Copolymerisation vinyl acetate

Copolymerisation of vinyl acetate and vinyl chloride yields resins of desirable properties they are strong and adhesive, thermoplastic, and are suitable for the manufacture of synthetic fibre (Vinyon). 

Organic peroxides are used in the polymer industry as thermal sources of free radicals. They are used primarily to initiate the polymerisation and copolymerisation of vinyl and diene monomers, eg, ethylene, vinyl chloride, styrene, acryUc acid and esters, methacrylic acid and esters, vinyl acetate, acrylonitrile, and butadiene (see Initiators). They ate also used to cute or cross-link resins, eg, unsaturated polyester—styrene blends, thermoplastics such as polyethylene, elastomers such as ethylene—propylene copolymers and terpolymers and ethylene—vinyl acetate copolymer, and mbbets such as siUcone mbbet and styrene-butadiene mbbet. 

J. Delgado, Miniemulsion Copolymerisation of Vinyl Acetate and n-ButylAcrylate, Ph.D. dissertation, 1986. 

Ethylene has also been copolymerised with a number of non-olefinic monomers and of the copolymers produced those with vinyl acetate have so far proved the most significant commercially . The presence of vinyl acetate residues in the chain reduces the polymer regularity and hence by the vinyl acetate content the amount of crystallinity may be controlled. Copolymers based on 45% vinyl acetate are rubbery and may be vulcanised with peroxides. They are commercially available (Levapren). Copolymers with about 30% vinyl acetate residues (Elvax-Du Pont) are flexible resins soluble in toluene and benezene at room temperature and with a tensile strength of about lOOOlbf/in (6.9 MPa) and a density of about 0.95 g/cm. Their main uses are as wax additives and as adhesive ingredients. 

As already mentioned in previous sections ethylene may also be copolymerised with several non-hydrocarbon polymers. Some of these copolymers are elastomeric and they also have a measure of oil resistance. Two monomers used commercially are vinyl acetate and, the structurally very similar, methyl acrylate ... 

If ethylene is copolymerised with vinyl acetate, and the vinyl acetate component hydrolysed to vinyl alcohol, a material is produced which is in effect a copolymer of ethylene and vinyl alcohol. 

Whilst vinyl acetate is reluctant to copolymerise it is in fact usually used today in copolymers. Two of particular interest to the plastics industry are ethylene-vinyl acetate (Chapter 11) and vinyl chloride-vinyl acetate copolymers (Chapter 12). In surface coatings internal plasticisation to bring the Tg to below ambient temperatures and thus facilitate film forming is achieved by the use of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and dialkyl maleates and fumarates. 

The greatest use of latex paints for indoor applications is based upon vinyl acetate, which constitutes 85% of the total polymer usage, the remainder being acrylates (e.g., n-butyl acrylate). For outdoors or bathroom usage, acrylates are the major components. For various applications, e.g., wood paints, styrene copolymerised with acrylates are used. Flowever, yellowing of the styrene units occurs. 

The copolymerisation of ethylene with vinyl acetate (VA) is another method by which the crystallinity of polyethylene can be reduced and a rubbery polymer obtained. The final properties of the copolymer depend on the VA content at a VA level of 50% the copolymer is entirely amorphous, and elastomeric grades generally contain 40-60% VA by weight. The oil resistance of the copolymer is also dependent on the VA content in general, however, this lies between that of SBR and polychloroprene. It is swollen by most organic solvents and not resistant to animal and vegetable oils, but has some resistance to weak acids and alkalis at ambient temperature. 

Ethylene can be copolymerised with several monomers like propylene, 1-butene, vinyl acetate, ethyl acrylate, etc. 

Other trialkyltin-containing monomers such as 3-tributyltinstyrene (84), tributyltin methacrylate (85) and 4-[bis(trimethylstannyl)methyl]styrene (86) were also reported to homo- and copolymerise with styrene under radical conditions175-177. In addition, 3-tributyltinstyrene (84) was copolymerised under radical conditions with ethyl acrylate, methyl methacrylate, vinyl acetate and acrylonitrile175. A functional methacrylate-based polymer was prepared by the copolymerization of the triorganotin methacrylate monomer 87 with styrene and divinylbenzene178,179. 

N. J. Earhart, The Grafting Reactions ofPoby(vinyl alcohol) During the Emulsion Copolymerisation of Poly(vinyl acetate-co-butyl acrylate), Ph.D. dissertation. 

This insight is strikingly illustrated by the observation of alternating copolymerisation. The radical-initiated polymerisation of a 1 1 mixture of dimethyl fumarate 7.3 and vinyl acetate 7.5 takes place largely to give a polymer in which the fragments derived from the two monomers alternate along the chain. In this case... 

Vinyl Halides. In copolymerising vinyl chloride with NMAM, the same precautions to ensure even copolymerisation should be taken as with vinyl acetate. 

Ethylene may be copolymerised with vinyl acetate to make ethyl-vinyl acetate, offering high seal integrity and clarity for frozen food applications where a high degree of toughness is required. Ethylene copolymers with other olefins such as propylene, 1-hexene and 1-octene allow a range of properties to be achieved. Linear low density polyethylene (LLDPE) has a... 

The photoinduced polymerisation of vinyl acetate by laser irradiation is associated with the decomposition of oligoperoxides present in the monomer while highly photosensitive copolymers have been prepared through the copolymerisation of methyl methacrylate with... 

Poly(vinyl acetate) (PVA) has a glass-rubber transition temperature in the region of room temperature and is therefore neither a useful rubber nor a useful plastic. It can, however, be plasticised like PVC to give a rubbery material with limited practical utility. Copolymerisation of vinyl acetate with ethylene in relatively low ( 3 mol %) concentration (EVA) is a useful way of introducing polar properties into hydrocarbon poly-... 

It is possible to raise affinity of a surface to other materials by introduction of polar units to a macromolecules by copolymerisation of ethylene with vinyl acetate [73,74], aciylonitrile [75], or methyl methacrylate [76],... 

Monomethyl maleic ester of epoxidised soybean oil (MESO) is prepared by the reaction of epoxidised oil with monomethyl maleate with AMC-2 catalyst. (AMC-2 is a mixture of 50% trivalent organic chromium complexes and 50% phthalate esters). This MESO is photo-polymerised with ultraviolet light and free radically homopolymerised and copolymerised with styrene, vinyl acetate and methylmethacrylate. MESO may also be reacted with maleic anhydride at the newly formed hydroxyl groups to give maleinised MESO. Thus a large number of resinous systems may be made from the epoxidised oil. 

It is often desirable to perform some kind of chemical modification to polymers once they have formed. Acetylation of cellulose, for example, represents the chemical modification of a naturally occurring polymer (see chapter 3) to give the technologically useful cellulose diacetate and triacetate polymers. Poly(vinyl alcohol) (PVA) is a well-known example of a polymer that can only be formed by chemical modification since vinyl alcohol monomer does not exist (except as its keto form, acetaldehyde). Instead, PVA is formed by hydrolysis of poly(vinyl acetate) (PVAc). Partly hydrolysed PVAc is, of course, simply a copolymer of VA and VAc. As another example, ethylene/vinyl chloride copolymers can be prepared by reductive elimination of chlorine from poly (vinyl chloride) (PVC). The driving force here is that, although ethylene and vinyl chloride can be copolymerised directly, the normal routes to these polymers give insufficient control over composition and sequence distribution. 

A broad range of monomers with relatively low water solubility have been polymerised by conventional emulsion polymerisation. Acrylics, methacrylics, styrene and vinyl acetate are the most common monomers used in preparing latexes for paints, textile binders, and adhesives. Acrylic, polyester, epoxy and urethane dispersions are used in industrial coatings, where higher strength is required. Butadiene is often copolymerised with styrene in producing synthetic rubber for tyre manufacture. 

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