Compatibility in polymer/plasticizer blend system: Thermal, X‐ray, and dynamic mechanical studies of PMMA/PTBF blends

Differential thermal and dynamic mechanical analysis (DTA and DMA) were carried out on the blend system of atactic poly(methyl methacrylate) (PMMA) with poly( p ‐ t ‐butyl phenol formaldehyde) (PTBF). In both the techniques, the PMMA/PTBF blend system exhibited a composition‐dependent, single glass‐transition temperature, indicating miscibility. The blends exhibited composition‐dependent morphology dominated by induced cluster formation of PMMA as a separate phase in blends. The DTA scans of blens exhibited broad melting endotherms. Also, in DMA, apart from the main relaxation (tan δ), the system showed an additional high‐temperature relaxation ( T u ), indicating the presence of a separate phase. In addition, wide‐angle X‐ray diffraction (WAXD), Fourier‐transform infrared (FTIR) spectroscopy, and sonic pulse propagation measurements provide evidence for the formation of PMMA clusters in the bulk PMMA/PTBF blends. The mechanical behavior of the blends is discussed in terms of the variations in shape and magnitude of tan δ, E″ , and E″ curves. It is concluded that PTBF acts as a compatible plasticizer in PMMA/PTBF blends and, because of changed morphology, improveds the elongation of blend films compared to pure PMMA. © 1995 John Wiley & Sons, Inc.