Epichlorohydrin elastomers

Epichlorohydrin Elastomers without AGE. ECH homopolymer, polyepichlorohydrin [24969-06-0] (1), and ECH—EO copolymer, poly(epichlorohydrin- (9-ethylene oxide) [24969-10-6] (2), are linear and amorphous. Because it is unsymmetrical, ECH monomer can polymerize in the head-to-head, tail-to-tail, or head-to-tail fashion. The commercial polymer is 97—99% head-to-tail, and has been shown to be stereorandom and atactic (15—17). Only low degrees of crystallinity are present in commercial ECH homopolymers the amorphous product is preferred. 

Epichlorohydrin Elastomers without AGE. Polymerization on a commercial scale is done as either a solution or slurry process at 40—130°C in an aromatic, ahphatic, or ether solvent. Typical solvents are toluene, benzene, heptane, and diethyl ether. Trialkylaluniinum-water and triaLkylaluminum—water—acetylacetone catalysts are employed. A cationic, coordination mechanism is proposed for chain propagation. The product is isolated by steam coagulation. Polymerization is done as a continuous process in which the solvent, catalyst, and monomer are fed to a back-mixed reactor. Pinal product composition of ECH—EO is determined by careful control of the unreacted, or background, monomer in the reactor. In the manufacture of copolymers, the relative reactivity ratios must be considered. The reactivity ratio of EO to ECH has been estimated to be approximately 7 (35—37). 

AH of the polyether elastomers, like other vulcanizable elastomers, can be compounded with processing aids, fillers, plasticizers, stabilizers, and vulcanizing agents to make useful mbber products. A typical compounding recipe for epichlorohydrin elastomer is as follows ... 

Modifications of epichlorohydrin elastomers by radical-induced graft polymeri2ation have been reported. Incorporated monomers include styrene and acrylonitrile, styrene, maleic anhydride, vinyl acetate, methyl methacrylate, and vinyHdene chloride (81), acryHc acid (82), and vinyl chloride (81,83,84). When the vinyl chloride-modified epichlorohydrin polymers were used as additives to PVC, impact strength was improved (83,84). 

The development and optimisation is described of a new curing system to replace lead-based compounds used in epichlorohydrin elastomers currently used in automotive applications. The system is based on 2,4,6-trimercapto-1,3,5-triazine and dialkyldithiophosphate, which is shown to produce a scorch-safe curing system and which confers excellent physical and ageing properties on epichlorohydrin rubbers. Trials are conducted in formulations for multilayer fuel hoses. 9 refs. 

Structure of epichlorohydrin elastomers. The commercial ECH-based available elastomers have the following structure ... 

Blends of epichlorohydrin elastomers have not met commercial success. 

Epichlorohydrin elastomers may be chemically modified by nucleophilic substitution reactions at the side-chain chloromethyl group. Numerous substituted products have found applications as flame retardants, flocculating agents, selectively permeable membranes, photosensi ti ve materials, etc. 

Applications. Epichlorohydrin elastomers have good low-temperature flexibility, a broad range of temperature utilization, outstanding resistance to ozone, air and heat aging, high resistance to a variety of fuels, and good chemical resistance. Therefore, they have found applications particularly in the automotive industry and in many oil-field specialities. 

The mechanism of polymerization is the same one as already described for epichlorohydrin elastomers. 

Elastomers, vulcanizable (synthetic rubber) Epichlorohydrin elastomers Estane... 

These polymers, developed by Vandenberg, are the natural extension of the successful development of two other chlorinated polyethers , namely poly-3,3-bis-(chloromethyl)oxetane (polyBCMO, Penton of Hercules Co) and the previously mentioned epichlorohydrin elastomers. The presence of two bulky chloromethyl groups hampers cyclization and increases the stability of the cationic active centers. 

ECO. See Epichlorohydrin elastomer Ecocryl. See Acrylic resin Ecomaty. See Polyvinyl alcohol Econase BG Econase BGP. See Glucanase... 

Classification Epichlorohydrin elastomer Definition Vulcanized with sulfur or peroxides vulcanizates have good heat/weather/flame/oil resist, exc. low temp, props. 

Hydrex . See Sodium silicoaluminate Hydridocarbonyltris (triphenylphosphine) rhodium (I). See Tristriphenylphosphine rhodium carbonyl hydride Hydrin C Hydrin C-CG. See Epichlorohydrin/ethylene oxide copolymer Hydrin H. See Epichlorohydrin elastomer Hydrin T, Hydrin T-CG, Hydrin TX-1. See Epichlorohydrin/ethylene oxide/allyl glycidyl ether terpolymer Hydrine . See PEG-2 stearate Hydriodic acid... 

Ethylene/propylene/dicyclopentadiene terpolymer Ethylene-propylene-ethylidene norbornene elastomer, adhesives Epichlorohydrin elastomer Epichlorohydrin/ethylene oxide/allyl glycidyl ether terpolymer Epichlorohydrin/ethylene oxide copolymer Polyisoprene Polyurethane, thermoplastic... 

Polymers Resins I Butyl Rubber, Epichlorohydrin Elastomers, Ethylene Propylene Rubber, Hypalon (TM) Production, Neoprene Production, Nitrile Butadiene Rubber, Polybutadiene Rubber, Polysulfide Rubber, Styrene-Butadiene Rubber Latex 07/31/97... 

ECO Copolymer of ethylene oxide and epichlorohydrin (elastomer ASTM) see... 

Epichlorohydrin elastomers (CO, ECO) are flame-retardant because of the presence of chlorine. Their electrical properties aie modesf but they age well and resist many chemical environments. 

Chlorosulfonated polyethylenes Epichlorohydrin elastomers Ethylene/acrylic elastomers Ethylene-propylene copolymers Fluoroelastomers Isobutylene-paramethylstyrene elastomers... 

Cure conditions (temperature, time and catalyst S5retem) can be used to control particle development during cure if the resin/LR blend is miscible prior to cure. However, very few miscible systems have been developed. Figure 2 shows the fracture surface of a tough blend of vinyl ester with poly(epichlorohydrin) elastomer. This system is single phase before cure. Under the proper cure conditions a fine particulate phase develops as shown in Figure 3. 

When Hercules entered the specialty rubber business in 1968 with its two HERCIX)R epichlorohydrin elastomers (Table I), very little was known about their structure. As indicated previously, it should be possible to change the microstructure by altering the catalyst system and in this way optimize the balance of properties. 

HERCLOR H epichlorohydrin elastomer was found by this procedure to have a very uniform structure with more than 97% head-to-tail monomer placements. This structure was confirmed by examination of the carbon-13 NMR spectra of HERCLOR H elastomer and of the poly(propylene oxide) obtained by dechlorination with LAH. 

EPI is highly reactive with polyhydric phenols such as bisphenol A and forms glycidyls with many compounds containing active hydrogens. Epichlorohydrin (ECH) is used primarily in the manufacture of epoxy resins and synthetic glycerol. The main other uses include the production of epichlorohydrin elastomers, polyamide-epichlorohydrin resins, water treatment chemicals, and a variety of glycidyl derivatives. 

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