CP/MAS C-13 nmr analysis of micromorphology in a thermoplastic elastomer prepared from nitrile rubber and poly(vinyl chloride)

A thermoplastic elastomer (TPE) prepared by mechanical blending of nitrile rubber (NBR) and poly(vinyl chloride) (PVC) was investigated by solid-state C-13 nuclear magnetic resonance (n.m.r.) spectroscopy with cross-polarization/magic-angle spinning (CP/MAS). The CP/MAS C-13 n.m.r. measurements of T-1(H) and T-1 rho(H) relaxation times for the TPE were used as a probe to analyse the microphase structures. The double-exponential decay T-1 rho(H) relaxation behaviour confirmed the presence of microphases in the TPE, which were PVC microcrystallites and the unmixed portion of NBR. The sizes of the microphases were about 1.1 nm or smaller. A schematic model of the phase morphology is suggested. The sizes of the PVC microcrystallites were decreased somewhat by mixing with NBR.