Use of titanate coupling agents in kevlar–phenolic composites

Abstract

AbstractSurface modification of Kevlar fibers with titanate coupling agents for improved adhesion of the fiber and resin in Kevla–phenolic composites has been attempted to explore the possibility of enhancement in adhesion and bulk properties of composites for friction materials. Titanate coupling agents were used and flexural properties of the Kevlar–fiber reinforced composites determined. A study of different amounts of the coupling agents at the fiber–matrix interface suggested that 2% by weight of fiber was the optimum amount, in terms of improvement in flexural properties. The composite samples with the coupling agents showed an increase in flexural strength over the untreated samples, with the maximum increase of about 18% over the control. Water‐absorption studies were conducted on Kevlar–phenolic composites treated with organotitanates to detemine the effectiveness of these coupling agents in improving resistance to moisture attack. The treated Kevlar–phenolic composite samples exhibited greater resistance to moisture‐ingress over the untreated samples. The control samples showed a decrease of 17% in flexural strength. The largest decrease in strength was 14% for the treated samples containing coupling agent tetrakis (2‐ethylhexyl) titanate (TYZOR TOT). Recovery in strength on reconditioning was also greater for treated samples over control. A recovery in strength of about 94% was seen for some treated samples. © 1994 John Wiley & Sons, Inc.