Interfacial Effects on Impact Fracture of Advanced Polymers

8.1橡胶增韧聚合物的断裂韧性对冲击速度的依赖性利用洛桑理工学院研制的高速拉伸试验机，测试了橡胶增韧PMMA拉伸试样的断裂韧性对冲击速度的依赖性。含有20wt%橡胶颗粒的试样在1 m/s的拉伸速度下表现出韧性的降低，而40wt%的试样在10 m/s下表现出韧性的轻微降低。通过TEM观察发现，增韧的主要原因是橡胶粒子的空穴化，同时伴随着大变形区的银纹引发、银纹生长、银纹分支和剪切变形。8.2耐热、高韧性聚合物共混物的相容性将Flory-Huggins自由能理论应用于三元聚合物共混物（接枝SAN、游离SAN和SMI）的相容性研究，以根据gSAN和fSAN中AN的重量含量以及SMI中PMI的重量含量设计最合适的材料，以改善冲击韧性。8.3具有热塑性基体和破坏机理的FRP的冲击性能在拉伸载荷下以高达10 m/s的不同加载速率测试了界面GF/PA 6、CF/PA 6、GF/mPA 6和CF/mPA 6（m ;改性）的冲击性能。8.4冲击试验机的可靠性研究通过引入洛桑理工学院开发的引伸计技术，构建了单元件和双元件高速引伸计，用于冲击试验中动态效应的实验验证。

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.