ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Based on the observations that high temperature accelerates creep rate of polymer whilephysical ageing plays a reverse role, and that there is an analogy between the influences of stressand temperature on the intrinsic times of polymers, the time-ageing time superposition principle(TASP) and the time-temperature-stress superposition principle (TTSSP) are used to evaluate thelong-term creep behavior of poly(methyl methacrylate) (PMMA). PMMA specimens were aged for2 to 120 hours at identical temperature, their short-term creep strains with 2-hour test duration weremeasured under various stress levels ranging from 14 to 30 MPa at room temperature, and modeledby means of time-ageing time equivalence and time-stress equivalence. The results show that thecreep rate increases with stress, but decreases with ageing time. The ageing time shift factors varywith the stresses at which the shifts are applied. The ageing shift rate is independent on imposedstress in linear viscoelastic region, while it decreases with increasing stress when the materialbehaves in a nonlinear viscoelastic manner. The master creep compliance curve up to about1-month at reference ageing time 120 hours and stress 18 MPa, which is nearly 2.5 decades longerthan the test duration, is constructed by shifting the creep curves horizontally along the logarithmictime axis. The result illustrates that TTSSP, combined with TASP, provides an effective acceleratedtest technique for long-term mechanical behaviors of polymers
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/18/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.575-578.1151.pdf
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