Polyethylene-graft-polyvinyl

When the active halogen is incorporated along the backbone of a (co)polymer, graft copolymers are formed. Many commercial polymers including modified polybutene, polyisobutylene, polyethylene, and polyvinyl chloride have been used as macroinitiators for the preparation of graft copolymers by the grafting from procedure [16 166]. 

Differential scanning calorimetry and Fourier transform infrared spectroscopy techniques were used to study the structure of water molecules in polyvinyl alcohol and polyethylene grafted acrylate hydrophilic polymers. Varying amounts of water were added to test samples and the samples conditioned to the sorption equilibrium state in sealed containers for 24 hours prior to evaluation. It was concluded that below a threshold water content, depending on the polymers physical and chemical stmcture, water molecules absorbed in hydrophilic polymer cannot form ice crystals in the polymer matrix. Above this threshold content, the water crystallises but below zero. It was also demonstrated that the absorbed water in hydrophilic polymers develops differing hydrogen bonds in the first and second hydration layers. It was concluded that the potential influence of these intermolecular interactions should therefore be taken into account whenever a polymer is used with a solvent. 25 refs. 

Experimental evidence is available to show that at room temperature diperoxides are formed in polyethylene, whereas polypropylene and polyvinyl chloride generate hydroperoxides. The temperature at which the peroxides decompose and initiate grafting depends on the type of polymer used. 

Studies in the grafting of mixed monomers to cellulose have also been reported by Sakurada (113). Binary mixtures studied included butadiene with styrene or with acrylonitrile, and styrene with acrylonitrile. Remarkable increases in rate in the case of mixed monomer similar to those found by RAPSON were found in many cases. For example, about 10% of butadiene increased the grafting yield about ten fold. Similar results were found with the addition of acrylonitrile to butadiene and to styrene. Ternary mixtures of monomers were also investigated by both Rapson (109) and Sakurada (113). The large increases in rate with certain mixtures were interpreted by Sakurada as due to a particular balance of gd effects akin in many ways to popcorn polymerization. The effects were found also with polyvinyl alcohol but not with polyethylene where gel effects would perhaps be less prominent. 

The compatibilizing effect of poly(ethylene-g-vinyl chloride), the characteristic constituent of these VC/PE graft copolymers, may be shown by electron photomicrographs of films consisting of a PVC-PE/50-50 mixture on the one hand, and of a VC/PE (50-50) graft copolymer containing about 50 of poly(ethylene-g-vinyl chloride), 25 of polyethylene and 25 of polyvinyl chloride on the other hand (see Figure 8). The films were obtained from a solution in o-dichlorobenzene. In the first case, the polyvinyl chloride and polyethylene phases are clearly separated in the second case, they interpenetrate closely. 

The curves of the raw graft copolymer and of the poly(ethylene-g-vinyl chloride) are rather close to that of the low-density polyethylene. The outstanding fact is the absence of the PVC transition peak (between 60° and 100°C) in the mechanical loss curves of these two products. This means that they contain no rigid PVC phase in spite of the presence of about 25 weight % of ungrafted polyvinyl chloride in the raw graft copolymer. This PVC seems thus to be strongly compatibilized with the other constituents by the poly(ethylene-g-vinyl chloride). 

Superabsorbent polymers are now commonly made from the polymerization of acrylic acid blended with sodium hydroxide in the presence of an initiator to form a polyacrylic acid, sodium salt (sometimes referred to as cross-linked sodium polyacrylate). Some of the polymers include polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxy-methyl-cellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile to name a few. The latter is one of the oldest SAP forms created. 

Alkyd and polyester resins, epoxy compounds, phenol-formaldehyde resin, urea and/or melamine-aldehyde resin, cyclic urea resin, carbamide acid ester formaldehyde resin, ketone formaldehyde resin, polyurethane, polyvinylester, polyvinyl acetate, polyvinyl chloride and polymer mixtures, polyethylene, polystryrene, styrene mixtures and graft copolymers, polyamide, polycarbonate, polyvinyl ether, polyacrylic and methacrylic acid esters, polyvinyl flouride, polyvinylidene chloride copolymers, UV and/or electron irradiated lacquers. 

Kollicoat IR is a unique polymer for pharmaceutical applications prepared by a graft polymerization process of polyethylene glycol (25%) with polyvinyl alcohol (75%). Kollicoat IR dissolves quickly in water and aqueous solutions of acid and alkali and reduces the surface tension of aqueous solutions to allow the solutions to have high spray rates. The polymer film is very flexible, not tacky, and easily colored. The polymer can be used as instant release coating, pore former, binder, protective colloid, etc. 

Another application in macromolecular chemistry is radiation-induced graft polymerization, by which favourable properties of two polymers can be combined. In this process, copolymers of A and B are produced by irradiation of the polymer A in the presence of the monomer B. Examples are graft polymers of polyethylene and acrylic acid or of polyvinyl chloride and styrene. The properties of textiles (cellulose, wool, natural silk, polyamides, polyesters) can also be modified by graft polymerization, for example for the production of weatherproof products. 

Other polymers which have been the subject of thermal degradation studies include ethylene-vinyl acetate [29, 66, 67], ethylene-vinyl alcohol [68], poly(aryl-ether ketone) [69], poly-2-vinyl-naphthalene-co-methyl maleate [34], polyphenylenes based on diethyl-benzophenone [70], polyglycollide [71-73], poly(a-methylstyrene tricarbonyl chromium [74], polytetrahydrofuran [75], polylactide [76-78], poly(vinyl) cyclohexane [79], styrene-vinyl cyclohexane [80], isopropenylacetate-maleic dianhydride [80], polyethylene glycol containing a 1,3-disubstituted phenolic group [81], poly-2-vinyl naphthalene-co-methacrylate [34], collagen biopolymers [82], chitin graft poly (2-methyl-oxazoline - polyvinyl chloride blends [83], cellulose [32, 83-88] and side-chain cholestric elastomers [89, 90]. 

Polymeric materials that have been used in the cardiovascular system include polytetrafluorethy-lene, polyethylene terephthalate, polyurethane, polyvinyl chloride, etc. Textiles bas on polytetra-fluorethylene and polyethylene terephthalate are us extensively as fabrics for repair of vasculature and larger-vessel replacement (greater than 6 mm in diameter). Stent-grafts are hybrid stent grafts placed by catheter to treat aortic aneurysms nonsurgically and are fabricated of the same metallic alloys used in stents and textiles similar to those used in vascular grafts. Table 14.1 lists many of the biomaterials currently used in the cardiovascular system. 

Polyvinyl caprolactam- polyvinyl acetate-polyethylene glycol graft copolymer (SOLUPLUS ) Polyvinyllactam polymers Nonionic 70°C 118,000g/mol Water soluble High 19.4 250 °C Hot melt extrusion... 

Polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus ) N/A > 5(XX) mg/kg (BASF test)... 

The chemical modification of homopolymers such as polyvinylchloride, polyethylene, poly(chloroalkylene sulfides), polysulfones,poly-chloromethylstyrene, polyisobutylene, polysodium acrylate, polyvinyl alcohol, polyvinyl chloroformate, sulfonated polystyrene block and graft copolymers such as poly(styrene-block-ethylene-co-butylene-block-styrene), poly(1,4-polybutadiene-block ethylene oxide), star chlorine-telechelic polyisobutylene, poly(lsobutylene-co-2,3-dimethy1-1,3-butadiene), poly(styrene-co-N-butylmethacrylate) cellulose, dex-tran and inulin, is described. 

Polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer Soluplus 70 -... 

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