Under the circumstances of accidental fire occurred in petrochemical industries,the polymer pipes exposed to the fire surrounding are often only affected by a long distance heat radiation.In order to avoid the complete waste,it shall be implemented of the fitness-for-service evaluation for the fire damaged materials.In the present research,the PE 100 high density polyethylene pipe material was investigated under the influence of fire damage on the mechanical properties through the simulated experiments under different temperature and different heat exposure time.The fire damaged materials were analyzed via macro mechanical testing and micro structure observation.The influences of different thermal exposure conditions to the chemical properties of PE 100 pipe were investigated.It was shown that the change of mechanical properties of fire materials was influenced by both the polymer chain fracture and annealing effect.For the tensile property,thermal exposure temperature played a dominant role.For the impact energy,the toughening effect induced from annealing was the main factor which made the fracture resistance of the material enhanced with the increase of temperature and heating time.%在石化行业中发生的火灾工况下,暴露于火场周边的高分子管件往往仅受到长距离热辐射的影响而不必完全判废,但须实施受火损伤影响下的材料评级和管件的合于使用评价.针对PE 100高密度聚乙烯管道用材,通过在不同热暴露温度、时间和冷却方式条件下模拟受火损伤的热暴露实验,并对受火损伤材料进行宏观力学性能测试和微观结构分析,研究不同热暴露条件对PE l 00聚乙烯管材机械性能的影响.结果表明:受火材料力学性能的变化受高分子链断裂与退火作用的双重影响;对于拉伸性能,在热暴露温度高时,退火时间的影响起主导作用,在温度较低时则受断链的影响较强;而对于冲击性能,退火的增韧作用起到了决定性的影响,使材料的耐冲击性随温度或时间的增加而增加.
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