onto excitatory neurons, excitatory connections onto GABAergic neurons, cellular excitability of GABAergic neurons: following chronic activity blockade there is a weakening of GABAergic inhibition, and following chronic increases in network activity there is a strengthening of GABAergic inhibition. Previous work on GABAergic homeostatic plasticity supports certain aspects of the model, but it is clear that the model cannot fully account for some results which do not appear to fit any simplistic rule. We consider potential reasons for these discrepancies.

Plasticity characteristic obtained by indentation

International Nuclear Information System (INIS)

Milman, Yu V

2008-01-01

A dimensionless parameter δ H = ε p /ε t (where ε p and ε t are the average values of plastic and total deformation of material on the contact area indenter-specimen) may be used as the plasticity characteristic of materials, which made it possible to characterize the plasticity of materials that are brittle in standard mechanical tests. δ H may be calculated from the values of microhardness HM, Young's modulus E and Poisson's ratio ν. In instrumented indentation the plasticity characteristic δ A = A p /A t (A p and A t are the work of plastic and total deformation during indentation) may be calculated. δ A ∼ δ H for materials with δ H > 0.5, i.e. for all metals and the majority of ceramic materials. In this case, the theoretical equation δ A ∼ δ H = 1-10.2 · (1 - ν - 2ν 2 )(HM/E) is satisfied in experiments with the Berkovich indenter. The influence of the temperature and structural parameters (dislocation density and grain size including nanostructured materials) on δ H is discussed

Smartphones and the plastic surgeon.

Science.gov (United States)

Al-Hadithy, Nada; Ghosh, Sudip

2013-06-01

Surgical trainees are facing limited training opportunities since the introduction of the European Working Time Directive. Smartphone sales are increasing and have usurped computer sales for the first time. In this context, smartphones are an important portable reference and educational tool, already in the possession of the majority of surgeons in training. Technology in the palm of our hands has led to a revolution of accessible information for the plastic surgery trainee and surgeon. This article reviews the uses of smartphones and applications for plastic surgeons in education, telemedicine and global health. A comprehensive guide to existing and upcoming learning materials and clinical tools for the plastic surgeon is included. E-books, podcasts, educational videos, guidelines, work-based assessment tools and online logbooks are presented. In the limited resource setting of modern clinical practice, savvy plastic surgeons can select technological tools to democratise access to education and best clinical care. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Smart film actuators using biomass plastic

International Nuclear Information System (INIS)

Yoneyama, Satoshi; Tanaka, Nobuo

2011-01-01

This paper presents a novel smart film actuator based on the use of a biomass plastic as a piezoelectric film. Conventional polymeric smart sensors and actuators have been based upon synthetic piezoelectric polymer films such as PVDF. Almost all synthetic polymers are made from nearly depleted oil resources. In addition combustion of their materials releases carbon dioxide, thereby contributing to global warming. Thus at least two important sustainability principles are violated when employing synthetic polymers: avoiding depletable resources and avoiding ecosystem destruction. To overcome such problems, industrial plastic products made from synthetic polymers were developed to replace oil-based plastics with biomass plastics. This paper applies a biomass plastic with piezoelectricity such as poly-L-lactic acid (PLLA). As a result, PLLA film becomes a distributed parameter actuator per se, hence an environmentally conscious smart film actuator is developed. Firstly, this paper overviews the fundamental properties of piezoelectric synthetic polymers and biopolymers. The concept of carbon neutrality using biopolymers is mentioned. Then a two-dimensional modal actuator for exciting a specific structural mode is proposed. Furthermore, a biomass plastic-based cantilever beam with the capability of modal actuation is developed, the validity of the proposed smart film actuator based upon a biomass plastic being analytically as well as experimentally verified

Finite element modelling of concrete beams reinforced with hybrid fiber reinforced bars

Science.gov (United States)

Smring, Santa binti; Salleh, Norhafizah; Hamid, NoorAzlina Abdul; Majid, Masni A.

2017-11-01

Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibre-reinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study.

Finding the missing plastic -resolving the global mass (im)balance for plastic pollution in the ocean

Science.gov (United States)

Wilcox, C.; van Sebille, E.

2016-02-01

Several global studies have attempted to estimate the standing stock of plastic debris in the oceans at the global scale. However, recent work estimating the amount lost from land on an annual basis suggests that the standing stock should be several orders of magnitude larger than the global estimates. We investigate the role of coastal deposition within the first few weeks after plastic enters the ocean and very near its sources, one of the hypothesized sinks for the missing plastic in this mass balance. We utilize a continental scale dataset of plastics collected along Australia's coast and in the offshore regions together with models of plastic release and transport based on Lagrangian tracking to investigate the role of local deposition in the coastal environment. Our models predict that the vast majority of positively buoyant plastic is deposited within a very short distance from its release point, with only a small fraction escaping into the open ocean. These predictions match our coastal and offshore observations, providing clear evidence that this mechanism of immediate coastal deposition is, at least in part, driving the apparent mismatch between coastal emissions and the standing stock in the ocean.

Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

Directory of Open Access Journals (Sweden)

Chelsea M Rochman

Full Text Available Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET, high-density polyethylene (HDPE, polyvinyl chloride (PVC, low-density polyethylene (LDPE, and polypropylene (PP. Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb, can be found on plastic debris composed of various plastic types.

Long-term sorption of metals is similar among plastic types: implications for plastic debris in aquatic environments.

Science.gov (United States)

Rochman, Chelsea M; Hentschel, Brian T; Teh, Swee J

2014-01-01

Concerns regarding plastic debris and its ability to accumulate large concentrations of priority pollutants in the aquatic environment led us to quantify relationships between different types of mass-produced plastic and metals in seawater. At three locations in San Diego Bay, we measured the accumulation of nine targeted metals (aluminum, chromium, manganese, iron, cobalt, nickel, zinc, cadmium and lead) sampling at 1, 3, 6, 9 and 12 months, to five plastic types: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polyvinyl chloride (PVC), low-density polyethylene (LDPE), and polypropylene (PP). Accumulation patterns were not consistent over space and time, and in general all types of plastic tended to accumulate similar concentrations of metals. When we did observe significant differences among concentrations of metals at a single sampling period or location in San Diego Bay, we found that HDPE typically accumulated lesser concentrations of metals than the other four polymers. Furthermore, over the 12-month study period, concentrations of all metals increased over time, and chromium, manganese, cobalt, nickel, zinc and lead did not reach saturation on at least one plastic type during the entire 12-month exposure. This suggests that plastic debris may accumulate greater concentrations of metals the longer it remains at sea. Overall, our work shows that a complex mixture of metals, including those listed as priority pollutants by the US EPA (Cd, Ni, Zn and Pb), can be found on plastic debris composed of various plastic types.

Plastics recycling: challenges and opportunities

OpenAIRE

Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

2009-01-01

Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3–4% is expended to pro...

ARE PLASTIC GROCERY BAGS SACKING THE ENVIRONMENT?

OpenAIRE

Mangal Gogte

2009-01-01

This paper is oriented on analysis impacts of plastic bags on environment. In this paper is analyzed did plastic bags are so harmful, and what are the main ingredients of it. One part of this paper is oriented on effects of plastic bags and management of their usage. There is also made comparative analysis between impacts of plastic and paper bags on environment.

Plastic surgery and global health: how plastic surgery impacts the global burden of surgical disease.

Science.gov (United States)

Semer, Nadine B; Sullivan, Stephen R; Meara, John G

2010-08-01

The global burden of surgical disease is estimated as being 11% of the total global burden of disease. In this article we discuss the portion of this burden which could be ameliorated with plastic surgical expertise. Although not necessarily seen as a major player in issues related to global health, plastic surgeons are uniquely qualified to decrease the burden of surgical disease afflicting people in the developing world. Burns, traumatic injuries, and congenital anomalies are some of the areas where the presence of plastic surgical expertise can make a significant difference in patient outcomes and thereby decrease the years of life lost due to disability due to these highly treatable conditions. In light of the severe shortage of plastic surgeons throughout the developing world, it falls to those concentrated in the developed world to harness their skills and address the vast unmet needs of the developing world so as to enhance global health. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Translation-rotation plasticity as basic mechanism of plastic deformation in macro-, micro- and nanoindentation processes

International Nuclear Information System (INIS)

Grabco, D; Shikimaka, O; Harea, E

2008-01-01

This paper presents a brief review of multilateral examinations for the purpose of detection of interrelation between processes occuring in solids at different levels of action of exterior loading, namely, at macro-, micro- and nanoindentation. Convincing arguments supporting the rotation deformation mechanism alongside the recognized dislocation one are adduced. It has been shown that the decrease in dislocation mobility leads at all scales to the intensification of rotation plasticity and to the involvement of other plastic deformation mechanisms, such as appearance and interaction of disclinations, twinning, phase transition and compression of material. The conversion from translation plasticity to the rotation-translation one means transition to the higher level of plastic deformation, the mesolevel, when the possibilities of the previous microscopic level are exhausted. It was established that the plastic deformation zone in the vicinity of indentations could be separated into two main specific regions: (i) peripheral region predominantly with the dislocation deformation mechanism; otherwise, translation mechanism: microlevel, and (ii) quasidestructured region mainly with the disclination or the intergranular sliding mechanism: rotation mechanism, mesolevel

Use of recycled plastics in concrete: A critical review.

Science.gov (United States)

Gu, Lei; Ozbakkaloglu, Togay

2016-05-01

Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Plasticized chitosan/polyolefin films produced by extrusion.

Science.gov (United States)

Matet, Marie; Heuzey, Marie-Claude; Ajji, Abdellah; Sarazin, Pierre

2015-03-06

Plasticized chitosan and polyethylene blends were produced through a single-pass extrusion process. Using a twin-screw extruder, chitosan plasticization was achieved in the presence of an acetic acid solution and glycerol, and directly mixed with metallocene polyethylene, mPE, to produce a masterbatch. Different dilutions of the masterbatch (2, 5 and 10 wt% of plasticized chitosan), in the presence of ethylene vinyl acetate, EVA, were subsequently achieved in single screw film extrusion. Very small plasticized chitosan domains (number average diameter <5 μm) were visible in the polymeric matrix. The resulting films presented a brown color and increasing haze with chitosan plasticized content. Mechanical properties of the mPE films were affected by the presence of plasticized chitosan, but improvement was observed as a result of some compatibility between mPE and chitosan in the presence of EVA. Finally the incorporation of plasticized chitosan affected mPE water vapor permeability while oxygen permeability remained constant. Copyright © 2014 Elsevier Ltd. All rights reserved.

Rigid-Plastic Approximations for Predicting Plastic Deformation of Cylindrical Shells Subject to Dynamic Loading

Directory of Open Access Journals (Sweden)

Michelle S. Hoo Fatt

1996-01-01

Full Text Available A theoretical approach was developed for predicting the plastic deformation of a cylindrical shell subject to asymmetric dynamic loads. The plastic deformation of the leading generator of the shell is found by solving for the transverse deflections of a rigid-plastic beam/string-on-foundation. The axial bending moment and tensile force in the beam/string are equivalent to the longitudinal bending moments and membrane forces of the shell, while the plastic foundation force is equivalent to the shell circumferential bending moment and membrane resistances. Closed-form solutions for the transient and final deformation profile of an impulsive loaded shell when it is in a “string” state were derived using the eigenfunction expansion method. These results were compared to DYNA 3D predictions. The analytical predictions of the transient shell and final centerline deflections were within 25% of the DYNA 3D results.

Leaching of plastic additives to marine organisms

International Nuclear Information System (INIS)

Koelmans, Albert A.; Besseling, Ellen; Foekema, Edwin M.

2014-01-01

It is often assumed that ingestion of microplastics by aquatic species leads to increased exposure to plastic additives. However, experimental data or model based evidence is lacking. Here we assess the potential of leaching of nonylphenol (NP) and bisphenol A (BPA) in the intestinal tracts of Arenicola marina (lugworm) and Gadus morhua (North Sea cod). We use a biodynamic model that allows calculations of the relative contribution of plastic ingestion to total exposure of aquatic species to chemicals residing in the ingested plastic. Uncertainty in the most crucial parameters is accounted for by probabilistic modeling. Our conservative analysis shows that plastic ingestion by the lugworm yields NP and BPA concentrations that stay below the lower ends of global NP and BPA concentration ranges, and therefore are not likely to constitute a relevant exposure pathway. For cod, plastic ingestion appears to be a negligible pathway for exposure to NP and BPA. - Highlights: • Uptake of plastic additives after plastic ingestion was modeled for worms and fish. • This was done for bisphenol A and nonylphenol. • Uncertainty was accounted for by Monte Carlo simulations. • It appeared that exposure by plastic ingestion was negligible for fish. • Plastic ingestion may occasionally be relevant for marine worms. - Leaching of nonylphenol and bisphenol A from ingested microplastic may be relevant for the lugworm, but is irrelevant for fish like cod

Evaluation of the reinforcing steel corrosion in concrete mixes that will be used for constructing mid activity disposal repositories

International Nuclear Information System (INIS)

Moreno, Manuel; Alvarez, Marta G.; Duffo, Gustavo S.

2000-01-01

This study presents an evaluation of the reinforcing steel bars (rebars) corrosion behavior embedded in high performance concrete's prepared with three different cement types (normal Portland, Sulfate resistant and with furnace slag). The results of the study will provide the basis to select the materials used for constructing the mid activity radioactive disposals containers. The effect of aggressive ions such as chlorides and sulfates, as well as concrete carbonation, on the rebar corrosion process is evaluated using concrete specimens containing rebar segments. The electrochemical parameters that characterize the rebar corrosion process (corrosion potential (E corr ), polarization resistance (Rp) and electrical resistivity of concrete (ρ)) where periodically monitored after a conditioning period of 100 days. The results show that under all exposure conditions evaluated the rebar segments in contact with the three concrete mixes achieve a passive state of corrosion. Due to the continuos curing process of concrete the values of ρ present an increasing trend within time, even in the specimens exposed to the immersed conditions. (author)

Flexural behavior of concrete beam with mechanical splices of reinforcement subjected to cyclic loading

International Nuclear Information System (INIS)

Nab, H. S.; Kim, W. B.

2008-01-01

In nuclear power plant structures, the mechanical rebar splices are designated and constructed on the basis of ACI and ASME code. Regardless of good performance on mechanical rebar splices, these splicing methods that did not be registered on ASME code have not restricted to apply to construction site. In this study, the main candidate splice is cold roll formed parallel threaded splice. This was registered newly in ASME Section III division 2 CC 4333 'Mechanical Splices' in 2004. To compare the traditional rebar splice with mechanical rebar splices, concrete beams were made to evaluate the ductility of spliced reinforcing bars. Based on Experimental results, it was identified that the mechanical rebar splices by parallel threaded coupler had better accumulated dissipation energy capacity to resist seismic behavior than the traditional lapping splices. It showed that concrete specimens with D36 reinforcing bar coupler are 1.8 times better performance and that concrete specimens with D22 reinforcing bar coupler are 2.8 times better performance. (authors)

Plastics and environmental health: the road ahead.

Science.gov (United States)

North, Emily J; Halden, Rolf U

2013-01-01

Plastics continue to benefit society in innumerable ways, even though recent public focus on plastics has centered mostly on human health and environmental concerns, including their endocrine-disrupting properties and the long-term pollution they represent. The benefits of plastics are particularly apparent in medicine and public health. Plastics are versatile, cost-effective, require less energy to produce than alternative materials like metal or glass, and can be manufactured to have many different properties. Due to these characteristics, polymers are used in diverse health applications like disposable syringes and intravenous bags, sterile packaging for medical instruments as well as in joint replacements, tissue engineering, etc. However, not all current uses of plastics are prudent and sustainable, as illustrated by the widespread, unwanted human exposure to endocrine-disrupting bisphenol A (BPA) and di-(2-ethylhexyl)phthalate (DEHP), problems arising from the large quantities of plastic being disposed of, and depletion of non-renewable petroleum resources as a result of the ever-increasing mass production of plastic consumer articles. Using the health-care sector as example, this review concentrates on the benefits and downsides of plastics and identifies opportunities to change the composition and disposal practices of these invaluable polymers for a more sustainable future consumption. It highlights ongoing efforts to phase out DEHP and BPA in the health-care and food industry and discusses biodegradable options for plastic packaging, opportunities for reducing plastic medical waste, and recycling in medical facilities in the quest to reap a maximum of benefits from polymers without compromising human health or the environment in the process.

Plastics and Environmental Health: The Road Ahead

Science.gov (United States)

North, Emily J.; Halden, Rolf U.

2013-01-01

Plastics continue to benefit society in innumerable ways, even though recent public focus on plastics has centered mostly on human health and environmental concerns, including endocrine-disrupting properties and long-term pollution. The benefits of plastics are particularly apparent in medicine and public health. Plastics are versatile, cost-effective, require less energy to produce than alternative materials – such as metal or glass – and can be manufactured to have many different properties. Due to these characteristics, polymers are used in diverse health applications, such as disposable syringes and intravenous bags, sterile packaging for medical instruments as well as in joint replacements, tissue engineering, etc. However, not all current uses of plastics are prudent and sustainable, as illustrated by widespread, unwanted human exposure to endocrine-disrupting bisphenol-A (BPA) and di-(2-ethylhexyl)phthalate (DEHP), problems arising from the large quantities of plastic being disposed of, and depletion of non-renewable petroleum resources as a result of ever increasing mass-production of plastic consumer articles. By example of the healthcare sector, this review concentrates on benefits and downsides of plastics and identities opportunities to change the composition and disposal practices of these invaluable polymers for a more sustainable future consumption. It highlights ongoing efforts to phase out DEHP and BPA in the healthcare and food industry, and discusses biodegradable options for plastic packaging, opportunities for reducing plastic medical waste, and recycling in medical facilities in the quest to reap a maximum of benefits from polymers without compromising human health or the environment in the process. PMID:23337043

ARE PLASTIC GROCERY BAGS SACKING THE ENVIRONMENT?

Directory of Open Access Journals (Sweden)

Mangal Gogte

2009-12-01

Full Text Available This paper is oriented on analysis impacts of plastic bags on environment. In this paper is analyzed did plastic bags are so harmful, and what are the main ingredients of it. One part of this paper is oriented on effects of plastic bags and management of their usage. There is also made comparative analysis between impacts of plastic and paper bags on environment.

Motor cortical plasticity in Parkinson’s disease

Directory of Open Access Journals (Sweden)

Kaviraja eUdupa

2013-09-01

Full Text Available In Parkinson’s disease (PD, there are alterations of the basal ganglia (BG thalamo-cortical networks, primarily due to degeneration of nigrostrial dopaminergic neurons. These changes in subcortical networks lead to plastic changes in primary motor cortex (M1, which mediates cortical motor output and is a potential target for treatment of PD. Studies investigating the motor cortical plasticity using non-invasive transcranial magnetic stimulation (TMS have found altered plasticity in PD, but there are inconsistencies among these studies. This is likely because plasticity depends on many factors such as the extent of dopaminergic loss and disease severity, response to dopaminergic replacement therapies, development of L-dopa-induced dyskinesias (LID, the plasticity protocol used, medication and stimulation status in patients treated with deep brain stimulation (DBS. The influences of LID and DBS on BG and M1 plasticity have been explored in animal models and in PD patients. In addition, many other factors such age, genetic factors (e.g. brain derived neurotropic factor and other neurotransmitters or receptors polymorphism, emotional state, time of the day, physical fitness have been documented to play role in the extent of plasticity induced by TMS in human studies. In this review, we summarize the studies that investigated M1 plasticity in PD and demonstrate how these afore-mentioned factors affect motor cortical plasticity in PD. We conclude that it is important to consider the clinical, demographic and technical factors that influence various plasticity protocols while developing these protocols as diagnostic or prognostic tools in PD. We also discuss how the modulation of cortical excitability and the plasticity with these non-invasive brain stimulation techniques facilitate the understanding of the pathophysiology of PD and help design potential therapeutic possibilities in this disorder.

Managing plastic waste in East Africa: Niche innovations in plastic production and solid waste

NARCIS (Netherlands)

Ombis, L.O.; Vliet, van B.J.M.; Mol, A.P.J.

2015-01-01

This paper assesses the uptake of environmental innovation practices to cope with plastic waste in Kenyan urban centres at the interface of solid waste management and plastic production systems. The Multi Level Perspective on Technological Transitions is used to evaluate 7 innovation pathways of

Catherine Malabou’s Hegel: One or several plasticities?

Directory of Open Access Journals (Sweden)

Moder Gregor

2015-01-01

Full Text Available Through an original and extraordinarily fruitful reading of the Hegelian conception of negativity, Catherine Malabou developed the concept of plasticity which she keeps working on as one of her cardinal concepts even to this day. Engaging in the problematic of unity in Hegel, the paper takes on the task of trying to answer the question whether plasticity is one or are there several plasticities. The author argues that one must be careful not to reduce the inherent multiple of plasticity to a single plasticity which becomes plasticity par excellence: the plasticity of plastic explosion, of an abrupt and absolute break, to be distinguished from a creative or productive plasticity of habit. Malabou claimed that Hegel was - contrary to what Deleuz read in him - a philosopher of conceptual multitude as a multitude which cannot be reduced to only one image, the image of unity. If this is true, then the concept of plasticity itself with which she grasped the essence of Hegel’s dialectics, should be understood at least as a “unity in conflict”, if not as an inorganic, inhomogeneous, composed unity - and perhaps even as a unity of the pack.

Degradation of plastic carrier bags in the marine environment

International Nuclear Information System (INIS)

O'Brine, Tim; Thompson, Richard C.

2010-01-01

Research highlights: → There is considerable concern about the hazards that plastic debris presents to wildlife. → Here we investigate breakdown of oxodegradable, compostable and conventional plastic bags. → Compostable plastic disappeared from our test rig between 16 and 24 weeks. → Approximately 98% of the other plastics remained after 40 weeks. → Fouling by marine organisms substantially reduced the amount of UV-light reaching the plastic. - Abstract: There is considerable concern about the hazards that plastic debris presents to wildlife. Use of polymers that degrade more quickly than conventional plastics presents a possible solution to this problem. Here we investigate breakdown of two oxo-biodegradable plastics, compostable plastic and standard polyethylene in the marine environment. Tensile strength of all materials decreased during exposure, but at different rates. Compostable plastic disappeared from our test rig between 16 and 24 weeks whereas approximately 98% of the other plastics remained after 40 weeks. Some plastics require UV light to degrade. Transmittance of UV through oxo-biodegradable and standard polyethylene decreased as a consequence of fouling such that these materials received ∼90% less UV light after 40 weeks. Our data indicate that compostable plastics may degrade relatively quickly compared to oxo-biodegradable and conventional plastics. While degradable polymers offer waste management solutions, there are limitations to their effectiveness in reducing hazards associated with plastic debris.

Dictionary of plastics. 7. rev. ed. Kunststoff-Lexikon

Energy Technology Data Exchange (ETDEWEB)

Stoeckhert, K [ed.

1981-01-01

The book starts with a list of about 400 acronyms for plastic materials and additives, caoutchouc types, and synthetic fibers. This is followed by a 500-page glossary of plastics and a 200-page appendix listing producers of plastic feedstocks, chemical substances and additives, recoverable materials, processing systems, semi-finished plastic products and end products, machinery, tools and further aids for plastics processing. (HK).

Neurogenomic mechanisms of social plasticity.

Science.gov (United States)

Cardoso, Sara D; Teles, Magda C; Oliveira, Rui F

2015-01-01

Group-living animals must adjust the expression of their social behaviour to changes in their social environment and to transitions between life-history stages, and this social plasticity can be seen as an adaptive trait that can be under positive selection when changes in the environment outpace the rate of genetic evolutionary change. Here, we propose a conceptual framework for understanding the neuromolecular mechanisms of social plasticity. According to this framework, social plasticity is achieved by rewiring or by biochemically switching nodes of a neural network underlying social behaviour in response to perceived social information. Therefore, at the molecular level, it depends on the social regulation of gene expression, so that different genomic and epigenetic states of this brain network correspond to different behavioural states, and the switches between states are orchestrated by signalling pathways that interface the social environment and the genotype. Different types of social plasticity can be recognized based on the observed patterns of inter- versus intra-individual occurrence, time scale and reversibility. It is proposed that these different types of social plasticity rely on different proximate mechanisms at the physiological, neural and genomic level. © 2015. Published by The Company of Biologists Ltd.

Charge carrier dynamics in PMMA-LiClO4 based polymer electrolytes plasticized with different plasticizers

Science.gov (United States)

Pal, P.; Ghosh, A.

2017-07-01

We have studied the charge carrier dynamics in poly(methylmethacrylate)-LiClO4 polymer electrolytes plasticized with different plasticizers such as ethylene carbonate (EC), propylene carbonate (PC), polyethylene glycol (PEG), and dimethyl carbonate (DMC). We have measured the broadband complex conductivity spectra of these electrolytes in the frequency range of 0.01 Hz-3 GHz and in the temperature range of 203 K-363 K and analyzed the conductivity spectra in the framework of the random barrier model by taking into account the contribution of the electrode polarization observed at low frequencies and/or at high temperatures. It is observed that the temperature dependences of the ionic conductivity and relaxation time follow the Vogel-Tammann-Fulcher relation for all plasticized electrolytes. We have also performed the scaling of the conductivity spectra, which indicates that the charge carrier dynamics is almost independent of temperature and plasticizers in a limited frequency range. The existence of nearly constant loss in these electrolytes has been observed at low temperatures and/or high frequencies. We have studied the dielectric relaxation in these electrolytes using electric modulus formalism and obtained the stretched exponent and the decay function. We have observed less cooperative ion dynamics in electrolytes plasticized with DMC compared to electrolytes plasticized with EC, PC, and PEG.

UTILIZATION OF WASTE PLASTIC BOTTLES IN ASPHALT MIXTURE

Directory of Open Access Journals (Sweden)

TAHER BAGHAEE MOGHADDAM

2013-06-01

Full Text Available Nowadays, large amounts of waste materials are being produced in the world. One of the waste materials is plastic bottle. Generating disposable plastic bottles is becoming a major problem in many countries. Using waste plastic as a secondary material in construction projects would be a solution to overcome the crisis of producing large amount of waste plastics in one hand and improving the structure’s characteristics such as resistance against cracking on the other hand. This study aimed to investigate the effects of adding plastic bottles in road pavement. Marshall properties as well as specific gravity of asphalt mixture containing different percentages of plastic bottles were evaluated. Besides, Optimum Asphalt Content (OAC was calculated for each percentages of plastic bottles used in the mix. The stiffness and fatigue characteristics of mixture were assessed at OAC value. Results showed that the stability and flow values of asphalt mixture increased by adding waste crushed plastic bottle into the asphalt mixture. Further, it was shown that the bulk specific gravity and stiffness of mixtures increased by adding lower amount of plastic bottles; however, adding higher amounts of plastic resulted in lower specific gravity and mix stiffness. In addition, it was concluded that the mixtures containing waste plastic bottles have lower OAC values compared to the conventional mixture, and this may reduce the amount of asphalt binder can be used in road construction projects. Besides, the mixtures containing waste plastic showed significantly greater fatigue resistance than the conventional mixture.

Fiberglass Grids as Sustainable Reinforcement of Historic Masonry

Science.gov (United States)

Righetti, Luca; Edmondson, Vikki; Corradi, Marco; Borri, Antonio

2016-01-01

Fiber-reinforced composite (FRP) materials have gained an increasing success, mostly for strengthening, retrofitting and repair of existing historic masonry structures and may cause a significant enhancement of the mechanical properties of the reinforced members. This article summarizes the results of previous experimental activities aimed at investigating the effectiveness of GFRP (Glass Fiber Reinforced Polymers) grids embedded into an inorganic mortar to reinforce historic masonry. The paper also presents innovative results on the relationship between the durability and the governing material properties of GFRP grids. Measurements of the tensile strength were made using specimens cut off from GFRP grids before and after ageing in aqueous solution. The tensile strength of a commercially available GFRP grid has been tested after up 450 days of storage in deionized water and NaCl solution. A degradation in tensile strength and Young’s modulus up to 30.2% and 13.2% was recorded, respectively. This degradation indicated that extended storage in a wet environment may cause a decrease in the mechanical properties. PMID:28773725

Irradiation effect of the insulating materials for fusion superconducting magnets at cryogenic temperature

Science.gov (United States)

Kobayashi, Koji; Akiyama, Yoko; Nishijima, Shigehiro

2017-09-01

In ITER, superconducting magnets should be used in such severe environment as high fluence of fast neutron, cryogenic temperature and large electromagnetic forces. Insulating material is one of the most sensitive component to radiation. So radiation resistance on mechanical properties at cryogenic temperature are required for insulating material. The purpose of this study is to evaluate irradiation effect of insulating material at cryogenic temperature by gamma-ray irradiation. Firstly, glass fiber reinforced plastic (GFRP) and hybrid composite were prepared. After irradiation at room temperature (RT) or liquid nitrogen temperature (LNT, 77 K), interlaminar shear strength (ILSS) and glass-transition temperature (Tg) measurement were conducted. It was shown that insulating materials irradiated at room temperature were much degraded than those at cryogenic temperature.

Extruded plastic scintillator for MINERvA

International Nuclear Information System (INIS)

Pla-Dalmau, Anna; Bross, Alan D.; FermilabRykalin, Victor V.; Wood, Brian M.; NICADD, DeKalb

2005-01-01

An extrusion line has recently been installed at Fermilab in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector Development). This new facility will serve to further develop and improve extruded plastic scintillator. Since polystyrene is widely used in the consumer industry, the logical path was to investigate the extrusion of commercial-grade polystyrene pellets with dopants to yield high quality plastic scintillator. The D0 and MINOS experiments are already using extruded scintillator strips in their detectors. A new experiment at Fermilab is pursuing the use of extruded plastic scintillator. A new plastic scintillator strip is being tested and its properties characterized. The initial results are presented here

Parametric Study of End Milling Glass Fibre Reinforced Composites

International Nuclear Information System (INIS)

Azmi, Azwan I.; Lin, Richard J. T.; Bhattacharyya, Debes

2011-01-01

This paper discusses the application of Taguchi 'Design of Experiment' method to investigate the effects of end milling parameters on machinability characteristics of unidirectional E-glass fibre reinforced polymer (GFRP) composites. A series of milling experiments were conducted using tungsten carbide end milling cutters at various spindle speeds, feed rates and depths of cut. Taguchi analysis was carried out and the signal to noise (S/N) ratio with analysis of variance (ANOVA) was employed to analyse the effects of those parameters on GFRP machinability. Overall, the results of the current investigations present some desirable combinations of the machining parameters that can further enhance the end milling machinability characteristics to suit the final requirements of the finished GFRP products.

Behavioral Response to Plastic Bag Legislation in Botswana

OpenAIRE

Dikgang, Johane; Visser, Martine

2010-01-01

This paper investigates the use of charges and standards in dealing with a common externality, plastic litter from shopping bags in Botswana. The country passed a plastic bag tax (effective 2007) to curb the plastic bag demand. Interestingly, the legislation did not force retailers to charge for plastic bags, which they did voluntarily at different prices. We assessed the environmental effectiveness and efficiency of the plastic bag legislation by analyzing consumers’ sensitivity to the impro...

PENGARUH PLASTICIZER PADA KARAKTERISTIK EDIBLE FILM DARI PEKTIN

Directory of Open Access Journals (Sweden)

Sang Kompiang Wirawan

2012-05-01

Full Text Available EFFECT OF PLASTICIzER ON THE PECTINIC EDIBLE FILM CHARACTERISTICS. The peel of Balinese Citrus contains high concentration of pectin which can be further processed to be edible films. The edible films can be utilized as a food coating which protects the food from any external mass transports such as humid, oxygen, and soluble material and can be served as a carrier to improve the mechanical-handing properties of the food. Edible films made of organic polymers tend to be brittle and thus addition of a plasticizer is required during the process. The work studies the effect of the type and the concentration of plasticizers on the tensile strength, the elongation of break, and the water vapor permeabilty of the edible film. Sorbitol and glycerol were used as plasticizers. Albedo from the citrus was hydrolized with hydrochloride acid 0.1 N to get pectinate substance. Pectin was then dissolved in water dan mixed with the plasticizers and CaCl2.2H2O solution. The concentrations of the plasticizers were 0, 0.03, 0.05, 0.1, and 0.15 mL/mL of solution. The results showed that increasing the concentration of plasticizers will decrease the tensile strength, but increase the elongation and film permeability. Sorbitol-plasticized films are more brittle, however exhibited higher tensile strength and water vapor permeability than of glycerol-plasticized film. The results suggested that glycerol is better plasticizer than sorbitol.  Kulit jeruk bali banyak mengandung pektin yang dapat dimanfaatkan sebagai bahan baku edible film. Edible film bisa digunakan untuk melapisi bahan makanan, melindungi makanan dari transfer massa eksternal seperti kelembaban, oksigen, dan zat terlarut, serta dapat digunakan sebagai carrier untuk meningkatkan penanganan mekanik produk makanan. Film yang terbuat dari bahan polimer organik ini cenderung rapuh sehingga diperlukan penambahan plasticizer. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh kadar dan jenis

Plastic waste associated with disease on coral reefs.

Science.gov (United States)

Lamb, Joleah B; Willis, Bette L; Fiorenza, Evan A; Couch, Courtney S; Howard, Robert; Rader, Douglas N; True, James D; Kelly, Lisa A; Ahmad, Awaludinnoer; Jompa, Jamaluddin; Harvell, C Drew

2018-01-26

Plastic waste can promote microbial colonization by pathogens implicated in outbreaks of disease in the ocean. We assessed the influence of plastic waste on disease risk in 124,000 reef-building corals from 159 reefs in the Asia-Pacific region. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. Structurally complex corals are eight times more likely to be affected by plastic, suggesting that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately affected. Plastic levels on coral reefs correspond to estimates of terrestrial mismanaged plastic waste entering the ocean. We estimate that 11.1 billion plastic items are entangled on coral reefs across the Asia-Pacific and project this number to increase 40% by 2025. Plastic waste management is critical for reducing diseases that threaten ecosystem health and human livelihoods. Copyright © 2018, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Can plastic mulching replace irrigation in dryland agriculture?

Science.gov (United States)

Wang, L.; Daryanto, S.; Jacinthe, P. A.

2017-12-01

Increasing water use efficiency (WUE) is a key strategy to maintaining crops yield without over-exploiting the scarce water resource. Plastic mulching technology for wheat and maize has been commonly used in China, but their effect on yield, soil moisture, evapotranspiration (ET), and WUE has not been compared with traditional irrigation method. Using a meta-analysis approach, we quantitatively examined the efficacy of plastic mulching in comparison with traditional irrigation in dryland agriculture. Our results showed that plastic mulching technique resulted in yield increase comparable to irrigated crops but used 24% less water. By covering the ridges with plastic and channeling rainwater into a very narrow planting zone (furrow), plastic mulching increased WUE and available soil moisture. Higher WUE in plastic-mulched croplands was likely a result of greater proportion of available water being used for transpiration than evaporation. If problems related to production costs and residual plastic pollution could be managed, plastic mulching technology would become a promising strategy for dryland farming in other regions.

Seabirds, gyres and global trends in plastic pollution.

Science.gov (United States)

van Franeker, Jan A; Law, Kara Lavender

2015-08-01

Fulmars are effective biological indicators of the abundance of floating plastic marine debris. Long-term data reveal high plastic abundance in the southern North Sea, gradually decreasing to the north at increasing distance from population centres, with lowest levels in high-arctic waters. Since the 1980s, pre-production plastic pellets in North Sea fulmars have decreased by ∼75%, while user plastics varied without a strong overall change. Similar trends were found in net-collected floating plastic debris in the North Atlantic subtropical gyre, with a ∼75% decrease in plastic pellets and no obvious trend in user plastic. The decreases in pellets suggest that changes in litter input are rapidly visible in the environment not only close to presumed sources, but also far from land. Floating plastic debris is rapidly "lost" from the ocean surface to other as-yet undetermined sinks in the marine environment. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Linking plastic ingestion research with marine wildlife conservation.

Science.gov (United States)

Avery-Gomm, Stephanie; Borrelle, Stephanie B; Provencher, Jennifer F

2018-05-16

Plastic is an increasingly pervasive marine pollutant. Concomitantly, the number of studies documenting plastic ingestion in wildlife is accelerating. Many of these studies aim to provide a baseline against which future levels of plastic ingestion can be compared, and are motivated by an underlying interest in the conservation of their study species and ecosystems. Although this research has helped to raise the profile of plastic as a pollutant of emerging concern, there is a disconnect between research examining plastic pollution and wildlife conservation. We present ideas to further discussion about how plastic ingestion research could benefit wildlife conservation by prioritising studies that elucidates the significance of plastic pollution as a population-level threat, identifies vulnerable populations, and evaluates strategies for mitigating impacts. The benefit of plastic ingestion research to marine wildlife can be improved by establishing a clearer understanding of how discoveries will be integrated into conservation and policy actions. Copyright © 2018. Published by Elsevier B.V.

Studies of elastic-plastic instabilities

DEFF Research Database (Denmark)

Tvergaard, Viggo

1999-01-01

Analyses of plastic instabilities are reviewed, with focus on results in structural mechanics as well as continuum mechanics. First the basic theories for bifurcation and post-bifurcation behavior are briefly presented. Then, localization of plastic flow is discussed, including shear band formati...

Neuromodulation, development and synaptic plasticity.

Science.gov (United States)

Foehring, R C; Lorenzon, N M

1999-03-01

We discuss parallels in the mechanisms underlying use-dependent synaptic plasticity during development and long-term potentiation (LTP) and long-term depression (LTD) in neocortical synapses. Neuromodulators, such as norepinephrine, serotonin, and acetylcholine have also been implicated in regulating both developmental plasticity and LTP/LTD. There are many potential levels of interaction between neuromodulators and plasticity. Ion channels are substrates for modulation in many cell types. We discuss examples of modulation of voltage-gated Ca2+ channels and Ca(2+)-dependent K+ channels and the consequences for neocortical pyramidal cell firing behaviour. At the time when developmental plasticity is most evident in rat cortex, the substrate for modulation is changing as the densities and relative proportions of various ion channels types are altered during ontogeny. We discuss examples of changes in K+ and Ca2+ channels and the consequence for modulation of neuronal activity.

Aktau Plastics Plant Explosives Material Report

Energy Technology Data Exchange (ETDEWEB)

CASE JR.,ROGER S.

1999-12-01

The U.S. Department of Energy (DOE) has been cooperating with the Republic of Kazakhstanin Combined Threat Reduction (CTR) activities at the BN350 reactor located at the Mangyshlak Atomic Energy Complex (MAEC) in the city of Aktau, Kazakhstan since 1994. DOE contract personnel have been stationed at this facility for the last two years and DOE representatives regularly visit this location to oversee the continuing cooperative activities. Continued future cooperation is planned. A Russian news report in September 1999 indicated that 75 metric tons of organic peroxides stored at the Plastics Plant near Aktau were in danger of exploding and killing or injuring nearby residents. To ensure the health and safety of the personnel at the BN350 site, the DOE conducted a study to investigate the potential danger to the BN350 site posed by these materials at the Plastics Plant. The study conclusion was that while the organic peroxides do have hazards associated with them, the BN350 site is a safe distance from the Plastics Plant. Further, because the Plastics Plant and MAEC have cooperative fire-fighting agreements,and the Plastics Plant had exhausted its reserve of fire-fighting foam, there was the possibility of the Plastics Plant depleting the store of fire-fighting foam at the BN350 site. Subsequently, the DOE decided to purchase fire-fighting foam for the Plastics Plant to ensure the availability of free-fighting foam at the BN350 site.

Microbial Enzymatic Degradation of Biodegradable Plastics.

Science.gov (United States)

Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

2017-01-01

The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Views of college students on plastic surgery.

Science.gov (United States)

Ahmad, Muhammad; Mohmand, Humayun; Ahmad, Nabila

2013-06-01

Various studies have been conducted in many countries to determine the perception/awareness about plastic surgery. The present study assessed the views of college students about plastic surgery. A questionnaire consisted of nine questions regarding the basic knowledge about plastic surgery was randomly distributed among college students. The students were given 20 minutes to fill out the forms. A total of 250 male and 250 female college students were randomly included in the study. The mean age of the male students was 21.1 years as compared to 20.7 years of female students. The top five conditions named were related to hair (89.8%) followed by face scars (88%). The most common procedure named by the students was liposuction (88.2%) followed by hair transplantation. 80.2% of the students opted not to be a plastic surgeon if given an opportunity to select the profession. 33.8% of the students had seen some kinds of plastic surgery operation. Only 5.6% of the students (3.4% male and 2.2% female) had seen some kinds of plastic surgery procedure. 68% of male students and 48% of female students wished to have a plastic surgery procedure sometime in their lives. Majority of the students (88%) got the information from the internet. The second most common source was magazines (85.2%). Majority of the students (53.4%) had an idea of an invisible scar as a result of having a plastic surgery procedure. Only 22% thought to have no scar. Late Michael Jackson was at the top of the list of celebrities having a plastic surgery procedure (97.8%) followed by Nawaz Shariff (92.4%). Despite the rapid growth of plastic surgery in the last two decades, a large portion of population remains unaware of the spatiality. It is essential to institute programs to educate healthcare consumers and providers about the plastic surgery.

River plastic emissions to the world's oceans

Science.gov (United States)

Lebreton, Laurent C. M.; van der Zwet, Joost; Damsteeg, Jan-Willem; Slat, Boyan; Andrady, Anthony; Reisser, Julia

2017-06-01

Plastics in the marine environment have become a major concern because of their persistence at sea, and adverse consequences to marine life and potentially human health. Implementing mitigation strategies requires an understanding and quantification of marine plastic sources, taking spatial and temporal variability into account. Here we present a global model of plastic inputs from rivers into oceans based on waste management, population density and hydrological information. Our model is calibrated against measurements available in the literature. We estimate that between 1.15 and 2.41 million tonnes of plastic waste currently enters the ocean every year from rivers, with over 74% of emissions occurring between May and October. The top 20 polluting rivers, mostly located in Asia, account for 67% of the global total. The findings of this study provide baseline data for ocean plastic mass balance exercises, and assist in prioritizing future plastic debris monitoring and mitigation strategies.

Structural Plasticity Denoises Responses and Improves Learning Speed

Directory of Open Access Journals (Sweden)

Robin Spiess

2016-09-01

Full Text Available Despite an abundance of computational models for learning of synaptic weights, there has been relatively little research on structural plasticity, i.e. the creation and elimination of synapses. Especially, it is not clear how structural plasticity works in concert with spike-timing-dependent plasticity (STDP and what advantages their combination offers.Here we present a fairly large-scale functional model that uses leaky integrate-and-fire neurons, STDP, homeostasis, recurrent connections, and structural plasticity to learn the input encoding, the relation between inputs, and to infer missing inputs. Using this model, we compare the error and the amount of noise in the network's responses with and without structural plasticity and the influence of structural plasticity on the learning speed of the network.Using structural plasticity during learning shows good results for learning the representation of input values, i.e. structural plasticity strongly reduces the noise of the response by preventing spikes with a high error.For inferring missing inputs we see similar results, with responses having less noise if the network was trained using structural plasticity.Additionally, using structural plasticity with pruning significantly decreased the time to learn weights suitable for inference.Presumably, this is due to the clearer signal containing less spikes that misrepresent the desired value. Therefore, this work shows that structural plasticity is not only able to improve upon the performance using STDP without structural plasticity but also speeds up learning.Additionally, it addresses the practical problem of limited resources for connectivity that is not only apparent in the mammalian neocortex but also in computer hardware or neuromorphic (brain-inspired hardware by efficiently pruning synapses without losing performance.

Degradation of plastic carrier bags in the marine environment.

Science.gov (United States)

O'Brine, Tim; Thompson, Richard C

2010-12-01

There is considerable concern about the hazards that plastic debris presents to wildlife. Use of polymers that degrade more quickly than conventional plastics presents a possible solution to this problem. Here we investigate breakdown of two oxo-biodegradable plastics, compostable plastic and standard polyethylene in the marine environment. Tensile strength of all materials decreased during exposure, but at different rates. Compostable plastic disappeared from our test rig between 16 and 24 weeks whereas approximately 98% of the other plastics remained after 40 weeks. Some plastics require UV light to degrade. Transmittance of UV through oxo-biodegradable and standard polyethylene decreased as a consequence of fouling such that these materials received ∼ 90% less UV light after 40 weeks. Our data indicate that compostable plastics may degrade relatively quickly compared to oxo-biodegradable and conventional plastics. While degradable polymers offer waste management solutions, there are limitations to their effectiveness in reducing hazards associated with plastic debris. Copyright © 2010 Elsevier Ltd. All rights reserved.

Plastic Recycling Experiments in Materials Education

Science.gov (United States)

Liu, Ping; Waskom, Tommy L.

1996-01-01

The objective of this project was to introduce a series of plastic recycling experiments to students in materials-related courses such as materials science, material technology and materials testing. With the plastic recycling experiments, students not only can learn the fundamentals of plastic processing and properties as in conventional materials courses, but also can be exposed to the issue of materials life cycle and the impact on society and environment.

Use of Plastic Mulch for Vegetable Production

OpenAIRE

Maughan, Tiffany; Drost, Dan

2016-01-01

Plastic mulches are used commercially for both vegetables and small fruit crops. Vegetable crops well suited for production with plastic mulch are typically high value row crops. This fact sheet describes the advantages, disadvantages, installation, and planting considerations. It includes sources for plastic and equipment.

Biological degradation of plastics: a comprehensive review.

Science.gov (United States)

Shah, Aamer Ali; Hasan, Fariha; Hameed, Abdul; Ahmed, Safia

2008-01-01

Lack of degradability and the closing of landfill sites as well as growing water and land pollution problems have led to concern about plastics. With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. The interest in environmental issues is growing and there are increasing demands to develop material which do not burden the environment significantly. Biodegradation is necessary for water-soluble or water-immiscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires understanding of the interactions between materials and microorganisms and the biochemical changes involved. Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. This paper reviews the current research on the biodegradation of biodegradable and also the conventional synthetic plastics and also use of various techniques for the analysis of degradation in vitro.

Methodology for plastic fracture - a progress report

International Nuclear Information System (INIS)

Wilkinson, J.P.D.; Smith, R.E.E.

1977-01-01

This paper describes the progress of a study to develop a methodology for plastic fracture. Such a fracture mechanics methodology, having application in the plastic region, is required to assess the margin of safety inherent in nuclear reactor pressure vessels. The initiation and growth of flaws in pressure vessels under overload conditions is distinguished by a number of unique features, such as large scale yielding, three-dimensional structural and flaw configurations, and failure instabilities that may be controlled by either toughness or plastic flow. In order to develop a broadly applicable methodology of plastic fracture, these features require the following analytical and experimental studies: development of criteria for crack initiation and growth under large scale yielding; the use of the finite element method to describe elastic-plastic behaviour of both the structure and the crack tip region; and extensive experimental studies on laboratory scale and large scale specimens, which attempt to reproduce the pertinent plastic flow and crack growth phenomena. This discussion centers on progress to date on the selection, through analysis and laboratory experiments, of viable criteria for crack initiation and growth during plastic fracture. (Auth.)

Recycling plastic bottles in a creative way

OpenAIRE

Pavlin, Suzana

2016-01-01

Beside other plastic products, plastic bottles represent a true environmental disaster in the last few years. We assume that hardly anyone asks what happens after they drink that last drop of water out of it. Just like most municipal waste, a plastic bottle can be reused, recycled, burned or deposited into landfill. When the Environment Protection Act is not respected, plastic bottle ends up in the nature, very often in the sea, where it decomposes very slowly and has negative influence on th...

Chemoreception drives plastic consumption in a hard coral.

Science.gov (United States)

Allen, Austin S; Seymour, Alexander C; Rittschof, Daniel

2017-11-15

The drivers behind microplastic (up to 5mm in diameter) consumption by animals are uncertain and impacts on foundational species are poorly understood. We investigated consumption of weathered, unfouled, biofouled, pre-production and microbe-free National Institute of Standards plastic by a scleractinian coral that relies on chemosensory cues for feeding. Experiment one found that corals ingested many plastic types while mostly ignoring organic-free sand, suggesting that plastic contains phagostimulents. Experiment two found that corals ingested more plastic that wasn't covered in a microbial biofilm than plastics that were biofilmed. Additionally, corals retained ~8% of ingested plastic for 24h or more and retained particles appeared stuck in corals, with consequences for energetics, pollutant toxicity and trophic transfer. The potential for chemoreception to drive plastic consumption in marine taxa has implications for conservation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Moisture Absorption/Desorption Effects on Flexural Property of Glass-Fiber-Reinforced Polyester Laminates: Three-Point Bending Test and Coupled Hygro-Mechanical Finite Element Analysis

Directory of Open Access Journals (Sweden)

Xu Jiang

2016-08-01

Full Text Available Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A. The flexural properties of dry (0% Mt/M∞, moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞ and moisture saturated (100% Mt/M∞ specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0% and flexural strength (16.4% for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.

Effect of severely thermal shocked MWCNT enhanced glass fiber reinforced polymer composite: An emphasis on tensile and thermal responses

Science.gov (United States)

Mahato, K. K.; Fulmali, A. O.; Kattaguri, R.; Dutta, K.; Prusty, R. K.; Ray, B. C.

2018-03-01

Fiber reinforced polymeric (FRP) composite materials are exposed to diverse changing environmental temperatures during their in-service period. Current investigation is aimed to investigate the influence of thermal-shock exposure on the mechanical behavior of multiwalled carbon nanotube (MWCNT) enhanced glass fiber reinforced polymeric (GFRP) composites. The samples were exposed to +70°C for 36 hrs followed by further exposure to ‑ 60°C for the similar interval of time. Tensile tests were conducted in order to evaluate the results of thermal-shock on the mechanical behavior of the neat and conditioned samples at 1 mm/min loading rate. The polymer phase i.e. epoxy was modified with various MWCNT content. The ultimate tensile strength (UTS) was raised by 15.11 % with increase in the 0.1 % MWCNT content GFRP as related to the thermal-shocked neat GFRP conditioned samples. The possible reason may be attributed to the variation in the coefficients of thermal expansion at the time of conditioning. Also, upto some extent the pre-existing residual stresses allows uniform distribution of stress and hence the reason in enhanced mechanical properties of GFRP and MWCNT filled composites. In order to access the modifications in the glass transition temperature (Tg) due to the addition of MWCNT in GFRP composite and also due to the thermal shock temperature modulated differential scanning calorimeter (TMDSC) measurements are carried out. Scanning electron microscopy(SEM) was carried out to identify different modes of failures and strengthening morphology in the composites.

Plastic Debris Is a Human Health Issue

NARCIS (Netherlands)

Vethaak, A.D.; Leslie, H.A.

2016-01-01

The global threat of highly persistent plastic waste accumulating and fragmenting in the world’s oceans, inland waters and terrestrial environments is becoming increasingly evident.1−3 Humans are being exposed to both plastic particles and chemical additives being released from the plastic debris of

Architecture of European Plastic Surgery

NARCIS (Netherlands)

Nicolai, J. -P. A.; Banic, A.; Molea, G.; Mazzola, R.; Poell, J. G.

2006-01-01

The architecture of European Plastic Surgery was published in 1996 [Nicolai JPA, Scuderi N. Plastic surgical Europe in an organogram. Eur J Plast Surg 1996; 19: 253-6.] It is the objective of this paper to update information of that article. Continuing medical education (CME), science, training,

49 CFR 192.321 - Installation of plastic pipe.

Science.gov (United States)

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false Installation of plastic pipe. 192.321 Section 192... Transmission Lines and Mains § 192.321 Installation of plastic pipe. (a) Plastic pipe must be installed below ground level except as provided by paragraphs (g) and (h) of this section. (b) Plastic pipe that is...

75 FR 34170 - Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC...

Science.gov (United States)

2010-06-16

... Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC, Troy, MI... the Anderson, South Carolina location of Plastic Omnium Automotive Exteriors, LLC, working out of Troy... certification to include workers in support of the Anderson, South Carolina facility working out of Troy...

Maximizing the life cycle of plastics. Final report

Energy Technology Data Exchange (ETDEWEB)

Hawkins, W. L.

1980-02-01

The Plastics Research Institute has conducted a coordinated research program designed to extend the useful life of plastics. Since feedstock for practically all synthetic plastics is derived from fossil fuel, every effort should be made to obtain the maximum useful life from these materials. Eventually, plastic scrap may be used as a fuel supplement, but this disposal route should be followed only after the scrap is no longer reusable in its polymeric form. The extent to which plastic scrap will be recovered and reused will be affected by the economic situation as well as the available supply of fossil fuel. The Institute's program was conducted at five major universities. Dedicated faculty members were assembled into a research team and met frequently with members of the Institute's Board of Trustees to review progress of the program. The research was conducted by graduate students in partial fulfillment of degree requirements. Summaries are presented of the following research projects: Improved Stabilization; Separation of Mixed Plastic Scrap; Compatibilizing Agents for Mixed Plastic Scrap; Controlled Degradation of Plastic Scrap; and Determination of Compatibility.

Space Plastic Recycling System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Techshot's proposed Space Plastic Recycler (SPR) is an automated closed loop plastic recycling system that allows the automated conversion of disposable ISS...

Plastics in the North Atlantic garbage patch: A boat-microbe for hitchhikers and plastic degraders.

Science.gov (United States)

Debroas, Didier; Mone, Anne; Ter Halle, Alexandra

2017-12-01

Plastic is a broad name given to different polymers with high molecular weight that impact wildlife. Their fragmentation leads to a continuum of debris sizes (meso to microplastics) entrapped in gyres and colonized by microorganisms. In the present work, the structure of eukaryotes, bacteria and Archaea was studied by a metabarcoding approach, and statistical analysis associated with network building was used to define a core microbiome at the plastic surface. Most of the bacteria significantly associated with the plastic waste originated from non-marine ecosystems, and numerous species can be considered as hitchhikers, whereas others act as keystone species (e.g., Rhodobacterales, Rhizobiales, Streptomycetales and Cyanobacteria) in the biofilm. The chemical analysis provides evidence for a specific colonization of the polymers. Alphaproteobacteria and Gammaproteobacteria significantly dominated mesoplastics consisting of poly(ethylene terephthalate) and polystyrene. Polyethylene was also dominated by these bacterial classes and Actinobacteria. Microplastics were made of polyethylene but differed in their crystallinity, and the majorities were colonized by Betaproteobacteria. Our study indicated that the bacteria inhabiting plastics harboured distinct metabolisms from those present in the surrounding water. For instance, the metabolic pathway involved in xenobiotic degradation was overrepresented on the plastic surface. Copyright © 2017 Elsevier B.V. All rights reserved.

49 CFR 178.517 - Standards for plastic boxes.

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for plastic boxes. 178.517 Section 178... PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for a...

Consumer Exposure to Bisphenol A from Plastic Bottles

Science.gov (United States)

Bidabadi, Fatemeh

2013-01-01

Bisphenol A (BPA) is a plastic monomer and plasticizer and is a chemical that has one of the highest volume production worldwide, with more than six billion pounds each year. Its primary use is the production of polycarbonate plastics, epoxy resins used to line metal cans in a host of plastic consumer products such as toys, water pipes, drinking…

Preparing Attitude Scale to Define Students' Attitudes about Environment, Recycling, Plastic and Plastic Waste

Science.gov (United States)

Avan, Cagri; Aydinli, Bahattin; Bakar, Fatma; Alboga, Yunus

2011-01-01

The aim of this study is to introduce an attitude scale in order to define students? attitudes about environment, recycling, plastics, plastic waste. In this study, 80 attitude sentences according to 5-point Likert-type scale were prepared and applied to 492 students of 6th grade in the Kastamonu city center of Turkey. The scale consists of…

Plastic crystal phases of simple water models

International Nuclear Information System (INIS)

Aragones, J. L.; Vega, C.

2009-01-01

We report the appearance of two plastic crystal phases of water at high pressure and temperature using computer simulations. In one of them the oxygen atoms form a body centered cubic structure (bcc) and in the other they form a face centered cubic structure (fcc). In both cases the water molecules were able to rotate almost freely. We have found that the bcc plastic crystal transformed into a fcc plastic crystal via a Martensitic phase transition when heated at constant pressure. We have performed the characterization and localization in the phase diagram of these plastic crystal phases for the SPC/E, TIP4P, and TIP4P/2005 water potential models. For TIP4P/2005 model free energy calculations were carried out for the bcc plastic crystal and fcc plastic crystal using a new method (which is a slight variation of the Einstein crystal method) proposed for these types of solid. The initial coexistence points for the SPC/E and TIP4P models were obtained using Hamiltonian Gibbs–Duhem integration. For all of these models these two plastic crystal phases appear in the high pressure and temperature region of the phase diagram. It would be of interest to study if such plastic crystal phases do indeed exist for real water. This would shed some light on the question of whether these models can describe satisfactorily the high pressure part of the phase diagram of water, and if not, where and why they fail.

Homeostatic role of heterosynaptic plasticity: Models and experiments

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Marina eChistiakova

2015-07-01

Full Text Available Homosynaptic Hebbian-type plasticity provides a cellular mechanism of learning and refinement of connectivity during development in a variety of biological systems. In this review we argue that a complimentary form of plasticity - heterosynaptic plasticity - represents a necessary cellular component for homeostatic regulation of synaptic weights and neuronal activity. The required properties of a homeostatic mechanism which acutely constrains the runaway dynamics imposed by Hebbian associative plasticity have been well-articulated by theoretical and modeling studies. Such mechanism(s should robustly support the stability of operation of neuronal networks and synaptic competition, include changes at non-active synapses, and operate on a similar time scale to Hebbian-type plasticity. The experimentally observed properties of heterosynaptic plasticity have introduced it as a strong candidate to fulfill this homeostatic role. Subsequent modeling studies which incorporate heterosynaptic plasticity into model neurons with Hebbian synapses (utilizing an STDP learning rule have confirmed its ability to robustly provide stability and competition. In contrast, properties of homeostatic synaptic scaling, which is triggered by extreme and long lasting (hours and days changes of neuronal activity, do not fit two crucial requirements for a hypothetical homeostatic mechanism needed to provide stability of operation in the face of on-going synaptic changes driven by Hebbian-type learning rules. Both the trigger and the time scale of homeostatic synaptic scaling are fundamentally different from those of the Hebbian-type plasticity. We conclude that heterosynaptic plasticity, which is triggered by the same episodes of strong postsynaptic activity and operates on the same time scale as Hebbian-type associative plasticity, is ideally suited to serve homeostatic role during on-going synaptic plasticity.

Leaching of plastic polymers by plastic vials used for storing homoeopathic medicines: A preliminary study

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Neeraj Gupta

2014-01-01

Full Text Available Background: In Homoeopathy, plastic containers/vials are used for the storing/dispensing of ethanol-based medicines instead of glass. Various studies have suggested that plastic components that leach out in stored substances tend to cause contamination and may produce adverse effects in living systems. The present study was aimed to find out chemical composition and leaching behaviour of commonly used plastic vials (PVs if any during the storage of ethanol-based homoeopathic medicines in optimal environment. Material and Methods: The experiments were conducted on two sample sets of PVs. Chemical properties of PV were assessed by Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR spectroscopy. PV were cut separately [sample-1 (S-1 and sample-2 (S-2] and immersed in Homoeopathic Grade Ethanol (HGE in conical flask and stored for 7 days at ambient temperature (25° ± 5C with constant rotary shaking. After 7 days, S-1 and S-2 of PV in Homoeopathic Grade Ethanol (HGE were decanted and filtered. Aliquots (A1 and A2 were analysed by proton nuclear magnetic resonance spectroscopy (H 1 NMR. The spectral graph obtained by FTIR-ATR spectroscopy for PV compositions and spectral graph obtained by H 1 NMR spectroscopy for PV ethanol aliquots were examined for PVs material and PV leaching effect in HGE. Results: FTIR-ATR spectra showed that PV are made up of two types of polyolefin′s compounds i.e. Low Density Polyethylene (LDPE and Linear Low Density Polyethylene (LLDPE. Aliquots of PV in HGE showed the presence benzophenone and its methyl derivative, heat and light stabiliser (2, 2, 6, 6-tetramethylpiperidine and amino derivative, antioxidant (4, 4′- thiobis and 2-tertbutyl-5-methylphenol and plasticizer bis 2-Diethylhexyl phthalate (DEHP or Dioctyl phthalate (DOP. Results of study suggest that PVs leach out plastic polymers in HGE. Conclusion: This preliminary experiment suggests that it is not safe to use LDPE/LLDPE plastic for storing

Developmental plasticity: Friend or foe?

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Michels, Karin B

2017-01-01

Developmental plasticity - the concept that adaptation to changing and unfavorable environmental conditions are possible but may come at the price of compromised health potentials - has evolutionary grounding as it facilitates survival but dissents with fundamental evolutionary principles in that it may advance the lesser fit. It is an important cornerstone of the Developmental Origins of Health and Disease (DOHaD). Unlike evolutionary adaptation developmental plasticity may be short-lived and restricted to one or few generations and inheritance is uncertain. Potential mechanisms include epigenetic modifications adopted in utero which may not transmit to the next generation; future insights may allow adjustments of the outcomes of developmental plasticity.

Radiation damage in plastic scintillators

International Nuclear Information System (INIS)

Majewski, S.

1990-01-01

Results of radiation damage studies in plastic scintillators are reviewed and critically analyzed from the point of view of applications of plastic scintillators in calorimetric detectors for the SSC. Damage to transmission and to fluorescent yield in different conditions is discussed. New directions in R ampersand D are outlined. Several examples are given of the most recent data on the new scintillating materials made with old and new plastics and fluors, which are exhibiting significantly improved radiation resistance. With a present rate of a vigorous R D programme, the survival limits in the vicinity of 100 MRad seem to be feasible within a couple of years

Waste product profile: Plastic film and bags

Energy Technology Data Exchange (ETDEWEB)

Miller, C. [Environmental Industry Associations, Washington, DC (United States)

1996-10-01

Plastic film is recycled by being pelletized following a granulation or densifying process. Manufacturing and converting plants are the major sources of plastic film for recycling because they can supply sufficient amounts of clean raw material of a known resin type. Post-consumer collection programs are more recent. They tend to focus on businesses such as grocery stores that are large generators of plastic bags. In this case, the recycling process is more complex, requiring sorting, washing, and removal of contaminants as a first step. Curbside collection of plastic bags is rare.

Photodegradable plastics useful for global environment conservation. Chikyu ni yasashii hikaribunkaisei plastic

Energy Technology Data Exchange (ETDEWEB)

Iwasa, T. (Harima Kasei K.K., Osaka (Japan))

1991-10-11

Photodegradable plastics and their additives were explained.Two methods are used to manufacture photodegradable plastics.The first method is made by using a copolymer and a monomer containing a functional group and the second method is made by adding a photodegradable agent to an undecomposable plastics.The copolymer based on ethylene and carbon monoxide is included in the first type. The copolymer based on the vinyl ketone to which the carboxyl group is introduced, and ethylene or styrene is also included in this type. A metal dithiocarbamate is included in the second additive type, for which several methods to improve weak points of the pigment compounding system have been proposed later. Benzophenone derivatives, transition metal salts of organic acids and anatase type titanium dioxide are also included in the second type. Any additives are usually supplied as the masterbatch. The performance evaluation and degrading mechanism of ferric tri(2-(methylbenzoyl)benzoate) of adittion type additives were explained. 8 refs., 3 figs., 1 tab.

Benthic plastic debris in marine and fresh water environments.

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Corcoran, Patricia L

2015-08-01

This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

The plastic brain: neoliberalism and the neuronal self.

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Pitts-Taylor, Victoria

2010-11-01

Neuroscience-based representations and practices of the brain aimed at lay populations present the brain in ways that both affirm biological determinism and also celebrate plasticity, or the brain's ability to change structure and function. Popular uses of neuroscientific theories of brain plasticity are saturated with a neoliberal vision of the subject. Against more optimistic readings of plasticity, I view the popular deployment of plasticity through the framework of governmentality. I describe how popular brain discourse on plasticity opens up the brain to personal techniques of enhancement and risk avoidance, and how it promotes a neuronal self. I situate brain plasticity in a context of biomedical neoliberalism, where the engineering and modification of biological life is positioned as essential to selfhood and citizenship.

Radiation crosslinking of highly plasticized PVC

Science.gov (United States)

Mendizabal, E.; Cruz, L.; Jasso, C. F.; Burillo, G.; Dakin, V. I.

1996-02-01

To improve the physical properties of highly plasticized PVC, the polymer was crosslinked by gamma irradiation using a dose rate of 91 kGy/h. The effect of plasticizer type was studied by using three different plasticizers, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), di(2-ethyl hexyl) phthalate (DOP), and di(2-ethylhexyl terephthalate) (DOTP), and varying irradiation doses. Gel content was determined by soxhlet extraction, tensile measurements were made on a universal testing machine and the mechano-dynamic measurements were made in a dynamic rheometer. It was found that a considerable bonding of plasticizer molecules to macromolelcules takes place along with crosslinking, so that the use of the solvent extraction method for measuring the degree of crosslinking can give erroneous information. Radiation-chemical crosslinking yield ( Gc) and molecular weight of interjunctions chains ( Mc), were calculated for different systems studied. Addition of ethylene glycol dimethacrylate (EGDM) as a crosslinking coagent and dioctyl tin oxide (DOTO) as a stabilizer was also studied. Plasticizers extraction resistance was increased by irradiation treatment.

Radiation crosslinking of highly plasticized PVC

International Nuclear Information System (INIS)

Mendizabal, E.; Cruz, L.; Jasso, C.F.; Burillo, G.; Dakin, V.I.

1996-01-01

To improve the physical properties of highly plasticized PVC, the polymer was crosslinked by gamma irradiation using a dose rate of 91 kGy/h. The effect of plasticizer type was studied by using three different plasticizers, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), di(2-ethyl hexyl) phthalate (DOP), and di(2-ethylhexyl terephthalate) (DOTP), and varying irradiation doses. Gel content was determined by soxhlet extraction, tensile measurements were made on a universal testing machine and the mechano-dynamic measurements were made in a dynamic rheometer. It was found that a considerable bonding of plasticizer molecules to macromolecules takes place along with crosslinking, so that the use of the solvent extraction method for measuring the degree of crosslinking can give erroneous information. Radiation-chemical crosslinking yield (G c ) and molecular weight of interjunctions chains (M c ), were calculated for different systems studied. Addition of ethylene glycol dimethyacrylate (EGDM) as a crosslinking coagent and dioctyl tin oxide (DOTO) as a stabilizer was also studied. Plasticizers extraction resistance was increased by irradiation treatment. (author)

Plastic Surgery Response in Natural Disasters.

Science.gov (United States)

Chung, Susan; Zimmerman, Amanda; Gaviria, Andres; Dayicioglu, Deniz

2015-06-01

Disasters cause untold damage and are often unpredictable; however, with proper preparation, these events can be better managed. The initial response has the greatest impact on the overall success of the relief effort. A well-trained multidisciplinary network of providers is necessary to ensure coordinated care for the victims of these mass casualty disasters. As members of this network of providers, plastic surgeons have the ability to efficiently address injuries sustained in mass casualty disasters and are a valuable member of the relief effort. The skill set of plastic surgeons includes techniques that can address injuries sustained in large-scale emergencies, such as the management of soft-tissue injury, tissue viability, facial fractures, and extremity salvage. An approach to disaster relief, the types of disasters encountered, the management of injuries related to mass casualty disasters, the role of plastic surgeons in the relief effort, and resource management are discussed. In order to improve preparedness in future mass casualty disasters, plastic surgeons should receive training during residency regarding the utilization of plastic surgery knowledge in the disaster setting.

The neurophysiologist perspective into MS plasticity

Directory of Open Access Journals (Sweden)

Elise eHoudayer

2015-09-01

Full Text Available Multiple sclerosis (MS is a frequent, highly debilitating inflammatory demyelinating disease, starting to manifest in early adulthood and presenting a wide variety of symptoms which are often resistant to pharmacological treatments. Cortical dysfunctions have been demonstrated to be key components of MS condition, and plasticity of the corticospinal motor system is highly involved in major MS symptoms, such as fatigue, spasticity or pain. Cortical dysfunction in MS can be studied with neurophysiological tools such as electroencephalography (EEG and related techniques (evoked potentials – EPs or transcranial magnetic stimulation (TMS. These techniques are now widely used to provide essential elements of MS diagnosis and can also be used to modulate plasticity. Indeed the recent development of non-invasive brain stimulation (NIBS techniques able to induce cortical plasticity, such as repetitive TMS or transcranial direct current stimulation (tDCS, has brought promising results as add-on treatments.In this review we will focus on the use of these tools (EEG, TMS to study plasticity in MS and on the major techniques used to modulate plasticity in MS.

The Neurophysiologist Perspective into MS Plasticity.

Science.gov (United States)

Houdayer, Elise; Comi, Giancarlo; Leocani, Letizia

2015-01-01

Multiple sclerosis (MS) is a frequent, highly debilitating inflammatory demyelinating disease, starting to manifest in early adulthood and presenting a wide variety of symptoms, which are often resistant to pharmacological treatments. Cortical dysfunctions have been demonstrated to be key components of MS condition, and plasticity of the corticospinal motor system is highly involved in major MS symptoms, such as fatigue, spasticity, or pain. Cortical dysfunction in MS can be studied with neurophysiological tools, such as electroencephalography (EEG) and related techniques (evoked potentials) or transcranial magnetic stimulation (TMS). These techniques are now widely used to provide essential elements of MS diagnosis and can also be used to modulate plasticity. Indeed, the recent development of non-invasive brain stimulation techniques able to induce cortical plasticity, such as repetitive TMS or transcranial direct current stimulation, has brought promising results as add-on treatments. In this review, we will focus on the use of these tools (EEG and TMS) to study plasticity in MS and on the major techniques used to modulate plasticity in MS.

Replacing fossil based plastic performance products by bio-based plastic products-Technical feasibility.

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van den Oever, Martien; Molenveld, Karin

2017-07-25

Larger scale market introduction of new bio-based products requires a clear advantage regarding sustainability, as well as an adequate techno-economic positioning relative to fossil based products. In a previous paper [Broeren et al., 2016], LCA results per kg and per functionality equivalent of bio-based plastics were presented, together with economic considerations. The present paper discusses the mechanical and thermal properties of a range of commercially available bio-based plastics based on polylactic acid (PLA), cellulose esters, starch and polyamides, and the feasibility of replacing fossil-based counterparts based on performance. The evaluation is approached from an end user perspective. First, potentially suitable bio-based plastics are selected based on manufacturers' specifications in technical data sheets, then a first experimental evaluation is performed on injection moulded ISO specimens, and finally a further selection of plastics is tested on large 50×70cm panels. This technical feasibility study indicates that so far bio-based plastics do not completely match the properties of high performance materials like flame retardant V-0 PC/ABS blends used in electronic devices. The performance gap is being decreased by the development of stereocomplex PLA and hybrid PLA blends with polycarbonate, which offer clearly improved properties with respect to maximum usage temperature and toughness. In addition, several materials meet the V-0 flammability requirements needed in specific durable applications. On the other hand, improving these properties so far has negative consequences for the bio-based content. This study also shows that replacement of bulk polymers like PS is feasible using PLA compounds with a bio-based content as high as 85%. Copyright © 2016 Elsevier B.V. All rights reserved.

History of plastic surgery: Art, philosophy, and rhinoplasty.

Science.gov (United States)

Macionis, Valdas

2018-03-23

The 200th anniversary of K. F. Graefe's "Rhinoplasty," E. Zeis' naming of the specialty of plastic surgery in 1838, and the continuing discussion on what is plastic surgery have prompted this historical-conceptual review with a semantic insight into the meaning of the word "plastic." A literature search has revealed that this term contains dual aspects: artistic and philosophical. The progressive development of these two connotations can be traced from their origin in the ceramics and the myths of ancient Greeks to their metamorphoses in fine arts, science, and philosophy of plasticity of the modern day. Although the names of plastic procedures and the title of the specialty carry both the artistic and philosophical features, the philosophical notion is less evident. This article underlines the importance of etymology in the interpretation of the concept of plastic surgery. Copyright © 2018 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

[Survey of plasticizers in polyvinyl chloride toys].

Science.gov (United States)

Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Yoko

2012-01-01

Plasticizers in 101 samples of polyvinyl chloride (PVC) toys on the Japanese market were surveyed. No phthalates were detected in designated toys, though bis(2-ethylhexyl)phthalate, diisononyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisodecyl phthalate and benzyl butyl phthalate were detected in more than half of other toys. 2,2,4-Tributyl-1,3-pentanediol diisobutylate, o-acetyl tributyl citrate, adipates and diacetyl lauroyl glycerol, which are alternative plasticizers to phthalates, were detected. The results of structural analysis confirmed the presence of di(2-ethylhexyl)terephthalate, tributyl citrate, diisononyl 1,2-cyclohexanedicarboxylate and neopentyl glycol esters; these have not previonsly been reported in Japan. There appears to be a shift in plasticizers used for designated toys from phthalates to new plasticizers, and the number of different plasticizers is increasing.