Crystalline Grafted

This chapter has so far dealt with the major fields of use of vinyl chloride polymers, namely plasticised PVC homopolymer, unplasticised PVC, including impact-modified grades, and copolymers particular based on vinyl acetate. There are, however, five particular special forms of vinyl chloride polymer which merit separate consideration, namely crystalline PVC, after-chlorinated PVC (often known as CPVC) and certain graft copolymers and two vinyl-chloride-based copolymers. 

Grafting of the unacetylated samples gives higher values in the case of wood pulp than in cotton linters. This is explained by the crystallinity of both pulps, which is 80% and 56.8% for cotton linters and wood pulp, respectively. 

Compatibility and various other properties such as morphology, crystalline behavior, structure, mechanical properties of natural rubber-polyethylene blends were investigated by Qin et al. [39]. Polyethylene-b-polyiso-prene acts as a successful compatibilizer here. Mechanical properties of the blends were improved upon the addition of the block copolymer (Table 12). The copolymer locates at the interface, and, thus, reduces the interfacial tension that is reflected in the mechanical properties. As the amount of graft copolymer increases, tensile strength and elongation at break increase and reach a leveling off. 

Cellulosic fibers contain a partly crystalline cellulose phase as the main constituent. The grafting reactions can usually occur only with the amorphous or disordered cellulose. Only highly swollen cellulose with an expanded lattice may react throughout the ordered regions. 

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