Abstract
The thickness of interfacial layer of a model incompatible polymer blend system was analyzed using1H pulse nuclear magnetic resonance (pulse NMR) spectroscopy. For this purpose, non-crosslinked andcrosslinked poly(n-butyl methacrylate) (PBMA) particles with a mean size of ca. 0.9 μm were prepared byseeded emulsion polymerization, and the degree of crosslinking was varied. The particles were dispersed inpoly(vinyl chloride) (PVC) by melt blending. Dynamic mechanical analysis indicated that the non-crosslinkedparticles were completely compatible. In contrast, mutual diffusion of the polymer chains was restricted withinthe particle/matrix interfacial layer for crosslinked particles. As a result, model incompatible phase structurewas formed. Dynamic mechanical analysis indicated that the composite has four phases of PVC (A), PBMA(B), PBMA in which molecular mobility was restricted by crosslinking point (C) and interfacial layer (D). Theproton ratio for these phases was measured by pulse NMR. The interfacial layer thickness was calculated fromthe proton ratio under the assumption that the dispersed phase is consisting of B, C and D and the addedparticle is consisting of B and C. The calculated thickness was in the range of 17 to 98 nm. The thicknessdecreased with an increase in the degree of crosslinking in the particles. The interfacial layer thickness in theparticles was approximately 10 times larger than that for the incompatible polymer pair.
