Interfacial Effects on Impact Fracture of Advanced Polymers

8.1橡胶增韧聚合物的断裂韧性与冲击速度的关系使用洛桑理工学院开发的高速拉伸测试仪，测试了橡胶增韧PMMA拉伸试样在高达10 m/s的拉伸速率下的断裂韧性依赖关系。当拉伸速度为1 m/s时，含20 wt%橡胶颗粒的试样的韧性下降。而wt%为40的试样在10m /s时韧性略有下降。通过透射电镜观察发现，引起增韧的主要原因是橡胶颗粒的空化，伴随着裂纹萌生、裂纹扩展、裂纹分支和大变形区剪切变形。8.2耐热、高韧性聚合物共混物的混相运用flory - huggins自由能理论研究了接枝SAN、自由SAN和SMI三元聚合物共混物的混相，根据gSAN和fSAN中AN的重量含量以及SMI中PMI的含量来设计最合适的材料，以提高冲击韧性。分析结果表明，最佳重量百分比为gSAN（33）、fSAN（30）和SMI（55）。8.3对含热塑性基体的FRP在不同加载速率下的冲击性能和损伤机理界面(egf /PA6、CF/PA6、GF/mPA6和CF/mPA6 （m；改性）进行了测试，加载速率可达10 m/s。研究发现GF/PA6是四种frp中最坚韧的。8.4冲击试验机可靠性研究通过引入美国洛桑理工学院开发的延伸仪技术，构建了单单元和双单元高速延伸仪，对冲击试验中的动态效应进行了实验验证。

8.1 Dependence of fracture toughness of rubber toughened polymers on impactvelocityUsing a high-speed tensile tester developed at Lausanne Institute of Technology, rubber toughened PMMA tensile specimens were tested for their fracture toughness dependence on the tensile rate up to 10 m/s. Specimens containing 20 wt% rubber particles exhibited decrease of the toughness at an elongation speed of 1 m/s.whereas specimens of 40 wt% showed a slight decrease in the toughness at 10 m/s. By TEM observation, it has been found that main causes for the toughening are cavitation of rubber particles accompanied by craze initiation, craze growth, craze branching and shear deformation at extensively deformed region. Craze branching behavior has been found for the first time by this work.8.2 Miscibility of heat-resistant, high toughness polymer blendsFlory-Huggins free energy theory was applied to a study of miscibility of three element polymer blends (grafted SAN,free SAN and SMI) to design most appropriate material regarding the AN weight contents in gSAN and fSAN,and PMI in SMI for the improvement of impact toughness. The analysis yielded that the optimum weight percents are gSAN (33), fSAN (30) and SMI (55).8.3 Impact performance of FRP with thermoplastic matrices and damage mechanismat interfaceGF/PA6, CF/PA6, GF/mPA6 and CF/mPA6 (m ; modified) were tested under tensile loading at various loading rate up to 10 m/s. It has been found that GF/PA6 is the toughest among the four FRPs.8.4 Reliability study of impact testersBy introducing an extensometry technique developed at Lausanne Institute of Technology, one-element, and two-element high-velocity extensometers were constructed for experimental verification of dynamic effects in impact testing.