DETERMINATION OF MICROPHASE STRUCTURE AND SCALE OF MIXING IN POLY-EPSILON-CAPROLACTONE (PCL) POLY(VINYL CHLORIDE) (PVC) BLEND BY HIGH-RESOLUTION SOLID-STATE C-13-NMR SPECTROSCOPY WITH MAGIC-ANGLE-SPINNING AND CROSS-POLARIZATION

High-resolution solid-state, pulsed Fourier-transform (FT) C-13-nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) and cross polarization (CP) was applied to a mechanical blend of poly-epsilon-caprolactone (PCL) and poly(vinyl chloride) (PVC) with 50/50 weight ratio (%) whose composition results in very complex morphology and phase structure in the solid state. Proton spin-lattice relaxation times, T-1(H-1) and T-1p(H-1), were used as a probe to determine the microphase structure, the degree of homogeneity in terms of the domain size, and the state of mixing of the blend. In particular, T-1p(H-1) was shown to be able to distinguish the separated domains at a level of a few nanometers; the scale of mixing was evaluated from the approximation based on spin-diffusion phenomenon to be similar to 4.7 nm below which two polymers were partially mixed and above which they were homogeneously mixed. Treatment of the T-1p(H-1) data with two exponential decay functions resulted in a resolution of individual T-1p(H-1) into rigid and mobile components, from which more detailed information on the phase structure and state of mixing were obtained. (C) 1994 John Wiley and Sons, Inc.