Deformation mechanisms in toughened poly(phenylene oxide)-polyamide blends

The deformation behaviour of several toughened poly(phenylene oxide)--Nylon 6,6 blends made with different coupling agent levels and having different copolymer concentrations has been studied by tensile dilatometry and scanning electron microscopy. Volume strains were measured at rates from 10 exp --3 -10 exp --1 s exp --1 . At high copolymer concentrations, shearing was the primary deformation mode, with dilation accounting for only 25% of the total strain. At lower copolymer levels, fracture occurred abruptly, with no measurable increase in the level of cavitation prior to failure. Samples without rubber exhibited lower levels of dilation than their toughened counterparts. The observed differences in behaviour are discussed in terms of microscopic failure processes in the materials. Rate-dependent values for selected engineering parameters are presented. 9 ref.--AA