为探讨微波干燥天然橡胶新技术,分别在温度115℃下,采用电热烘箱产生热空气和微波干燥装置干燥湿天然橡胶胶粒,对二者的干燥特性及硫化胶性能进行对比分析研究。结果表明,微波干燥只需13.467min就可使胶料含水量降至0.791%,热空气干燥则需211min。天然橡胶微波干燥和热空气干燥主要包含失水率加速期、失水率减速期、失水率相对恒速期3个失水阶段。整个干燥过程中,微波干燥失水率较大,而热空气干燥失水率比较小。微波干燥天然橡胶硫化胶的耐热氧老化性能得到显著提高:其老化前后拉断伸长率变化率(-35%)和拉伸强度变化率(-59%)明显高于热风干燥天然橡胶硫化胶的拉断伸长率变化率(-62%)和拉伸强度变化率(-89%)。
For exploring the microwave drying technology of NR, the wet granules of NR were dried by 115 ℃ hot-air from electrothermal oven and by microwave device, both of the drying characteristic and the vulcanized rubber properties of NR for two drying methods were contrast analyzed. The results showed that it needed 13. 467 minutes to let the water content of NR dried by microwave fell to 0. 791 percent, but hot-air drying needed 211 minutes. The entire process of microwave drying and hot-air drying for wet natural rubber could be divided into three stages: acceleration, deceleration, relatively constant speed drying. The rate of water loss was high of microwave drying for the entire drying process, but the hot-air drying was low. The thermal oxidative resistance of vulcanizate of natural rubber dried by microwave improved significantly. The variation rate of elongation at break of -35% and tensile strength of -59% before and after aging for vuleanizate of natural rubber dried by microwave were apparently higher than those for vulcanizate of natural rubber dried by hot air, which were -62% and - 89% , respectively.