Polymer, Vol.42, No.20, 8415-8424, 2001
Orientation of uniaxially stretched poly(vinyl phenol)/poly(vinyl methyl ether) blends
Orientation of poly(vinyl phenol) (PVPh)-poly(vinyl methyl ether) (PVME) amorphous miscible blends has been studied using FTIR spectroscopy. Blends of 33, 42, 53 and 66% (mol/mol) in PVPh were uniaxially stretched at 0.1 s(-1) and T-g + 15. Both polymers showed similar orientation values in the blend. Whereas, at high PVPh concentration, the orientation function is linear with deformation, at intermediate compositions a non-linear relationship was observed, attributed to a fast relaxation. Orientation of both polymers increases with PVME concentration up to 48 mol% (40 wt%) composition. For blends richer in PVME, orientation decreases. It is proposed that the maximum in orientation is related to the presence of strong intermolecular PVPh-PVME hydrogen bonds, which hinder relaxation and increase the friction coefficient. Comparison with PVPh-poly(methyl methacrylate) and PVPh-poly(ethylene oxide) blends, which are both hydrogen bond containing systems, suggest that hydrogen bonds hinder relaxation and could favor cooperativity. Moreover, comparison to poly(styrene)-poly(vinyl methyl ether) blends, a similar system that does not present hydrogen bonds and that was studied by various groups previously, shows that the maximum in orientation is related to interaction fluctuations.