Use of Block Copolymer as Polymer Blend Compatibilizer

Mechanical properties of polymer blends can be improved by the addition of block copolymers as compatibilizers. The objective of this study has been to systematically investigate the effect of added block copolymer to gain an understanding of the factors -- such as the amount, size, and structure of block copolymer -- that control the efficacy of the compatibilization. The rate of particle coarsening that occurs at the late stage of phase separation has been shown to be affected in terms of sensitivity by the presence of even a very small amount of block copolymer. On the assumption that the late stage proceeds by the Lipshitz-Slyozov mechanism, one can estimate the change in the interfacial tension resulting from the adsorption of block copolymer at the interface. The larger the size of the block copolymer, the more pronounced the reduction in the particle coarsening rate. When polymers are melt-blended, a larger block copolymer additive is again found to be more effective than smaller amounts of block copolymer.