Study On The Bonding Interface And Mechanism Of Bamboo Based Fiber Composites

Bamboo-based fiber composites are made from oriented bamboo fiber mat and BrPF resin via hot-pressing,in addition,several analytical techniques such as fluorescence microscope(FM),Laser scanning confocal microscope(LSCM),Micro X-ray computed tomography(XCT),fourier transform infrared spectrometer(FTIR),X-ray photoelectron spectrometer(XPS),Solid-state nuclear magnetic resonance technology(NMR),scanning electron microscopy energy dispersive X ray analysis(SEM-EDS),transmission electron microscopy energy dispersive X ray analysis(TEM-EDS),and Nanoindentation(NI)are employed to investigate the cell structural changes as well as chemical,physical and mechanical properties,and to study the penetration,wettability and curing phenomenon of phenolic resin on the oriented bamboo fiber mat,and then to explore the compatibility,interaction and bonding properties between bamboo cell and phenolic resin.Finally,the response mechanism of cell wall and the bonding formation mechanism will be revealed and then their effects on the physical and mechanical properties of bamboo-based fiber composites will be also studied.The results of this fundamental work have a promise to provide a theoretical basis for solving the common problems in the industry of bamboo-based fiber composites such as dimensional stability and performance modulation.Several conclusions were drawn from these experiments:(1)The BrPF was introduced to track the distribution and permeability of resin in bamboo based fiber composites.Results showed that after the high pressure and temperature treatment,the adherent PF resin were redistributed in bamboo-based fiber composites,some of the PF resin distributed in cracks and damaged catheter due to rolling compaction and fluffing of oriented bamboo fiber mat,and some of the PF resin infiltrated into the cell lumen and the middle lamella of parenchyma cells,especially,the PF resin attached on the inner surface of the parenchyma cells lumen.Almost had no PF resin distributed in the fiber cells because of close-packed array.(2)Covalent bonding were formed between the PF resin and bamboo fiber mat.FTIR and NMR analysis showed that the hydrogen bond were formed between the PF resin and holocellulose,and the condensation reaction or substitution reaction proceeded between the PF resin and Guaiacyl or Syringyl of lignin.(3)Physical bonding were formed between the PF resin and bamboo fiber mat.SEM(EDS)and TEM(EDS)observation showed that the BrPF resin penetrated into the cell cavity through the pit,andformed glue film and glue nails in the compressed parenchyma cells cavity.(4)Interpenetrating network structure were formed between the PF resin and bamboo fiber mat.SEM(EDS)and TEM(EDS)observation showed that the BrPF resin can infiltrated into the cell wall of parenchyma cells and forming interpenetrating network structure with parenchyma cell wall.(5)NI analysis showed that the elastic modulus and meyer hardness were increased by 41.77%and 47.95%of parenchyma cells respectively,and elastic modulus and meyer hardness were increased by 7.16%and 3.57%of fiber cells respectively,which indicated that the PF resin permeated into the cell walls of parenchyma cells and formed interpenetrating network structure.(6)After heat treatment with the 200℃,the width swelling,thickness swelling and water absorption were reduced by 21.60%,32.27%and 21.60%respectively,which indicated that the water resistance were obviously improved;the modulus of rupture and horizontal shear strength were reduced by 56.14%and 42.15%.