Polychloroprene plasticisers

The hydrohalide is usually prepared by passing hydrogen chloride into a solution of masticated high-grade raw rubber in benzene at 10°C for about six hours. Excess acid is then neutralised and plasticisers and stabilisers are added. The benzene is removed by steam distillation and the product washed and dried. Alternatively the solution is cast on to a polychloroprene rubber belt, leaving a tough film after evaporation of the solvent. 

If polypropylene is too hard for the purpose envisaged, then the user should consider, progressively, polyethylene, ethylene-vinyl acetate and plasticised PVC. If more rubberiness is required, then a vulcanising rubber such as natural rubber or SBR or a thermoplastic polyolefin elastomer may be considered. If the material requires to be rubbery and oil and/or heat resistant, vulcanising rubbers such as the polychloroprenes, nitrile rubbers, acrylic rubbers or hydrin rubbers or a thermoplastic elastomer such as a thermoplastic polyester elastomer, thermoplastic polyurethane elastomer or thermoplastic polyamide elastomer may be considered. Where it is important that the elastomer remain rubbery at very low temperatures, then NR, SBR, BR or TPO rubbers may be considered where oil resistance is not a consideration. If, however, oil resistance is important, a polypropylene oxide or hydrin rubber may be preferred. Where a wide temperature service range is paramount, a silicone rubber may be indicated. The selection of rubbery materials has been dealt with by the author elsewhere. ... 

The use of plasticisers, with other than PVC applications, is extensive. Many polar rubber sealants or caulking materials are plasticised in order to make them more pliable, e.g., polysulfides, polychloroprene (Neoprene ), nitrile rubber. Esters, similar to those employed with PVC, are used to render cellulose diacetate ("Acetate") overhead projection sheets more flexible. 

Consideration is given to the influence of combinations of zinc hydroxystannate (ZHS) with hydrated fillers, on the fire properties of plasticised PVC and polychloroprene. It is shown that magnesium and aluminium hydroxides specially coated with ZHS, confer significantly increased combustion resistance and lower levels of smoke evolution to these polymers. This permits large reductions to additive loading relative to unmodified filler, without sacrificing flame retardant or smoke suppressant performance. 10 refs. 

The 1930s marked the start of the poly era. It had been known since the nineteenth century that a number of organic compounds could yield tarry insoluble materials under certain conditions, but it was not until the 1930s that the chemical nature of these compounds was understood. It was Hermann Staudinger (1881-1965) who established that these materials, as well as natural rubber, consisted of very long-chain molecules. Commercial production of polyvinyl chloride (PVC) commenced in the 1930s with the development of suitable plasticisers, and other thermosoftening addition polymers which were first produced at this time include polystyrene, polyethylene (Polythene), polymethyl methacrylate (Perspex) and polychloroprene (Neoprene), which is similar to natural rubber except that the methyl side chain has been replaced by chlorine. 

The swelling of polychloroprene vulcanisates by oils, chemicals and solvents may be reduced considerably by increasing the state of cure, by increasing the amount of loading, or by using a plasticiser which is miscible with the immersion fluid and consequently is extracted by it. Highly... 

Polychloroprene vulcanisates have excellent resistance to flex cracking. However, for products that will be flexed severely in service, compounds should be soft, with low modulus and high elongation wherever possible. This should be done using well dispersed loadings of soft carbon blacks (MT or SRF) rather than mineral fillers, although up to 20 phr precipitated silica will be beneficial. A good antioxidant/antiozonant protection system such as 2 phr octylated diphenylamine and 1 phr mixed diaryl /7-phenylene diamine is required. The plasticiser should be kept to a minimum and preferably be an aromatic oil esters should be avoided. 

Compounds of either type of colour must contain a non-discolouring type antioxidant (particularly Antioxidant 2246), which will inhibit discolouration in sunlight, and must avoid the use of aromatic oils in favour of organic ester plasticisers. These compounds are normally made from mercaptan modified types of polychloroprene which do not darken during cure, provided the curing system is free from sulphur or lead oxide. 

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