Mechanical behaviour above Tg of a plasticised PVC reinforced with cellulose whiskers;: a SANS structural study

In previous works, the processing of nanocomposites of cellulose whisker filled thermoplastics was presented as well as their mechanical behaviour in the glassy state, both in the linear and non-linear domains. The purpose of the present work is to evaluate the mechanical properties of these composites in the rubbery state. A simple modelling of the mechanical behaviour, using the classical entropy elasticity theory, is proposed and discussed. Particular attention was paid to damage phenomena, already observed with stretched composite in the glassy state. Damage is mainly explained as a debonding of the matrix at the whisker interface. Small-Angle Neutron Scattering experiments performed on stretched composites provide supplementary information on the matrix microstructure with and without whiskers, and on the evolution of this microstructure with the sample deformation. Results confirm the heterogeneous characteristic of the matrix. Void scattering is identified and interpreted. (C) 1999 Elsevier Science Ltd. All rights reserved.