0000000001006094
AUTHOR
Ali E. Akinay
Time–temperature correspondence prediction of stress relaxation of polymeric materials from a minimum of data
Abstract We have determined the stress relaxation of a longitudinal polymer liquid crystal (PLC), polypropylene and their blends containing 10 and 20% of the PLC at the constant strain of 0.5%. The results for nine temperature levels in the range between 20 and 100 °C were used to create master curves for T ref =20 ° C . The temperature shift factors aT were calculated using a general formula derived by one of us and based on free volume vf and the chain relaxation capability model. The predicted values agree with the experimental ones for all materials studied within limits of the experimental accuracy. Moreover, the relation between the shift factor aT and the reduced volume ṽ has been us…
Prediction of long-term service performance of polymeric materials from short-term tests: Creep and prediction of the stress shift factor of a longitudinal polymer liquid crystal
The material studied is a longitudinal polymer liquid crystal (PLC). The creep behavior of the PLC is examined in the region of nonlinear viscoelasticity. The creep compliance D curves at nine different stress (T levels, from 10 to 50 J.cm3 at a constant temperature are determined and shifted along the log time axis for uRf = 10 J . to produce the D versus t/a, master curve. A fairly general formula for stress shift factor a,, based on free volume vf and the chain relaxation capability (CRC) derived by one of the authors is applied. The formula predicts values that agree with the experimental ones within the limits of the experimental accuracy. Thus, experiments at several stress levels can…