非复用型单翼迷宫式滴灌带人工紫外老化和热老化性能研究

Study on artificial UV aging and thermal aging performance of non-reusable drip tape with labyrinth on one side

分别对滴灌带进行人工加速紫外老化和50℃热老化试验,研究了两种老化后氧化诱导时间(OIT)、熔融温度(T_(m))、拉伸强度(σ_(m))、拉伸断裂应变(ε_(m))、熔体质量流动速率(MFR)和炭黑含量(c)指标的变化,以及50℃热老化后流量均匀性、爆破压力、耐水压、耐拉拔和抗泥沙堵塞水力学使用性能变化或符合国标情况。结果表明,滴灌带人工加速紫外老化后的性能指标变化幅度明显大于50℃热老化的,尤其是OIT;在老化624 h后,人工加速紫外老化的OIT下降速率是50℃热老化的4.25倍。人工加速紫外老化的σ_(m)、ε_(m)、c、T_(m)和MFR下降速率分别是50℃热老化的1.24、1.17、1.11、1.02和1.01倍;滴灌带在人工加速紫外老化后,OIT、σ_(m)、ε_(m)和c的指标保持率变化相对较大;在50℃热老化后OIT保持率变化相对较大,水力学使用性能受50℃热老化影响较小,且在老化过程及624 h后均符合国标要求;对国标OIT不小于5_(m)in的要求而言,当保持率为21%时,σ_(m)保持率达到失效程度;因此,使用过程中滴灌带的OIT应不小于1.05_(m)in,否则可能失效。

An artificial accelerated UV aging experiment and a thermal aging test at 50℃were carried out on a drip tap.The changes in oxidation induction time(OIT),melting temperature(T_(m)),tensile strength(σ_(m)),tensile fracture strain(ε_(m)),melt flow rate(MFR),and carbon black content(c)before and after aging were investigated.The changes of flow uniformity,burst pressure,water pressure resistance,drawing resistance,and sediment blockage resistance hydraulics after thermal aging at 50℃as well as their accordance with national standards were also studied.The results indicated that the variation range of performance indexes of the drip tape after the accelerated UV aging was significantly greater than that after the thermal aging at 50℃,especially fir OIT.After aging for 624 h,the OIT obtained from artificial accel-erated UV aging was 4.25 times the decrement rate of that from the thermal aging at 50℃.Theσ_(m),ε_(m),c,T_(m)and MFR from the artificial accelerated UV aging are 1.24,1.17,1.11,1.02 and 1.01 times as decrement rates of those from the thermal aging at 50℃,respectively.The changes in the retention rates of OIT,σ_(m),ε_(m)and c of the drip tape were very significant after the accelerated UV aging.After thermal aging at 50℃,the change in the OIT retention rate was greater than that of other indexes.The hydraulic performance was less influenced by the thermal aging at 50℃,which could meet the requirement of the national standard for the 624 h aging.As for the OIT of no more than 5 minutes in the national standard,the retention rate ofσ_(m)reaches a failure level at 21%.Therefore,the OIT of drip tapes should not be less than 1.05 min to avoid the invalidation of practical use.