Low-temperature Thermogravimetry Study of Post-Infrared-Exposure PMMA and PMMA/zircon Composites

A thermogravimetruic study of PMMA/zircon composites was performed at temperatures between 30 and 200°C, instead of above degradation temperature of PMMA at around 300°C. The focus of the study was to observe mass changes between the designated temperatures due to zircon filler and infrared (IR) exposure. Four samples were prepared, i.e. pure PMMA without IR exposure and with IR exposure, each without and with 1 wt.% zircon filler. The success of the synthesis of the composites was examined using x-ray diffraction (XRD). Thermal gravimetry (TG) data of samples at the designated temperatures were plotted to explain several thermal phenomena. Results showed that all samples exhibited a drop of 1.5-2% weight between 30 and 75°C with only a slight increase after IR exposure. The slight drop maybe due to water loss or evaporation of broken weak hydrocarbon bonds. There is a further slight increase in mass for the unexposed samples between 75 and 105°C, i.e. just before the glass transition temperature of PMMA. The mass decrease continued up to 135 °C for the unexposed pure PMMA and up to 135°C for the other samples, indicating that filler and IR exposure favored PMMA mass loss. After that, up to 200 °C, all samples gained mass which was presumably due to oxidation. The presence of filler and the IR exposure promoted a larger oxidation as a result of some breaking PMMA bonds.