ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760120610
