Studies of the steric structures of poly(vinyl alcohol), as deduced from studies of the structures of its esters, particularly poly(vinyl formate) are described. Two types of tactic poly(vinyl formate) crystallize with different structures, corresponding to their different molecular structures. Therefore, the type of molecular stereoregularity in poly(vinyl formate) samples can be deduced from an examination of the crystals produced by a given crystallization treatment. From the results of the study of the poly(vinyl formate) crystals, some conclusions can be drawn concerning the steric structure of poly(vinyl alcohol). Crystallizabilities of other tactic poly(vinyl esters) have also been investigated.

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For studying the branching of polyvinyl acetate(PVAc)and polyvinyl alcohol(PVA),the polymerization of vinyl trimethylacetate in the presence of PVAc was examined.The differences between PVAc and polyvinyl trimethylacetate (PVTMAc) are as follows:1 PVTMAc is thoroughly insoluble in 25 aqueous methanol.2.The rate of alkali-catalized saponification of PVTMAc is remarkably slower than that of PVAc.3.The infra-red absorption band at 12.49 tt for PVAc and the band at 13.05 it for PVTMAc are the key bands.From these bands, the chemical composition of graft polymer can be determined. From these results, the graft copolymer of PVTMAc into PVAc was separated and saponified in order to examine the branching of PVAc and PVA.Consequently,it has been shown that methyl group of the acetyl radical in PVAc is the principal site of branching and tertiary hydrogen atom also makes a small contribution.

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