Investigations on the intrinsic viscosity of poly(vinyl chloride)(PVC) affected by polymer-polymer interactions in solution

The concentration-dependent intermolecular interactions between poly(vinyl chloride) (PVC) and various polymers selected to form polymer solvent were thoroughly investigated by the method of polymer solvent. It has been found that these interactions depended upon both the polymer selected to form th e polymer solvent and the concentration of the selected polymer in polymer solvent. If polystyrene (PS): an incompatible polymer with PVC, was chosen to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent, [eta(PVC)](PS), decreased with the increasing of the concentration of PS ( C-PS) in polymer solvent, indicating that repulsive interaction between PVC and PS became stronger in concentrated polymer solvent. If poly(epsilon-ca rprolactone) (PCL) or poly(N-vinyl-2-pyrrolidone)(PVP), the compatible poly mers with PVC, was chosen to form polymer solvent, the intrinsic viscosity of PVC in poll mer solvent, [eta(PVC)](PCL) or [eta(PVC)](PVP) increased wi th the increasing of the concentration of PCL(C-PCL) or PVP(C-PVP) ill poly mer solvent, and reached its maximum at the concentration of about C-PCL = 0.3 g/dl or C-PVP =0.4 g/dl, respectively. Obviously, the attractive intera ction between PVC and PCL or PVP is believed to be responsible for the resu lts. However, with the further increase of C-PCL or C-PVP in polymer solven t (C-PCL = 0.3 g/dl, C-PVP > 0.4 g/dl), both [eta(PVC)](PCL) and [eta(PVC)] (PVP) decreased. On these occasions, the increased concentration-dependent intermolecular excluded volume effect is believed to be dominant, resulting in the contraction of the PVC coils and thus the reduction of [eta(PVC)](P CL) or [eta(PVC)](PVP) in polymer solvent. (C) 1998 Elsevier Science Ltd. A ll rights reserved.