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폴리올레핀 배관의 기계-화학적 열화에 따른 응력 재분포
최병호(Byoung-Ho Choi),Alexander Chudnovsky 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The fracture phenomena in engineering thermoplastics resulting from chemical degradation is usually observed in the form of a microcrack network within a surface layer of degraded polymer exposed to a combined action of mechanical stresses and chemically aggressive environment. Degradation of polymers is usually manifested in a reduction of molecular weight, increase of crystallinity in semi crystalline polymers, increase of material density, a subtle increase in yield strength, and a dramatic reduction in toughness. The critical level of degradation for fracture initiation depends on the rates of toughness deterioration and build-up of the degradation related stresses as well as on the manufacturing and service stresses. In this paper, the evlauation of mechano-chemical degradation induced stress is attempted, and the application of the evaluated stress to the fracture initiation of polymer pipes is presented.