Thepolyethylene is ofunique predominance in light armor applications.The mechanical properties ofextruded polymers are strongly affected by their molecular structures and distribution.Therefore,twotypicaldifferenttypes of extrudedpolyethylene:low-density polyethylene(LDPE)and ultra-high molecular weightpolyethylene(UHMWPE)werechosenin thisstudy to experimentally investigate the dependency of molecule structures towardsmechanical properties of polyethylene over a wide range of strain rate from 0.001 s~(-1)up to3300s~(-1).The static anddynamic material testsrevealed thatextruded UHMWPE showed a much more obvious strain-hardening effect than that ofLDPE,in addition,it is of an extraordinary higher elongation and stress at failure in Quasi-static tensile tests,and much higher yield stress at SHPB tests.Furthermore,Cowper-Symonds model wasemployed to predict the strain rate effect and in good agreement with the experimental results.It indicates that UHMWPEperforms abettermechanicalbchaviorunderhigh strainratesdeformationthanLDPE;hence,the extruded UHMWPE is more amenable to large deformation and high high-speed impact conditions,benefits from its long molecular chains and few brancbed chains.
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