Effect of 60Co-γ on the melting behaviour of single and poly-crystalline polyethylene

International Journal for Radiation Physics and Chemistry Pub Date : 1976-01-01 DOI:10.1016/0020-7055(76)90026-7

S. Rafi Ahmad, A. Charlesby

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引用次数: 20

Abstract

The effect of ionizing radiation on high density poly (HD) and single (SC) crystals of polyethylene samples were investigated by DSC. For HD material the heat of fusion (ΔH_f) was found to drop by only ∼ 17% at about 700 Mrad of radiation dose with no detectable corresponding change in the melting temperature T_m. In contrast approximately 67% drop in ΔH_f and 18 K in T_m was observed for SC specimen. Such drastic differences in the melting behaviour were ascribed to greater sensitivity of the SC material to irradiation as far as effecting the crystal structure is concerned. Crosslinking taking place in the fold surface of the SC specimen (amorphous region) increases the strain energy at the fold and progressively affects the nearby crystal lattices. The amorphous region in HD material is different in morphology, and crosslinking taking place in that region does not affect the crystal structure substantially.

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60Co-γ对单晶和多晶聚乙烯熔融行为的影响

用DSC法研究了电离辐射对聚乙烯样品高密度聚(HD)和单晶(SC)的影响。对于HD材料，在约700 Mrad的辐射剂量下，熔合热(ΔHf)仅下降了约17%，而熔化温度Tm没有检测到相应的变化。相比之下，SC样品的ΔHf和Tm中的18k含量下降了约67%。这种熔化行为的巨大差异归因于SC材料对辐射的更大敏感性，就影响晶体结构而言。在SC试样的褶皱表面(非晶区)发生的交联增加了褶皱处的应变能，并逐渐影响到附近的晶格。HD材料的非晶态区形态不同，该区域发生的交联对晶体结构影响不大。

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International Journal for Radiation Physics and Chemistry

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