Effects of thermal aging and moisture absorption on mechanical and physical properties of cyanate ester polymers

The aim of this research is to study the effects of thermal aging and hygrothermal effects on the mechanical and physical properties of cyanate ester (CE) and siloxane modified cyanate ester (SMCE) polymers. Thermal aging was conducted on these polymers in air at temperatures of 60°C, 80°C, 100°C in order to assess their susceptability to thermo-oxidation processes, since thermo-oxidation can degrade the properties of some polymers. Also, the properties of polymers can be degraded by absorption of moisture, which can pose significant problems in CE and SMCE. Spectrographic techniques such as, fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) and thermal analysis techniques such as differential scanning calorimeter (DSC) were employed to evaluate and interpret changes observed in the physical properties. Environmentally induced changes in the mechanical properties of CE and SMCE were determined by conducting flexure and microhardness tests. Moisture absorption studies revealed that CE absorbed substantially more water than SMCE resin regardless of how the samples were pre-conditioned. Microhardness tests showed the changes in the microhardness of CE and SMCE due to moisture absorption. The present investigation reconfirms that there are performance differences between CE and SMCE resins. The primary focus of this research is to discern the reasons for such observations.