Preparation And Characterization Of Kraft Fiber Reinforced Unsaturated Polyester Composites

Thermoset Kraft-wood fiber reinforced unsaturated polyester resin were made with hot-press mouding.Varies the preparation condiciton to optimal the preparation technology. Two vinyl isocyanate modifiers were made to modified the composites, mercetization treatment on the Kraft fiber and PAPI modified kraft fiber-unsaturated polyester resin composites were made with the treated fiber to investigate the effect of mercetization treatment on the PAPI modified kraft fiber-unsaturated polyster resin composites. The performances of composits were investigated in terms of tensile evaluation, DSC, DMA, FTIR, XRD and SEM. The result indicate that:The apparent cure activation energy of UPE formulation with0.5PHR (per hundred resin) methyl ethyl ketone peroxide (MEKP) as initiator and the styrene as crosslinking monomer is64.80KJ.mol-1. The optimal preparation condictions are initiator content0.5PHR, moulding pressure15MPa, moulding temperature125℃, and moulding time300s.PAPI can effectively improved the tensile properties, aging resistant and water adsorption of the composites. Mercetization treatment on the Kraft fiber for a long time decrease the degree of crystallinity, and, therefore, led to the negative effect on the composites properties.TDI grafted to Castor oil vinyl isocyanate modifier(TCVI) was prepared, Kraft fiber reforced unsaturated resin composites with varies modifier content were prepared at the optimized hot press condiction. The result indicated that the TCVI can improve the tensile strength of composites with small amount of modifier, increasing the modifier content will introdcuce too many flexible chain which have negative effect on the tensile strength of the composites. Low content of NCO group and C=C double bond of castor oil also influence the modify effect.Another VI modifier (THVI) was prepared with TDI and HEMA, resulting in the tensile strength of modified composites up to167.6MPa. The better aging resistant and lower water adsorption were attributing to the significantly improved interfacial adhesions between the Kraft fiber and the UPE matrix because the coupling agent VI has both active isocyano groups which react with the Kraft fiber and vinyl groups which are co-polymerizable with the UPE resin.