STRUCTURAL ASPECTS OF SUSPENSION POLY(VINYL CHLORIDE) - RELATIONSHIP BETWEEN MOLECULAR-STRUCTURE AND STRUCTURAL ORDER

The structural order of poly(vinyl chloride) (PVC) has been investigat ed using modified PVC samples. A lack of order in the polymer chain di rection is evidenced by comparison between the experimental and the th eoretical crystalline wide-angle scattering pattern of PVC. Variation of the molecular structure by specific substitution of chlorine proves to be a very useful tool to acquire some additional information with respect to the structural order of PVC. In this way, it is demonstrate d that the isotactic sequences disturb the formation of structural ord er but do not totally exclude it. The structural order of PVC is prefe rentially ordered perpendicular to the polymer backbone and consists o f short primarily syndiotactic sequences, belonging to different polym er chains or chain segments. The wide variety of size and perfection o f these ordered entities as well as the lack of order in the polymer c hain direction signifies that the term ''crystallinity'' in the case o f PVC has to be used with some prudence.