Abstract：The water blade electrode method was applied to accelerate water-tree aging of SEBS (styrene-ethylene/butylene-styrene triblock copolymer)/PP (polypropylene) composites and LDPE (low density polyethylene), and their differences in anti-water-treeing performance were analyzed through crystallization and mechanical properties experiments. The water tree morphology, spherulitic structure, melting-crystallization characteristics and lamella structure of the materials were obtained by PLM (polarizing microscope), DSC (differential scanning calorimeter) and SEM (scanning electron microscope), respectively. In addition, the dynamic relaxation characteristics and stress-strain characteristics of the material were studied by DMA (dynamic thermomechanical analyzer) and electronic tensile machine respectively. The results of water blade electrode method show that there is no water-tree aging phenomenon appears in PP with high crystallinity and elastomer SEBS. Although SEBS/PP composites have water tree structure after accelerate water tree aging experiments, its water tree size is significantly lower than that of LDPE. It indicates from crystallization and mechanical properties that PP has larger crystal size, higher mechanical strength and lower dynamic relaxation loss factor compared with LDPE. The SEBS exists as "islands" in the composite material. The PP lamella is shortened and its spherulite boundary is blurred due to the addition of SEBS. Moreover, the anti-sliding ability of PP will decrease under external force in the existence of SEBS. The main reason for SEBS/PP composite has better anti-water-aging performance than LDPE is that the former has higher crystallinity and stronger anti-slip ability between lamella reflected by crystallization and mechanical properties experiments.
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2019, Vol. 34 
