STUDY ON IMPROVEMENT OF MECHANICAL PROPERTIES OF CFRP DUE TO RUBBER MODIFICATION OF EPOXY MATRIX USING SUBMICRON SPHERES

首先，为了了解亚微米级CNBR(直径70~100 nm的交联型丁腈橡胶)对橡胶改性后环氧乙烷与基材界面强度的改善情况，用DCB试件测试了一种环氧树脂在I类载荷(静态和循环)下的粘接强度。实验结果表明，当CNBR体积分数为10%时，环氧树脂的粘接强度最大。在疲劳裂纹扩展速率较高的情况下，由于CNBR橡胶的改性，在静态载荷和循环载荷下，界面强度都得到了很大的提高。在这两种情况下，断裂都以内聚方式发生，而界面破坏发生在包括门槛值附近的低裂纹速度下。在这种情况下，橡胶改性并没有提高阈值。利用CRABON织物评价了橡胶改性对环氧基复合材料强度…的影响碳纤维增强塑料的更多性能本研究中使用的层合板是通过手工铺设的方法制成的。测试了静态载荷下的拉伸、压缩强度和不同温度下的疲劳强度，以及I类载荷下的层间强度。通过实验得出了以下结论。在较宽的环境温度范围内，由于CNBR的改性，I型层间强度(断裂韧性)得到了极大的提高。这比未修改的情况高出两倍多。冲击强度也得到了提高，而在强度方面，在任何测试温度下拉伸和压缩都会发生下降。CNBR改性对玻璃化转变温度(Tg)也没有影响。这是抗拉和抗压强度性能没有退化的原因之一。环氧树脂对CNBR的改性对CFRP的疲劳寿命影响不大。由于CNBR中含有亚微米级的CNBR微球，寿命有所降低。较少

Firstly, in order to obtain information on improvement of interfacial strength properties between rpoxy eesin and substrate due to rubber modification using submicron CNBR (Cross-linked acrylo Nitrile Butadiene Rubber : 70-100 nm in diameter) spheres, adhesive strenghts of an epoxy resin under Mode I loadings (both static and cyclic) were examined using DCB specimens. The experimental results revealed that The adhesive strength of the epoxy resin became maximum when the CNBR volume fraction was 10%. The interfacial strengths were greatly improved due to CNBR rubber modification under static loading as well as under cyclic loading when the fatigue crack growth rate was relatively high. In both cases, fracture occurred in a cohesive manner while interfacial failure occurred at low crack velocity including near threshold. In this case, the threshold was not improved due to rubber modification.Crabon fabric was used to evaluate the effect of rubber modification of epoxy matrix on strength … More properties of CFRP.The laminates used in the study were fabricated by the hand-lay-up method. Tensile and compressive strenghts under static loading and fatigue strength at several temperatures were measured as well as inter-laminar strength under Mode I loading. The following conclusions were drawn from the experiment. Mode I inter-laminar strength (fracture toughness) is greatly improved due to CNBR modification at a wide range of environmental temperature. It is more than two times higher than that for unmodified cases. Impact strength is also improved while on strength reduction in tension at any test temperature occurs as well as in compression. No reduction in Tg (glassy transition temperature) due to CNBR modification is found as well. That is one of reason for no degradaiton in both tensile and compressive strength properties. CNBR modification of epoxy matrix does not badly affects on the fatigue life of CFRP.Any life reduction was found due to inclusion of submicron spheres of CNBR. Less