Influence Factor Analysis on Microbond Test Measuring Interfacial Shear Strengths of Composites

The interfacial shear strengths between two kinds of mesophase pitch-based carbon fibers and epoxy resin matrix were respectively measured by microbond test. The forces when microdebonding occurring between resin microdroplets and carbon fibers were obtained from the load-displacement curve,and the morphologies of debonded microdroplets and carbon fibers were observed by scanning electron microscopy. Then,the average interfacial shear strength,standard deviation and coefficient of variation for samples were quantitatively calculated. Moreover,the relationships between interfacial shear strength and the lengths, diameters of microdroplets, carbon fiber diameter were analyzed. The results show that interfacial shear strength is proportional to the ratio of length-to-diameter of the resin microdroplet,and inversely proportional to the carbon fiber diameter,to the ratio of the microdroplet length-to-carbon fiber diameter,and to the ratio of the microdroplet diameter-to-carbon fiber diameter