Study On The Composite Mechanism And Properties Of Glueless Bamboo Composite

China is rich in bamboo resources,and the bamboo industry is developing rapidly.It is beneficial for the healthy,stable and sustainable development of the bamboo industry to make rational use of the surplus of the bamboo industry and realize the utilization of all bamboo resources.In this study,bamboo and its derivatives were taken as the research object to explore the best preparation process of bamboo composite,analyze the mechanical properties,volatile properties,heat-resistant properties and antibacterial properties of bamboo composite,and analyze the composite mechanism and volatile reduction mechanism of bamboo composite.The specific conclusions are as follows:1.Obtain the best preparation process.The effects of bamboo vinegar treatment time,hot pressing temperature,hot pressing pressure and hot pressing time on the mechanical properties of bamboo composite were studied by orthogonal test and response surface method.According to the test results and feasibility,the best preparation process was obtained:bamboo vinegar treatment time 15 minutes,hot pressing temperature 165?,hot pressing pressure 4 MPa,hot pressing time 15minutes.Hot pressing temperature and bamboo vinegar treatment time are the main factors affecting the mechanical properties of bamboo composite.2.Clarify the properties of bamboo composite.(1)mechanical properties,verification test results,static bending strength,internal bonding strength,elastic modulus,water absorption thickness expansion rate aremeet the requirements of mechanical properties in GB/T4897-2015.(2)the characteristics of volatiles.By TD-GC-MS method,it was found that the acid flavor of bamboo composite volatiles came from acetic acid,oleic acid and phenols,the smoke flavor came from guaiacol and phenol derivatives,and the sweet smell came from syringaldehyde,vanillin,furfural,etc.(3)The second stage is the main stage of weight loss.In the process of hot pressing,cellulose and furfural,the pyrolytic product,react with lignin to form more sticky components,hinder the decomposition of bamboo fiber,and improve the thermal stability of bamboo composite.(4)the bacteriostatic characteristics of the bamboo composite were studied by the method of bacteriostatic circle test.The treatment time of bamboo vinegar was prolonged and the bacteriostatic effect was enhanced.The organic acids,phenols,ketones,aldehydes and alcohols in bamboo vinegar have strong bacteriostatic effect,which make bacteria lose activity,interfere with microbial metabolism and inhibit the growth rate of microorganisms.3.Analyze the composite mechanism of bamboo composite.The results of chemical composition analysis,infrared spectrum analysis,nuclear magnetic resonance analysis and X-ray diffraction analysis are as follows:(1)the water molecules in the bamboo vinegar enter into the amorphous area,combine with the free hydroxyl group,or combine with the hydroxyl group of cellulose to form the hydrogen bond,reduce the number of the free hydroxyl group,which makes the bamboo composite have a good binding force and is conducive to enhance the strength of the bamboo composite;(2)lignin It is hydrolyzed with hemicellulose to form pentose,formic acid,acetic acid and other acidic substances.Bamboo vinegar itself contains acetic acid,oleic acid and other acidic components.Under this acidic catalysis,pentose dehydrates to form furfural,condenses with phenols to form stable new polymers with adhesive effect;(3)lignin softens and becomes sticky above the glass temperature,with certain adhesive force and strength The internal combination of bamboo fibers.Compared with pure bamboo powder laminate,the cross-section of bamboo composite has small gap,compact cross-section structure,even surface and regular fiber morphology.4.To explore the properties and composite mechanism of bamboo composite after the reduction of volatiles.Therefore,bamboo charcoal and Ti O₂were added to prepare bamboo composite with reduced volatiles.(1)the mechanical properties,static bending strength,internal bonding strength,elastic modulus and water absorption thickness expansion rate are respectively 15.22MPa,1.10MPa,2275.01MPa and2.95%.Compared with bamboo composite,the mechanical properties of bamboo charcoal and Ti O₂were improved.(2)the content of acids,esters and phenols decreased significantly when bamboo charcoal and Ti O₂were added.The main reason for the decrease of acid taste and smoke taste is that bamboo charcoal has strong adsorption.Ti O₂can promote the transfer of the compounds adsorbed by bamboo charcoal to Ti O₂.The synergistic effect of bamboo charcoal and Ti O₂accelerates the adsorption of volatile matter.(3)the thermal stability of the bamboo composite with bamboo charcoal and Ti O₂was improved to some extent.The surface of Ti O₂can be attached with chemisorption water,which can interact with hydroxyl groups in bamboo cellulose,making Ti O₂grains deposit on the surface of bamboo or enter into its cell cavity.These grains block part of water and oxygen from entering into bamboo composite,to a certain extent,improving the heat resistance of bamboo.(4)The synergism of bamboo charcoal,Ti O₂and bamboo vinegar enhanced the antibacterial properties of bamboo composite.Bamboo charcoal can absorb toxic,harmful substances,bacteria and other substances.Ti O₂can promote the formation of-OH?O^2-?H₂O₂and other strong oxidizing substances in the composite powder.These strong oxidizing substances penetrate the cell wall of bacteria and inhibit the growth of bacteria.(5)the odor level of bamboo composite after the reduction of volatiles is 1.5,which meets the odor detection method and technical requirements of Q/SFYTJ15-2015 household materials.Chemical composition analysis,infrared spectrum,nuclear magnetic resonance analysis,X-ray diffraction analysis,SEM and other technical methods were used to reveal that the composite mechanism of bamboo composite after the reduction of volatile matter is basically the same as that of bamboo composite.