ISSN:
0449-2978
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Past differential scanning calorimetry and dielectric relaxation measurements have established that polystyrene (PS)-poly(vinyl methyl ether) (PVME) mixtures exhibit a degree of compatibility when cast from toluene, whereas they are incompatible when cast from chloroform or trichloroethylene. The present study reports that toluene-cast mixtures can be phase-separated by thermal treatment at temperatures exceeding 125°C. This is true for samples containing 20-80 wt-% PS. The temperature of phase separation varies with heating rate; isothermal heating times needed to cause phase separation increase rapidly as the temperature approaches 125°C. Reversibility of the phase separation process depends upon such factors as cooling rate, annealing time, treatment temperature, and thermal history. By annealing and/or slow cooling, all thermally phase-separated mixtures have been brought back to their original state of compatibility. That is, there is no evidence for true irreversiblity of phase separation in thermally treated samples. Quench-cooled samples remain phase-separated indefinitely at room temperature, but this is attributed to rapid cooling below the glass transition of the PS. Chloroform-cast and trichloroethylene-cast mixtures have not been brought to a compatible state by thermal treatment, even after lengthy annealing and slow cooling steps.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1972.160100611
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