Plasticizers polychloroprene

Poly(methyl methacrylate) (PMMA) plastics Polychloroprene elastomer (Neoprene Carothers)... 

Physical Factors. Unsatuiated elastomers must be stretched for ozone cracking to occur. Elongations of 3—5% are generally sufficient. Crack growth studies (10—18) have shown that some minimum force, called the critical stress, rather than a minimum elongation is required for cracking to occur. Critical stress values are neady the same for most unsaturated mbbers. However, polychloroprene has a higher critical stress value than other diene mbbers, consistent with its better ozone resistance. It has been found that temperature, plasticization, and ozone concentration have httie effect on critical stress values. 

Since polychloroprene crystallizes under stress, fine particle size carbon black is not ordinarily needed or used to enhance tensile strength. More frequently, mineral fillers, for example clay, can be added to reduce cost. A light process oil, free of polycycHc aromatics, can be used to improve the flexibihty or hand of films. On the other hand, an ester plasticizer can be used to improve low temperature properties (161). 

Other polymers used in the PSA industry include synthetic polyisoprenes and polybutadienes, styrene-butadiene rubbers, butadiene-acrylonitrile rubbers, polychloroprenes, and some polyisobutylenes. With the exception of pure polyisobutylenes, these polymer backbones retain some unsaturation, which makes them susceptible to oxidation and UV degradation. The rubbers require compounding with tackifiers and, if desired, plasticizers or oils to make them tacky. To improve performance and to make them more processible, diene-based polymers are typically compounded with additional stabilizers, chemical crosslinkers, and solvents for coating. Emulsion polymerized styrene butadiene rubbers (SBRs) are a common basis for PSA formulation [121]. The tackified SBR PSAs show improved cohesive strength as the Mooney viscosity and percent bound styrene in the rubber increases. The peel performance typically is best with 24—40% bound styrene in the rubber. To increase adhesion to polar surfaces, carboxylated SBRs have been used for PSA formulation. Blends of SBR and natural rubber are commonly used to improve long-term stability of the adhesives. 

Chlorinated rubber is also used to promote the adhesion of solvent-borne CR adhesives to metals and plasticized PVC. Addition of a low molecular weight chlorinated rubber (containing about 65 wt% chlorine) improves the shear strength and creep resistance of polychloroprene adhesives [75] but a reduction in open time is also produced. A heat reactivation (process in which the surface of the adhesive film is raised to 90-100°C to destroy the crystallinity of the film and allowing diffusion to produce polymer chain interlocking more rapidly) restores tack to the polychloroprene adhesives. 

Polychloroprene (neoprene) Good Discolors. The addition of aromatic plasticizers renders the material more stable to irradiation. 

The costs, as for all plastics, fluctuate highly with the crude oil price. Most common TPE/PVCs are cheaper than SEES, TPVs and general-purpose cured rubbers such as EPDMs and polychloroprenes but are more expensive than TPOs and SES. 

In Table 8.4 we see that most butadiene is polymerized either by itself or with styrene or acrylonitrile. The most important synthetic elastomer is styrene-butadiene rubber (SBR). SBR, along with polybutadiene, has its biggest market in automobile tires. Specialty elastomers are polychloroprene and nitrile rubber, and an important plastic is acrylonitrile/butadiene/styrene (ABS) terpolymer. Butadiene is made into adiponitrile, which is converted into hexamethylenediamine (HMDA), on of the monomers for nylon. 

Berlin and coworkers (5,56) desired to obtain a material with an increased mechanical strength. They carried out a plasticization of bulk ami emulsion polystyrene molecular weight 80000 and 200000 respectively at 150-160° C, with polyisobutylene, butyl rubber, polychloroprene, polybutadiene, styrene rubber (SKS-30) and nitrile rubber (SKN 18 and SKN 40). The best results were obtained with the blends polystyrene-styrene rubber and polystyrene-nitrile rubber. An increase of rubber content above 20-25% was not useful, as the strength properties were lowered. An increase in the content of the polar comonomer, acrylonitrile, prevents the reaction with polystyrene and decreases the probability of macroradical combination. This feature lowers the strength, see Fig. 14. It was also observed that certain dyes acts as macroradical acceptors, due to the mobile atoms of hydrogen of halogens in the dye, AX ... 

Effect of Internal Mobility (Flexibility). It seems that the internal mobility or flexibility of the plasticizer molecule plays an important, if not the most important, role in determining plasticizer efficiency. This appears to be true irrespective of the polymer which is being plasticized, unless there are overriding physical factors involved, such as polymer crystallinity. In general, the lowering of T0 will be proportional to the temperature difference between (Tg)polymer and (Tg)plasticizer- This is illustrated in Table XIV. This table also shows that if the polymer itself is quite flexible, such as polychloroprene (Neoprene), the plasticizer efficiency is quite small, and may even result in negative AT values. 

Neoprene, or polychloroprene rubber (CR) was one of the very first synthetic rubbers produced. It was a material of choice for exterior applications such as profiles used in vehicles, building seals, and cables. Many more marketable products have benefited from this plastic. Except for SBR and IR, neoprene (CR) elastomers are perhaps the most rubberlike of all materials, particularly with regard to its dynamic response (Table 2.6). CRs are a family of elastomers with a property profile that approaches that of NRs (natural rubbers) but has better resistance to oils, ozone, oxidation, and flame. CRs age better and do not soften up on exposure to heat, although their high-temperature tensile strength may be lower than that of NRs. They are suitable for service at 250C (480F). 

Polymerization of dienes to form substitutes for rubber was the forerunner of the enormous present-day plastics industry. Polychloroprene (Neoprene, Duprene) was the first commercially successful rubber substitute in the United States. 

Elastomers include natural rubber (polyisoprene), synthetic polyisoprene, styrene-butadiene rubbers, butyl rubber (isobutylene-isoprene), polybutadiene, ethylene-propylene-diene (EPDM), neoprene (polychloroprene), acrylonitrile-butadiene rubbers, polysulfide rubbers, polyurethane rubbers, crosslinked polyethylene rubber and polynorbomene rubbers. Typically in elastomer mixing the elastomer is mixed with other additives such as carbon black, fillers, oils/plasticizers and accelerators/antioxidants. 

MAJOR USES Used in the manufacture of carbon tetrachloride, trichloroethylene, chlorinated hydrocarbons, polychloroprene, polyvinylchloride, hydrogen chloride, hypochlorous acid, ethylene dichloride, metallic chlorides, chlorobenzene, chloroacetic acid, chlorinated lime, chloroform Used in the manufacturing process of water purification, flame retardant compounds, paper products, textiles, petroleum products, medicines, antiseptics, insecticides, solvents, paints, plastics, disinfectants, synthetic rubber. 

Since the 1940s continuous polymerization processes have been developed for a variety of products and with different reactor configurations. Latex products manufactured in continuous systems include polychloroprene and other synthetic elastomers, ethylene-vinyl acetate copolymers, components for engineering plastics and coating formulations. 

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