著者
東藤 貢 高橋 清 / KAUSH H. Henning
出版者
一般社団法人日本機械学会
雑誌
日本機械学会論文集. A編 = Transactions of the Japan Society of Mechanical Engineers. A (ISSN:03875008)
巻号頁・発行日
vol.64, no.617, pp.36-43, 1998-01-25
参考文献数
13
被引用文献数
2 2

Mode I fracture behavior of rubber toughened PMMA (RTPMMA) was studied over five decades of displacement rates (10<SUP>-4</SUP>-13 m/s) using a high-speed tensile testing machine. Two kinds of RTPMMA, extruded RTPMMA containing 20 wt.% rubber particles (EM20) and pressed RTPMMA containing 40 wt.% rubber particles (PM40), exhibited different rate dependences of the maximum stress intensity factor K<SUB>1max</SUB> and the maximum energy release rate G<SUB>1max</SUB>. K<SUB>1max</SUB> and G<SUB>1max</SUB> of EM20 decreased rapidly at high rates (1-11 m/s). This suggests that the toughening effect due to rubber blending was dramatically reduced at the high rates. On the other hand, PM40 maintained high K<SUB>1max</SUB> and G<SUB>1max</SUB> values at all rates tested in this study. Thus, PM40 maintained the toughening effect even at high rates up to 13 m/s. For comparison, unmodified PMMA was also examined, and the results showed that K<SUB>1max</SUB>of neat PMMA increased with the increase in displacement rates and G<SUB>1max</SUB> remained constant as the rate increased. Discussion is given on the rate-dependent K<SUB>1max</SUB> and G<SUB>1max</SUB> values, taking (K<SUB>1max</SUB>)<SUP>2</SUP>/G<SUB>1max</SUB>into account. The fracture surface morphology of the specimens is also discussed.
著者
東藤 貢 高橋 清 JAR BenP.Y. BEGUELIN Philippe
出版者
一般社団法人日本機械学会
雑誌
日本機械学會論文集. A編 (ISSN:03875008)
巻号頁・発行日
vol.65, no.631, pp.432-438, 1999-03-25
参考文献数
21
被引用文献数
1 1

Toughening mechanisms of three types of rubber toughened poly (methyl methacrylate) (RT-PMMA) were investigated under mode I loading condition by optical and electron microscopies in conjunction with the quantitative evaluation of mode I fracture toughness. Polarized optical microscopy clearly exhibited damage zone development ahead of a crack-tip of the RT-PMMAs. The three RT-PMMAs revealed different shapes of the damage zone. Transmission electron microscopy exhibited microcrazes nucleated in the equator of rubber particles within the damage zones. Extensive deformation of rubber particles corresponding to localized shear yielding of the PMMA matrix was also found in a region close to a propagating crack-tip. In addition, cavitation of rubber particles was observed in the vicinity of the crack. It is therefore understood that the toughening of the RT-PMMAs is due to energy dissipation caused by the microdamage formations such as microcrazing, matrix shear deformation and rubber particle cavitation ahead of the crack-tip.