The influence of solvent and temperature on the miscibility of poly(methyl methacrylate)/poly(vinyl acetate) (PMMA/PVAc) was investigated. Experiments using differential scanning calorimetry (DSC) and viscometry were performed. LCST curve was determined by measurements of transmitted light intensity against temperature, at several compositions of PMMA/PVAc, 15/85, 25/75, 50/50, 75/25 and 85/15. It was observed that the miscibility of the PMMA/PVAc blends depends on the solvent. The blends are miscible in chloroform at 308C and 508C, whereas in N,N-dimethyl formamide (DMF) at the same temperatures, the blends are immiscible. In toluene the miscibility depends on the temperature: the blends are miscible at 308C and immiscible at 508C. Results from viscometry match very well those of DSC. The film of PMMA/PVAc 50/50 cast from chloroform presents only one Tg. If cast from DMF, the blend presents two Tg values, close to those for pure polymers. The thermogram of the opalescent film, cast from DMF, is similar to the one obtained after a transparent film, cast from chloroform, was heated above the LCST curve.
Посилання на статтю:
Solvent effects on the miscibility of poly(methyl methacrylate)/poly(vinyl acetate) blends I: Using differential scanning calorimetry and viscometry techniques / Edson Golembievski Crispim, Adley Forti Rubira, Edvani Curti Muniz // Polymer. – 1999. – N 40. – P. 5129–5135.