Time-dependent heat capacity in the glass transition region

✍ Scribed by Wolpert, Stephen M. ;Weitz, Alexander ;Wunderlich, Bernhard

• Publisher: Wiley (John Wiley & Sons)
• Year: 1971
• Tongue: English
• Weight: 930 KB
• Volume: 9
• Category: Article
• ISSN: 0449-2978
• DOI: 10.1002/pol.1971.160091010

✦ Synopsis

Abstract

Time‐dependent, apparent heat capacities of glucose, poly(vinyl chloride), polystyrene, selenium, poly(methyl methacrylate), and poly(2,6‐dimethyl‐1,4‐phenylene ether) in the glass transition region were determined by differential thermal analysis. The thermal history was set by linear cooling at rates between 0.007 and 160°C/min. Linear heating for analysis was carried out at rates between 0.3 and 600°C/min. Average activation energies of 52, 81, 90, 54, 77, and 108 kcal/mole, respectively, were evaluated by using the hole theory of glasses previously developed. Within experimental limitations all data could be described quantitatively by the theoretical expressions using only one parameter, the number of frozen‐in holes, to described the thermal history. Experimental and theoretical limitations are discussed.