Glass Transition Determination by Thermomechanical Analysis, a Dynamic Mechanical Analyzer, and a Differential Scanning Calorimeter

Abstract

A suitable specimen was selected to compare the glass transition measurement by several thermal analysis techniques. The specimen, an epoxy composite, was analyzed by Thermal mechanical analysis (TMA) using three different methods, including flexure, expansion, and stress relief, as a function of temperature. A dynamic mechanical analyzer (DMA) was then performed at three frequencies. A portion of the specimen was then selected for differential scanning calorimeter (DSC) analysis. Special care was taken to ensure that the specimen pre-treatment was identical and that thermal lag errors were corrected for, so that a direct glass transition comparison could be made between analytical techniques. The best agreement in Tg values between the various measurement methods was obtained between: DSC heat flow midpoint; TMA onset of expansion, flexure or stress relief; and the onset of the storage modulus for DMA data taken at 0.1 Hz. These were all within one degree of 122°C. The best correlations with the DSC and TMA data to be obtained from a 1-Hz DMA run was that of the onset of the loss modulus peak (121.7°C). The methods employed are described, and the results discussed.

Monitoring the reaction progress of a high‐performance phenylethynyl‐terminated poly(etherlmide). Part II: Advancement of glass transition temperature

“…Several analytical techniques can be used to measure Tg, and there has been considerable discussion in the literature as to which techniques provide the most consistent and accurate Tg results (6-11 analyzing transition regions, and assigning onset criteria (6). DSC measured glass transition temperatures are commonly reported by finding the half-height, inflection point, or onset of the transition in heat capacity or heat flow.…”

Problem solving and applications of thermal methods

“…The sample is loaded into the pan, making sure there is good contact between the sample and the pan. Characterisation using TMA and DMA is also very useful [27]. The sample is heated under nitrogen at 10 Klmin to 30°C above the melting point and held for 10 min to erase thermal history.…”

“…Measurement of the heat capacity might give additional confirmation, as might the study of the crystallisation behaviour [27,28]. (b) The TG trace shows a mass loss of about 5% at low temperature, which is probably moisture.…”

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

“…In the literature, generally, DMA Tis, defined by the tan 6 peak, are reported to be 10-30°C higher than Tg's measured by DSC, but the effect of frequency is usually not considered in detai1. [2][3][4][5][6][7] The aim of the present study was to develop a Cross-linked acrylic polyurethane paint films were made using a release agent to cast, bake, and remove the coating from steel panels as free films. Both solvent-cast and powder paint coatings were prepared and studied.…”

“…The effect of thermal history imposed on one PS pellet sample by annealing is shown in Table 111. Representative thermal curves are presented as Figures [5][6][7]. Figure 5 shows the T, as the only thermal event in the 30-150°C temperature range; no thermal events are observed during the isothermal annealing at 150°C.…”