This book presents the papers given at a conference on plastics. Topics considered at the conference included the direct in-line fluorination of HDPE fuel tanks, polymer blends as high explosive binders, PVC injection molded blends and laminated films, long fiber reinforced thermoplastics, the applications of plastics in the automotive industry, and polyurethane technology.

Long fiber reinforced thermoplastics (LFRTP) are a class of injection molding materials that extend the physical property envelope of thermoplastics polymers. These materials are manufactured by pulling continuous fiber tows through a thermoplastic polymer melt in a specialized processing die. The strands are subsequently cooled and chopped into pellets of equal length. LFRTP materials are available in virtually every common thermoplastic resin with glass, aramid, stainless steel, or carbon fiber reinforcement at levels up to 60% by weight. Unlike short fiber reinforced thermoplastics manufactured by conventional screw compounding processes, LFRTP exhibit simultaneous improvements in both flexural modulus and impact resistance. Improvements in load transfer, creep resistance at elevated temperatures, and dimensional stability can also be attributed to the long fiber network formed in the molded part. This unique combination of properties makes LFRTP the material of choice for replacement of metal structural assemblies in many automotive, industrial, consumer and recreational applications.

This paper applies a recently developed model to predict the elastic-plastic stress/strain response and strength of injection-molded long-fiber thermoplastics (LFTs). The model combines a micro-macro constitutive modeling approach with experimental characterization and modeling of the composite microstructure to determine the composite stress/strain response and strength. Specifically, it accounts for elastic fibers embedded in a thermoplastic resin that exhibits the elastic-plastic behavior obeying the Ramberg-Osgood relation and J-2 deformation theory of plasticity. It also accounts for fiber length, orientation and volume fraction distributions in the composite formed by the injection-molding process. Injection-molded-long-glass-fiber/polypropylene (PP) specimens were prepared for mechanical characterization and testing. Fiber length, orientation, and volume fraction distributions were then measured at some selected locations for use in the computation. Fiber orientations in these specimens were also predicted using an anisotropic rotary diffusion model developed for LFTs. The stress-strain response of the as-formed composite was computed by an incremental procedure that uses the Eshelby’s equivalent inclusion method, the Mori-Tanaka assumption and a fiber orientation averaging technique. The model has been validated against the experimental stress-strain results obtained for these long-glass-fiber/PP specimens.

In this study, the effects of processing parameters on the mechanical properties of injection molded thermoplastic polyolefin (TPO) foams are investigated. Closed cell TPO foams were prepared by injection molding process. The microstructure of these foamed samples was controlled by carefully altering the processing parameters on the injection molding machine. The foam morphologies were characterized in terms of skin thickness, surface roughness, and relative foam density. Tensile properties and impact resistance of various injection molded TPO samples were correlated with various foam morphologies. The findings show that the mechanical properties are significantly affected by foam morphologies. The experimental results obtained from this study can be used to predict the microstructure and ...

We present a novel method to fabricate an all in polymer injection molded chip for electrochemical cell recordings and lateral cell trapping. The complete device is molded in thermoplastic polymer and it results from assembling two halves. We tested spin-coated conductive polymer poly(3,4-ethylenedioxythiopene) and showed that it can be used as an electrode material for detecting neurotransmitters electrochemically in biosensors.

Topics discussed include the economic advantages of reinforced plastics in high-volume applications, directional reinforcements, the Fiber Fusion laminate composite method, and new developments in reinforced thermoplastics. The reaction injection molding of polyurethanes and the use of composite construction in a general aviation aircraft are also discussed.

This report on the project “Molded Interconnect Device (MID) by two shot injection molding and laser induced selective activation” has been submitted to fulfil the requirements for the master project at department of Manufacturing Engineering and Management of Technical University of Denmark (IPL-DTU). MID is defined as an injection molded plastic substrate with electrical infrastructures on the surface and integrates both mechanical and electrical functionalities on the single device. This paper describes many aspects of MID such as the background information, manufacturing process chain, comparative process analysis, applications and specially two shot injection molding and laser induced selective activation in the MID area. There is also an experimental part which contains fabrication of a MID demonstrator, selective metallization as well as characterization. The realization of molded interconnect device was achieved with two innovative processes such as two shot injection molding which combines platetableand none-platetable thermoplastics, and laser induced selective activation which uses a laser to draw circuit on the thermoplastic surface containing laser sensitive additive. Different material combinations such as PEI (GE Ultem 1000) +PPO (GTX 810) and PEEK (Victrex 150GL30) +PPO (GTX 810) were investgated which can be selected electroless plating for metallization. Several plastics such as PC (GE Lexan 500R) and PEEK (Victrex 150GL30) were applied to the laser induced activation and reacted differently with the diverse structure.

Abstract Poly(butylene succinate) (PBS) and its copolymers are a family of biodegradable polymers with excellent biodegradability, thermoplastic processability and balanced mechanical properties. In this article, production of the monomers succinic acid and butanediol, synthesis, processing and properties of PBS and its copolymers are reviewed. The physical properties and biodegradation rate of PBS materials can be varied in a wide range through copolymerization with different types and various contents of monomers. PBS has a wide temperature window for thermoplastic processing, which makes the resin suitable for extrusion, injection molding, thermoforming and film blowing. Finally, we summarized industrialization and applications of PBS.

Thermoplastic composite materials have been under intense evaluation for the past decade in a variety of applications. Engineering polymers reinforced with long (12 mm) carbon fiber are a class of materials that provide easy processing and performance benefits between that of continuous and chopped carbon fiber reinforced materials. Commercially available materials include polyamide 66, polyphenylene sulfide and thermoplastic polyurethanes. Injection molding of these materials permits the fabrication of complex shapes that retain fiber length and have performance intermediate to that of chopped and continuous carbon fiber reinforced materials. Performance characteristics, processing costs and applications will be discussed.

Polymer bonded ferrites composed of a mixture of Mn-Zn ferrites or Ni-Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic-wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100-1000 MHz. Absorption measurements of injection molded polymer-ferrite cases display a 3-5 dB better attenuation characteristics compared to graphite-loaded polyamide housings. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Polymer-gebundene Ferritwerkstoffe auf der Basis von Ferrit (Mn-Zn oder Ni-Zn Ferrite) - Thermoplast Mischungen wurden praepariert und hinsichtlich ihrer Eignung zur Absorption elektromagnetischer Strahlung untersucht. Es wurden sowohl Testproben wie auch komplette Gehaeusekomponenten durch Heisspressen oder Spritzgiessen hergestellt. Die Permeabilitaetsspektren weisen verlustbehaftete Komponenten im Frequenzbereich von 100-1000 MHz auf. Schirmdaempfungsmessungen an spritzgegossenen Gehaeuseteilen zeigen eine um 3-5 dB bessere Daempfung im Vergleich zu Graphit-gefuellten Polyamid-Gehaeusen. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Abstract Thermal conductivity (TC) of injection-molded main-chain smectic liquid-crystalline polymers and the composites containing hexagonal boron nitride (h-BN) particles is investigated. Shear flow during injection molding induces alignment of chain-folding lamellar crystals of polymer matrices, in which polymer chains are aligned in the normal direction (ND) with respect to the molding surface, thus leading to a high TC (1.2 W m-1 K-1) in the ND. The composites exhibit a dramatic enhancement of TC in not only the ND but also the in-plane direction. The enhanced TC is much higher than that of common thermoplastic composites at comparable loading levels. These results indicate that the polymer matrices serve as effective heat conductors between h-BN particles.

Until now the utilization of plastics for exterior parts of automobiles has been mainly limited to front and rear ends using polyurethane (PUR), sMC or modified polypropylene (PP-EPDM). Saving energy by reducing vehicles' weight and optimizing their drag coefficients (csub(w) values) is the most important goal in modern motor vehicle development. In addition, it is necessary to observe the safety regulations in force and to make production more cost-efficient. Thermoplastic parts can be processed economically by injection-molding, but their characteristics must be improved. Improvements must be aimed at their stability in environments containing gasoline and developing heat; impact strength at low temperatures, paintability and dimensional stability.

DuPont has developed a compression-moldable composite made from the thermoplastic polyester PET and long glass fibers. This material, XTC{trademark}, is part of the class of materials known as GMT`s, or glass-mat thermoplastics. The PET content in XTC{trademark} allows the use of a wide variety of recycled material that might otherwise end up in landfills and incinerators. DuPont has succeeded in using 100% post-consumer polyester, from bottles, film, or fibers, in the composite. Since processing involves heating the material to the melt in air, the main technical issues are hydrolysis and oxidative degradation. Impurities in the recycled material must be carefully monitored, as they often increase the extent of degradation. The product itself, used to mold shaped structures and body panels for automobiles, may be recycled after its useful life. Depending on the needed purity level, processes ranging from injection molding to methanolysis can turn ground XTC{trademark} parts back into new, useful products.

Several polyster/cotton waste blends were successfully used as feedstock to make injection molded products. Nucleating and plasticizing additives (commonly required in the production process) were found to be unnecessary; their functions were fulfilled by the cotton component of the waste feedstock. The properties of the injection molded parts were comparable generally to those of a great many other plastics. Cotton caused a notable increase in stiffness (modulus) of the molded part, but failed to produce a significant increase in tensile strength. Plant trials revealed difficulties that were unobserved in the smaller scale runs: sticking in the mold, release of water and other volatiles at the molding temperature, and intermittent flow. Sticking in the mold probably can be solved by including a small amount of mold release compound in the formulation just prior to pelletization. The problems of release of volatiles and intermittent flow can possibly be solved. Polyester/cotton molded products would have a price advantage as feedstock in the commodity thermoplastics market, but it is possible that this could be dissipated by higher molding costs.

We have recently developed a naphthalene-based binder system for use in powder injection molding (PIM) of ceramic and metallic materials. The use of a binder that can be removed via sublimation offers several unique advantages relative to the typical thermoplastic and/or thermoset binders employed in PIM. One of these is that essentially no volume change takes place during debindering. This offers a relatively facile method of introducing porosity into a net-shape part of potentially complex geometry. In the study described in this paper, the effects of powder loading and subsequent isostatic compaction on the size and amount of porosity in the components produced by this technique were investigated. In general, it was found that the amount of porosity is inversely proportional to the initial concentration of metal powder in the PIM feedstock. Likewise, average pore size displays a similar relationship with powder loading.

Abstract Thermoplastic elastomers were prepared from recycled low density polyethylene [rLDPE] and virgin low density polyethylene (LDPE), respectively, ground tyre rubber (GTR), and ethylene vinyl acetate (EVA) copolymer. The amounts of the rLDPE and GTR were fixed at 40 and 30 wt %, respectively, in the formulations, whereas the LDPE and EVA contents varied each between 0 and 30 wt %. The fresh LDPE served for reduction of the melt viscosity and EVA was used for improving the elastomeric properties. Blends of different compositions (by varying the LDPE/EVA ratio) were produced by twin-screw extrusion and pelletized. Specimens were produced by injection molding and subjected to tensile and instrumented falling weight impact (IFWI) tests. To improve the mechanical performance of the blends...

The purpose of this study is to examine a new method to obtain fine bamboo fibers (fiber bundles), which are used to reinforce thermoplastics instead of glass fibers. The tensile strength of FRTP was also examined using polypropylene as the matrix and bamboo fibers as the reinforcement. In this study, two types of bamboo fibers were used. One was mechanically extracted fiber (crushed fiber) while the other was steam explosion fiber. These fibers were frozen in a freezer or liquid nitrogen in order to decrease only their diameter. By freezing bamboo fibers, some soft cells sticking on the fiber surface were well removed, but we could not reduce fiber diameter due to freezing even at cryogenic temperature. It is found that a satisfactory tensile strength of FRTP using bamboo fibers can be achieved when fine bamboo fibers smaller than 120µm in diameter are used for injection molding.   

Components made of short glass fiber reinforced (SGFR) thermoplastics are increasingly used in the automotive industry, and more frequently subjected to fatigue loadings during their service life. The determination of a predictive fatigue criterion is therefore a serious issue for the designers, and requires the knowledge of the local mechanical response under a large range of environmental conditions (temperature and relative humidity). As the cyclic behavior of polymeric material is reckoned to be highly nonlinear, even at room temperature, an accurate constitutive model is a preliminary step for confident fatigue design. The injection molding process induces a complex fiber orientation distribution (FOD), which affects both the mechanical response and the fatigue life of SGFR thermoplas...

The present conference on state-of-the-art materials and processing technologies considers a rapid-cure adhesive for aircraft field repairs, the strength of adhesives under combined loading, the nonlinear analysis of bonded joints, the enhancement of graphite/epoxy structures' radiographic inspection, ultrasonic crack detection in graphite/aluminum composites, eddy current inspection of graphite/epoxy, the use of curvilinear fiber formats to increase structural efficiency, the unified life cycle engineering of composites, SiC-reinforced Ti corrugated structures, and third-generation two-part epoxy adhesives. Also discussed are solid-solution single-crystal growth, the residual strength of Arall laminates, toughened bismaleimides, novel polyamide-imides, the injection molding of advanced ceramics, continuous-length thermoplastic composites, internal stress superplasticity in metal-matrix composites, hollow carbon microspheres, and SiC fiber-reinforced carbon-matrix composites.

New approaches to the fabrication of microstructures of special shape were developed for polymers. Unusual superhydrophobic surface structures were achieved with the use of flexible polymers and hierarchical molds. Flexible polyurethane-acrylate coatings were patterned with microstructures with use of microstructured aluminum mold in a controlled UV-curing process. Electron microscope images of the UV-cured coatings on polymethylmethacrylate (PMMA) substrates revealed micropillars that were significantly higher than the corresponding depressions of the mold (even 47 vs. 35 ?m). The elongation was achieved by detaching the mold from the flexible, partially cured acrylate surface and then further curing the separated microstructure. The modified acrylate surface is superhydrophobic with a water contact angle of 156° and sliding angle of < 10°. Acrylic thermoplastic elastomers (TPE) were patterned with micro-nanostructured aluminum oxide molds through injection molding. The hierarchical surface of the elastomer showed elongated micropillars (57 ?m) with nail-head tops covered with nanograss. Comparison with a reference microstructure of the same material (35 ?m) indicated that the nanopores of the micro-nanomold assisted the formation of the nail-shaped micropillars. The elasticity of the TPE materials evidently plays a role in the elongation because similar elongation has not been found in hierarchically structured thermoplastic surfaces. The hierarchical micronail structure supports a high water contact angle (164°), representing an increase of 88° relative to the smooth TPE surface. The sliding angle was close to zero degrees, indicating the Cassie-Baxter state.

Abstract in english The main objective of the research presented here is to relate anatomical features of wood species that affect the interactions between polymeric phases and performance of wood plastic composites (WPC). These interactions are related to the probable interlocking volume and surface area for stress transfer in a WPC. Composites were produced from different wood species and analyzed using SEM (scanning electron microscopy). Results showed that wood species with high interfac (more) ial areas may increase mechanical interlocking, reflected in the viscous constant of the Maxwell model. A complicating factor is that the relation of cell wall thickness-lumen diameter and the interconnectivity between wood cells in a wood, affect the potential for cell collapse. When wood cells collapse, the penetration of the thermoplastic into the wood structure is almost always ceased. The collapse of wood cells during extrusion-injection molding processes reduced the potential surface for stress transfer between phases affecting the mechanical properties of composites. Undamaged wood cells may potentially be filled with HDPE thermoplastic enhancing modulus and increase the strength of WPC.

With the advent of modern coupling agents (MAPP or maleic anhydride grafted polypropylene), the potential use of various types of renewable, sustainable agricultural byproducts as fillers in thermoplastics is explored. Over 7.7 billion pounds of fillers were used in the plastics industry in 1993. With sharp price increases in commodity thermoplastics (i.e. approximately 25% in 94`), the amount of fillers in thermoplastic materials will increase throughout the 90`s. Various types of agricultural fibers are evaluated for mechanical properties vs. 50% wood flour and 40% talc filled polypropylene (PP). The fibers included in this study are: kenaf core, oat straw, wheat straw, oat hulls, wood flour (pine), corncob, hard corncob, rice hulls, peanut hulls, corn fiber, soybean hull, residue, and jojoba seed meal. Composite interfaces were modified with MAPP to improve the mechanical properties through increased adhesion between the hydrophilic and polar fibers with the hydrophobic and non-polar matrix. The agro-waste composites had compositions of 50% agro-waste/48% PP/2% MAPP. All of the agricultural waste by-products were granulated through a Wiley mill with a 30 mesh screen and compounded in a high intensity shear-thermo kinetic mixer. The resultant blends were injection molded into ASTM standard samples and tested for tensile, flexural, and impact properties. This paper reports on the mechanical properties of the twelve resultant composites and compares them to wood flour and talc-filled polypropylene composites. The mechanical properties of kenaf core, oat straw, wheat straw, and oat hulls compare favorably to the wood flour and talc-filled PP, which are both commercially available and used in the automotive and furniture markets.

The present research work assesses the manufacture of long fiber thermoplastic matrix composite materials (GreenComposites). Thermoplastic matrices are too viscous to be injected into the conventional LCM (Liquid Comopsite Molding) molds, and then epoxy, polyester o vinylester resins are used. Nevertheless, the groundbreaking anionic polymerization of ?-caprolactam allows such a synthesis of a thermoplastic APA6 matrix inside the mold. This matrix is sintered from the starting monomers, and presents high mechanical performance and recyclability. In order to do the reactive injection in a LCM mold, it is necessary to control the polymerization mechanism of such a thermoplastic matrix. Likewise, it puts special emphasis on detecting and solving all problems which arose during synthesis. For instance, moisture values were assessed for all starting reactants, since humidity keeps polymerization from occurring. It is thought that once the synthesis and the resulting material characterization are well controlled, the manufacture of GreenComposites through monomers injection and in situ polymerization, as well as addition of state-of-the-art fabrics such as basalt, can proceed successfully.

This paper presents a status report on the injection molding of sinterable silicon nitride at GTE Laboratories. The effort involves fabrication of single axial turbine blades and monolithic radial turbine rotors. The injection molding process is reviewed and the fabrication of the turbine components discussed. Oxidation resistance and strength results of current injection molded sintered silicon nitride as well as dimensional checks on sintered turbine blades demonstrate that this material is a viable candidate for high temperature structural applications.

Jan 1, 1983 ... Abstract: Pure silicon nitride shows a remarkable resistance to ... the composition, raw material impurities, and processing contaminants. ... Subject Terms: CERAMICS; DENSIFICATION; INJECTION MOLDING; LIQUID ...

Injection-molded samples of thermoplastic polyetherurethane (TPU) were treated with low-temperature oxygen plasma for different processing times in order to enhance cellular attachment for a gastric implant. Its effects were investigated by contact angle measurement, surface topography, cytotoxicity and cell colonization tests. No significant changes were found in the surface roughness of plasma treatment with plasma treatment time of less than 5 min. Longer treatment showed significantly higher surface roughness. It seems that there was a link between the changes in contact angle and enhanced cell growth on the treated surface, although only for the range up to plasma treatment times of 3 min. Prolonged treatment times did not cause any major changes in the water contact angle, but strongly improved the number of growing cells on the surface. Plasma treatment for 3-7 min led to a twofold increase in the number of cells compared to untreated samples and did not significantly alter the WST-1 nor worsened the lactate dehydrogenase activity compared to the control. Thus, it appears that O{sub 2} plasma treatment is a suitable surface modification method for a gastric implant made of TPU in order to improve surface cell attachment where 3-7 min is the recommended treatment time.

Plastic injection molding has been widely used in the past and is a dominant forming approach today. As the customer demands require materials with better engineering properties that were not feasible with polymers, powder injection molding with metal and ceramic powders has received considerable attention in recent decades. To better understand the differences in the plastic injection molding, metal injection molding, and ceramic injection molding, the effects of the core process parameters on the process performances has been studied using the state-of-the-art computer-aided engineering (CAE) design tool, PIMSolver? The design of experiments has been conducted using the Taguchi method to obtain the relative contributions of various process parameters onto the successful operations.

The present paper involves a metal/polymer joint in a tailcone in a kinetic energy penetrator (KEP), one of the ammunition types used by the military. It is currently made of aluminum 7075 alloy, which could be partly replaced by long fiber thermoplastic (LFT) composite. Two different types of aluminum insert geometries were considered, viz., beaded and threaded. Thermal stresses set in during cooling of the tailcone from the processing temperature mainly because of the difference in the values of coefficients of thermal expansion and differential cooling between the aluminum and the LFT composite. Finite element (FE) modeling was done to predict the temperature profile during the cooling of the tailcone from the processing temperature. FE results showed that the LFT composite part of the ...

A laminated glass-plastic lens parquet using injection molded point focus Fresnel lenses is described. The second phase of a program aimed at investigating the cost effectiveness of a glass-plastic concentrator lens assembly is reported. The first phase dealt with the development of a first generation lens design, the selection of the preferred glass coverplate and glass-to-lens adhesive and initial injection molding lens molding trials. The second phase has dealt with the development of an improved lens design, a full size parquet lamination process, and a second group of injection molding lens molding trials.

Five different calculation methods, either for laboratory analysis or industrial application, which permit the modeling of plastic materials flow conditions in injection molding equipment are presented. Two of the methods are sufficiently developed to all...

powders and green compacts before monolithic ceramics are densified .... porosity. These data are needed because of the interrelations among velocity, texture, ..... processing stages such as forming, injection molding, slip casting, infiltration, ...

111. AN EVALUATION. OF COMPOSITES. FABRICATED. FROM. POWDER ..... porosity. (for ease of resin impregnation) are quite important in composition .... and structural reaction injection molding. To achieve this potential, however, ...

The approach combines novel ceramic injection molding technology to ... sub- micron aluminum oxide and 60 to 70 volume percent nano-porosity. ... If successful, this approach will eliminate defects associated with consolidating powders into ...

Center using a Ferro Corporation powder. Sample sizes were .... The highest degree of strength reduction occurred in the injection molded sil- iconized KXOl material .... It is likely that salt penetration through residual porosity in the mullite was ...

A manufacturing line has been designed, fabricated and installed to produce finished lightweight insulated footwear from liquid injection molded expanded polyurethane. The minimum production rate is sixty pair of boots per week, utilizing the equipment on...

Silicon nitride has been the favored material for manufacturing high-efficiency engine components for transportation due to its high temperature stability, good wear resistance, excellent corrosion resistance, thermal shock resistance, and low density. The use of silicon nitride in engine components greatly depends on the ability to fabricate near net-shape components economically. The absence of a material database for design and simulation has further restricted the engineering community in developing parts from silicon nitride. In this paper, the design and manufacturability of silicon nitride engine rotors for unmanned aerial vehicles by the injection molding process are discussed. The feedstock material property data obtained from experiments were used to simulate the flow of the material during injection molding. The areas susceptible to the formation of defects during the injection molding process of the engine component were identified from the simulations. A test sample was successfully injection molded using the feedstock and sintered to 99% density without formation of significant observable defects.

Process Control Equipment for Vertical Clamping Injection Molder . .... Properties of Ford Injection Molded Reaction Bonded Silicon Nitride at 5313°C ..... temperature time response is measured with a liquid nitrogen-cooled indium antimonide ...

Advances in processing of LCPs could permit the incorporation of these polymers into other than .... Properties of injection molded LCP ASTM bars. 58. 3.4 ...... Third, LINbO3 is not readily integrated with silicon- or GaAs- based technology.

Jul 10, 2002 ... This process might include synthesis of adhesives for use in ... This is the basic concept behind the design of silicone polymers, the most ..... liquids and can be processed by extrusion, injection molding, and vacuum forming.

The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

The bibliography contains citations concerning the recycling of scrap plastic produced in the injection molding process. Plastic pellets made from scrap, that are used in the injection molding process, are also discussed. Recycling equipment and automated recycling systems are described. The reuse of plastic scrap culled from junk automobiles and packaging materials is discussed, and waste byproducts from polyurethane production are described. (Contains a minimum of 88 citations and includes a subject term index and title list.)

Injection molding of polymers is currently utilized for numerous industrial applications. Because of high productivity and stable quality of molded products, the injection-molding process makes the production costs lower, and therefore, is expected to spread more widely in the future. This paper deals with a technique for improving the optical quality of injection molded polymer products using radiative heating. The birefringence frozen in a skin-layer of the molded part was reduced by CO{sub 2} laser heating, and the efficiency of this technique was investigated experimentally. Namely, a simple numerical calculation was performed to estimate the heating efficiency of CO{sub 2} laser in the polymer, effects of radiation heating on the skin-layer of the molded polymer were observed by using a mold with transparent windows, and the residual birefringence frozen in the final molded specimen was measured. The results clearly showed that the birefringence in the skin-layer of injection molded polymer strips was reduced with CO{sub 2} laser heating. The authors believe that the proposed method for reducing the birefringence frozen in injection-molded polymer products is suitable for practical molding, because process time required for the injection-molding is only slightly increased with this method.

A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding prameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

This study investigates warpage of electronic dictionary battery covers fabricated using thin-wall injection molding as a replacement for conventional insert molding. The primary concern is the molding window in thin-wall injection molding for acrylonitrile?butadiene styrene (ABS) and polycarbonate (PC)+ABS plastics. Finally, the process parameters for thin-wall injection molding that eliminate warpage of electronic dictionary battery covers are identified. Experimental results demonstrate that the area of the molding window for ABS exceeds that for PC+ABS. Analysis of the molding window reveals that ABS is more appropriate than PC+ABS for battery covers. Low melt temperature, high injection speed, and high packing pressure eliminate battery cover warpage. Melt temperature is the most impo...

A new method of fabricating translucent alumina brackets using powder injection molding (PIM) is reported. Alumina powder was mixed with MgO, La2O3, and Y2O3 to control grain size and porosity. The powders were mixed with a binder consisting of a mixture of paraffin wax and polyethylene in a 1:1 ratio to make feedstock for injection molding. The total amount of binder was limited to 14 wt% to minimize shrinkage and cracking after sintering. After injection molding, debinding was performed using the wicking method and samples were sintered in a vacuum at 1700 °C to achieve high density. Ultimately, translucent corundum was fabricated. The sintering additives resulted in a decrease in porosity and an improvement in translucency by promoting grain growth during pressure-less sintering. After ...

Abstract Multifunctional mobile products, such as cellular phones, laptop computers, personal media players, etc., have become smaller and lighter; so the technology of thin-wall injection molding (TWIM) has been highlighted for making lightweight and compact mobile electronic products. Regarding mechanical properties, many portable electronic products should pass the so-called -drop test-; therefore, the evaluation of the dart (or impact) property of the housing that is made by the TWIM process is crucial for commercializing a product. However, extant research on the effect of injection molding process parameters on the physical properties of TWIM plates is insufficient as yet. Therefore, in this study, the pressure and temperature inside the cavity during the injection molding process ar...

High-frequency induction is an efficient, non-contact means of heating the surface of an injection mold through electromagnetic induction. Because the procedure allows for the rapid heating and cooling of mold surfaces, it has been recently applied to the injection molding of thin-walled parts or micro/nano-structures. The present study proposes a localized heating method involving the selective use of mold materials to enhance the heating efficiency of high-frequency induction heating. For localized induction heating, a composite injection mold of ferromagnetic material and paramagnetic material is used. The feasibility of the proposed heating method is investigated through numerical analyses in terms of its heating efficiency for localized mold surfaces and in terms of the structural safety of the composite mold. The moldability of high aspect ratio micro-features is then experimentally compared under a variety of induction heating conditions.

Determination of the rheological behavior of a polymer melt under high shear rate is generally considered to be crucial for accurate simulation modeling of ultra high speed injection molding, a process that has been attracting more attention from researchers. In this study, a melt viscosity measurement system under high shear rate was established using an instrumented injection molding machine combined with a slit die. Polystyrene melt was studied. From measured pressure drop and volumetric flow rate, the slit flow model was used for the calculation of viscosity at wall shear strain rates up to 10^5 s^-^1. Good agreement in shear viscosity was found between results from conventional capillary rheometry and in-line measurement made using an injection molding machine for strain rates of 7 x ...

A load-cell-embedded burnishing tool has been newly developed and integrated with a machining center, to improve the surface roughness of the PDS5 plastic injection mold steel. Either the rolling-contact type or the sliding-contact type was possible for the developed ball burnishing tool. The characteristic curves of burnishing force vs. surface roughness for the PDS5 plastic injection mold steel using the developed burnishing tool for both the rolling-contact type and the sliding-contact type, have been investigated and constructed, based on the test results. The optimal plane surface burnishing force for the PDS5 plastic injection mold steel was about 420N for the rolling-contact type and about 470N for the sliding-contact type, based on the results of experiments. A force compensation s...

Kenaf bast fiber was used to prepare kenaf fiber/linear low-density polyethylene (LLDPE) composite by injection molding technique. Degradation of LLDPE during the processing was investigated using FT-IR analysis. It was observed that slight degradation of pure LLDPE took place after injection molding. It was also found that the extent of degradation of LLDPE became higher when kenaf fiber was used as the filler for LLDPE composite. The addition of kenaf fiber would cause higher shear stress on LLDPE during processing, resulting in higher extent degradation of LLDPE.   

Virtual reality has wide applications in many domains in recent years. It supports a real-time, immersive and interactive simulation technology to approve training effect. Injection molding machine is one of the most important but dangerous machines. To ensure safe operation, the development of a complete safe program of training is really essential. This article proposed a visual simulator based on virtual reality for the training of an injection molding machine. It can assist students in learning to operate this machine but without actually handling a real machine.

This work is concerned with the design, development, and testing of nanostructured polymer surfaces with self-cleaning properties that can be manufactured by injection molding. In particular, the superimposed micro- and nanometer length scales of the so-called Lotus effect were investigated in detail with an engineering perspective on choice of materials and manufacturability by injection molding. Microscope slides with superhydrophobic properties were succesfully fabricated. Preliminary results indicate a contact angle increase from 95° for the unstructured polymer to a maximum 150°. The lowest drop roll off angles observed were in the range 1° to 5°.

The influence of process parameters on ?-injection molding (?IM) and on ?-injection molded parts has been investigated using Design of Experiments. A mold with a sensor applied at injection location was used to monitor actual injection pressure and to determine the cavity filling time. Flow markers position was measured on the polymer ?-parts to evaluate filling behavior of the polymer melt flowing through ?-features. Experimental results obtained under different processing conditions were evaluated to correlate the process parameter levels influence on the selected responses. Results showed that the injection speed in one of the most influencing process parameters on the ?IM process and on the ?-parts filling.

The local fluctuations of magneto-optical (MO) signals were investigated in the vicinity of the preformat pits of polycarbonate (PC) substrates fabricated under different injection molding conditions and also using stampers which had different shapes of grooves and preformat pits. A strong correlation was observed between the substrate birefringence and the fluctuation of the MO signal. The rate-of-change of the fluctuations, as the phase shift of the optical head was varied, was attributed to the shapes of preformat pits and grooves. The fluctuation of the MO signal could be controlled by varying the injection molding conditions and the shapes of preformat pits and grooves.   

Long fibers are generally preferred for reinforcing foams for performance reasons. However, uniform dispersion is difficult to achieve because they must be mixed with liquid resin prior to foam expansion. New approaches aiming to overcome such problem have been developed at USC's Composites Center. Fiber-reinforced syntactic foams with long fibers (over 6 mm in length) manufactured at USC's Composites Center have achieved promising mechanical properties and demonstrated lower density relative to conventional composite foams. Fiber-reinforced syntactic foams were synthesized from thermosetting polymeric microspheres (amino and phenolic microspheres), as well as thermoplastic PVC heat expandable microspheres (HEMs). Carbon and/or aramid fibers were used to reinforce the syntactic foams. Basic mechanical properties, including shear, tensile, and compression, were measured in syntactic foams and fiber-reinforced syntactic foams. Microstructure and crack propagation behavior were investigated by scanning electron microscope and light microscopy. Failure mechanisms and reinforcing mechanisms of fiber-reinforced syntactic foams were also analyzed. As expected, additions of fiber reinforcements to foams enhanced both tensile and shear properties. However, only limited enhancement in compression properties was observed, and fiber reinforcement was of limited benefit in this regard. Therefore, a hybrid foam design was explored and evaluated in an attempt to enhance compression properties. HEMs were blended with glass microspheres to produce hybrid foams, and hybrid foams were subsequently reinforced with continuous aramid fibers to produce fiber-reinforced hybrid foams. Mechanical properties of these foams were evaluated. Findings indicated that the production of hybrid foams was an effective way to enhance the compressive properties of syntactic foams, while the addition of fiber reinforcements enhanced the shear and tensile performance of syntactic foams. Another approach to produce ultralight sandwich core materials was explored in which towpreg (fiber bundles impregnated with resin) were configured to produce 3D pyramidal truss structures. The composite truss structures were subsequently filled with foam to improve resistance to buckling. Mechanical properties of the foam-filled truss structures were measured and contrasted with analytical predictions based on simple truss theory. Results indicated that combination of foams and carbon fiber truss structures had synergistic effects that enhanced the capacity to carry compressive and shear loads.

Generally, the traditional LGP is fabricated by injection molding technology. MEMS and hot embossing technologies are applied to fabricate the integrated LGP in this research. The concentric circle v-cut structure and the pyramid arrays are constructed on the integrated LGP. Therefore, the new backl...

In industry, material composites are of great interest if new applications can be developed by combining their physical properties. In two-component powder injection molding materials are required that can be co-fired, and that are characterized by an adjusted, stress-defined expansion behavior in t...

The purpose of this program was to design, select, and evaluate plastic materials for an injection molded, half-size steamtable tray to be used for the storage, reheat, and serving of processed food items at government facilities. In performance of this s...

A new two-step method, facilitating the rapid generation of super-hydrophobic surface structures via parallel laser processing followed by a replica generation by injection molding is reported. A self-made fused silica-based diffractive optical element (DOE) is applied to distribute the laser energy...

Sorbitol and glycerol were used to plasticize sugar beet pulp-poly (lactic acid) green composites. The plasticizer was incorporated into sugar beet pulp (SBP)at 0, 10, 20, 30 and 40% w/w at low temperature and shear and then compounded with PLA using twin-screw extrusion and injection molding. The...

In order to determine the degree of compatibility between Polycaprolactone resin (PCL) and vital wheat gluten (VG), PCL was compounded with VG at 90:10, 80:20, 70:30, 60:40, 50:50, and 30:70. The composites were blended by extrusion followed by injection molding. Thermal, morphological, and struct...

Molded Interconnect Devices (MIDs) are plastic substrates with electrical infrastructure. The fabrication of MIDs is usually based on injection molding and different process chains may be identified from this starting point. The use of MIDs has been driven primarily by the automotive sector, but rec...

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber composites were melt-compounded and injection-molded. Tensile, impact and dynamic mechanical properties of the composites were studied. In contrast to many other short natural fiber reinforced biocomposites which demonstrate decre...

the matrix because of shrinkage in PIP-process are also examined. .... aqueous or non aqueous liquid medium that also contains an appropriate dispersant ... advantages of this process are (1) ease in infiltration, including injection-molding, (2) lower ..... pyrolysis and a final step of silicon melt infiltration to prepare the C/ SiC ...

Abstract in portuguese Compósitos que utilizam fibras vegetais como reforço têm despertado crescente interesse por parte da comunidade científica e industrial. O bagaço e a palha de cana são materiais renováveis e quando usados como reforço em uma matriz termoplástica podem dar origem a compósitos com baixo custo, baixa densidade e interessantes propriedades mecânicas. Este trabalho teve como objetivo avaliar as propriedades mecânicas e morfológicas de compósitos de polipropileno (more) reforçados com celulose de bagaço e palha. A celulose foi obtida através do processo NaOH/AQ a 170ºC durante 3,5 h de reação. Os compósitos reforçados com 20 e 30% em massa de fibras foram preparados utilizando um misturador "Dryser". Após moagem e moldagem por injeção, esses materiais foram analisados por ensaios de tração, flexão, microscopia ótica (MO) e microscopia eletrônica de varredura (MEV). A resistência à tração dos compósitos reforçados com 20% em massa de fibras foi similar ao polipropileno puro, no entanto, diminuiu com o aumento de reforço. Os módulos de elasticidade em tração e flexão aumentaram em até 79,4 e 81,7 %, respectivamente, influenciados pelo alto módulo das fibras inseridas dentro da matriz polimérica. A análise por MO da superfície dos compósitos mostraram distribuição homogênea das fibras na matriz, comprimento e forma variada das fibras e ainda que as fibras celulósicas da palha são menores que as do bagaço. A análise por MEV dos compósitos fraturados mostrou descolamento das fibras em relação à matriz e comportamento típico de fratura frágil. As fibras celulósicas obtidas a partir do bagaço e da palha deram origem a compósitos com propriedades mecânicas e morfológicas semelhantes e forneceu à matriz uma maior rigidez. Abstract in english Composites utilizing vegetable fibers as reinforcement have demonstrated attracted increasing interest ofcrescent advantages from the scientific and industrial communities. Sugarcane bagasse and straw are renewable materials and when used as reinforcement in thermoplastic matrix can give origin to composite materials with low cost, low density and interesting mechanical properties. This work aimed to evaluate the mechanical and morphological properties of polypropylene co (more) mposites reinforced with cellulose from sugarcane bagasse and straw. The cellulose was obtained through NaOH/AQ pulping process at 170ºC for 3.5 h. The composites reinforced with 20 and 30 % wt of fibers were preparated utilizing a Dryser mixer. After ground and injection molding, these materials were analyzed by tensile and flexural tests, optical microscopy (OM) and scanning electron microscopy (SEM). The tensile strength of composites reinforced with fibers (20 wt.%) was similar to that of pure polypropylene, however, it decreased with the increase increasing amount of reinforcement. The tensile and flexural elasticity moduli increased up to 79.4 and 81.7 %, respectively, due to the high modulus of the fibers inserted inside the polymeric matrix. The composite surface analysis by OM showed homogeneous distribution of fibers inside the matrix and variable length and shape of the fibers. The cellulosic fibers from straw were also smaller than those from bagasse. SEM analysis of fractured composites exhibited pullout displacement of the fiber in with respect to thematrix and a typical behavior of brittle fracture. Cellulosic fibers obtained from sugarcane bagasse and straw resulted in composites with similar mechanical and morphological properties and provided rigidity to thematrix.

Abstract Purpose: The purpose of this study was to investigate the effect of four solutions [saliva (control group), saliva+tea, saliva+coffee, saliva+nicotine] on the color of different denture base acrylic resins (heat-polymerized, injection-molded, autopolymerized) and a soft denture liner. Materials and Methods: Twenty specimens from each type of test material were prepared (2.5 mm diameter, 2 mm thickness). Five specimens from each test material (heat-polymerized, chemically polymerized, injection-molded acrylic resin, soft denture reliner) were stored in each solution in 37degreeC in a dark environment. Colorimetric measurements were done on the 1st, 7th, and 30th days. Color differences among specimens immersed in saliva (control group), and staining solutions were evaluated over ti...

Kenaf (Hibiscus cannabinus) is a fast growing annual growth plant that is harvested for its bast fibers. These fibers have excellent specific properties and have potential to be outstanding reinforcing fillers in plastics. In these experiments, the fibers and polypropylene (PP) were blended in a thermokinetic mixer and then injection molded, with the fiber weight fractions varying to 60%. A maleated polypropylene was used to improve the interaction and adhesion between the nonpolar matrix and the polar lignocellulosic fibers. The specific tensile and flexural moduli of a 50% by weight (39% by volume) of kenaf-PP composite compare favorably with a 40% by weight of glass fiber-PP injection-molded composite. These results suggest that kenaf fibers are a viable alternative to inorganic/mineral-based reinforcing fibers as long as the right processing conditions are used and they are used in applications where the higher water absorption is not critical.

In order to enhance the industries which supply assembly parts to Japan`s assembly industries in Thailand, research cooperation project on the plastic parts production technology has started. For the research cooperation, the mold design is effectively conducted using simulation technique of CAE (computer aided engineering), and an international easy injection molding control system is made using the molding support software for injection molding machines. In FY 1996, actual situations of plastic parts and assembly industries in Thailand have been investigated through the cooperation with the counterpart of Thailand. Demand and supply of engineering plastics, receive and inspection of parts, and current circumstances of molding processing makers in Thailand have been grasped. Based on the results of this investigation, proposal of basic plan, time schedule, and delivery plan of molding machines and testing equipment have been discussed, to make the basic plan. 18 refs., 4 figs., 23 tabs.

Understanding and controlling the structural anisotropies of injection-molded polymers is vital for designing products such as cantilever-based sensors. Such micro-cantilevers are considered as cost-effective alternatives to single-crystalline silicon-based sensors. In order to achieve similar sensing characteristics, structure and morphology have to be controlled by means of processing parameters including mold temperature and injection speed. Synchrotron radiation-based scanning small- (SAXS) and wide-angle x-ray scattering techniques were used to quantify crystallinity and anisotropy in polymer micro-cantilevers with micrometer resolution in real space. SAXS measurements confirmed the lamellar nature of the injection-molded semi-crystalline micro-cantilevers. The homogenous cantilever material exhibits a lamellar periodicity increasing with mold temperature but not with injection speed. We demonstrate that micro-cantilevers made of semi-crystalline polymers such as polyvinylidenefluoride, polyoxymethylene, and polypropylene show the expected strong degree of anisotropy along the injection direction.

The crystalline morphologies of high-density polyethylene (HDPE) molded by multi-melt multi-injection molding (MMMIM) and conventional injection molding (CIM) were studied by employing polarizing light microscopy (PLM) and scanning electronic microscopy (SEM). It was found that a special double skin-core structure was formed in MMMIM parts. Namely cylindritic structures appeared in both sub-skin layer and core layer, which were attributed to the strong shear flow introduced by the secondary melt penetration process. As the decrease in temperature and injection pressure of the second melt, the number of cylindritic structures in the core layer decreases and the cylindritic structures gradually develop into irregularly-arranged spherulites. Strong shear flow, as compared to CIM, is an import...

The ground coils to be used along the entire length of a Magnetically Levitated transportation (MAGLEV) system need to withstand long-term outdoor service and be provided in extremely large quantities. It is for these reasons that we require them to be durable and inexpensive. Dicyclopentadiene, a major component of low viscous liquid in Reaction Injection Molding (RIM), is injected into the mold. It reacts with catalyst and cures in a short time to produce a substance featuring superior quality not obtainable by the conventional injection molding. Besides, the molding process may be undertaken at normal temperature and pressure, the molding equipment is inexpensive, and the insulation scheme of the wound coils can be simplified. Thus, there are several reasons that the ground coils are suitable for mass production. In this paper we discuss the application of RIM technology through our trial manufacture of practical ground coils incorporated with several improvements. We investigated the economic effect as well.   

This paper introduces the development of a double-sided micro lens array (DSMLA) for application in micro laser projectors. For commercial mass production, it is necessary to investigate the concurrent engineering of optical design, mold fabrication, and plastic injection molding at once. This experiment based the design of the micro lens array on the scalar diffraction theory. The proposed DSMLA can simultaneously shape red, green, and blue laser beams into a uniform projection pattern. An ultra precision diamond turning machine using a slow tool servo method fabricated the mold. The study considered optical design constraints from the feedback of mold fabrication and plastic injection molding, measuring and comparing fabricated samples with calculated results. Experimental results show t...

A variety of computer simulation codes have recently emerged in the market, enabling up-front simulation of manufacturing processes such as casting, forging, welding, powder-injection molding, and powder consolidation. Typically, a computer simulation consists of three distinct steps: preprocessing, analysis, and postprocessing. Visualization plays a key role in preprocessing and especially postprocessing, where it assists in the intelligent and rapid interpretation of a huge amount of data. A good visualization capability has now become an essential part of any comprehensive process simulation code. This article discusses recent work in developing visualization tools for pre- and post-processing of casting and powder injection molding simulations. The essential features of these visualization tools are summarized and their applications are illustrated with the help of suitable examples showing details such as solid models, filling patterns, hot spots, porosity criteria functions, grain size, and weld line formation.

Ti-Mo getters have been fabricated via metal injection molding (MIM) using three kinds of Ti powders with different mean particle sizes of 46 ?m, 35 ?m and 26 ?m, respectively. The surface morphology, porosity, and hydrogen sorption properties of Ti-Mo getters formed by MIM using paraffin wax as a principal binder constituent were examined. It has been proven that the powder injection molding is a viable forming technique for porous Ti-Mo getters. The particle size of Ti powders and the powder loading influence the porosity of getters, and this affects the sorption capacity of Ti-Mo getters. Ti-Mo getters produced with the Ti powders possessing a mean particle size of 35 ?m using a powder loading of 40 vol.% have a high porosity, resulting in a good sorption capacity.

The present invention relates to methods for embedded a micrometer and/or nanometer pattern into an injection molding tool. In a first main aspect, a micro/nanometer structured imprinting device is applied in, or on, an active surface so as to transfer the micro/nanometer patterned structure to the tool while the imprinting device is, at least partly, within a cavity of the injection molding tool. In a second main aspect, a base plate with a micro/nanometer structured pattern positioned on an upper part is positioned on the active surface within the tool, the lower part of the base plate facing the tool, the active surface receiving the base plate being non-planar on a macroscopic scale. Both aspects enable a simple and effective way of transferring the pattern, and the pattern may be transferred on the active working site of tool immediately prior to molding without the need for extensive preparations or remounting of the tool before performing the molding process.

Abstract The poly(lactic acid) (PLA)/ramie fiber biocomposites were fabricated, which exhibited considerable reinforcement effect comparable to the glass fiber at the same loading. The attempts were made to understand the flow-induced morphology of ramie fibers and PLA crystals in the injection-molded PLA/ramie fiber biocomposites, thus revealing its relationship to biocomposite mechanical properties. The polarized optical microscopy (POM) and two-dimensional wide-angle X-ray diffraction (2D-WAXD) were for the first time used to determine the distribution of nature fibers, which interestingly showed the ramie fibers aligned well along the flow direction over the whole thickness of injection-molded parts, instead of skin-core structure. This easy alignment of ramie fibers during the common ...

Purpose: It was the aim of the present study to develop sustained-release matrix tablets by means of injection molding of ethylcellulose (EC) and polyethylene oxide (PEO) mixtures and to evaluate the influence of process temperature, matrix composition, and viscosity grade of EC and PEO on processability and drug release. Methods: Formulations consisting of metoprolol tartrate (MPT, concentration: 30%), EC plasticized by dibutyl sebacate, and PEO were extruded and consequently injection molded into tablets. The influence of process temperature (120degreeC and 140degreeC), matrix composition, viscosity grade of EC (4, 10, 20, 45, and 100 mPas) and PEO (7 x 106, 1 x 106, and 1 x 105 Mw) on processability and drug release was determined. Results: Formulations consisting of 70% EC and 30% MPT ...

The phenomenon of shrinkage in injection molding is particularly relevant in semi-crystalline polymers. Despite of this, if compared with the considerable effort spent by researchers to investigate (both experimentally and theoretically) the evolution of shrinkage and thermal stresses in amorphous polymers, the relevant research work is scarce for semicrystalline polymers. This is probably due to the fact that the phenomenon is strictly related to the evolution of crystallinity, which is per se quite difficult to be predicted. In fact, modern approaches to the phenomenon of dimensional accuracy in injection molding link the evolution of shrinkage from the moment of first solidification to a force balance between restraining and constraining forces which sets in inside the mold before eject...

Aluminum nitride has been favored for applications in manufacturing substrates for heat sinks due to its elevated temperature operability, high thermal conductivity, and low thermal expansion coefficient. Powder injection molding is a high-volume manufacturing technique that can translate these useful material properties into complex shapes. In order to design and fabricate components from aluminum nitride, it is important to know the injection-molding behavior at different powder?binder compositions. However, the lack of a materials database for design and simulation at different powder?polymer compositions is a significant barrier. In this paper, a database of rheological and thermal properties for aluminum nitride?polymer mixtures at various volume fractions of powder was compiled from ...

It is essential to study and optimize multiple objective functions such as binder system design, feedstock, part geometry, mold design, and processing conditions in order to develop a successful powder injection molding process. A powder with different combinations of binder systems and a binder system with different combinations of powder systems were investigated with a combined experimental and simulation study. First, an experimental rheological study was performed to evaluate the influence of the powder/binder combinations on the rheological behavior and thermal stability of carbonyl iron and stainless steel powder injection molding (PIM) feedstocks. Second, based on the characterization of the feedstock, the simulation study revealed that the pressure-related parameters such as wall ...

Manufacturing of 3D micro-components by powder injection molding process consists of four main stages: preparation of the feedstock of metal powders and binders, injection of powder/binder feedstock using micro-injection molding equipment, thermal or solvent debinding and sintering by solid state diffusion. For our research pruposes, the feedstocks have been realized with stainless steel 316L powders of 3.4 ?m (D50) and polymer binders. Finite element method has been used for the simulation in order to estimate shrinkage, relative density and evolution of the shapes of the micro-components, the parameters used in the sintering model have been identified in using Matlab® procedures before to be used in the simulation with Abaqus®.

In the field of micro-technology the production of metallic and ceramic micro-components by powder injection molding (PIM) has become a more and more established fabrication method. But in order to fulfill the demand for more complex-shaped high-precision micro-components further development work has to be performed. This is especially true if more efficient production routes for multi-component-micro-assemblies consisting of different materials or sub-components are envisaged. To meet these challenges, investigations are performed to realize and to establish two primary shape micro-processes. These are two-component micro-injection molding (2C-MicroPIM) and sinter-joining. The realization of these technologies will lead to a markedly reduction of the efforts for handling, adjustment, and ...

Today complex-shaped ceramic parts are mass fabricated by many different methods, two of which are slip casting and injection molding. The selection of the appropriate technique is governed by the geometric shape, the number of pieces to be manufactured, and the chemistry of the ceramic. Both slip casting and injection molding introduce imperfections in the green part, which lead to inhomogeneous microstructures in the sintered parts. A new fabrication method, direct coagulation casting (DCC), may be suitable for the mass production of complex ceramic parts with high strength and reliability. In DCC, an aqueous suspension is coagulated by a change in pH or an increase in ionic strength after casting, producing a rigid green body. The use of DCC can avoid most of the limitations of conventional shaping techniques, and it can be applied to a large variety of ceramic powders, sols, and polymers, alone or in combination.

A portable battery device is provided which dampens shock incident upon the battery device such that an electrical energizable apparatus connected to the battery device is subject to reduced shock whenever the battery device receives an impact. The battery device includes a battery housing of resilient shock absorbing material injection molded around an interconnecting structure which mechanically and electrically interconnects the battery housing to an electrically energizable apparatus.

Unlike polyolefins (e.g., isotactic polypropylene), it is still a great challenge to form rich shish-kebabs in biodegradable poly(L-lactic acid) (PLLA) because of its short chain length and semi-rigid chain backbone. In the present work, a modified injection molding technology, named oscillation shear injection molding, was applied to provide an intense shear flow on PLLA melt in mold cavity, in order to promote shear-induced crystallization of PLLA. Additionally, a small amount of poly(ethylene glycol) (PEG) with flexible chains was introduced for improving the crystallization kinetics. Numerous shish-kebabs of PLLA were achieved in injection-molded PLLA for the first time. High-resolution scanning electronic microscopy and two-dimensional small-angle X-ray scattering showed a structure feature of shish-kebabs with a diameter of around 0.7 µm and a long period of ~20 nm. The two-dimensional wide-angle X-ray diffraction results showed that shish-kebabs had more ordered crystalline structure of ?-form. A significant improvement of the mechanical properties was obtained; the tensile strength and modulus increased to 73.7 and 1888 MPa from the initial values of 64.9 and 1684 MPa, respectively, meanwhile the ductility is not deteriorated. Interestingly, when shish-kebabs form in the PLLA/PEG system, a bamboo-like bionic structure comprising a hard skin layer and a soft core develops in injection-molded specimen. This unique structure leads to a great balance of mechanical properties, including substantial increments of 26%, 20% and 112% in the tensile strength, modulus, and impact toughness, compared to the control sample. Further exploration will give a rich fundamental understanding in the shear-induced crystallization and morphology manipulation of PLLA, aiming to achieve superior PLLA products. PMID:23153180

The aim of this work was to obtain nanocomposites with balanced mechanical properties. The nanocomposites were prepared in a twin screw extruder, followed by injection molding, and characterized by X-Ray Diffraction, Heat Distortion Temperature, mechanical properties and Scanning Electron Microscopy. The results showed that for the systems containing clay, nanocomposites with intercalated structure were formed. PA6-EG-HDPE-CL20A system presented higher heat distortion temperature, balanced mechanical properties and an apparently homogeneous morphology. (author)

Thermoplastic starch was blended with carbon black to form an electroactive polymer composite. Thermoplastic starch is naturally insulative, and the electroactive polymer composite takes advantage of the conductive pathways formed through the percolation of conductive particles through the polymer ...

Discussions were given on mechanical properties of AM-series magnesium alloy made by injection molding process. In the discussions, tensile test pieces of the AM-series magnesium alloys (AM50A and AM60B) were formed by the injection molding process to investigate effects of different molding conditions on their mechanical properties in relation with microstructures. The experiment had the mold temperature setting kept constant at 443K, and the barrel temperature and injection velocity varied. For the microstructures, observations using an optical microscope were performed on cross section in the vicinity of test piece fracture section after polishing and etching. The following findings were obtained as a result of the discussions: rise in the barrel temperature reduces solid phase rate and improves the mechanical properties, but the properties saturate above the melting point; increased injection velocity reduces average grain size in the liquid phase, and improves the mechanical properties; and the AM-series alloy forms made by the injection molding process have finer microstructures and show better mechanical properties than die-cast materials. 10 refs., 9 figs., 2 tabs.

Eight test specimens were fabricated using an injection-molding process with a borosilicate-glass matrix reinforced with chopped-graphite fibers. These specimens were then tested under quasi-static and cyclic loading at room temperature. Due to the infancy of CMC materials and, especially, CMC components, the program included a very broad-based investigation into many areas considered well-established for more conventional materials, and a very extensive and diverse set of achievements were realized. A tubular CMC test specimen representing an engineering component was designed and fabricated. A high-temperature multiaxial test facility for ceramic-matrix composite components was developed an installed. Nondestructive and destructive test methods for CMC components were developed, and a thorough investigation of the failure mechanisms in injection-molded CMC tubes subjected to room-temperature, quasi-static and cyclic loading was conducted in spite of a very limited quantity of material. Performance-limiting defects in the injection-molded tubes were identified, and a generalized modeling approach was investigated for the analysis of complex, composite components.

Thermoplasticity of coking coals and the extracted residues were investigated by Gieseler plastometry and dynamic viscoelasticity measurements. Dynamic viscoelasticity was found to be a useful index for the description of thermoplasticity of coals. The effect of extraction on thermoplasticity was also studied. 4 refs., 4 figs., 2 tabs.

A study of light scattering by surfaces of injection molded particle filled polymers is presented. In particular the effect that molding conditions have on surface roughness is studied by mechanical and optical profilometry as well as by light scattering. It is shown that Kirchhoff scalar theory with a Gaussian probability density of heights and a negative exponential correlation function between heights predicts reasonably well the surface scattering properties in an angular interval around the specular angle for all the molding conditions studied. This leads to a simple analytical model for gloss with only two parameters.

An experimental study of the effect of mold surface roughness on in-process in-flow linear part shrinkage in injection molding has been carried out. The investigation is based on an experimental two-cavity tool, where the cavities have different surface topographies, but are otherwise identical. The study has been carried out for typical commercial polystyrene and polypropylene grades. The relationship between mold surface topography and linear shrinkage has been investigated with an experimental two-cavity mold producing simple rectangular parts with the nominal dimensions 1 x 25 x 50 mm (see figure 1). The cavities have different surface topographies on one side, but are otherwise identical (see discussion of other contribution factors).

A problem with micromechanics is that the commonly used fabrication methods and materials are relatively expensive. To be competitive on the market, new low-cost materials and manufacturing methods are necessary. Different micro-devices have already been made, e.g., micropumps. Micro-replication also enables different materials like polymers, metals and ceramics to be used. The research was conducted through part design, mold fabrication, experimental analysis, and quality test. The process parameters including injection speed, melt temperature, mold temperature and packing pressure on quality of micropumps were investigated. The injection molded part was actuated by a piezoelectric disc. Flow test was conducted to check the micropump performance.

Abstract This research investigates the effect of exfoliated graphene nanoplatelets (GNP) on the crystallization behavior, thermal conductivity, and electrical conductivity of high-density polyethylene (HDPE)/GNP nanocomposites. HDPE/GNP nanocomposites were fabricated by melt blending followed with injection molding. Results indicate that GNP is a good nucleating agent at low loading levels and as a result can significantly increase crystallization temperature and crystallinity of HDPE. At high GNP loadings, however, the close proximity of GNP particles retards the crystallization process. The thermal stability and thermal conductivity of HDPE/GNP nanocomposites were found to be significantly enhanced as a function of GNP concentration owing to the excellent thermal properties of GNP. Fina...

The mechanical responses including monotonic and cyclic tensile responses have been investigated on a microphase-separated poly (styrene-isoprene-styrene) triblock copolymer (SIS). The specimens were injection-molded by using different melt temperatures to acquire different microphase structures. As a result of temperature-dependent segregation driving force, the specimens with reduced microphase separation can be obtained by increasing processing melt temperature from 180 degreeC to 240 degreeC. On the basis of stress-strain behavior, Youngs modulus was found to increase with increasing PS domain continuity in the order of disorder state to disordered spheres to body-cubic-centered (BCC) spheres to oriented cylinders morphology. Meanwhile, cyclic hysteresis decreases with reduced micropha...

The effects of two different rheological models used in the simulation of the micro injection molding (µIM) process are investigated. The Cross-WLF viscous model and the Giesekus viscoelastic model are selected and their performance evaluated using 3D models implemented on two different commercially available software packages. Simulation results are then compared with the experimental µIM process. Validation parameters for the comparison are the flow front position during filling of the micro cavity. They are respectively obtained by applying the short-shots method and the flow-markers method. The µIM part is a polystyrene tensile bar test weighting 20mg and with three µ-features 300µm wide.

Sodium chloride (NaCl) was added as a space holder in synthesis of porous titanium by using metal injection molding(MIM) method. The microstructure and mechanical properties of porous titanium were analyzed by mercury porosimeter, scanning electron microscope(SEM) and compression tester. The results show that the content of NaCl influences the porosity of porous titanium significantly. Porous titanium powders with porosity in the range of 42.4%-71.6% and pore size up to 300 mm were fabricated. The mechanical test shows that with increasing NaCl content, the compressive strength decreases from 316.6 to 17.5 MPa and the elastic modulus decreases from 3.03 to 0.28 GPa.

Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites incorporated with different contents of boron compounds; borax/boric acid and zinc borate, and phosphate compounds; mono and diammonium phosphates were investigated. The effect of the coupling agent content, maleic anhydride-grafted polypropylene, on the properties of the composites with fire-retardant was also investigated. The composites with the zinc borate had the highest dimensional stability and strength in the bending, tensile, and izod impact, followed by the monoammonium phosphate, borax/boric acid, and diammonium phosphate treatments. The treatments produced modest improvements in fire performance as indicated by reductions in the heat release rates. Best results were achieved wi...

In this work, a new method of rapidly fabricating thermopolymer and elastomer microfluidic channels has been developed and characterized for production of microfluidics with fixed aspect ratio and 3D tapered channels. A unique way to attain a desired channel depth by simply altering channel width is demonstrated. This rapid prototyping method is compatible with replication methods such as injection molding, hot embossing and elastomer casting and offers the ability to fabricate multiple channel depths (5 microm-1 mm) simultaneously in a single lithographic step. This method yields facile fabrication of 3-dimensionally tapered channels and polymer lab chips. PMID:19789747

The effects of nanoparticle addition on the pressureless sintering of injection molded and thermally debound silicon carbide (SiC) samples were studied. The influence of increased powder content and reduced particle size on the densification, microstructure and properties are discussed. The sintered parts of bimodal @m-n SiC mixtures exhibited comparable sintered density but lower shrinkage than the corresponding monomodal @m-SiC powder mixtures. Additionally, the mechanical and thermal properties of sintered monomodal and bimodal SiC samples were measured and compared with literature data for conventional monomodal @m-SiC systems.

Fibrin gel has proven a valuable scaffold for tissue engineering. Complex geometries can be produced by injection molding; it offers effective cell seeding and can be produced autologous. In order to evaluate its suitability for respiratory tissue engineering, we examined proliferation, functionality, and differentiation of respiratory epithelial cells on fibrin gel in comparison to culture on collagen-coated, microporous membranes. Respiratory epithelial cells formed a confluent layer by day 4, and proliferation showed no significant difference with respect to surface. Measurement of the transepithelial electrical resistance reflected the development of a confluent epithelial cell layer and the subsequent initiation of adequate ion-transfer processes. Appearance of ciliae could be detecte...

In this report, a balloon-expandable, biodegradable, drug-eluting bifurcation stent (DEBS) that provides a sustainable release of anti-proliferative sirolimus was developed. Biodegradable bifurcation stents, made of polycaprolactone, were first manufactured by injection molding and hot spot welding techniques. Various properties of the fabricated stents, including compression strengths, collapse pressures, and flow pattern in a circulation test, were characterized. The experimental results showed that biodegradable bifurcation stents exhibited comparable mechanical properties with those of metallic stents and superior flow behavior to that of metallic bifurcation stents deployed via the T And small Protrusion approach. Polylactide-polyglycolide (PLGA) copolymer and sirolimus were then diss...

This paper presents a finite element algorithm for the simulation of thermo-hydrodynamic instabilities causing manufacturing defects in injection molding of plastic and metal powder. Mold-filling parameters determine the flow pattern during filling, which in turn influences the quality of the final part. Insufficiently, well-controlled operating conditions may generate inhomogeneities, empty spaces or unusable parts. An understanding of the flow behavior will enable manufacturers to reduce or even eliminate defects and improve their competitiveness. This work presents a rigorous study using numerical simulation and sensitivity analysis. The problem is modeled by the Navier-Stokes equations, the energy equation and a generalized Newtonian viscosity model. The solution algorithm is applied t...

Purpose To demonstrate rapid (~1 min) lidocaine delivery using 3M???s solid microstructured transdermal system (sMTS) for prolonged, local analgesic action. Methods Polymeric microneedles were fabricated via injection molding and then dip-coated using an aqueous lidocaine formulation. The amount of lidocaine coated onto the microneedles was determined by high performance liquid chromatography (HPLC). To assess drug delivery and dermal pharmacokinetics, lidocaine-coated microneedles were inserted into domestic swine. Skin punch biopsies were collected and analyzed to determine lidocaine concentration in skin using HPLC-mass spectrometry (LC-MS). Commercial lidocaine/prilocaine EMLA (Eutectic Mixture of Local Anesthetic) cream was used as comparative control. Results Lidocaine dissolves rap...

The powder space holder (PSH) and powder injection molding (PIM) methods have an industrial competitive advantage that is capable of net-shape production of the micro-sized porous parts. In this study, a micro-porous austenitic stainless steel part was produced by the PSH-PIM process. Spherical poly(methyl methacrylate) (PMMA) particles were used as a space holder material. The effects of fraction and average size of PMMA on properties of sintered micro-porous austenitic stainless steel samples were investigated. It was shown that the fraction and average size of PMMA could be controlled properties.

Abstract in english High-strength copper alloys are used as materials for injection molding tools or as cores and inserts in steel molds because of their high thermal conductivity, corrosion and wear resistance. Unfortunately, there is little technological knowledge on the electrical discharge machining (EDM) of copper-beryllium ASTM C17200 alloy. In this work, rough and finish machining conditions were tested using copper and tungsten-copper as materials for the electrodes. Cross-sectional (more) micrographic and hardness examinations as well as surface roughness measurements were also carried out on workpieces after machining in order to study the thermally affected zones. Appropriate parameters settings for EDM of the investigated alloy are suggested.

Progress in the processing of ceramics has made these materials very important for current and future technologies. Internationally renowned experts have contributed to this first of two volumes which provide a wealth of information indispensable for materials scientists and engineers. Contents of Volume A: Morrell: Microstructural Targets for Ceramics. De With: Process Control in the Manufacture of Ceramics. Schönert/Segal: Physical Preparation of Powders. Scarlett: Characterization of Powders. Bortzmeyer: Die Pressing and Isostatic Pressing. Rand: Slip Casting and Extrusion. Hellebrand: Tape Casting. Evans: Injection Molding. Bonekamp/Veringa: Green Microstructrues and their Characterization.

Current ceramic materials, component fabrication processes, and reliability prediction capability for ceramic stators in an automotive gas turbine engine environment are assessed. Simulated engine duty cycle testing of stators conducted at temperatures up to 1093 C is discussed. Materials evaluated are SiC and Si3N4 fabricated from two near-net-shape processes: slip casting and injection molding. Stators for durability cycle evaluation and test specimens for material property characterization, and reliability prediction model prepared to predict stator performance in the simulated engine environment are considered. The status and description of the work performed for the reliability prediction modeling, stator fabrication, material property characterization, and ceramic stator evaluation efforts are reported.

A micromechanics based finite element model (FEM) is developed to facilitate the design of a new production quality fiber reinforced plastic injection molded part. The composite part under study is composed of a polyetheretherketone (PEEK) matrix reinforced with 30% by volume fraction of short carbon fibers. The constitutive material models are obtained by using micromechanics based homogenization theories. The analysis is carried out by successfully coupling two commercial codes, Moldflow and ANSYS. Moldflow software is used to predict the fiber orientation by considering the flow kinetics and molding parameters. Material models are inputted into the commercial software ANSYS as per the predicted fiber orientation and the structural analysis is carried out. Thus in the present approach a coupling between two commercial codes namely Moldflow and ANSYS has been established to enable the analysis of the short fiber reinforced injection moulded composite parts. The load-deflection curve is obtained based on three constitutive material model namely an isotropy, transversely isotropy and orthotropy. Average values of the predicted quantities are compared to experimental results, obtaining a good correlation. In this manner, the coupled Moldflow-ANSYS model successfully predicts the load deflection curve of a composite injection molded part.

Ti and its alloys have been widely used for various industrial and medical applications because of their excellent characteristics of low density, high strength, high corrosion resistance and high biocompatibility. However, it is not easy to produce the complicated shape and precise parts because of their poor workability. Therefore, the advanced powder processing techniques such as Metal Injection Molding (MIM) are hoped to be a suitable technique for fabricating complex shaped Ti or its alloy parts with low cost. In this paper, various high performance Ti alloy materials such as Ti-6Al-4V added Mo or Fe or Cr have been developed by MIM process. The effect of powder type and sintering conditions on the microstructures, relative density and mechanical properties of injection molded compacts were investigated. Also the oxygen and carbon contents were checked in detail for obtaining high performance properties as same as the wrought materials. Eventually, more than 1000MPa of strength and 15% of elongation were achieved with MIM process.   

On production of sintered Co-Cr-W-C alloy using metal injection molding (MIM) process, effect of debinding and various conditions in the sintering process on the carbon content, microstructure and mechanical properties of the sintered compact was examined. Powders of Co, Cr, Cr3C2 and W mixed in a wet mill were dried. Mixed powder and waxy binder in equal volume were mixed and heated, and molded into specimens. Sixty-five wt% of the binder was extracted in the heptane gas, and the residual binder was dissipated under heating in the H2 and N2 mixture gas. It was shown that carbon content was variously controlled with change of gas compositions. The following coexisting phases were observed in the sintered compact: Co-phase, {eta}(Co3W3C) phase, M23C6 phase and M7C3 phase. Injection molded alloys showed almost the same microstructure and mechanical properties as those of conventional powder metallurgy alloys. Possibility of application of MIM with excellent moldability was shown in sintered Co-Cr-W-C alloy. 3 refs., 7 figs., 1 tab.

Plastic injection molding plays a key role in the production of high-quality plastic parts. Shrinkage is one of the most significant problems of a plastic part in terms of quality in the plastic injection molding. This article focuses on the study of the modeling and analysis of the effects of process parameters on the shrinkage by evaluating the quality of the plastic part of a DVD-ROM cover made with Acrylonitrile Butadiene Styrene (ABS) polymer material. An effective regression model was developed to determine the mathematical relationship between the process parameters (mold temperature, melt temperature, injection pressure, injection time, and cooling time) and the volumetric shrinkage by utilizing the analysis data. Finite element (FE) analyses designed by Taguchi (L27) orthogonal arrays were run in the Moldflow simulation program. Analysis of variance (ANOVA) was then performed to check the adequacy of the regression model and to determine the effect of the process parameters on the shrinkage. Experiments were conducted to control the accuracy of the regression model with the FE analyses obtained from Moldflow. The results show that the regression model agrees very well with the FE analyses and the experiments. From this, it can be concluded that this study succeeded in modeling the shrinkage problem in our application.

A phase-separated structure of the injection-molded isotactic polypropylene (iPP)/poly(ethylene-co-octene) (EOR) binary blend was studied in three-dimension (3D) by transmission electron microtomography (TEMT). Highly oriented EOR domains along both flow- (FD) and transverse-to-flow (TD) directions resulting in stacking lamella-sheet like structures to normal direction (ND) were confirmed. Some irregularities in morphology and intervals between the EOR sheets, and thickness heterogeneity of the sheets, were observed more frequently in the TD rather than in the FD. Using the 3D information obtained by the TEMT, we have tried to elucidate massive anisotropy in linear thermal expansion coefficient (CLTE) along the injection directions in this blend. We found that the CLTE anisotropy was well correlated with the lamella-like sheets arrays and their irregularities. The 3D-TEMT image of the injection-molded iPP/ethylene-co-octene rubber blend is shown as a volume rendering. The frames are shown in reconstructed geometry. The Z-axis is taken parallel to transverse-to-flow direction (TD).   Fullsize Image

This research characterizes the material which is used in High Brightness Light Emitting Diode applications. It also makes an effort towards understanding the particle size distribution on the surface and how it affects the reflectance of the surface in molded part. Titanium dioxide pigments are used in molding compounds as a means to improve opacity by increasing the scattering efficiency of the medium. The light reflected back from the surface of the injection molded part depends on the particle size distribution of Titanium dioxide pigments. One of the fundamental investigations carried out was a study of particle size distribution on the surface of the injection molded parts. After using several different characterizing techniques it was observed that particle size as well as their distribution (Interparticle distance) in polymer matrix plays an important role in reflecting the light back from the surface. In order to characterize the particle size distribution on the surface of the molded part, Environmental Scanning Electron Microscope (ESEM) is used for imaging. Image analysis method has been developed using Matlab and ImageJ softwares. Quantitative measures of the particle distribution of Titanium dioxide pigments in polymer composites have been experimentally determined, including area fraction, average diameter, Interparticle distance, and diameter volume. Different optical techniques were used to understand the light scattering phenomenon by Titanium dioxide particle in composite material. Theory about light scattering from particle was developed based on experimental data and MIE theory.

A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with neutron-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

The sticking of product material to injection molding tools is a serious problem, which reduces productivity and reliability. Depositing alloy nitride coatings (TiN, ZrN, CrN, and TiAlCrN) using closed field unbalanced magnetron sputter ion plating and electrodeposition of chromium, and characterizing their surface free energies in the temperature range 20–120°C have led to the development of a non-sticking (with a low surface free energy) coating system for semiconductor IC packaging molding dies. The contact angles of water, diiodomethane and ethylene glycol on the coated surfaces were measured at temperatures in the range 20–120°C using a Dataphysics OCA-20 contact angle analyzer. The surface free energy of the coatings and their components (dispersion and polar) were calculated using the Owens-Wendt geometric mean approach. The surface roughness of these coatings were investigated by atomic force microscopy (AFM). The adhesion force of these coatings were measured using direct tensile pull-off test apparatus. The experimental results revealed that TiAlCrN, CrN and ZrN coatings outperformed Hard-Cr and TiN coatings in terms of anti-adhesion, and thus have the potential as working layers for injection molding industrial equipment, especially in semiconductor IC packaging molding applications.   

A study of the flow behavior during sequential co-injection molding is shown using a three-dimensional finite element flow analysis code. Solutions of the non-Newtonian, non-isothermal melt flow are obtained by solving the momentum, continuity and energy equations. Two additional transport equations are solved for tracking polymer/air and skin/core polymers interfaces. The co-injection model is integrated into the NRC's 3D injection molding software. Solutions are shown for the filling of a spiral-flow mould for which experimental measurements are available. The numerical approach predicts the core advance stage during which the core flow front catches up on the skin flow front and the core expansion phase when the flow fronts of core and skin materials advance together without breakthrough. The breakthrough phenomenon is also predicted. The predicted flow front behavior is compared to the experimental observations for various skin/core melt temperature and skin/core viscosity ratio. Simulation results are in good agreement with experimental data and indicate correctly the trends in solution change when processing parameters are changing.

AGT-5 gasifier vane seat platforms with 14 vane pockets were fabricated by Ceramics Process Systems Corporation under contract to GM-Allison for the US Department of Energy sponsored ATTAP program. A newly developed SiAlon, engineered for gas turbine engine use at 1370{degrees}C, was formed into the component using the Quickset{trademark} injection molding process followed by pressureless sintering. The as-sintered components gave average 4-point flexural strengths of 102 kpsi at 25{degrees}C, 80 kpsi at 1000{degrees}C, 73 kpsi at 1200{degrees}C, 67 kpsi at 1300{degrees}C and 53 kpsi at 1370{degrees}C. Injection molded billet strengths were similar except at 1370{degrees}C where the average flexural strength was 72 kpsi. Creep rates at secondary steady state, were determined for CM200 material at 1300{degrees}C, 36 kpsi, 190 hr to be 0.0006%/hr and at 1300{degrees}C, 50 kpsi, 190 hr to be 0.0014%/hr. As sintered 3-sigma dimensional tolerances for the vane seat platforms were less than + 0.20 mm, within the component specification tolerance of {plus minus}0.30 mm. Components have been delivered to GM-Allison for evaluation and test. 2 refs.

The research was investigated the effect of boron additions on sintering characteristics, mechanical, corrosion properties and biocompatibility of injection molded austenitic grade 316L stainless steel. Addition of boron is promoted to get high density of sintered 316L stainless steels. The amount of boron plays a role in determining the sintered microstructure and all properties. In this study, 316L stainless steel powders have been used with the elemental NiB powders. A feedstock containing 62.5 wt% powders loading was molded at different injection molded temperature. The binders were completely removed from molded components by solvent and thermal debinding at different temperature. The debinded samples were sintered at different temperature for 60 min. Mechanical property, microstructural characterization and electrochemical property of the sintered samples were performed using tensile testing, hardness, optical, scanning electron microscopy and electrochemical corrosion experiments. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. Results of study showed that sintered 316L and 316L with NiB addition samples exhibited high mechanical and corrosion properties in a physiological environment. Especially, 316L with NiB addition can be used in some bioapplications. PMID:23114463

Cost effective manufacturing processes have been demonstrated for 1-3 PZT-polymer composite transducers which can be scaled to large areas. PZT ceramic preforms containing uniform rods aligned in a precise array are produced by injection molding. The PZT preforms contain 361 rods which are 1.1 mm diameter and 8 mm long. The preforms are sintered, poled, laid up to make composites of arbitrarily large size, and then encapsulated into a polymer matrix. Composites have been produced with both flexible and rigid polymers. The composites are machined flat and parallel and then electroded. Several 100 mm square transducers with a composite thickness of 6.3 mm have been fabricated and evaluated. These have shown good performance both as projectors and hydrophones. Transducer fabrication has been scaled to 250 mm square panels. Ultrafine scale 1-3 PZT composites have also been produced by injection molding. Uniform arrays of 120 {mu}m diameter, 1000 {mu}m long PZT fibers in an epoxy matrix have been produced. PZT 1-3 composite arrays with fibers as small as 70 {mu}m diameter and an aspect ratio of 10 have also been fabricated.

We investigated the occurrence of cutaneous depigmentation (vitiligo) among employees of a company that manufactured hydraulic pumps. The interiors of these pumps were injection-molded with rubber. We identified a small but significant cluster of vitiligo cases among a group of employees who frequently handled the rubber used in this injection molding process. Although none of the additives specified in the rubber formulations was a phenolic or catecholic derivative, known to be potential causes of chemically induced vitiligo, gas chromatographic analysis identified a para-substituted phenol (2,4-di-tert-butylphenol, DTBP) in solid samples of the most frequently used rubber. Surface wipe analysis confirmed that workers could be exposed to DTBP from simple handling of the rubber. We subsequently established that the solid bulk rubber used as the base in these stock rubber formulations contained both DTBP and smaller quantities of p-tert-butylphenol. Both had formed as unsuspected byproducts during chemical synthesis of two antioxidants added to the solid bulk rubber by a major rubber supplier. We conclude that the unsuspected presence of potential chemical depigmenting agents in solid bulk rubber, from which industrial rubber products are formulated, may contribute to the occurrence of occupational vitiligo, and that a simple review of ingredients in rubber formulations is inadequate to detect their presence.

Slip casting and low pressure injection molding were tested as forming methods of fine ceramics powder, and the results are described in this report. In the slip casting method, selection of a binder which gives plasticity to the green body is important. In case of slip casting of Si {sub 3} N {sub 4} powder with PVA as a binder, plasticity of the compact increased and higher strength was obtained after sintering. Then, a method to apply high pressure to the slurry was examined in order to shorten the casting time of slip casting. It was found that the casting time was shortened appropriately and drying shrinkage was decreased by applying pressure up to 200kgf/cm {sup 2}. Moreover, strength of the alumina compact was investigated by the low pressure injection molding method with a paraffin wax binder at 80-100 centigrade under the pressure of 3-5 atm. When the slurry prepared by the ball mill was formed in the vertical mold, such good results as mean flexural strength of 46kgf/mm {sup 2} with Weibull constant of 14.5 were obtained. 4 refs., 10 figs.

Prior thermoelastic analyses were conducted to assess the thermostructural response of the Galileo radioisotope thermoelectric generators general-purpose heat-source (GPHS) modules upon possible accidental reentry into earth's atmosphere. These analyses are extended through the inclusion of thermoplasticity of the composite material of the GPHS modules. The thermoplastic analysis methods for GPHS composite material are presented.

Thermoplastic matrix composites offer several advantages over thermoset matrix composites such as higher interlaminar toughness and infinite shelf life and rapid manufacturing. However, traditional welding techniques for joining thermoplastics require intimate contact between the components, localized heating at the interface and moderate consolidation pressure. Assembly tolerances represent a challenge in scaling welding techniques to large structures where any gaps in the bondline may result in overheating and poor joint quality and performance. Thermoset adhesives offer a low pressure solution to fill gaps. However joining thermoplastic composite components with structural thermoset adhesives often requires elaborate surface treatment of the thermoplastic composite adherents. These surface treatments have several limitations in production environments including finite shelf life, cost, and possible restrictions on part size and shape. These limitations may potentially hinder the widespread use of these materials in structural applications. Other methods for enhancing the bond performance are available. Previous work at the authors` institution has shown that adhesion between thermoplastic composites and epoxy-based adhesives is improved in instances where polymer interdiffusion across the interface is suspected. The improved joint performance has been attributed to interfacial diffusion of the adhesive pre-polymers into the thermoplastic material during processing. Upon final cure, bonding is believed to be enhanced through entanglements between the thermoplastic polymer chains and the network structure of the adhesive. Optimization of this bonding process requires an understanding of the rate of diffusion of the adhesive prepolymers into the thermoplastic and the structure and properties of the interfacial region. This paper focuses on the diffusion study.

The effect of ultrasound on the deformation properties of thermoplastic slips was investigated. It was shown that in treatment with ultrasound, the change in the plastic strength of beryllium oxide ? thermoplastic binder casting system in the process temperature range (40?55°C) was due to cavitation and dissipative heat release effects and can be characterized with the equation for a thermal activation process.

Reactive thermoplastics are increasingly used as toughening modifiers for epoxy resins. A way to understand the influence of the reactive end-groups on the toughening and curing mechanisms is to observe in situ the reaction between the thermoplastic and the growing epoxy network. For this purpose, R...

The results of mathematical modeling of hot-cast molding of ceramic are presented. The computational data describe the changes of the aggregate state of thermoplastic slip as it cools in the molding cavity. The casting properties giving uniform properties of the thermoplastic slip during hot-cast molding of ceramic are obtained.

This research aims to investigate the functionality of nano-precipitated calcium carbonate (NPCC) as filler in thermoplastic resins based on property enhancement. Three types of thermoplastics were used: polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC). The resins were evaluated by determining the effect of different NPCC loading on the chemical structure, thermal and mechanical properties of thermoplastics. Results showed that there was an interfacial bonding with the NPCC surface and the thermoplastics. Change in absorption peak and area were predominant in the PVC filled composite. There was a decreased in crystallinity of the PE and PP with the addition of filler. Tremendous increase on the tensile and impact strength was exhibited by the NPCC filled PVC composites while PE and PP composites maintained a slight increase in their mechanical properties. Nano-sized filler was proven to improve the mechanical properties of thermoplastics compared with micron-sized filler because nano-sized filler has larger interfacial area between the filler and the polymer matrix.   

A method for joining two or more items having surfaces of thermoplastic material includes the steps of depositing an electrically-conductive material upon the thermoplastic surface of at least one of the items, and then placing the other of the two items adjacent the one item so that the deposited material is in intimate contact with the surfaces of both the one and the other items. The deposited material and the thermoplastic surfaces contacted thereby are then exposed to microwave radiation so that the thermoplastic surfaces in contact with the deposited material melt, and then pressure is applied to the two items so that the melted thermoplastic surfaces fuse to one another. Upon discontinuance of the exposure to the microwave energy, and after permitting the thermoplastic surfaces to cool from the melted condition, the two items are joined together by the fused thermoplastic surfaces. The deposited material has a thickness which is preferably no greater than a skin depth, .delta..sub.s, which is related to the frequency of the microwave radiation and characteristics of the deposited material in accordance with an equation.

Scanning Electron Micrographs (SEM) were taken of chlorinated polypropylene (CPO) on polypropylene and thermoplastic olefin to study the interface. The effect of CPO carrier, either toluene or water, on the interface between CPO and polypropylene was investigated, and the effect of a heat treatment for waterborne CPO on polypropylene. A waterborne CPO on thermoplastic olefin interface is compared to waterborne CPO on polypropylene. Intimate contact is observed in all instances except for waterborne CPO on thermoplastic olefin. This corroborates earlier data that showed strong waterborne CPO to PP adhesion following a heat treatment.

Abstract Here we evaluate poly(2-ethyl-2-oxazoline)s (PEtOx) as a matrix excipient for the production of oral solid dosage forms by hot melt extrusion (HME) followed by injection molding (IM). Using metoprolol tartrate as a good water-soluble model drug we demonstrate that drug release can be delayed by HME/IM, with the release rate controlled by the molecular weight of the PEtOx. Using fenofibrate as a lipophilic model drug we demonstrate that relative to the pure drug the dissolution rate is strongly enhanced by formulation in HME/IM tablets. For both drug molecules we find that solid solutions, i.e. molecularly dissolved drug in a polymeric matrix, are obtained by HME/IM.

Plastic inserts may enhance the performance of a product, enlarge its application scope or make it possible to apply plastic in situations where this material may not have been applied previously. The type of insert may vary from metal to plastic, ceramic, glass, or fireproof materials on a macro-scale. Glass is a typical type of fragile material. As an insert, this fragile part is easily broken or scraped during the processing of PVC injection molding, and flashes may occur at the shared boundaries of PVC and insert. The proper gap should be set between the core or cavity and the insert. In this paper, the function of the pressure attenuation and the shear flowing distribution variation along the runner is set to get the optimal gap distribution. First, two types of power loss functions a...

The purpose of this 2-part opinion article was to project the developments expected to occur in the next few years in orthodontic materials research and applications. Part 1 reviewed developments in bonding to enamel. Part 2 looks at other orthodontic materials applications and explores emerging research strategies for probing the biological properties of materials. In the field of metallic brackets, expansion of the use of titanium alloys with improved hardness and nickel-free steels with better corrosion resistance and increased hardness is expected. Manufacturing techniques might be modified to include laser-welding methods and metal injection molding. Esthetic bracket research will involve the synthesis of high-crystallinity biomedical polymers with increased hardness and stiffness, de...

Nanocomposites based on polyamide 6/polypropylene (PA6/PP) blends containing organophilic montmorillonite (OMMT) and maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MA) were prepared by melt compounding method followed by injection molding. Four different types of OMMT were used in this work, i.e. dodecylamine modified MMT (D-MMT), 12-aminolauric acid modified MMT (A-MMT), stearylamine modified MMT (S-MMT), and commercial organo-MMT (C-MMT). X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed the presence of SEBS-g-MA did not produce any apparent effect on the dispersion of OMMT in the PA6/PP matrix. Incorporation of SEBS-g-MA into the nanocomposites enhanced strength, ductility, and impact strength but slightly reduced stiffness. A good b...

Silicon carbide (SiC) is an extremely hard and difficult-to-shape engineering ceramic material used extensively in industry because of its superior mechanical properties, wear and corrosion resistance even at elevated temperature. Conventional ceramic processing and structuring techniques such as injection molding and grinding are costly and difficult to obtain flawless complex shaped components. By infiltrating free Si into the SiC, the electrical conductivity of the matrix is largely improved. Thus it can be machined by electrical discharge machining (EDM). In this paper, a die-sinking EDM technology for manufacturing components in a commercial available silicon infiltrated silicon carbide (SiSiC) is developed. The influences of the major operating EDM parameters (discharge current ie, o...

It has been well established that periodical shear stress can improve the mechanical performance of isotactic polypropylene during injection molding. In the current study, Polarized Light Microscopy (PLM), two-dimensional Wide-Angle X-ray Diffraction (2D-WAXD), Scanning Electron Microscopy (SEM) were employed to investigate the morphology evolution of vibration sample. Compared with static sample, the morphology of vibration one, which is derived from periodical shear field, exhibits different hierarchy structure: there is an additional fiber layer containing cylindrulites between the shear layer and the core layer, and the orientation is enhanced obviously. Through etching technique, it is found that there exists non-crystalline component in the fibril (core) of cylindrulite, and it may i...

Blends of polystyrene/polyamide 6 (PS/PA6) compatibilized by styrene-ethylene/butylene-styrene (SEBS) elastomer grafted with maleic anhydride were prepared by melt blending. Wide-angle X-ray diffraction (WAXD) scans indicated a skin?core structure formed in the specimens during the injection-molding process. The results showed that the specimens tended to form the ?-crystalline form in the core region, but the ?-crystalline form in the skin region. The influences of PS and SEBS-g-MA on the crystallization of PA6 were different in the core region and skin region. In the core region, PS made the PA6 tend to be in the ?-crystalline form, but the influence of PS was contrary in the skin region. SEBS-g-MA had both enhancement and toughening effects on the blends. The mechanical properties of th...

The paper is concerned with optimization and parametric identification of Powder Injection Molding process that consists first in injection of powder mixture with polymer binder and then to the sintering of the resulting powders parts by solid state diffusion. In the first part, one describes an original methodology to optimize the injection stage based on the combination of Design Of Experiments and an adaptive Response Surface Modeling. Then the second part of the paper describes the identification strategy that one proposes for the sintering stage, using the identification of sintering parameters from dilatometer curves followed by the optimization of the sintering process. The proposed approaches are applied to the optimization for manufacturing of a ceramic femoral implant. One demonstrates that the proposed approach give satisfactory results.

Abstract Composites of Phormium tenax fibers in a poly(lactic acid) matrix with fiber content of up to 40 wt%, produced by injection molding and twin screw compounding, were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests (static and dynamic). Thermal analysis showed that cold-crystallization peak shifted to lower temperatures with increasing fiber content, confirming that the addition of Phormium fiber has the effect of promoting crystallinity. Dynamic mechanical analysis (DMA) results showed that the addition of Phormium fiber did not affect significantly the Tg of the polymer and the area under the tan decreased with the addition of Phormium fiber. Tensile modulus has been consistently increased by reinfo...

We present a compact portable chip-based capillary electrophoresis system that employs capacitively coupled contactless conductivity detection (C4D) operating at 4 MHz as an alternative detection method compared to the commonly used optical detection based on laser-induced fluorescence. Emphasis was put on system integration and industrial manufacturing technologies for the system. Therefore, the disposable chip for this system is fabricated out of PMMA using injection molding; the electrodes are screen-printed or thin-film electrodes. The system is designed for the measurement of small ionic species like Li+, Na+, K+, SO42- or NO3- typically present in foods like milk and mineral water as well as acids e.g. in wine.

This paper presents an adaptive method that couples the finite element (FE) method and the meshfree (MF) method in the arbitrary Lagrangian-Eulerian (ALE) description for numerical simulation of injection molding processes. The ALE feature is used to accurately capture moving free surfaces of flow problems and, meanwhile, to alleviate mesh distortion and its influence on the accuracy and robustness of numerical solutions. Based on the continuous blending method, originally presented for properly imposing the essential boundaryconditions in MF methods, the coupled ALE FE and MF method is developed, to exploit the respective advantages of both FE and MF methods, but to avoid their respective weak points. The method features self-adaptivity in view of the fact that moving free surfaces in an ...

In this review, recent development in micro- and nano-technologies based on anodizing of aluminum is introduced and several applications of anodic oxide films in the fabrication of micro-devices are also described. In the application work, aluminum covered with anodic oxide films is irradiated with a pulsed Nd-YAG laser to remove the oxide film locally and then metal, acrylic acid resin, and polypyrrole are deposited at the film-removed area electrochemically. Grooves, chambers, and through-holes on aluminum are also fabricated by the laser irradiation technique. By combining anodizing with the laser irradiation techniques and electrochemical treatments, novel fabrication processes are developed for printed circuit boards, plastic injection molds, electrochemical reactors, and freestanding structures, 3D manipulators, and also micro-printing rolls.   

The debinding process in the case of metal injection molding for fabrication of the Fe–6Ni–4Cu compact and variables such as temperature and time has been studied. The debinding process of multiple organic binders in the Fe–6Ni–4Cu compact was investigated by thermal gravimetric analysis (TGA) weight loss and mercury porosimetry analysis. The weight loss of wax and SA dramatically increases from below 10 wt% to 76.0 wt% and 86.0 wt% after immersion in 35°C and 40°C n-hexane for 6 h, respectively. The interdiffusion coefficients of the binder and solvent are 9.763× 10-7 cm2/s and 1.295× 10-6 cm2/s, respectively. The temperature dependent interdiffusion coefficient for the Fe–6Ni–4Cu compact can be expressed as Dx=4.534× 10exp(-5437.2/T). The distribution of pore size is about 0.1–1.9 ?m for the Fe–6Ni–4Cu compact.   

Abstract in english As an example for an environmentally benign and low-cost material we prepared blends from 1. copolyester-urethanes (PEU) and 2. cellulose acetate recycling material (CAR). The copolyester-urethanes were prepared by joining blocks of alpha, omega-(poly-(R)-3-hydroxybutyrate)-diol and poly-butylenglycol-adipate-diol with hexamethylene diisocyanate. Fibrous CAR was transformed into a short-fiber felt by textile technology and calendared into the PEU melt. The processing of t (more) he blends was done at 80 - 100 °C mainly by injection molding. The mechanical properties of the tough-elastic materials were studied with respect to the influence of the PEU composition and the ratio of CAR admixture. The starting materials, (R)-PHB and cellulose derivatives are obtained from agrarian resources. Therefore, the resulting polymers are stable under conditions of usage, yet readily bio-degradable on soil deposition. Mixing with cellulose acetate waste material allows for cost-effective production of such blends.

Pure silicon nitride shows a remarkable resistance to sintering without the use of densification additives. The present investigation is concerned with results which show the effect of chemical content on sinterability, taking into account the composition, raw material impurities, and processing contaminants. Aspects of sintering are discussed along with strength characteristics, and oxidation relations. Attention is given to phase field I and II materials, phase field III and IV materials, tungsten carbide and oxidation at 600 C, and studies involving shape fabrication by injection molding. It was found that in sintering Si3N4 + Y2O3 an increase in the amount of Y2O3 and, in particular, the addition of Al2O3 enhances the fluidity of the liquid phase.

In manufacturing a DC motor body including a motor magnet by conventional processes, a magnet is fitted to the cylindrical molding core and a motor body is injection-molded within a cavity formed between a motor-body-forming mold and a cylindrical molding core to which the magnet is attached. Therefore, the magnet has to be molded and stocked before molding the motor body, thus being inapplicable to mass-production processes. To overcome these problems, the motor magnet and the motor body are molded in sequence in accordance with two separate molding steps by the use of the same molding core. This method can eliminate troublesome magnet fitting work and the need of magnet stock, and enhance the dimensional precision of motor magnet, thus being applicable to mass-production process while increasing the energy transduction efficiency of the DC motor.

The hygroscopicity of woody materials results in moisture absorption into wood-based composites, including wood-plastic composites (WPC). The objective of this research was to improve the water resistance and mold resistance of WPC by extraction of hemicelluloses from the wood raw material. The treatment may also eliminate extractives such as free sugars, starches, and lipids that can serve as food for fungi. Liquid hot water extraction was performed on southern yellow pine flakes under different temperatures (140, 155, and 170 ^oC) and over a period of 60 min. Wood flour from extracted or control flakes was compounded with isotactic polypropylene in an extruder, both with and without a coupling agent. Injection molding was used to make tensile test samples. Wood-plastic composite samples ...

Microstructures of alloys with three compositions in the pseudobinary PbTe-Sb2Te3 system cast in copper molds using the injection molding technique were examined by scanning electron microscopy (SEM), energy-dispersive spectrometry, and X-ray diffraction (XRD). The microstructural length scales such as interlamellar spacing (ILS) and secondary dendrite arm spacing vary over two orders of magnitude, e.g., from 0.2 to 20 ?m for SDAS in the hypereutectic alloy, depending on injection pressure, distance from surface, or thickness. The decrease in the microstructural length scale with the decrease in distance from the surface, thickness, and increase in injection pressure is attributed to an increase in the cooling rates estimated using the heat-transfer theory in solids. The difference in the injection pressures is represented as the difference in the heat-transfer coefficients.

Gelcasting requires making a mixture of a slurry of ceramic powder in a solution of organic monomers and casting it in a mold. Gelcasting is different from injection molding in that it separates mold filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging were used for in-situ monitoring of the gelation process and gelcasting of alumina. {sup 1}H NMR spectra and images are obtained during polymerization of a mixture of soluble reactive acrylamide monomers. Polymerization was initiated by adding an initiator and an accelerator to form long- chain, crosslinked polymers. Multidimensional NMR imaging was used for in-situ monitoring of the process and for verification of homogeneous polymerization. Comparison of the modeled intensities with acquired images shows a direction extraction of T{sub 1} data from the images.

Topics discussed include hot isostatic pressing, powder forging, metal injection molding, modeling of consolidation processes, liquid-phase sintering, novel P/M technology, innovation in tooling, soft magnetic materials, and superconductivity and shielding. Attention is given to the processing and properties of carbides, new tungsten alloys, refractory alloys, tool steels and cutting materials, spray-formed aluminum alloys, copper base and bearing alloys, P/M titanium, and plasma processing. Consideration is also given to powder-production mechanical processes, P/M composite materials, intermetallic compounds, high-temperature nickel-base materials, rapidly solidified materials, and the structure and properties of ferrous alloys. Additional topics include the fatigue properties of P/M materials, improved material properties, engineering properties via sintering, the generation and the effects of sintering atmospheres, improved dynamic properties in P/M parts, nonequilibrium P/M processing, Japan's progress in ferrous P/M ceramics, high-porosity materials, and process control and simulation.

At Karlsruhe Institute of Technology (KIT), a He-cooled divertor design for future fusion power plants has been developed. This concept is based on the use of modular cooling fingers made from tungsten and tungsten alloy, which are presently considered the most promising divertor materials to withstand the specific heat load of 10MW/m^2. Since a large number of the finger modules (n>250,000) are needed for the whole reactor, developing a mass-oriented manufacturing method is indispensable. In this regard, an innovative manufacturing technology, Powder Injection Molding (PIM), has been adapted to W processing at KIT since a couple of years. This production method is deemed promising in view of large-scale production of tungsten parts with high near-net-shape precision, hence, offering an ad...

Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63mm were used. Isothermal and non-isothermal sintering behavior of the loose powders under hydrogen and argon atmospheres, which is a simulated condition of 2C-PIM and 3DP processes after de-binding, was studied. Microstru...

Injection molded bulk-shape Poly (L-lactide) (PLLA) specimens were hydrolyzed in the phosphate buffered solution and the mechanical properties were evaluated after the hydrolysis tests. In order to evaluated the effect of crystallinity on the hydrolysis, specimens were annealed with 70 and 130°C for 24h. Hydrolysis tests were conducted with soaking the specimens in the phosphate buffered solution (pH 7.4) in an incubator where temperature was kept as 37°C. Vickers hardness was not influenced by hydrolysis until 30 days. Tensile tests results, however, indicated the strength reduction with hydrolysis. From the appearance inspection, whitened regions were observed at the inner of the specimen. These results indicated the bulk erosion with accelerated inside erosion occurred.

Microceramic injection molding (µCIM) has shown great potential in making small-scale intricate near-net-shape parts with the competitive price for mass production. In this study, multi-exposure multi-development UV-Lithographie, Galvanoformung, Abformung (LIGA), µCIM, variothermal temperature control, and Taguchi experimental method are integrated and applied to develop a multilayer micropart with zirconia (ZrO2) feedstock. With the variothermal temperature control, a 335 ?m thickness multilayer micropart having 100 microholes of 21.6 ?m in diameter has been successfully molded. Optimization of the molding parameters to achieve high microhole replication quality molding was carried out with Taguchi experimental method. Results from Taguchi experiments reveal that mold temperature (40.9%),...

Induction heating in injection molding has the advantages of rapid heating, reduced cycle time, and improved product quality. In this research, using both experiment and simulation, externally wrapped coil induction heating was applied to verify the heating capacity of a pair of mold plates. By applying different coil designs and mold gap, the effect of the externally wrapped coil induction heating was evaluated. Results showed that when a serial coil was used as an inductor, the heating rate reached 8.0^oC/s. From an initial mold temperature of 40^oC, after 15s heating, the mold surface temperature reached 159.9^oC with the serial coil. The parallel coil shows a better heating uniformity but its heating rate is far lower than the serial coil. For the serial coil, the temperature distribut...

This work summarizes the development of green composites from distillers dried grains with solubles (DDGS), a major co-product of the corn ethanol industry, and poly (butylene adipate-co-terephthalate), PBAT. The composites were fabricated using a twin-screw micro extruder with micro injection molding. The DDGS was pretreated, yielding a noticeable improvement in the degradation onset temperature of DDGS from 140 to 240^oC, which was shown by thermogravimetric analysis (TGA). The composite fabricated with pretreated DDGS showed better mechanical and thermal properties compared to the composite with non-treated DDGS. TGA analysis showed that the maximum degradation rate shifted slightly to lower values with the increase of filler content. Differential scanning calorimetry (DSC) analysis sho...

Abstract As solid lubricants, Polytetrafluoroethylene (PTFE), graphite, and ultra-high molecular weight polyethylene (UHMWPE) can improve the tribological properties of PA6. The mechanical and the tribological properties of polyamide 6 (PA6) composites filled with solid lubricants were researched. The blended materials were injection molded to provide the test samples. Mechanical properties were studied in terms of the tensile strength and impact strength. Friction and wear experiments were run at a rotating speed of 1500 rpm and under loads of 40 and 160 N. The worn surfaces were examined using a scanning electron microscope. It was found that an improvement of tribological properties can be obtained by preparing PA6 composites, which was closely related to the varieties and the contents ...

A one person level oxygen generation subsystem was developed and production of the one person oxygen metabolic requirements, 0.82 kg, per day was demonstrated without the need for condenser/separators or electrolyte pumps. During 650 hours of shakedown, design verification, and endurance testing, cell voltages averaged 1.62 V at 206 mA/sq cm and at average operating temperature as low as 326 K, virtually corresponding to the state of the art performance previously established for single cells. This high efficiency and low waste heat generation prevented maintenance of the 339 K design temperature without supplemental heating. Improved water electrolysis cell frames were designed, new injection molds were fabricated, and a series of frames was molded. A modified three fluid pressure controller was developed and a static feed water electrolysis that requires no electrolyte in the static feed compartment was developed and successfully evaluated.

A noncontact measuring system using a digital image analysis has been devised for the two-dimensional deformation of a powder compact during sintering, which is applicable to non-uniform shrinkages of graded compacts as well as complex-shape compacts prepared by metal injection molding. This article roughly introduces the system and describes an example of the measurement of two-dimensional sintering shrinkage of a metal/ceramic multilayer compact of the material combination of stainless steel (SUS304) and partially stabilized zirconia (PSZ). The measurement involves the edge enhancement of input images, the reading of the intensities of each pixel (picture element), and the determinations of the outline of a specimen and the distribution of diameter changes. It has been confirmed that thermal expansion and nonuniform deformation during sintering can be measured two dimensionally. In comparison with measurement by a conventional dilatometry, this method has enough accuracy for measuring sintering shrinkage in the temperature range from room temperature to 1,573 K.

Microfluidic devices are mainly used within the life sciences or chemical analysis. Polymers are ideally suited for these applications due to their physical and chemical properties. In this report, we describe a rapid low cost processing technology to fabricate mold inserts for microfluidic structures with high aspect ratio, as well as excellent surface quality and high hardness. These tools are used for hot embossing and as mold inserts for injection molding. They enable cost effective structuring of technical polymers like polycarbonate or cycloolefin copolymer. The main advantage of our approach is the availability of the geometry and the specific target material right from the start of the evaluation process of microfluidic devices. The process described enables a rapid prototyping for the development and evaluation of different microfluidic devices, and they can be used for a low-cost mass production of micro structured parts.

Abstract in english The effect of the filler content and size, as well as accelerated aging on the mechanical properties of polypropylene composites reinforced with woodflour (WF/PP) were evaluated. The composites were prepared by the extrusion of polypropylene with woodflour (Pinus elliotti) based on following ratios: 15, 25 and 40 wt% with two different granulometries. The specimens were injection molded according to ASTM standards. The composite properties did not show significant differe (more) nces as a function of the filler granulometry. We also observed that by increasing the filler content, both the mechanical properties and the melt flow index (MFI) decreased, and the elasticity modulus, hardness and density increased. Concerning the accelerated aging, the composite presented a reduction in tensile properties. The results showed that the composite properties are extremely favorable when compared to other commercial systems reinforced by inorganic fillers.

Two series of uniaxial tensile tests are performed on isotactic polypropylene with the strain rates ranging from 5 to 200 mm/min. In the first series, injection-molded specimens are used without thermal pre-treatment, whereas in the other series, the samples are annealed for 51 h at 160C prior to testing. A constitutive model is developed for the viscoplastic behavior of isotactic polypropylene at finite strains. A semicrystalline polymer is treated as an equivalent heterogeneous network of chains bridged by permanent junctions (physical cross-links and entanglements). The network is thought of as an ensemble of meso-regions connected with each other by links (lamellar blocks). In the sub-yield region of deformations, junctions between chains in meso-domains slide with respect to their reference positions (which reflects sliding of nodes in the amorphous phase and fine slip of lamellar blocks). Above the yield point, sliding of nodes is accompanied by displacements of meso-domains in the ensemble with respect...

The effects of nanoparticle addition on the pressureless sintering of injection molded and debound aluminum nitride (AlN) samples were studied. Variations in the densification, microstructure, and properties owing to the increased powder content and reduced particle size are discussed. The results indicate the formation of liquid phase at 1500^oC in the bimodal micro (@m)-nano (n) AlN samples, a temperature that is at least 100^oC lower than typically reported values in the literature. Consequently, a densification >= 99% was achieved by pressureless sintering at a relatively lower temperature of 1650^oC with ~14% isometric shrinkage. Additionally, thermal and mechanical properties of the sintered bimodal AlN samples are presented and compared with sintering studies on conventional monomod...

This study investigates the effect of mixing technique and particle characteristics on the rheology and agglomerate dispersion of tungsten-based powder injection molding (PIM) feedstock. Experiments were conducted with as-received (agglomerated) and rod-milled (deagglomerated) tungsten powder mixed in a paraffin wax-polypropylene binder. Increase in the mixing shear rate decreased the agglomerate size of the agglomerated tungsten powder, decreased the viscosity, and improved the flow stability of the feedstock, interpreted as increased homogeneity of the feedstock. Higher solids volume fraction, lower mixing torques, and improved homogeneity were observed with deagglomerated tungsten powder, emphasizing the importance of particle characteristics and mixing procedures in the PIM process. Hydrodynamic stress due to mixing and the cohesive strength of the tungsten agglomerate were calculated to understand the mechanism of deagglomeration and quantify the effect of mixing. It was concluded that deagglomeration occurs due to a combination of rupture and erosion with the local hydrodynamic stresses exceeding the cohesive strength of the agglomerate.

Micro/nano replication processes, including micro/nano thermal forming (compression molding and hot embossing), UV-molding, micro injection molding, and glass micro molding are regarded as the most promising mass-production methods for micro/nano optical components because they offer high repeatability, mass producibility with low-cost and versatility in terms of molding material selection. To replicate micro/nano optical components, it is required to prepare the mold inserts that have the cavities of the same shape as the components. One can use any established methods to make mold, such as direct machining, wet etching, dry etching, electroforming, compaction and sintering, and so on. This paper reviews the general issues on mold fabrication and replication technologies for micro/nano optical components with our recent work and results in these areas.   

The blends of acrylonitrile-butadiene-styrene (ABS)/poly (ethylene terephthalate) (PET) compatibilized by styrene maleic anhydride (SMA) and toughened by ABS high glue powder (ABS-HGP) were prepared by extrusion and injection molding. Adding SMA, the Izod impact strength, elongation at break, viscosity and Vicat temperature of blends were improved. Differential scanning colorimeter showed ABS and SMA hindered the crystallization process of PET and scanning electron microscopy (SEM) showed the domain size of PET in compatibilized blends became small and the distribution appeared to be uniform. ABS-HGP can toughen ABS/PET/SMA blends well. Adding 20 wt% ABS-HGP, the Izod impact strength of the blends improved from 8.9 KJ/m2 to 18.6 KJ/m2 and elongation at break increased from 38.9% to 76...

Bioactive ceramics, ?-tricalcium phosphate (?-TCP), particles reinforced bioabsorbable plastics poly-L lactide (PLLA) composites have been expected to apply for the fracture fixations which have more biocompatibility than monolithic PLLA. In this study, ?-TCP/PLLA composites containing three different ?-TCP contents (4.8, 9.5, 14.3wt%) were prepared by injection molding. The results of bending tests show bending strength decreases with increasing ?-TCP contents. On the other hand, bending modulus increases with increasing ?-TCP contents. After immersion tests in PBS at 37°C up to 8 weeks, the mechanical properties were hardly degraded in all specimens. The results of fracture surface observation by scanning electron microscopy indicated that microscopic damage such as debonding between ?-TCP and PLLA initiates at ?-TCP agglomeration and grows with increasing loading. Analytical predictions of the relationship between stress and strain based on micromechanics considering the progress of debonding between ?-TCP and PLLA were in good agreement with experimental results.   

A micro-molding process was used to fabricate parts in the 0.1 to 10 mm size range from a stainless steel nano-powder. The two types of molds used were both produced from parts fabricated using the LIGA process so that they had precise dimensional tolerance and straight sidewalls. Rigid PMMA molds were made by injection molding and flexible silicone rubber molds were made by casting. Mold filling was accomplished by mixing the powder with epoxy to form a putty-like material that was then pressed into the mold cavities and allowed to cure. After pyrolysis of the epoxy, the parts were sintered in forming gas. The densification kinetics were measured in situ using a video system. Full densification was achieved after 1 hour at 1350 C. The microstructure of the sintered parts was examined using the SEM. The hardness, dimensional tolerance and surface roughness of the sintered parts were also measured.

Abstract PHB/PBS and PHBV/PBS blends are prepared via in situ compatibilization using DCP as a free-radical grafting initiator. A considerable reduction in PBS particle size and a significant increase in the interfacial adhesion between the PHB(V) and PBS phases are observed after the compatibilization. The elongation at break of the PHBV/PBS blends was considerably increased. The local deformation mechanism indicates that matrix yielding together with dilatation, deformation, and fibrillation of the PBS particles are responsible for the improved tensile toughness of the compatibilized PHBV/PBS blends. The tensile strength, impact toughness, and elongation at break of injection-molded PHB(homopolymer)/PBS blends are also increased after in situ compatibilization.

Micro Porosity Sintered wick is made from metal injection molding processes, which provides a wick density with micro scale. It can keep more than 53 % working fluid inside the wick structure, and presents good pumping ability on working fluid transmission by fine infiltrated effect. Capillary pumping ability is the important factor in heat pipe design, and those general applications on wick structure are manufactured with groove type or screen type. Gravity affects capillary of these two types more than a sintered wick structure does, and mass heat transfer through vaporized working fluid determines the thermal performance of a vapor chamber. First of all, high density of porous wick supports high transmission ability of working fluid. The wick porosity is sintered in micro scale, which limits the bubble size while working fluid vaporizing on vapor section. Maximum heat transfer capacity increases dramatically as thermal resistance of wick decreases. This study on permeability design of wick structure is 0.5...

H13 tool steel powder was clad on copper alloy substrate both directly and using 41C stainless steel (high Ni steel) powder as a buffer layer by direct metal deposition (DMD). Cu-steel bimetallic die casting and injection molding tools are of high interest for reduction of cycle time by efficient heat extraction due to high thermal conductivity of copper. The mechanical properties of these bimetallic structures were investigated in terms of bond strength, impact energy and fracture toughness. The bond interfaces of these claddings showed porous and crack free transition regions. The bond strength was higher in the directly clad H13 tool steel compared to the H13 tool steel clad with 41C stainless steel as buffer layer. The fracture morphology in tensile test specimens showed ductile dimple...

Simulation of the injection molding process is a helpful way for the engineers who work with plastics processing. By simulation, they will get some important parameters which sometimes are highly necessary for the mold design and processing. Thus, the engineers will save much time to do experiments for the parameters. Two simulation programs are used in this report, namely CADMOULD and CADMOULD MEFISTO which are designed by Institut fur Kunststoffverarbeitung (IKV) in Aachen, W. Germany. CADMOULD works with 2-D geometry and is specialized for rheological, thermal and mechanical calculation. It is installed on a personal computer, while CADMOULD MEFISTO works in 3-D and is installed on a VAX 8530 computer at SINTEF. A PC version of this program is also available. This report deals with CADMOULD and CADMOULD MEFISTO. The construction of flow lines, balancing of sprue system, the optimizing of injection time, and gate(s) optimizing are mainly included.

Six microlens arrays are fabricated in a single step process using diamond milling techniques, plunging and micromilling. Four of the lenses are cut using plunging, two each in poly(methyl methacrylate) and polystyrene (Rexolite 1422), and the other two are cut in polystyrene using 3D micro-milling. Half of the lenses are concave and the other half are convex. These are high power lenses having steep sag at the edges and radii between 2.0 - 2.1 mm for each array. The clear aperture diameters of the lenses are about 3.2 mm for plunged lenses and 2.6 mm for micro-milled lenses. The lenses are spaced 4 mm apart in a square grid. Setup and method of these techniques is described and the lens arrays are characterized based on radius (power) error, wavefront error, roughness, and grid position error. Micro-milled lenses are shown to be of high optical quality compared with standards for injection molded plastic lenses.

Abstract A new method is proposed, which can be used to analyze the influence of different additives and fillers on the nonisothermal crystallization of polymers. The composites of talc in isotactic polypropylene (i-PP) were prepared using a corotating twin-screw extruder. The compounds were subsequently dried and injection molded. PP morphology and talc dispersion were visualized using optical microscopy and computed tomography. Wide-angle X-ray scattering and small-angle X-ray scattering measurements provided an insight into the crystal structure of PP. The data obtained from nonisothermal DSC measurements were fitted to the Avrami model for the nonisothermal case. The calculated Avrami's exponent (n), which takes into account the influence of talc on the nucleation and growth of the PP ...

Bulk amorphous alloys having dimensions of at least 1 cm diameter have been prepared in the Pd-Ni-P, Pd-Cu-P, Pd-Cu-Ni-P, and Pd-Ni-Fe-P systems using a fluxing and water quenching technique. The compositions for bulk glass formation have been determined in these systems. For these bulk metallic glasses, the difference between the crystallization temperature T{sub x}, and the glass transition temperature T{sub g}, {Delta}T = T{sub x} - T{sub g}, ranges from 60 to 1 10 K. These large values of {Delta}T open the possibility for the fabrication of amorphous near net-shape components using techniques such as injection molding. The thermal, elastic, and magnetic properties of these alloys have been studied, and we have found that bulk amorphous Pd{sub 40}Ni{sub 22.5}Fe{sub 17.5}P{sub 20} has spin glass behavior for temperatures below 30 K. 65 refs., 14 figs., 3 tabs.

The focus of this study is to evaluate the effective modulus of carbon nanotube (CNT) reinforced polypropylene (PP) composites based on numerical techniques that account for CNTs non-uniform distribution, agglomeration, waviness and alignment with respect to the applied load direction. A three-dimensional (3D) finite element model with multiple CNTs embedded within the PP matrix in presence of CNT/PP interphase is built and subjected to tensile loading. The thickness and stiffness of CNT/PP interphase, dispersion and distribution of CNTs within the PP matrix, their alignment with respect to the applied load and their waviness are characterized using atomic force microscopy and scanning electron microscopy of the CNT/PP composites made by melt mixing and injection molding. The modulus predi...

Most common mechanical applications require parts with specific properties as hard faced features. It is well known that treating parts under suitable atmospheres may improve hardness and strength yield of steels. Heat treatment process and more particularly thermo-chemical diffusion processes (such as carburizing or its variation: carbonitriding) can be performed to reach the industrial hardness profile requirements. In this work, a low-alloyed steel feedstock based on water soluble binder system is submitted to the MIM process steps (including injection molding, debinding and sintering). As-sintered parts are then treated under a low pressure carbonitriding treatment. This contribution focuses on preliminary results such as microstructural analyses and mechanical properties which are established at each stage of the process to determine and monitor changes.

Abstract Injection molded poly(trimethylene terephthalate) (PTT)/carbon fiber (CF) composites have been fabricated using a twin screw micro compounder. The effect of CF reinforcement on the thermal, mechanical, dynamic mechanical, and microscopic properties of the composite was investigated. Addition of 30 wt% of CF into PTT resulted in the significant enhancement of tensile (120%) and flexural (30%) strength compared to neat PTT. The rule of mixture was successfully employed for theoretical calculations of tensile modulus and the calculated values were compared with the experimental results. Similarly, CF reinforced (30 wt%) PTT composites exhibited an increase of more than a 150C in the heat deflection temperature. Scanning electron microscopy analysis of the tensile fracture specimens r...

Abstract Microcellular foamed (wood fiber)-reinforced recycled polypropylene composites (MFWPCs) were prepared by an injection molding process where azodicarbonamide was used as a chemical foaming agent. The influence of injection parameters (injection temperature, dwell pressure) on the microcellular structure (cell diameter and cell density) and the mechanical properties of the MFWPCs were investigated. The results indicated that when the melting temperature was 180C and the dwell pressure was 12.5 MPa, a uniformly distributed microcellular structure of MFWPCs was obtained. Compared with solid wood plastic composites, the density of the MFWPCs decreased by 24.5%, and its impact strength of MFWPCs increased by 53%, because the propagation direction of the crack changed to the -skip- or -b...

Abstract This study has been carried out to mimic the thermo oxidative degradation of polypropylene (co PP) during service life and recycling. Injection molded specimens were heat aged at 130 C for different times up to maximum of 300 h to simulate the degradation of co PP during the service life. These aged specimens were mixed with stabilizers in internal mixer and again heat aged up to 300 h. A small increase in melt flow rate (MFR) value was observed for aged co PP but it showed large increase after recycling. The presence of carbonyl peak at 1713 cm 1 confirmed the oxidation of co PP during aging and it increases with aging time. Carbonyl index (CI) is increased in recycled sample with aging, whereas oxidation induction time (OIT) decreased. The stabilizers used during reprocessing ar...

The standard ISO 1.2738 medium-carbon low-alloy steel has long been used to fabricate plastic molds for injection molding of large automotive components, such as bumpers and dashboards. These molds are usually machined from large pre-hardened steel blooms. Due to the bloom size, the heat treatment yields mixed microstructures, continuously varying from surface to core. Negative events (such as microcracks due to improper weld bed deposition or incomplete extraction of already formed plastic objects) or too large thermal/mechanical stresses can conceivably cause mold failure during service due to the low fracture toughness and fatigue resistance typically encountered in large slack quenched and tempered ISO 1.2738 steel blooms. Alternative steel grades, including both non-standard microallo...

Abstract The weight and dimensional changes of injection-molded glass-fiber reinforced polyamide 66 composites based on two glass fiber products with different sizing formulations and unreinforced polymer samples have been characterized during conditioning in water, ethylene glycol, and a water-glycol mixture at 50C and 70C for a range of times up to 900 h. The results reveal that hydrothermal ageing in these fluids causes significant changes in the weight and dimensions of these materials. All conditioned materials showed a time dependent weight and dimension increase. The change observed in water could be well modeled by a simple Fickian diffusion process; however, the absorption process followed a more complex pattern in the other conditioning fluids. It was not apparent that changing t...