Fatigue-Fracture Surface of Polycarbonate Subjected to Heating/Cooling Cycles under Longitudinal Confinement

• Published in: KOBUNSHI RONBUNSHU Vol. 63; no. 12; pp. 767 - 773
• Main Authors: TANAHASHI, Mitsuru, KOHSAKA, Noriaki, MORI, Masao, HATAO, Takuya, KATSUMURA, Akifumi, TAKEDA, Kunihiko
• Format: Journal Article
• Language: Japanese
• Published: The Society of Polymer Science, Japan 01.01.2006
• Subjects: Fatigue; Fracture; Heat Stress; Polycarbonate; Striation
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.63.767

A specimen of bisphenol-A-type polycarbonate (BPA-PC) was firmly held between two copper plates with coefficients of thermal expansion different from that of BPA-PC and subjected to thermal cycles in the temperature ranges of 233 K to 363 K and 218 K to 398 K. The fatigue-fracture surfaces were examined by scanning electron microscopy. The relation among the internal strain of the specimens, temperature range, and fatigue-fracture surface was investigated. The regular and clear wavelike pattern observed on the fracture surface was similar to those of metals, such as steel and aluminum, but it characteristically had two kinds of patterns, i.e., widely and narrowly spaced waves. The number of the patterns was proportional to the thermal cycles. The fracture surface was influenced by the temperature range of the thermal cycle. The width of the crack propagation occurring in the wider temperature range was 5 times as large as that occurring in the narrower temperature range. Polymer chain relaxation did not play an important role in the fatigue phenomena observed in the BPA-PC subject to thermal cycles.