SYNOPSISComposites with polypropylene (PP) and jute fiber were prepared by injection molding technique. Maleic anhydride-grafted polypropylene was added as coupling agent to improve the adhesion between jute fiber and PP. A high fiber attrition was noted during injection molding, which had negative effects on the mechanical properties of the composites. The coupling agent improved the tensile and bending strengths, however the elastic and bending moduli were found not to be influenced by the coupling agent. The role of the average fiber length in strengthening of the composites was interpreted with help of the critical fiber length. Fracture surfaces of the composites, and the fiber orientations, were investigated by scanning electron microscopy and light microscopy, respectively. 0 1996 John Wiley & Sons, Inc.
SYNOPSISJute fiber-reinforced polypropylene composites have been produced and characterized in order to investigate the influence of water on their mechanical properties. Being hydrophilic, jute fibers absorb a high amount of water causing swelling of fibers. On the other hand, the thermal shrinkage of polypropylene melt leaves some gaps between jute fibers and matrix material. We investigated whether these gaps could be filled by the swelling of wetted fibers. The fillup of these gaps would result in a higher shear strength between fibers and matrix during fracture. Our results suggest that swelling of jute fibers in a composite material can have positive effects on mechanical properties. 0 1994
The purpose was to study the effect of silane treatment of fillers on viscosity, flexural strength, and hydrolytic degradation of experimental dental composite resins fabricated with these fillers. The fillers consisted of a mixture of barium glass and amorphous silica. The resin was mainly based on ethoxylated bisphenol A dimethacrylate and polycarbonate dimethacrylate. The adsorption of silane on the filler surface was characterized by FTIR. There was significant correlation between the adsorbed silane on filler surface and the silane concentration in silane/methanol solution used for filler treatment. The silane concentration varied from 0.75 to 14% by weight. An increase in silane concentration led to a decrease in viscosities of the corresponding composite resins. The flexural strengths of composites with silanated fillers were greater than that of composites with unsilanated fillers: however, no significant difference was found between the flexural strengths of various silanated groups. The resistance to hydrolytic degradation of different composites increased when the fillers were treated with silane and was the highest at 1.1% silane.
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