Crazing in glassy polymers: Studies on polymer‐glass bead composites

Stress‐strain curves of glass bead‐filled glassy polymers show a slope discontinuity related to crazing in the matrix. This discontinuity serves as basis for a simple method for determining ε p ′ the critical strain in the polymer to initiate crazing. The stress at the discontinuity (σ D ) is governed by the nature of the dispersed particles acting as stress concentrators. The two parameters, ε p ′ and σ D , (neither of which is a function of the filler content) have the following values in ascending order σ = 1540, 1750, 1880, 2390 and 3300 psi for polystyrene, ABS, poly(vinyl chloride), SAN and poly(phenylene oxide) respectively; ε p = 0.63, 0.72, 0.81, 1.10 and 1.67 percent for poly(vinyl chloride), polystyrene, SAN, ABS and poly(phenylene oxide) respectively. In coupled particulate systems, (σ D ) is increased and apparently vaies with the efficiency of the coupling agent. The modulus of a particulate system can be predicted by a one‐parameter equation.