IMPACT PROPERTIES OF CARBON-FIBER-REINFORCED LINEAR AND SHORT-CHAIN BRANCHED POLYETHYLENES

An investigation of the influence of short-chain branched length on im pact behavior of linear high density polyethylene (HDPE), short-chain branched polyethylenes (SBPEs) and their fiber reinforced samples is r eported. The result shows that the total impact energies (E(t)) increa sed with increasing branch length at any given temperature used in thi s study. Similar trend was found for their fiber reinforced samples. F or a given polyethylene resin, E(t) increased with fiber content up to 5%, and then decreased consistently with further increase of fiber co ntent. The amount of E(t) improved due to the presence of 5% carbon fi bers increased significantly with the branch length at temperatures hi gher than 25-degrees-C. In addition, the fracture surface morphology i ndicated that the adhesion between carbon fibers and PE resins increas ed with the branch length. However, the adhesion and the amount of E(t ) improved due to the presence of 5% carbon fibers reduced significant ly with decreasing temperature. Finally, it was found that E(t) decrea sed slightly with rising temperature until the temperature reached aro und 40-degrees-C, and then increased sharply with increasing temperatu re. It is suggested that this ''transition'' behavior is related to th e molecular motion accounting for the alpha transition of PE resins.