Polyepichlorohydrin elastomer

As with most halogen-containing elastomers, polyepichlorohydrin polymers can corrode metal surfaces, but only noticeable under extreme conditions, such as being left in the mold at 200°C for 2 h. The Zisnet F-PT cure system is much better than the ETU/red lead curative package as given in Table 7.8, for Iowct mold fouling and better... 

In 1957, it was discovered that organometaUic catalysts gave high mol wt polymers from epoxides (3). The commercially important, largely amorphous polyether elastomers developed as a result of this early work are polyepichlorohydrin (ECH) (4,5), ECH—ethylene oxide (EO) copolymer (6), ECH—aUyl glycidyl ether (AGE) copolymer (7,8), ECH—EO—AGE terpolymer (8), ECH—propylene oxide (PO)—AGE terpolymer (8,9), and PO—AGE copolymer (10,11). The American Society for Testing and Materials (ASTM) has designated these polymers as follows ... 

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. 

Although these curative systems may also be used with the polyepichlorohydrin elastomers containing AGE, the polymers were developed to be cured with conventional mbber curatives, sulfur, and peroxides. These polymers containing the pendent aHyl group are readily cured with a typical sulfur cure system such as zinc oxide, and sulfur along with the activators, tetramethylthiuram mono sulfide [97-74-5] (TMTM) and... 

Vulcanisation can be effected by diamines, polyamines and lead compounds such as lead oxides and basic lead phosphite. The homopolymer vulcanisate is similar to butyl rubber in such characteristics as low air permeability, low resilience, excellent ozone resistance, good heat resistance and good weathering resistance. In addition the polyepichlorohydrins have good flame resistance. The copolymers have more resilience and lower brittle points but air impermeability and oil resistance are not so good. The inclusion of allyl glycidyl ether in the polymerisation recipe produces a sulphur-curable elastomer primarily of interest because of its better resistance to sour gas than conventional epichlorhydrin rubbers. 

Polyepichlorohydrin (PECH) is well known as a reactive elastomer. Displacement at the carbon-chlorine bond of PECH has been accomplished with a wide variety of nucleophilic reagents, for the purposes of polymer modification, grafting and crosslinking (1, 2). On the other hand, the PECH structure (1) is hardly optimal from the point of view of its reactivity as a substrate for nucleophilic... 

Table II summarized the ratios of major absorbances of HTE liquid polymers. Only the ratio of hydroxyl absorbance is sensitive to the molecular weight, whereas the other two ratios are independent of it. For comparison, the ratios of absorbances of high molecular weight elastomers (Hydrin 100) made by a coordination catalyst (R3AI/H2O) are also shown in Table II. No hydroxyl absorbance is detected. The two ratios of CH/CO and CC1/C0 absorbances of HTE liquid polymers match well with those of elastomers and are characteristic feature of polyepichlorohydrin.

The complicated pattern for the methylene carbon of the polymers indicates the presence of an irregular structure of head to head and tail to tail linkages. On the other hand, the uniformly head to tail structure of polyepichlorohydrin elastomers made by the coordination catalyst shows a doublet for the methylene carbon at 70.2 and 70.0 ppm (21). No peak corresponding to the terminal methine or chloromethyl carbons is detected in elastomers. 

Polyepichlorohydrin and copolymers and terpolymers of epichlorohydrin with ethylene oxide and allyl glycidyl ether are useful elastomers [Body and Kyllinstad, 1986]. 

Sequence distribution studies on several types of rubber by 13C-NMR technique have been reported. Some of the more recent reports include silicone rubbers [28-30], SBR [31], acrylonitrile-butadiene rubber (NBR) [32,33], polyurethane [34,35], polyepichlorohydrin [36], ethylene-norbonene [37] and ethylene-propylene rubber [4, 16, 25, 38-44]. The NMR studies on EPDM have been carried out extensively, because it is one of the important parameters, which control the physical properties of the elastomer. For example, ethylene sequence can influence the crystallisation kinetic and melting behaviour of the rubber [38]. 

FIGURE 9.17 Dependence of productivity and separation factor /3p C6H5CH3/H2O of membranes based on various rubbery polymers on the glass transition temperature of the polymer (pervaporation separation of saturated toluene/water mixture, T = 308 K) (1) polydimethyl siloxane (2) polybutadiene (3) polyoctylmethyl siloxane (4) nitrile butadiene rubber with 18% mol of nitrile groups (5) the same, 28% mol of nitrile groups (6) the same, 38% mol of nitrile groups (7) ethylene/propylene copolymer (8) polyepichlorohydrin (9) polychloroprene (10) pol3furethane (11) polyacrylate rubber (12) fluorocarbon elastomer. (From analysis of data presented in Semenova, S.I., J. Membr. Sci., 231, 189, 2004. With permission.)... 

A number of chlorinated poly(ethers) have practical uses. A common compound from this group is polyepichlorohydrin, [-CH(CH2CI)CH20-]n. Polyepichlorohydrin has practical applications as an elastomer and is used in copolymers with propylene oxide, ethylene oxide, allyl glycidyl ether (1-allyloxy-2,3-epoxypropane), etc. Another example is poly oxy[2,2 -bis(chloromethyl)-1,3-propandiyl] or poly[oxy-1,3-(2,2 -dichloromethyl)propylene], CAS 25323-58-4, which can be used as inert lining material for chemical plant equipment, as adhesive, coating material, etc. This macromolecule can be prepared starting with pentaerythritol in the sequence of reactions shown below ... 

Uses Modifier for elastomers, adhesives, fibers reactive diluent for epoxies reactive intermediate for coatings sizing/finishing agent for fiberglass silane intermediate in elec, coatings stabilizer of chlorinated compds., vinyl resins, rubber defoamer comonomer for polyepichlorohydrin rubber, unsat. polyester resins, and crosslinked PU elastomers curing system additive in bisphenol A-epichlorohydrin epoxies for food-contact articles... 

Acrylate elastomers Polyvinyl butyral Polyepichlorohydrin Cellulose acetate butyrate Polystyrene Polyvinyl alcohol Polychloroprene Polyethylene... 

Most compounders use a combination of physical and chemical antiozonants and achieve excellent protection in this way. For more severe ozone-resistance problems, there are, of course, a number of specialty elastomers that are saturated and therefore completely ozone-resistant ethylene/propylene rubber, chlorinated and chlorosulfonated polyethylene, ethylene/vinyl acetate, ethylene/acrylic esters, butyl rubber, SEES, plasticized PVC, butyl acrylate copolymers, polyepichlorohydrin and copolymers, polyetherester block copolymer, polyurethane, and silicone. 

Hydrin Polyepichlorohydrin elastomer, can be blended with any elastomer, sulfur or peroxide curable Zeon Chemicals, Inc. 

Naderil, G., Razavi-Nouril, M.,Taghizadeh, E., Lafleur, P.G. and Dubois, C. (2011), Preparation of thermoplastic elastomer nanocomposites based on polyamide-6/ polyepichlorohydrin-co-ethylene oxide , Polymer Engineering Science, Vol. 51, No. 2, pp. 278-284. 

Synthetic rubbers are produced as commodities. Polybutadiene, polybutylene, polychloroprene and polyepichlorohydrin are examples of elastomeric homopolymers. Copolymeric rubbers comprise poly-(butadiene-co-styrene), poly(butadiene-co-acryloni-trile), poly(ethylene-co-propylene-co-diene), and poly-(epichlorohydrin-co-ethylene oxide). The unsaturated group in the comonomer provides reactive sites for the crosslinking reactions. Copolymers combine resilience with resistance to chemical attack, or resilience in a larger temperature range, and thermoplastic-like properties. There are several studies in the literature describing the preparation of blends and composites of elastomers and conductive polymers. A description of some significant examples is given in this section. 

Further confirmation of the uniformly head-to-tail structure of HERCLOR H elastomer was obtained from its carbon-13 NMR spectrum. Since no literature spectra of polyepichlorohydrin were available for comparison, the carbon-13 NMR spectra of the poly-(propylene oxideD resulting from dechlorination with LAH were also examined. Published spectra of poly(propylene oxideD with detailed peak assignments are available. 

Some specialty elastomers are used in mature markets, such as nitrile rubber and polychloroprene. Others such as polyepichlorohydrin rubber have not found their... 

TABLE 2 Properties of Polyepichlorohydrin Elastomers (From Refs. 107, 113, 114.)... 

The tensile properties of poly(propylene oxide) and polyepichlorohydrin elastomers were presented in Tables 5.1 and 5.2, respectively. The tensile properties of high-molecular-weight poly(ethylene oxide) are given in Table 6. These properties can be altered markedly when the relative humidity is greater than 70 to 80 percent. For example, at 90 percent relative humidity, the tensile modulus decreases from 50,000 psi (345 MPa) to 1000-5000 psi (6.9-34.5 MPa) (268). Ultradrawn filaments of different molecular weight poly(ethylene oxide)s have been investigated as a function of uniaxial draw ratio (269, 270). 

Elastomers containing polyepichlorohydrin, also known as ECO, CO, or GECO according to ASTM, offer an excellent balance of properties, combining certain desired dynamic properties of namral mbber (NR), with much of the fuel, oil, and chemical resistance of other specialty elastomers such as nitrile (NBR), polyacrylate (ACM), and neoprene (CR) mbbers. The combination of the basic properties of oil, fuel, heat, low-temperature flexibility, and ozone resistance imparted by the saturated main chain and the chlorine groups, coupled with low permeability, makes polyepichlorohydrin a very useful elastomer for automotive applications. Specific applications include fuel hoses, emission tubing, air ducts, seals, and diaphragms. 

There are three classes of polyepichlorohydrins, the homopolymer CO and GCO, the copolymer ECO, and the terpolymer GECO, as shown in Table 7.1. The stmctuie of these is given in Figure 7.1. Each family of these elastomers has its own characteristics as illustrated in Table 7.2. 

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