Effects of uniaxial drawing and heat‐treatment on gas sorption and transport in PVC

Abstract

SynopsisSorption and transport measurements for various gases in rigid poly(viny1 chloride) were made following uniaxial drawing and heat treatment. The permeabilities of He, Ar, N,, and CHI were found to be essentially independent of pressure in PVC while CO, showed a complex pressure dependence which varied with prior exposure and degassing history. Sorption is* therms were analyzed by the dual mode sorption model, and the parameters obtained were correlated with the Lennard-Jones potential-well depth of the gas. The Henry's law coefficient for CO, was found to be significantly larger than expected which is believed to be the result of a specific interaction with PVC. Uniaxial drawing of PVC above its glass transition caused significant reductions in gas permeabilities, of which roughly one-third is attributable to the accompanying heat treatment rather than molecular orientation per se. The physical state of the polymer was characterized by density, birefringence, and calorimetry. Changes in gas sorption and permeation behavior are discussed in terms of these results.

Polymer Transport Properties

“…In another study of the effects of uniaxial orientation on PVC and other essentially amorphous glasses (136), a wide range of penetrants has been considered and permeability, solubility, and diffusivity effects caused by various orientation variables have been explicitly determined (136). The orientation, measured by birefringence, leads to improved barrier properties and appears to have an effect on both the apparent solubility coefficient k a = C/p and the apparent diffusivity determined by time lag measurements.…”

Sorption and transport of inert gases in PVF2/PMMA blends

“…For atm, is smaller than for most polymers but larger than a recently reported value of 0.002 cm3 (STP)/cm3 atm for PVC. 45 To explore further the issues shown in Figures 17 and 18, we have examined the analogous behavior for poly(methy1 acrylate) and poly(viny1 acetate) which are isomers and similar to PMMA by each having COO linkages in their pendant groups. Data from this work and four other source^^^-^^ are plotted vs. E / K in Figure 19.…”

Heat Curing of Whey Protein Films

“…Curing is commonly used to cross-link synthetic thermoset polymers, though some researchers have examined heat curing of thermoplastic polymers (El-Hibri and Paul, 1985;Perkins, 1988). In addition to the application or generation of heat, curing may involve a reaction catalyst (Chan and Feke, 1993) or irradiation (MacDonald and Huang, 1981) to induce desired cross-linking.…”