天然橡胶老化时间对橡胶弹簧力学性能的影响

Effect of Accelerated Aging of Natural Rubber on Mechanical Properties of Materials

采用烘箱加速老化法对天然橡胶进行热老化实验,通过对试样进行硬度测试、单轴静态拉伸试验和动态力学性能测试(TMA),研究了老化时间对材料力学性能的影响,并根据老化得到了力学性能随时间变化曲线,为可用于高铁中的橡胶弹簧的寿命采集系统提供了失效判定数据。结果表明,随着老化时间的增加,天然橡胶的力学性能呈下降趋势,当老化时间小于96 h时,防老剂4020以及偶联剂Si69能够有效延缓了NR的热氧老化及NR力学性能下降的速度;在120℃下,加速老化144 h时,天然橡胶硬度达到40.2 MPa,断裂伸长率达到211.72%,弹性模量为3.22 MPa,此时,硬度达到了极限值,其他力学性能下降较快,橡胶弹簧的采集系统应在此时输出更换新制品的信号。

The thermal aging test of natural rubber was carried out by oven accelerated aging method.The effects of different aging time on the mechanical properties of the materials were studied by hardness test,uniaxial static tensile test and dynamic mechanical property test(TMTA).According to the change of mechanical performance parameters obtained by aging,the failure determination data was provided for the life collection system of the rubber spring for high iron.The results showed that the mechanical properties of natural rubber showed a decreasing trend with the increase of aging time.Before the aging of 96 h,the addition of antioxidant 4020 and coupling agent Si69 effectively delayed the thermal oxygen aging of NR and make NR mechanical performance slower.When the natural rubber accelerates aging at 120 ℃ for 144 h,the hardness reached 40.2 MPa,the elongation at break reached 217.12%,and the elastic modulus was 3.22 MPa,at this time,the hardness had reached the limit value,and other mechanical properties were reduced rapidly.The rubber spring collection system should output a new product signal at this time.