For swelling experiments, strips of dimensions 20 10 0.2 mm were immersed in toluene at room temperature for three days and the lengths and the widths changes were measured in the immersed state by means of a Digimatic Caliper from Mitutoyo, with an accuracy of0.01 mm. The swelling ratio Q, defined as the ratio of the volume of the swollen to unswollen composite, were expressed as: