Comparison of thermal techniques for glass transition measurements of polystyrene and cross‐linked acrylic polyurethane films

摘要

AbstractThere are few quantitative comparisons in the literature between glass transitions (Tg) measured by differential scanning calorimetry (DSC) and by dynamic mechanical analysis (DMA). Also, in the case of DMA, two different operational definitions have been used to obtain the glass transition, namely, the loss modulus (E″) and damping (tan δ) peak temperatures. We propose a new DMA definition ofTgand demonstrate that it agrees with DSCTgmeasurements within ±2°C for both thermoplastic polystyrene and thermoset cross‐linked acrylic polyurethane films with measurable tan δ peaks. The glass transitions for a single polystyrene standard and several cross‐linked acrylic polyurethane films were measured by DSC. Additionally,E″and tan δ peak temperatures were measured by DMA as a function of frequency and temperature. Empirically, it was determined that the average of theE″and tan δ peak temperatures measured at 1 rad/s oscillation frequency corresponds to the glass transition measured by the ASTM E1356 DSC test method. © 1994 John