標題: FRACTURE AND IMPACT PROPERTIES OF POLYCARBONATES AND MBS ELASTOMER-MODIFIED POLYCARBONATES
作者: CHANG, FC
WU, JS
CHU, LH
交大名義發表
應用化學系
National Chiao Tung University
Department of Applied Chemistry
公開日期: 25-一月-1992
摘要: Mechanical properties of polycarbonates (PCs) and elastomer-modified polycarbonates with various molecular weights (MW) are investigated. Higher MW PCs show slightly lower density, yield stress, and modulus. The ductile-brittle transition temperature (DBTT) of the notched impact strength decreases with the increase of PC MW and with the increase of elastomer content. The elastomer-modified PC has higher impact strength than does the unmodified counterpart if the failure is in the brittle mode, but has lower impact strength if the failure is in the ductile mode. The critical strain energy release rate (G(c)) measured at -30-degrees-C decreases with the decrease of PC MW. The extrapolated zero fracture energy was found at M(n) = 6800 or MFR = 135. The G(c) of the elastomer-modified PC (MFR = 15, 5% elastomer) is about twice that of the unmodified one. The presence of elastomer in the PC matrix promotes the plane-strain localized shear yielding to greater extents and thus increases the impact strength and G(c) in a typically brittle fracture. Two separate modes, localized and mass shear yielding, work simultaneously in the elastomer-toughening mechanism. The plane-strain localized shear yielding dominates the toughening mechanism at lower temperatures and brittle failure, while the plane-stress mass shear yielding dominates at higher temperatures and ductile failure. For the elastomer-modified PC (10% elastomer), the estimated extension ratio of the yielding zone of the fractured surface is 2 for the ductile failure and 5 for the brittle crack. A criterion for shifting from brittle to ductile failure based on precrack critical plastic-zone volume is proposed.
URI: http://dx.doi.org/10.1002/app.1992.070440314
http://hdl.handle.net/11536/3548
ISSN: 0021-8995
DOI: 10.1002/app.1992.070440314
期刊: JOURNAL OF APPLIED POLYMER SCIENCE
Volume: 44
Issue: 3
起始頁: 491
結束頁: 504
顯示於類別:期刊論文


文件中的檔案:

  1. A1992GW09700014.pdf