Preparation Of Fungal Modified Bamboo Fiber/HDPE Composites And Its Performance

Bamboo-plastic composite materials can effectively utilize bamboo processing residues,improve the comprehensive utilization rate of bamboo resources,and expand the application scope of bamboo resources.It is a new material that promotes the development of green circular economy industries.However,unmodified bambooplastic composites have problems such as high brittleness,poor weather resistance,and poor interfacial compatibility,which seriously reduce their use value.Therefore,improving the toughness and weather resistance of bamboo-plastic composites is an important research in the field of bamboo-plastic composites.direction and hot research topics.In this study,Trametes versicolor(white-rot fungus)was selected as the pretreatment strain of bamboo fiber,and the effects of white-rot fungus pretreatment on bamboo microstructure and chemical composition were investigated by means of Fourier transform infrared spectroscopy,specific surface area determination,scanning electron microscope analysis,and chemical composition analysis;the bamboo fiber/high density polyethylene(HDPE)composites modified by fungi were prepared by injection molding,and the influence law and mechanism of fungi modification on the mechanical properties,mold resistance and weather resistance of bamboo-plastic composites were revealed,so as to provide theoretical and scientific basis for the research of biological modification of bamboo-plastic composites.The following are the main conclusions of this paper:(1)With the extension of pretreatment time of white-rot fungus,the microstructure and chemical composition of bamboo fiber changed more and more significantly.In the process of white-rot fungus pretreatment,with the extension of decay time(3 days,6 days,9 days,12 days and 15 days),the amount of mycelium attached to the surface of bamboo fiber,specific surface area and pore volume gradually increased,while the content of lignin and reducing sugar in bamboo showed a downward trend.When the pretreatment time was 15 days,the specific surface area and pore volume increased by 60%and 100%respectively,the lignin content decreased from 28%in the untreated group to 22%,and the degradation rate of reducing sugar reached 57%;(2)White-rot fungus pretreatment can significantly improve the mechanical toughness and mildew resistance of bamboo fiber/HDPE composites.After short-term(15 days)modification by white-rot fungus,the mechanical toughness of bamboo-plastic composites increased significantly(elongation at break increased by 57%and impact strength increased by 18%).Compared with the untreated group,the growth of mold spores on the surface of bamboo-plastic composites modified by fungi decreased significantly;(3)The properties of modified bamboo fiber/HDPE composites are related to the size of bamboo fiber and the ratio of bamboo to plastic.In this study,the effects of bamboo fiber size(40～60,60～80,80～100,100～120 mesh)and bamboo-plastic ratio(3:7,4:6,5:5)on fungi-modified bamboo-plastic composite are investigated respectively.The results show that when the bamboo fiber size is 60-80 mesh,the bamboo-plastic ratio was 3:7,and the pretreatment time of white-rot bacteria is 15 days,the comprehensive performance of the bamboo-plastic composite material is the strongest,and the bamboo-plastic composites have the strongest comprehensive performance.The water absorption rate and moisture absorption weight increase rate are small,and it has excellent mechanical toughness and thermal stability;(4)The modified bamboo fiber/HDPE composites have excellent weather resistance.After fungus modification,the color change,surface cracking degree and contact angle of bamboo-plastic composites decreased after accelerated aging for 960h.After fungus modification,the mechanical toughness retention rate increased,the weathering degree decreased,and the mold resistance improved.