Effects of different drying methods on the microstructure and thermal oxidative aging resistance of natural rubber

摘要

In this work, the wet natural rubber granules were dried by hot air and by microwave at 115°C, respectively; the morphological structures of dried natural rubber granules were studied by using a scanning electronic microscope, whereas the thermal oxidative properties of dried natural rubber granules were investigated by comparison of variation in properties before and after aging, and the changes in the thermal oxidative decompose temperatures. The results showed that it needed 13.47 min for microwave drying and 210.00 min for hot air drying to reduce the moisture content of wet natural rubber to the required value. The granules of natural rubber dried by microwave were of rough surfaces and the cutting traces produced during the processing of wet natural rubber remained on the natural rubber surface; whereas, the natural rubber granules dried by hot air were of smooth surfaces, and the cutting traces produced during the processing of wet granules disappeared. The thermal oxidative resistance of vulcanized natural rubber dried by microwave improved significantly. The initial plasticity (P _0), plasticity retention index, and thermo-oxidative decomposition temperature of natural rubber dried by microwave were higher than those of natural rubber dried by hot air.