Tensile yield energy in glassy polymers

Christopher W. Macosko, Gary J. Brand

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


An activation energy theory of yielding in glassy polymers has been proposed by Starita and Keaton. It predicts a linear relation between energy to yield and test temperature. This concept was tested and found valid for five amorphous polymers; poly(methyl methacrylate), polycarbonate, polyarylsulfone, polysulfone and poly(vinyl chloride), in uniaxial extension at temperatures from 25°C to the glass transition. For extenstion rates of 0.2 in/min, yield energy was found to go to zero at Tg, as commonly determined by thermodynamic methods like dilatometry or scanning calorimetry. The effect of other extension rates, plasticizer and molecular weight appears to affect only the intercept much as Tg is affected by the same changes. The slope, or the ratio of thermal to mechanical energy efficiency in overcoming the flow activation barrier, is largely unchanged.

Original languageEnglish (US)
Pages (from-to)444-449
Number of pages6
JournalPolymer Engineering & Science
Issue number6
StatePublished - Nov 1972


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