DUPONT DOW ELASTOMERS

Also in existence is the joint-venture web site for leading elastomers suppliers that include Bayer, CK Witco Corp., DSM Elastomers, DuPont-Dow Elastomers L.L.C., Flexsys, M.A. Hanna Rubber Compounding, and Zeon Chemicals L.P. They targeted to create www.ElastomerSolutions.com, a global marketplace and customer-focused, web-based community devoted solely to the sale of elastomers and associated products. 

In addition to the two-phase TPEs, two new technologies have emerged. They are the metallocene-catalyzed polyolefin plastomers (POPs, the name given to Exxon s EXACT product line) and polyolefin elastomers (POEs, DuPont Dow Elastomer s ENGAGE), and reactor-made thermoplastic polyolefin elastomers (R-TPOs). These new types of TPEs are often called metallocene elastomers-TPEs (MEs-TPEs) [87]. The new POPs and POEs are essentially very low-molecular-weight-Unear low-density PEs (VLMW-LLDPE). These new-generation TPEs exhibit mbber-like properties and can be processed on... 

DuPont Dow Elastomers, Product Information Literature, Freeport, TX, 1999. 

Chloroprene is available commercially on a restricted basis in the United States as crude P-chloroprene with a minimum purity of 95% (Lewis, 1993 DuPont Dow Elastomers, 1997). The principal impurities are dichlorobutene and solvents, with smaller amounts of 1-chlorobutadiene (a-chloroprene), chlorobutenes and dimers of both chloroprene and butadiene. Due to its reactivity, chloroprene is stored at 0°C or below under nitrogen and contains significant quantities of inhibitors, such as phenothiazine, tert-butylcatechol, picric acid and the ammonium salt of A -nitroso-N-phenylhydroxy lamine, to prevent degradation and polymerization (Stewart, 1993). Generally within six weeks of manufacture, crude chloroprene is distilled to produce polymerization grade, which is used within approximately 24 h of distillation. 

In the production of chloroprene from butadiene, there are three essential steps liquid- or vapour-phase chlorination of butadiene to a mixture of 3,4-dichloro-l-butene and l,4-dichloro-2-butene catalytic isomerization of 1,4-dichloro-2-butene to 3,4-dichloro-l-butene and caustic dehydrochlorination of the 3,4-dichloro-l-butene to chloroprene. By-products in the first step include hydrochloric acid, 1-chloro-1,3-butadiene, trichlorobutenes and tetrachlorobutanes, butadiene dimer and higher-boiling products. In the second step, the mixture of l,4-dichloro-2-butene and 3,4-dichloro-l-butene isolated by distillation is isomerized to pure 3,4-dichloro-l-butene by heating to temperatures of 60-120°C in the presence of a catalyst. Finally, dehydrochlorination of 3,4-dichloro-l-butene with dilute sodium hydroxide in the presence of inhibitors gives crude chloroprene (Kleinschmidt, 1986 Stewart, 1993 DuPont Dow Elastomers, 1997). 

It is reported that dry polychloroprene no longer contains detectable chloroprene (detection limit, 0.5 ppm). In polychloroprene latexes, residual chloroprene is less than 1%, varying with the manufactunng process and intended use (DuPont Dow Elastomers, 1998). 

DuPont Dow Elastomers (1997) Submission from C.A. Palmiotto, DuPont Dow Elastomers, to United States Department of Labor, Occupational Safety and Health Administration, 4 November 1997... 

DuPont Dow Elastomers (1998) Letter from M.A. Lynch to T. Junghans. 13 January 1998 Eller, P.M., ed. (1994) NIOSH Manual of Analytical Methods (DHHS (NIOSH) Publ. No. 94-113),... 

Berard M T Sabbagh A B DuPont Dow Elastomers LLC (Institute of Materials)... 

Source Processing Guide Viton Fluoroelastomer, Technical Information Bulletin VTE-H90171-00-A0703, DuPont Dow Elastomers, 2003 (With permission). 

Viton DuPont Dow Elastomers, 300 Bellevue Parkway, Suite 300, Wilmington, Delaware 19809,... 

Division Chemist, DuPont Dow Elastomers L.L.C., Newark, Delaware... 

The sheer size and value of the polyethylene industry ensure that there is continued research, progress, and development in catalysis, for their potential commercial impact. Although this whole subject is not within the scope of this chapter, we mention a couple of aspects of the progress, which offer the potential to impact this industry. In 1995, DuPont introduced work, carried out with them at the University of North Carolina—via the largest patent applicafion ever in the USA. They disclosed what are described as post-metallocene catalysts. These are transition and late transition metal complexes with di-imine ligands, which form part of the DuPont Versipol technology. Such catalysts create highly branched to exceptionally linear ethylene homopolymers and linear alpha-olefins. Late transition metals offer not only the potential for the incorporation of polar comonomers, which until now has only been possible in LDPE reactors, but also their controlled sequence distribution, compared to the random composition of free radical LDPE copolymers. Such copolymers account for over 1 million tons per annum [20]. Versipol has so far only been cross-licensed and used commercially by DuPont Dow Elastomers (a former joint venture, now dissolved) in an EPDM plant. 

Storage Store in a cool, dry, and well ventilated area Hypalon CP 826 [DuPont Dow Elastomers DuPont Canada]... 

Hypalon H-20 [DuPont Dow Elastomers DuPont Canada R.T Vanderbilt] Chem. Descrip. Chlorosulfonated polyethylene elastomer CAS68037-3 A... 

Neoprene AC [DuPont Dow Elastomers R.T. Vanderbilt] them. Descrip. Polychloroprene (2-chlorobutadiene 1,3)... 

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