SynopsisCopolymers of vinyl acetate and vinyl alcohol were studied by differential thermal analysis. The melting points of the copolymers are not a simple function of the composition, but depend on the method of preparation of the copolymers. Partial saponification of poly(viny1 acetate) with sodium hydroxide leads to high melting, ordered copolymers, while reacetylation of poly(viny1 alcohol) leads to low melting, random copolymers. Catalytic alcoholysis of PVAc yields copolymers intermediate in melting point and order. The results are treated by assuming that equal melting points indicate similar sequence length distributions of crystallizable units.
Differential thermal analysis was used to study the effect of a diluent, glycerol, and copolymer units, acetate groups, on the melting point of poly(vinyl alcohol) (PVA). The melting point of PVA was found to be 228°C. and the heat of fusion by the diluent and copolymer methods was 1.64 and 0.56 kcal./mole, respectively, based on vinyl alcohol units. Flory's theory was used as a basis for analysis. The results are compared with literature values for the heat and entropy of fusion of polyethylene, and the differences briefly discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.