SynopsisPoly(viny1 chloride) displays a normal DSC or DTA curve for the glass transition when quenched from above its T,. However if cooled slowly or annealed near the glass transition temperature, a peak appears on the DSC or DTA curve a t the T,. In this paper quantitative studies of the time and temperature effects on the production of this endothermal peak during the annealing of PVC homopolymer and an acetate copolymer are presented. The phenomenon conforms to the Williams, Landell, and Ferry equation for the relaxation of polymer chains, the rate of the peak formation becoming negligible a t more than 50°C below T,. The energy difference between the quenched and annealed forms is small. For a PVC homopolymer annealed 2 hr a t 68OC, which is Z ' , -lO"C, the difference is 0.25 cal/g. For a 13% acetate copolymer of PVC similarly annealed, the difference is 0.36 cal/g. The measured rates of the process give a calculated activation energy of 13-14 kcal/mole for PVC homopolymer and copolymer.This appearance of a peak on the T, curve for a polymer when annealed near the glass temperature appears to be a general phenomenon.

SynopsisA difference has been observed in the DTA and DSC curves for the glass transition of both PVC homopolymer and acetate copolymer, depending on the rate of quenching or annealing below the glass transition temperature. The difference has the appearance of an endothermal peak added to the glass transition curve and is attributed to an.alignmerit of stereoregular chain segments of adjacent polymer molecules. The lengths of chain segments are assumed to be so short that no x-ray evidence of crystallinity was obtained. The orientation process involved has an activatiop energy of 47.8 kcal./mole in the homopolymer and 43.6 kcal./mole in the copolymer. The measured rate of the process agrees with the principle of time-temperature superposition, the rates becoming equal for homopolymer and copolymer at equal temperatures below their glass transition temperatures.

SynopsisCorrelations between processing characteristics and measurable physical properties were investigated for 16 commercial polX(viny1 chloride) polymers and acetate copolymers. Processing was evaluated with the Brabender Plasti-Corder. Tbe glass transition temperature and dry blending procedure were examined by differential thermal analysis. The polymers included high and low molecular weight materials and examples of suspension, emulsion, and solution methods of polymerization. Effects due to the amount of plasticizer, stabilizere, and other additives were measured and are discussed.

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7. The isotherms, and isobars prepared from them, give effective evidence for the presence of two forms of adsorption, that occurring at the higher temperature requiring an activation energy.8. The heat of activated adsorption is calculated as 15,000 calories per mole on the less active portions of the surface. 9. The determination of the effect of the change of temperature upon the amount of adsorption is shown to be a practical method for the investigation of the various forms of adsorption.Princeton, New Jersey