聚乙烯燃气管材热压老化特性研究

Study on Hot Pressing Aging Characteristics of Polyethylene Gas Pipe

以PE80管材为研究对象,用水代替燃气,以PE80管材作为老化试样,开展热压老化性能实验,对不同承压条件下的老化管材试样的力学性能、热稳定性、熔融特性进行研究,探究热压条件下聚乙烯燃气管材的性能指标随老化时间的变化规律。在老化前期试样主要发生交联反应,聚合物相互键合交联,拉伸强度上升,在老化后期试样主要发生氧化反应,分子链断裂,拉伸强度下降。老化前期承压试样拉伸强度上升趋势更明显,老化后期承压试样拉伸强度下降趋势更明显。承压老化试样比未承压老化试样拉伸强度下降幅度大1.3%。在整个老化周期,抗氧化剂不断被消耗,导致材料的抗氧化能力减弱,氧化诱导时间下降。不同压力下试样的氧化诱导时间均呈下降趋势。承压试样比未承压试样氧化诱导时间下降幅度大2.4%。熔体质量流动速率在不同的老化时间下变化幅度较小,且承压试样和未承压试样的熔体质量流动速率基本都在0.08 g/min上下波动。管材试样在不同老化时间下的熔体质量流动速率不受压力影响。

Taking PE80 pipe as the research object,using water instead of gas,using the PE80 pipe as the aging sample,the hot pressing aging performance experiment is carried out,and the mechanical properties,thermal stability and melting characteristics of the aging pipe sample under different pressure conditions are studied to explore the change rule of performance index of polyethylene gas pipe with aging time under hot pressing conditions.In the early stage of aging,the specimens mainly undergo cross-linking reaction,the polymers are bonded and cross-linked,and the tensile strength increases.In the late stage of aging,the specimens mainly undergo oxidation reaction,the molecular chain is broken,and the tensile strength decreases.The tensile strength of pressure-bearing specimens in the early stage of aging has a more obvious upward trend,and the tensile strength of pressure-bearing specimens in the later stage of aging has a more obvious downward trend.The tensile strength of the pressure-bearing aged specimens is 1.3%larger than that of the non-pressure-bearing aged specimens.During the whole aging cycle,antioxidants are consumed continuously,resulting in the decrease of antioxidant capacity and oxidation induction time.The oxidation induction time of samples decreases under different pressures.The oxidation induction time of pressure-bearing aged samples decreases by 2.4%more than that of non-pressure-bearing aged samples.The melt mass flow rate varies lttle under different a aging times,and the melt mass flow rates of pressure-bearing samples and non-pressure-bearing samples basically fluctuate up and down 0.08 g/min.The melt mass flow rate of the samples under different aging times is not affected by pressure.