Orientation of a miscible polymer blend with strong interchain hydrogen bonds: Poly(vinylphenol)-poly(ethylene oxide)

The orientation of miscible poly(vinylphenol) (PVPh)-poly(ethylene oxide) (PEO) blends for compositions of 20-35 wt % PEO and from T-g + 10 to T-g + 18 was studied using FTIR spectroscopy. In uniaxially deformed samples, both polymers were oriented for all compositions studied. For the POE component, a nonlinear relationship was observed between the orientation function [P-2] and the draw ratio lambda, which was ascribed to a rapid relaxation of this polymer. The fact that orientation does occur is noteworthy, since for the poly(methyl methacrylate)/PEO blend system studied by Zhao, Jasse, and Monnerie, PEO did not show any orientation, which was attributed to a fast relaxation. Hydrogen bonds are here proposed to hinder the relaxation process. A maximum in the orientation of the PEO component was observed for 30 wt % PEG, whereas the orientation of the PVPh component began to increase significantly at this composition. The composition for this maximum, 30 wt %, is close to a 1:I mole ratio of interacting units, and data from the literature indicate that it is in this range that the number of hydrogen bond interactions reaches a maximum. The observed orientation behavior is attributed to the formation of these strong hydrogen bonds which can influence entanglement density, chain friction coefficient, and local organization of the chains. The curves of ln(Delta P-2/Delta lambda) vs 1/T yield similar apparent activation energies for the processes, suggesting that local organization, and therefore alpha angles used to calculate [P-2], are affected by these interactions.