標題: TOUGHENING BEHAVIOR OF ELASTOMER-MODIFIED POLYCARBONATES BASED ON THE J-INTEGRAL
作者: LEE, CB
CHANG, FC
應用化學系
Department of Applied Chemistry
公開日期: 1-Jun-1992
摘要: The J-integral method to determine the fracture toughness of tough and ductile polymeric materials previously developed has been applied to the elastomer-modified polycarbonates. This investigation compares three different methods to obtain Jc: the conventional crack growth length, the stress whitening zone, and the newly developed hysteresis method. Jc values obtained from these three comparative methods are fairly close. The hysteresis method has the advantage over the other two methods of obtaining Jc without requiring the measurement of the crack growth length or the stress whitening zone, therefore avoiding the controversy in defining crack blunting. Results also indicate that the effect of elastomer quantity in polycarbonate on Jc is insignificant as long as the crack is in a stable condition. Higher elastomer contents in polycarbonate result in higher dJ/d-DELTA-a, dJ/d-DELTA-l, and tearing modulus (Tm). This indicates that the elastomer toughening mechanism is due to the increase of the energy required for crack growth extension. The hysteresis loss energy is directly related to the size of the crack tip plastic zone, and the presence of more elastomer indeed increases the crack tip plastic zone, thus making the polycarbonate tougher. Besides, the presence of elastomer tends to increase the crack initiation displacement and shift the failure modes from an unstable fracture. Jc and the criterion for crack initiation based on rate change of hysteresis energy are discussed in detail.
URI: http://dx.doi.org/10.1002/pen.760321206
http://hdl.handle.net/11536/3402
ISSN: 0032-3888
DOI: 10.1002/pen.760321206
期刊: POLYMER ENGINEERING AND SCIENCE
Volume: 32
Issue: 12
起始頁: 792
結束頁: 803
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