Determination of microphase structure and scale and scale of mixing in poly‐ε‐caprolactone (PCL)/poly(vinyl chloride) (PVC) blend by high‐resolution solid‐state 13 C‐NMR spectroscopy with magic angle spinning and cross polarization

High‐resolution solid‐state, pulsed Fourier‐transform (FT) 13 C‐nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) and cross polarization (CP) was applied to a mechanical blend of poly‐ε‐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 ( 1 H) and T 1ρ ( 1 H), 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 1ρ ( 1 H) 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 ∼ 4.7 nm below which two polymers were partially mixed and above which they were homogeneously mixed. Treatment of the T 1ρ ( 1 H) data with two exponential decay functions resulted in a resolution of individual T 1ρ ( 1 H) into rigid and mobile components, from which more detailed information on the phase structure and state of mixing were obtained. © 1994 John Wiley & Sons, Inc.