Phase separation and chemical structure changes occurring during thermal degradation are studied by high-resolution solid-state 13C n.m.r, methods for poly(vinyl alcohol)/poly(methacrylic acid) (PVA/PMAA) = 1/1 complex and poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA)= 1/l blend. 13C cross-polarization/magic-angle spinning spectra and 1H Tap are measured for samples subjected to various heat treatments. The results indicate that when the systems are heated to higher temperatures, phase separation occurs first because of the dissociation of intermolecular hydrogen bonding between the two different polymers. Further increases in temperature bring about thermal degradation. Degradation products of the complex and the blend are similar to those of the corresponding single-polymer systems. The thermal degradation temperatures for the complex and the blend are lower than for the single-polymer systems. This is ascribed to the loss of the crystalline phase of the PVA component and a lowering of glass transition temperatures of the PMAA and PAA components in the miscible system
Посилання на статтю:
Phase separation and thermal degradation of poly (vinyl alcohol )/poly ( methacrylic acid ) and poly (vinyl alcohol ) / poly ( acrylic acid ) systems by 13C c.p./m.a.s.n.m.r. / Xiaoqing Zhang*, K. Takegoshi and Kunio Hikichi // Polymer. – 1992. – Vol 33. – P. 718-724.