Miscibility and interactions in blends of poly(vinyl chloride) with the SAN's copolymer were studied. PVC was shown to be miscible styrene/acrylonitrile copolymers having AN compositions from 11.5 to 26 wt %. The blends of PVC with modified SAN i.e. αmethylstyrene/acrylonitrile copolymer(αSAN), αmethyl styrene/ methancrylonitrile copolymer was found to have different misicility window and the PVC/αSAN blend have shown the broadest miscibility windows with respect to acrylonitrile content in copolymer.
To investigate the factors governing the misciblity of these blends, the sequence distribution of various copolymers were studied by using NMR technique and intra and inter molecular interaction by using the FT-IR spectroscopy. NMR analysis gave the result that αSAN has the most alternating sequence among the series of the SAN's copolymers. From FT-IR analysis the intramolecular hydrogen bond was formed in SAN, αSAN near the boundary of their miscibility windows. It was also attempted to extend the FT-IR analysis to their blends with PVC and obtained the results that the mechanism which leaded to form miscible blend has been attributed to the interaction between the aromatic quadrupole and the halogen induced dipole interaction. Unlikely the other blend systems, PVC/αSAN blends have shown that there were additionally specific interactions between acrylonitrile and α hydrogen of PVC.
Finally we have tried to illuminate on the microphase structures of blendsby using the solid state NMR relaxation techniques. From the analysis of the relaxation patterns of blends have given rise to the results that the blends of PVC with the series of SAN's copolymer were not homogeneous at a molecular level and showed a different phase structure from the prepared samples.
From the above study we could reach the result that the miscibility of blends of homopolymer and copolymer were affected by the sequence of copolymer as well as the intra and intermolecular interactions.
