Separation Mechanism Of Fiber Bundles And Improvement Mechanism Of Bamboo-based Fiber Composites

Bamboo scrimber is a kind of bamboo-based fiber composite material with high physical and mechanical properties,high bamboo utilization rate and wide application.The preparation process of bamboo-based fiber composite materials is to use the fluffing and the recombination of bamboo fiber bundles.Through the fluffing equipment on the flattened bamboo surface to create segment-like cracks,the bamboo was in situ fiber separated to form a network-interwoven bundles,and then the fiber bundles are uniformly impregnated with low molecular weight phenolic resin adhesive,and then the recombination of fiber bamboo bundles is realized by hot pressing and cold pressing curing,and the bamboo-based fiber composite material is prepared.It is of great significance to study the separation mechanism of fiber bamboo bundles under fluffing and the enhancement mechanism of mechanical properties of bamboo-based fiber composites under hot compaction,which is of great significance for the preparation of recombinant bamboo and the development of bamboo fine processing equipment to reveal the principle of recombinant bamboo fluffing and recombination.In order to deeply explore the separation mechanism of fiber bamboo bundles under fluffing and the reinforcement mechanism of bamboo-based fiber composite material structure under hot compaction,the change of bamboo grade structure and mechanical properties during the separation and recombination of bamboo fiber bundles,this study first systematically explored the relationship between multi-scale components-structure-mechanical properties at the cell and cell wall level of bamboo,and constructed a multi-scale structural model of bamboo.The stress distribution of multi-scale cell structures under fluffing was analyzed by finite element analysis,and the separation mechanism of bamboo-based fiber composites was elucidated.The weak phase structure of fiber bamboo bundles and bamboo-based fiber composites under applied load was accurately located by mechanical tests and microscopic means,and the enhancement mechanism of different components of bamboo-based fiber composites was revealed by combining the micromechanical properties at the cellular scale.The toughening mechanism of recombinant bamboo was analyzed by microscopic analysis and mechanical experiments.The main research conclusions are summarized as follows:Fiber and parenchymal cells are the main cellular structures of bamboo,through microscopic equipment,nanoindentation instrumentation of fiber and parenchymal cells secondary wall different wall and intercellular layer indentation modulus and hardness,through laser confocal raman infrared spectroscopy to explore the chemical composition of bamboo fiber and parenchymal cells,so as to establish the relationship between bamboo cells and cell wall scale structure-mechanical properties and components,and use nanoindentation to measure the size and wall thickness of two types of bamboo cells.The finite element software was used to construct a multi-scale structural model of bamboo fibers and thin-walled cells,which provided a basis for analyzing the preparation mechanism and mechanical property enhancement mechanism of bamboo-based fiber composites.In order to analyze the preparation mechanism of bamboo-based fiber composites,this study modeled the dredge roller and bamboo sheet based on the dredging device,and carried out static analysis to obtain the interaction type between the dredge roller and the bamboo sheet.The stress distribution law of bamboo fiber cells and thin-walled cells under the action of finite element analysis was used to analyze the separation mechanism of bamboo-based fiber composites theoretically.In order to verify the separation mechanism of recombinant units of bamboo-based fiber composites,this study observes the crack growth path and separation law of vascular bundles,thin-walled tissues,fiber,parenchymal cells,cell layers and intercellular layers of bamboo under dredging through mechanical experiments and fiber equipment,obtains the separation behavior of bamboo multi-scale structure under dredging,and combines the micromechanical properties and chemical component distribution of cellular-scale fiber and parenchymal cells to elucidate the separation mechanism of fiber bamboo bundles.The effects of PF resin impregnated fiberized bamboo veneer were prepared with different impregnation amounts and densities,and the effects of PF resin impregnation amount and density on the flexural strength,modulus and shear strength of bamboo-based fiber composites were discussed,and the gluing interface structure of bamboo-based fiber composites was explored through microscopic equipment,and the mechanical gluing interface properties of bamboobased fiber composites were obtained.In order to explore the mechanism of fibroblasts,parenchymal cells and intercellular layer enhancement in bamboo-based fiber composites,this study prepared outer bamboo and inner bamboo recombinant bamboo by impregnating phenolic resin in the bamboo green and bamboo yellow areas without changing the longitudinal and radial bonding forms of bamboo components,and obtained bamboo-based fiber composite composites that maintain the structure and strength of bamboo.Through the combination of in-situ three-point bending and scanning electron microscopy,the process of bamboo green,bamboo green recombinant bamboo,bamboo yellow and bamboo yellow recombinant bamboo under the three-point bending loading mode was monitored in real time,the cross-sectional morphology and crack growth path of bamboo-based fiber composite fibers and thin-walled cells were analyzed by environmental scanning electron microscopy,and finally the enhancement mechanism of the mechanical properties of bamboobased fiber composites at the cellular level in the compression and compacting process was analyzed by nanoindentation technology.In this study,by constructing a finite element model of the multi-scale structure of fluffing roller and cell,the stress distribution law of bamboo multi-scale structure under fluffing was analyzed,and the separation behavior of bamboo multi-scale structure under fluffing was characterized by mechanical experiments,and the separation mechanism of recombinant unit of bamboo-based fiber composite material was revealed.Finally,the pager fiber composite was prepared by the recombinant unit,and the mechanical behavior of bamboo fiber cells,parenchymal cells and intercellular layer under the action of external force was detected by in situ mechanical test,and the mechanical property enhancement mechanism of bamboo-based fiber composites was explained,which provided a theoretical basis for the development of key equipment of the recombinant unit and the fine processing of bamboo.