報告書番号

H07018

タイトル（和文）

陽電子消滅法の高分子材料評価への適用可能性

タイトル（英文）

Applicability of Positron Annihilation Spectroscopy to Evaluation of Polymer Materials

概要 （図表や脚注は「報告書全文」に掲載しております）

近年、高分子材料の微細構造変化との関連性が指摘されている自由体積の存在が注目されており、材料物性との相関を解明できれば劣化現象の詳細な理解につながると考えられる。本研究では、代表的な高分子材料として、密度の異なる6種類のポリエチレンと架橋ポリエチレン（XLPE）を対象に、陽電子消滅測定法を用いて自由体積を測定し、熱膨張係数や引張り強さなどの材料物性値との関係を調べた。その結果、自由体積半径はいずれの試料でも約0.3nmで、材料の違いはほとんど見られなかったが，自由体積の数密度は材料により異なった。また、体積と数密度を考慮した比自由体積量は材料密度が大きいものほど小さくなる関係が明らかになった。さらに、比自由体積量が多い材料ほど熱膨張係数は大きく，引張り強さは小さくなり，比自由体積量と両者は強い相関があることが判明した。

概要 （英文）

Recently, it's been pointed out that free volumes in polymer materials are related to change in their microscopic structure, and thus it is considered that degradation mechanism of polymer materials will be well understood if correlations between free volumes and various characteristics of polymer materials are clarified. In this study, six types of polyethylene with different densities and cross-linked polyethylene (XLPE) were selected as typical polymer materials, and their free volumes were evaluated. Then, their relationship between free volumes and material characteristics such as thermal expansion and tensile strength were investigated. As a result, it was found that their free volume radii are about 0.3nm and the difference was small, but their number densities were different. We proposed the relative free volume quantity by taking account of both of the volume and the number density. The relative free volume quantity decreased with the material density. Moreover, it increased with the increase in the coefficient of thermal expansion and with the decrease in the tensile strength. Thus, the correlation between the relative free volume quantity and both of the material characteristics were confirmed.

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