Preparation And Properties Of Bamboo Flour/Polypropylene Composites

Nearly,following shortage of global resources and strengthen of environment awareness,people’s demand for wood and petrochemicals has also been increased.Given this background,wood-fiber plastic composites(WPCs)have been a research hotspot in the field of chemical materials.Using natural plant fibers filled polymer matrix not only can enhance its mechanical performance,but also reduce the cost.As all natural fibers are more inclined to be high hydrophilic and high moisture sensitivity,resulting in a poor interfacial adhesion with hydrophobic polymer matrix.To overcome this problem,numerous chemical treatments have been performed to improve the interfacial adhesion of WPCs.In this paper,enhanced the interfacial adhesion between polypropylene matrix(PP)and bamboo flour fillers(BF)that improve the mechanical performance of BF/PP material,the BF was treated by chemical process.The structure and morphology of as-prepared samples were characterized using Fourier transform infrared(FT-IR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and thermogravimetry-differential thermal(TG-DTA).The performance of BF/PP composites treated before and after were studied,and finally the compatible mechanism was evaluated.(1)The modification conditions of BF with KH-550,stearic acid and sodium hydroxide(NaOH)were optimized with indexes of crystallinity,active index and the water contact angle.It is found that when the concentration of NaOH was 10%,the modification effect of bamboo flour was best and the crystallinity can up to 37.2%;when the dosage of KH-550 was 2%,the reaction temperature was 80 ℃,the reaction time was 30 min,best modification results were achieved that the active index could up to be 78.4% and the water contact angle reached 120.4 °.FTIR analysis showed that the bamboo flour was successfully modified that a hydrophobic layer was formed on the surface of bamboo flour in molecular membrane by the reaction between silane coupling agent and hydroxyl group on the surface of bamboo flour.Also,when stearic acid was used as the modifier of bamboo flour,the best modification effect was obtained when the dosage of stearic acid was 2.5%,the reaction temperature was 80 ℃,the reaction time was 30 min,best modification results were achieved that the activation index could up to be 83.2% and the water contact angle reached 132.4 °.FTIR analysis showed that stearic acid was successfully grafted onto bamboo flour through an esterification process.And then,under optimum reactionconditions,BF was composite modified by NaOH and KH-550,and NaOH and stearic acid,respectively.The results showed that composite modified can significantly increase the degree of twisting,roughness and the area of BF surface,which was useful to improve the composites mechanical performance.(2)BF fillers enhanced PP matrix was prepared by melt blending to improve strength and thermal stability.Maleic anhydride grafted PP(MAH-g-PP)was used as compatibilizer.The effects of the filling amount and various modifications on the mechanical performance,thermal stability and microstructure of BF/PP composites were studied.Based on the contrasting analysis,we got that when the dosage of filler was 10%,the BF/PP composites that modified with NaOH and KH-550 composite-modification agent had the best impact strength and tensile strength,which could be 8.49 kJ/m2 and 33.69 MPa respectively,corresponding to 85.8% and 8.6% higher than that of pure PP.As a whole,composite modification agent’s effect was better than single modification agent,and a better disperse ability of BF and higher interficial strength is available.