Effect of Simple Stress on the Glass Transition of Polymers at High Pressure
Interim technical rept.
RUTGERS - THE STATE UNIV PISCATAWAY NJ HIGH PRESSURE MATERIALS RESEARCH LAB
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Experimental studies showed the yield strength in tension, compression, and shear in the rubbery and the glassy states increased with increasing hydrostatic pressure. Moreover, the Youngs modulus also increased with pressure and the amount of the increase across the glass transition temperature T sub g at a given pressure can be as large as three orders of magnitude in case of elastomers. An extension of Gibbs-Dimarzio theory is proposed to account for the effect of applied stress on the glass transition temperature of glass forming polymers. When a simple stress, such as tensile, compressive or shear stress, is applied to a polymer, the T sub g will decrease, compared to the polymer without applied stress. A glass forming polymer in the vicinity of the transition would behave differently than what than what is predicted by rubber elasticity. The Youngs modulus increases with increasing pressure range but the increase is rather small at very high pressure range.
- Elastomers and Rubber