Apparent Physical Aging of Polymeric Composites

Micromechanics and the finite element method are used to explore the importance of the relaxation of thermal residual stresses in the momentary creep compliance of polymeric composites. The relaxation of thermal residual stresses is shown to produce an apparent aging of the material. The relative importance of this apparent aging as compared to physical aging is assessed. It is shown that a significant portion of the phenomenon that is generally attributed to physical aging may not be due to aging at all, but to the relaxation of thermal residual stress.