Effect of interfacial adhesion on the mechanical properties of poly(vinyl chloride) modified with cross-linked poly(methyl methacrylate) particles prepared by seeded emulsion polymerization

摘要

The effect of interfacial adhesion on the mechanical proper- ties of an incompatible polymer blend was investigated. For this purpose, the preparation of non- cross-linked and cross-linked poly(methyl methacrylate) particles having mean sizes of about 0.8 Jlm was completed by seeded emulsion polymerization, and the number and the distribution of cross-linked points in the particles were varied. The emulsion particles obtained were powdered by a freeze-dry method and dispersed into a poly(vinyl chloride) matrix by melt blending. The non-cross-linked par- ticles were completely dissolved in the matrix because poly(methyl methacrylate) has good compatibili- ty with poly(vinyl chloride). On the other hand, in the case of the cross- linked particles, the mutual diffusion of the polymer molecules was restricted within the particle/matrix interfacial regions owing to the cross-linked points. Additionally, interfacial structures with different concentration slope dependent upon the number and the distribution of inner cross-linked points were de- veloped with the same domain size. Mechanical and fracture properties were measured. As a result, both yield stress and fracture toughness decreased with a decrease in the interfacial adhesion, and the de- crease was found to occur as a result of interfacial debonding. When the interfacial adhesion was sufficient it was never observed that the level was lower than that of the compo- nents.