Fracture toughness and Microstructures of Carbon Fibers

本研究旨在评价各种类型碳纤维的机械性能。在本实验中，对13种碳纤维进行了评价。利用自行研制的扭转振动试验机对碳纤维的剪切模量进行了测试。通过这种设置，可以获得剪切模量和内摩擦。内耗是与碳纤维微观结构密切相关的重要指标之一。通过这些实验，总共评价了13种PAN基（高模量型、高强度型）和沥青基碳纤维。不同的机械性能和内部摩擦之间的关系，清楚地观察到的差异。在PAN基碳纤维中，剪切模量随杨氏模量的增加而减小。另一方面，沥青基碳纤维的剪切模量随着拉伸强度的增加而降低。在PAN基碳纤维中，拉伸强度的增加导致内耗的增加。这种力学性能与内耗之间的关系可以用碳纤维微观结构的差异来解释。

This study is aiming at evaluation of mechanical properties of various types of carbon fibers. In this experiment, 13 kinds of carbon fibers were evaluated. Shear modulus of carbon fiber (GLT) was measured using torsional vibration testing machine, which was originally manufactured by ourselves. With this set-up, shear modulus and internal friction can be obtained. The internal friction is expected as one of the important indication closely relating tothe microstructure of carbon fibers. With these experiments, totally 13 kinds of PAN based (high modulus type, high strength type) and pitch based carbon fibers were evaluated. Difference in the relations between various mechanical properties and internal friction were clearly observed. In PAN based carbon fibers, shear modulus was decreased with Young’s modulus. On the other hand, shear modulus decreased with tensile strength in pitch based carbon fibers. In PAN based carbon fibers, increase in tensile strength resulted in increase in the internal friction. Such relations between mechanical properties and the internal friction were expected to be explained by the difference in the microstructures of the carbon fibers.