Plastic deformation of poly(tetramethylene oxide). II. Molecular orientation as measured by x‐ray diffraction and NMR measurements

Abstract

AbstractThe orientation of the crystalline and amorphous phases in uniaxially drawn samples of polytetramethylene oxide has been studied by x‐ray and NMR methods. Pole figure measurements give the orientation of the crystalline phase. Its dependence on the draw ratio does not obey the pseudoaffine model. The crystalline fraction is derived from NMR measurements at temperatures between Tg and Tm, where the free induction decay (FID) of the unoriented sample can be analyzed in terms of a rigid (crystalline), a constrained, and an amorphous phase. Low temperature (T < Tg) measurements of the NMR second‐moment anisotropy in protonated and deuterated samples give a mean orientation of the chains higher than that corresponding to the crystalline phase. The lack of anisotropy in the tail of the FID at temperatures between Tg and Tm indicates no appreciable anisotropy in the truly amorphous interlamellar phase. From this and from the ratio of the P4/P2 orientations, factors which obey the “most probable distribution,” it is concluded that the amorphous orientation is due to the layer of constrained chains at the surface of the lamellae.