Modifications On Palm Fiber And Research On Interface Properties Of Modified Palm Fiber Reinforced Polypropylene Composites

With the increasing depletion of non-renewable resources and people’s growing awareness of environmental protection,research and development of natural fiber reinforced composites catch more and more attention.Natural fiber as reinforcement is a renewable resource,the thermoplastic matrix are soluble and meltable.Natural fiber reinforced thermoplastic matrix composites are more environmental,and are advantageous to the recycling of composite materials.But the strong water absorption of natural fibers and hydrophobic of thermoplastic matrix are harmful to interface compatibility of the two phases.the interface can be improved by modifying natural fibers.The main subject of this paper is to improve the performance of the interface between the palm fiber and polypropylene matrix by surface modification on palm fiber.Firstly.by designing orthogonal experiments optimize the process parameters of alkali treatment and heat treatment,examine four factors:concentration of the alkali treatment, temperature of alkali treatment.temperature of heat treatment.time of heat treatment.each factor arrange four levels.testing the static contact angle of modified libers to research welting property.testing transverse tensile properties of modified fiber reinforced polypropylene composite.By orthogonal analysis ot these two indicators,we optimized the process parameters of alkali treatment and heat treatment:the concentration of alkali treatment is10%:temperature of heat treatment is110℃:the time of alkali processing is12h;the time of heat treatment is30min. Secondly.the optimal alkali heat treatment process was regard as the fibers pretreatment,the fibers was applied to three different chemical modification methods on the basis of pretreatment.Such as polyvinyl chloride (PVC) coating.maleic anhydride (MA) graft-modification,stearic acid modification.For each method,testing surface morphology of modified fibers by a scanning electron microscope (SEM);analyzing fibers’ infrared spectroscopy by using a Fourier transform infrared spectrometer: using computer controlled universal testing machine to test the transverse and longitudinal tensile properties of modified fiber reinforced polypropylene composites;observing the morphology of fracture section of composites through SEM.After comparison among testing data of tensile experiments we found:when the concentration of PVC coating was2%,the transverse and longitudinal tensile strength of fiber-reinforced composites reached the maximum, and the thin PVC film was distributed uniformly on the surface of modified fibers at this time while compared with unmodified fibers,hydroxyl absorption peak on the infrared spectra of the fiber was significantly reduced,fibers were pulled out from the matrix through observing fracture section of composite,the matrix cracked;When the concentration of the maleic anhydride graft-modification reached to20%,the fiber surface was uniformly distributed fine granular white substances, the hydroxyl absorption peak on the infrared spectra was significantly weakened,the transverse and longitudinal tensile strength of the fiber-reinforced composite at this concentration reached a maximum,the interface between the fiber and matrix slightly debonded through observing the fracture section of composite; when the concentration of stearic acid reached15%,the transverse and longitudinal tensile strength of fiber-reinforced composite material reached a maximum,the fibers were not pulled out from the matrix, composite had a well-bonded interface.Finally,we compared the three modification methods’ influence on the tensile properties of the composites,after comparison we found that PVC (2%) coated fiber reinforced polypropylene composite reached the maximum of longitudinal tensile strength;stearic acid (15%) modified fiber-reinforced composite material reached a maximum of transversal tensile strength.