Study On The Preparation Of Biomass Composites Reinforced By Modiifed Bagasse Fiber

Plastics came from oil and brought human interests and convenience, but it also causedglobal environmental pollutions and energy crises. The use of biomass materials is one of theeffective methods to mitigate these problems. Bagasse fiber(BF) is a renewable agriculturalwaste resource, and in our country we haven’t made good use of BF which waste a lot of BFresources. In PVA/ST biodegradable material, if BF was added as a renewable agriculturalwaste resource, it can make use of abandoned bagasse resources and produce a high strengthand good water resistance biodegradable material at the same time.On the basis of the research group’s preliminary studies, this paper studied processingmethods and optimize the preparation of PVA/ST/BF composite, and use heat treatment andmicrowave alkali treatment to produce a new PVA/ST/BF composite, then analyzed bagassefiber and composite by surface contact angle, FTIR, XRD, XPS and SEM.This paper studied the effect of starch and PVA types, plasticizer content, PVA/ST ratiosand bagasse particle size for PVA/ST/BF blends in thermoplastic processing and mechanicalproperties. As a result, we chose PVA1799, corn starch, PVA: ST=40:60,40phr plasticizerand100mesh bagasse as research subjects. In the contrast of three processing methods,Extrusion-injection was the best method and can significantly improve elongation in thecompare to other methods.Studied the effect of BF content for PVA/ST/BF composite’s properties, as BF were rigidmolecules, with the increasing content of BF, its elongation and thoughness began to decline,while tensile strength and tensile modulus had significantly improved. On the other hand, BFcontent increased, the toughness of the composite declined, so that the elongation of thecomposite fell at the same time. When BF content was no more than40phr, the compositecan maintain a good toughness and strength. Composite torque rised with increasing BFcontent, but when BF content was between10-30phr, plasticzing time decreased, so it canenhance processing performance of the composite to some extent. The water resistance of thecomposite had been significantly improved with BF content increased.BF through heat treatment, low boiling point extracts was removed, part of hemicellulosedegraded and fiber surface hydroxyl’s content reduced. It decreased the polarity of the fiber’s surface and crystallinity at the same time. If heat treatment was too high temperature or toolong heat treatment time, it will result in the degradation of lignin and cellulose, whichdeclined fiber’s strength, badly affected mechanical strength of the composite. With theincreasing temperature, tensile strength of the composite was improved at first and thendecreased. When temperature of200℃was10.13Mpa, which was increased by79%compare to the original. And the tensile modulus remained the same trend as the tensilestrength, and it was about100%higher than the original. Fixed temperature at200℃, thecomposite can get the best performance at5min heat treatment.With microwave alkali treatment, the polarity of fiber’s surface decreased. After3%NaOH treatment, BF became very shiny, fibrosis significantly and most of the hemicellulosewas removed. After20%NaOH treatment, not only hemicellulose was removed but alsodestroyed cellulose, and celluloseⅠchanged into cellulose II which lowered fiber’s strength.With3%NaOH treatment, composite attained a maximum tensile strength, doubled theoriginal. Meanwhile, tensile modulus of the composite was3.4times of the original. Thenwith the increase of the concentration of alkali solution, tensile strength and tensile modulusof the composite decreased. When the concentration of NaOH was20%, tensile strength andtensile modulus were even lower than the original.