Interfacial Shear Strength of Pitch and High Strain Pan Fibers in an Epoxy Matrix

摘要

In advanced polymeric composites reinforced with fibers of glass, carbon, or graphite the ability to effectively use the strength and stiffness of these reinforcing fiber depends on properties of the matrix material and the degree of bounding between fiber and matrix. This work uses the embedded fiber method to directly determine the interfacial shear strength between 1) PAn high strain carbon fibers with different surface modifications and 2) mesophase pitch based carbon fibers of various moduli and surface modifications with an epoxy matrix. The effect of the various surface modifications on the interfacial shear strength was evaluated in an attempt to determine their interrelationships. The results show that sizing of the fiber increases the interfacial shear strength by 23% over an unsized fiber while an oxidative surface treatment produces an increase of over 200% over the untreated PAN carbon fiber. The mesophase pitch based fibers showed a general decrease in the interfacial shear strength with an increasing fiber modulus.