微波干燥对天然橡胶硫化胶热氧老化性能的影响

The Influence of Microwave Drying on Thermal-oxidation Ageing Properties of Nature Rubber Vulcanized

研究3种不同干燥方式所得天然橡胶硫化胶的热氧老化性能。采用TG和DTG测定了空气氛围下干燥后样品硫化胶的热氧降解温度,运用Coats-Redfern方程计算N2氛围下样品硫化胶热降解活化能;采用RPA 2000在应变为0.5 deg下进行频率扫描来评估样品耐热老化性能,并测定了样品硫化胶老化前后的力学性能。结果表明,微波干燥天然橡胶的力学性能明显优于热空气干燥和自然干燥,性能变化率和老化系数更大,样品RPA频率扫描tanδ值的增值更大,微波干燥样品的热降解活化能高于热空气干燥9 kJ/mol,与自然干燥样品接近,说明微波干燥天然橡胶硫化胶的热稳定性好,耐热氧老化性能得到显著提高。

The thermal-oxidation ageing properties of nature rubber vulcanized dried by three methods was studied. TG and DTG was used to determine the thermal-oxidation degradation temperature in air atmosphere and thermal degradation active energy in N2 atmosphere using Coats-Redfern equation; the frequency sweep was used to estimate the ageing resistance of nature rubber vulcanized at strain of 0.5, also, the mechanical properties of rubber vulcanized was tested before and after ageing. Showed from the results, the mechanical properties of NR dried by microwave was higher than the hot-air drying and nature drying; the increasing value of tan8 in frequency sweep was larger than the other drying methods; the degradation active energy, dried by microwave was 9 kJ/mol bigger than hot-air drying, so, the thermal stability of nature rubber dried by microwave was remarkably improved compared with the other two drying methods.