Abstract: Thermally induced phase separation in the mixture of poly (methyl methacrylate) (PMMA) with poly (styrene-co-acrylonitrile) (SAN) has been studied with pulsed nuclear magnetic resonance(NMR). It is shown that the single spin-lattice relaxation time T_1 of the compatible mixture splitted into two T_1 corresponding to those of PMMA-rich and SAN-rich domains. Meanwhile, both T_1 gradually changing with annealing time provides the direct evidence that the phase separation takes place with a spinodal decomposition mechanism. Diffusion coefficient was estimated to be negative, indicating an uphill diffusion characteristics. The basic parameters governing its kinetics were estimated using NMR data which were in good agreement with those evaluated from time-resolved light scattering experiments for a 60/40(PMMA/SAN) mixture annealed at 180.0 ℃.

Key words: Solid state NMR, Phase separation, Mixture, Poly(methyl methacrylate), Poly(styrene-co-acrylonitrile), Diffustion