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 + 1 8 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 proc ess. 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 s ignificantly 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 lite rature indicate that it is in this range that the number of hydrogen bond i nteractions reaches a maximum. The observed orientation behavior is attribu ted to the formation of these strong hydrogen bonds which can influence ent anglement density, chain friction coefficient, and local organization of th e chains. The curves of ln(Delta P-2/Delta lambda) vs 1/T yield similar app arent activation energies for the processes, suggesting that local organiza tion, and therefore alpha angles used to calculate [P-2], are affected by t hese interactions.