Scanning Electron Microscopy Studies on Tear and Wear Failure of Short Kevlar Fiber-Thermoplastic Polyurethane Composite

Abstract Tear and wear properties of short kevlar fiber, Thermoplastic polyurethane (TPU) composite with respect to fiber loading and fiber orientation has been studied and the fracture surfaces were examined under scanning electron microscope (SEM). Tear strength first decreased up to 20 phr fiber loading and then gradually increased with increasing fiber loading. Anisotropy in tear strength was evident beyond a fiber loading of 20 phr. Tear fracture surface of unfilled TPU showed sinusoidal folding characteristic of high strength matrix. At low fiber loading the tear failure was mainly due to fibermatrix failure whereas at higher fiber loading the failure occurred by fiber breakage. Abrasion loss shows a continuous rise with increasing fiber loading, the loss in the transverse orientation of fibers being higher than that in the longitudinal orientation. The abraded surface showed long cracks and ridges parallel to the direction of abrasion indicating an abrasive wear mechanism. In the presence of fiber, the abrasion loss was mainly due to fiber loss.