The effect of interfacial adhesion on toughening behaviour of rubber modified poly(methyl methacrylate)

In order to study the effect of interfacial adhesion and particle size on the toughening behaviour of rubber-toughened poly(methyl methacrylate) (PMMA), a systematic model study has been carried out using two different kinds of particles, i.e. 'core' and 'core-shell' type particles. The core particle consists of poly(n-butyl acrylate) (PBA), while the core-shell particle has a PBA core and a PMMA outer shell. The prepared particles were blended with matrix PMMA. The values of fracture toughness, K-IC, determined by three-point-bending tests at a relatively low strain rate and room temperature, did not show any difference for core blends and core-shell blends. However, the value of K-IC at a high strain rate and relatively low temperature and impact strength showed a marked difference between core blends and core-shell blends. These results imply that even though there is no primary chemical bonding between PBA particles and the PMMA matrix for core blends, the interfacial adhesion strength is strong enough to induce matrix deformation at relatively low strain rate, which resulted in similar fracture toughness for both of the blends. However, at a relatively high strain rate, the interfacial failure occurs predominantly, which would not induce much of the matrix PMMA deformation, so the core blends show relatively low fracture toughness. (C) 1997 Elsevier Science Ltd.