MATRIX-SIZE INTERACTIONS IN EPOXY-GLASS FIBERS COMPOSITES IN RELATIONTO MECHANICAL RELAXATIONS AND EFFECTS OF THERMAL AGING

A study was carried out to examine the effect of removing the size fro m the surface of glass fibers in order to determine its role with resp ect to thermoxidative aging. Dynamic mechanical relaxation data have r evealed that mechanical losses were always greater than the calculated upper bound values. The effects of removing the size from the surface glass fibers for epoxy matrix composites were found to be completely different when a fluoroligomer was used to modify the resin. Contrary to the case of the conventional epoxy resin, the characteristics of th e composites containing fluoroligomer-modified resin were found to be insensitive to the removal of the size from the glass fibers surface. The presence of the size on the surface of the fibers provides an inte rlayer that degrades through the formation of more lightly crosslinked products than the matrix, thereby providing a large increase in dynam ic mechanical losses after thermal aging. (C) 1995 John Wiley and Sons , Inc.