Allyl stearate copolymers and terpolymers: Thermal, mechanical, and solution properties of polymers incorporating vinyl chloride

Abstract

AbstractPoly(allyl stearate) and selected copolymers and terpolymers modified by allyl stearate were investigated in this work. The systems selected and studied over a wide range of composition, included copolymers with vinyl stearate and with vinyl chloride, and terpolymers containing vinyl chloride and allyl stearate, modified further by vinyl stearate or vinyl acetate. Copolymers of allyl stearate and vinyl stearate were studied incrementally across the range of composition. In the ester copolymers the effect of degradative chain transfer on crystallization and solution properties was studied. A relation was obtained between intrinsic viscosities and number‐average molecular weights; a shift in molecular weight distribution with increase in allyl component was demonstrated. The crystallinity contributed by the side chains was shown to be characterized by isomorphic replacement regardless of molecular weight. Mechanical properties of internally plasticized copolymers of allyl stearate and vinyl chloride, in a limited composition range, were compared with corresponding data for copolymers of vinyl stearate and vinyl chloride. While molecular weight reduction of the allylic copolymers exceeded that for the vinyl ester system, the effect, in the useful plasticization composition range, was not enough to grossly affect ultimate properties. The glass transitions of the hypothetical amorphous homopolymers of both fatty esters were estimated to be the same. Because this Tg was low (ca. −110°C), only relatively small mole fractions of allyl stearate were needed for effective plasticization. Isochronal temperature–composition diagrams also showed both systems to be essentially identical, but marked differences were found for diluent mixtures incorporating di‐2‐ethylhexyl phthalate (DOP). An empirical equation, previously derived, adequately predicted the decline in degree of polymerization with increase in allyl stearate between the limits of the respective homopolymers for all copolymers studied. Terpolymers followed the trends of the copolymers and offered no special property advantage.