Vinyl Acetate System Research Articles

Viscosity and Normal Stresses in Poly(vinyl acetate) Systems

Viscosity and Normal Stresses in Poly(vinyl acetate) Systems

Dynamic mechanical properties of titanium dioxide‐filled poly(vinyl acetate) at 0–40°C.

AbstractThe dynamic mechanical properties of titanium dioxide‐filled poly(vinyl acetate) have been studied at filler concentrations of 0, 10, 20, 30, and 40 wt.‐% TiO2 by using a torsional pendulum. The damping factor was found to increase with higher temperatures. At 40°C., the damping factors for the different TiO2 concentrations were estimated to be the same. Damping factors above 40°C. were difficult to obtain due to the rubbery nature of the TiO2–poly(vinyl acetate) systems. From 24 to 35°C., 10 wt.‐% TiO2‐poly(vinyl acetate) was closer in damping factor increase to unfilled poly(vinyl acetate) than to the higher TiO2‐content polymers. At all temperatures, damping factors decreased with higher TiO2 concentration. As the temperature decreased to 0°C., damping factors for the filled systems approached a common value. Potential energy of filled systems as indicated by shear modulus values is increased by higher TiO2 concentrations and lower temperature. Kinetic energy for the filled systems, as shown by the out‐of‐phase modulus, is actually increased by larger filler concentration and higher temperature. A model is proposed where introduction of TiO2 filler acts to increase general long‐range polymer chain stiffening and at the same time enables short‐range chain mobility to rise, possibly through greater side‐chain motion.

Tensile stress relaxation behavior of a mechanical mixture of two polymer components

AbstractAs one in a series of studies relating the rheological properties of mechanical mixtures of two polymer components to the degree of mixing, the temperature dependence of tensile stress relaxation behavior of two types of mixed systems, i.e., poly(methyl methacrylate)–poly(vinyl acetate) system and lightly crosslinked poly(methyl methacrylate–poly(vinyl acetate)) system, was investigated over a temperature range covering the glass transition temperatures of both polymer components. The time–temperature superposition procedure was carried out for comparison of several parameters, such as fractional free volume and its thermal expansion coefficient, which were determined on the basis of the free volume concept from the viscosity in relation to the William‐Landel‐Ferry equation, with those of the individual polymer components. Although the fractional free volume and its thermal expansion coefficient thus determined for the mixed systems were apparent values, the results may, at least qualitatively, deny the simple additivity of the free volumes of the two‐polymer mixed phases and suggest the existence of a sort of physical interaction between the phases, i.e., the internal pressure induced by one phase or the other due to a difference in thermal expansion coefficient between the phases.

Vapor pressures of polymer solutions. I. Apparatus for measurement and some results on poly(vinyl acetate) solutions

AbstractAn apparatus is described for the measurement of the vapor pressures and concentrations of high polymer solutions. Results are given for the poly(vinyl acetate)‐benzene and poly(vinyl acetate)‐vinyl acetate systems. For both, the interaction constant, χ12, decreases linearly as the volume fraction of polymer increases from 0.4 to 0.9.

Polyvinyl trifluoroacetate

AbstractVinyl trifluoroacetate and its homopolymer have been investigated. In copolymerization, the monomer behaves normally, having a Q similar to that of vinyl acetate and a positive e value resulting from fluorine substitution. Unlike the vinyl acetate system, polyvinyl trifluoroacetate is insoluble in its monomer and polymerization leads to no increase in DP with conversion. It is suspected that substitution of CH3 by CF3 has greatly reduced chain transfer and branching. Infrared spectra of vinyl trifluoroacetate and its polymer are presented and solubilities of the latter reported. Polyvinyl trifluoroacetate is very unstable to the hydrolytic loss of the perfluoro acid. The fluoropolymer is much harder than polyvinyl acetate and higher values are obtained for its softening point and apparent second‐order transition temperature. Although no difference can be found by infrared measurements between authentic polyvinyl alcohol and that obtained by hydrolysis of the fluoropolymer, a large difference in their water solubilities exists. Polyvinyl trifluoroacetate is readily oriented by stretching and some polarized infrared absorption data are presented. X‐ray diffraction photographs of stretched specimens indicate moderate order and considerable orientation. These results are surprising when considered in the light of the general concepts regarding polymer structure and crystallinity. Extremely highly ordered and highly birefringent polyvinyl alcohol can be obtained readily from stretched polyvinyl trifluoroacetate by conversion of the latter with gaseous ammonia.