Abstract
The effect of cross-link density on the visco-elastic performance of an advanced polymer matrix (LaRC™-PETI-SI) was investigated through creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of each material with different cross-link density. Through the use of time-aging-time superposition procedures, the material constants, material master curves and aging-related parameters were evaluated at each temperature for a given cross-link density. It was shown that the high cross-link density materials have increased creep compliance and creep compliance rate, and are less sensitive to physical aging than the low cross-link density materials. The temperature sensitivity of the time-temperature superposition (TTSP) shift factor was shown to increase monotonically with increasing cross-link density. Furthermore, at the highest temperature, a separation in the TTSP shift factors was apparent between different cross-link densities. This separation occurred at a molecular weight (Mc ) of ~3321 g/mol.