The effect of particle fraction on mechanical properties of particle-reinforced composites was studied using tensile and hardness testing. Unsaturated polyester (UP) was used as polymer matrix, and aluminum hydroxide as the reinforcing particles. The fracture morphology of tensile samples was observed by scanning electron microscopy (SEM). The results showed that the tensile strength and absorbed energy increased to a maximum at 10% particle content and then decreased. With increasing content of aluminum hydroxide, the elastic modulus increased, and the fracture elongation decreased. The SEM showed that the failure of the Al(OH) 3 /UP composites was one of macroscopically brittle fracture. In addition, the study showed that appropriate amount of filler can enhance the surface hardness of Al(OH) 3 /UP composite.

Artificial weathering tests on ethylene-propylenediene monomer (EPDM) rubber were conducted in a fluorescent UV/condensation weathering equipment (E-UV environment) and a xenon lamp light exposure and weathering equipment (E-Xe environment) for different time periods. The correlation between E-UV and E-Xe environment was investigated by using crosslink density as criteria. Thermal gravimetric analysis (TGA) was used to evaluate the thermal stability of EPDM. The fracture morphology was monitored by scanning electron microscope (SEM). The results showed that the correlation between E-UV and E-Xe environments can be expressed as: t Xe ¼ À7:4818 þ 1:1837t XeÀUV ; where the correlation coefficient R is 0.9856. The thermal stability of EPDM did not deteriorate dramatically on exposure to the two artificial weathering environments. An oxidation layer was formed after 90 days of exposure.

Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to artificial weathering environment produced by a xenon lamp light exposure and weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylenediene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased.