Popcorn polymerisation of chloroprene. A kinetic investigation

International Nuclear Information System (INIS)

Brough, Neil

1997-01-01

The project was sponsored by Du Font Dow Elastomers Ltd (Maydown, N. Ireland), in whose neoprene plant the popcorn polymers are found. The material itself has no commercial value, but grows rapidly and has the ability to block pipes and halt production. Therefore the production equipment containing monomers is all scheduled for 'popcorn search' inspections at intervals that differ according to the prevailing temperatures and monomer concentrations; a process which adds to costs. Prior work within the Queen's University of Belfast has identified the factors which affect the initiation of chlorobutadiene popcorn polymers, but available published and unpublished kinetic studies are in conflict concerning their rate of growth, and there is no data on the dichlorobutadiene popcorn polymer. In consequence, current relief system design procedures are based on a worst case scenario about popcorn growth rates and thus the design may be unduly expensive. The research obtained reliable kinetic data to allow these 'popcorn search' schedules to be rationalised and relief system designs to be improved and as a result to reduce the company's expenditure and improve operational safety margins. The proposed research was to investigate the kinetic behaviour of chlorinated butadiene monomers in the formation of omega- or 'popcorn' polymers. The growth rates of the chloroprene popcorn polymer were investigated at various temperatures in the liquid phase in the pure chloroprene monomer, mixed with other monomers and diluted with toluene in what we term 'Korean' type experiments. In these experiments the growth of popcorn polymer was terminated in a set of identically prepared ampoules after a fixed time. The growth rates of popcorn polymer seeds were obtained over various time periods, namely 24, 43 and 54 hours, at temperatures ranging from 10 deg C to 60 deg C. It was observed that the results differ greatly from those obtained by J.Op.Li. In particular, in the present work it was

NTP Toxicology and Carcinogenesis Studies of Chloroprene (CAS No. 126-99-8) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Science.gov (United States)

1998-09-01

rats based on increased incidences of neoplasms of the oral cavity; increased incidences of neoplasms of the thyroid gland, mammary gland, and kidney were also attributed to exposure to chloroprene. Low incidences of urinary bladder neoplasms in male and female rats and lung neoplasms in female rats may also have been related to exposure to chloroprene. There was clear evidence of carcinogenic activity of chloroprene in male B6C3F1 mice based on increased incidences of neoplasms of the lung, circulatory system (hemangiomas and hemangiosarcomas), and harderian gland; increased incidences of neoplasms of the forestomach and kidney were also attributed to exposure to chloroprene. There was clear evidence of carcinogenic activity of chloroprene in female B6C3F1 mice based on increased incidences of neoplasms of the lung, circulatory system (hemangiomas and hemangiosarcomas), harderian gland, mammary gland, liver, skin, and mesentery; increased incidences of neoplasms of the forestomach and Zymbal's gland were also attributed to exposure to chloroprene. Exposure of male and female rats to chloroprene was associated with increased incidences of alveolar epithelial hyperplasia in the lung; nephropathy; and several nonneoplastic effects in the nose including olfactory epithelial atrophy, fibrosis, adenomatous hyperplasia, basal cell hyperplasia, chronic inflammation, respiratory metaplasia, and necrosis. Exposure of male and female mice to chloroprene was associated with increased incidences of bronchiolar hyperplasia and histiocytic cell infiltration in the lung; epithelial hyperplasia in the forestomach; renal tubule hyperplasia (males only); several effects in the nose including olfactory epithelial atrophy, respiratory metaplasia, and adenomatous hyperplasia; and hematopoietic cell proliferation in the spleen. Synonyms: Chlorobutadiene, 2-chlorobuta-1,3-diene, 2-chloro-1,3-butadiene, -chloroprene