Study On The Fiber Forming Mechanism Of Bamboo Chip Roll Reverse Pull Off Layer

After years of development,bamboo fiber preparation technology has formed a natural bamboo fiber production pattern with cooking and rolling method and combing method as the main body.Although these preparation methods have their own characteristics,the processing methods are generally complicated,the production efficiency is low,the utilization rate of bamboo is low,the quality of fiber production is unstable,the processing process is not clean,the energy consumption is large,and the environmental pollution problem is prominent.The bamboo fiber produced has a low degree of separation,and the fiber is coarse,short and hard.The uniformity,length,fineness and strength of the fiber not only fail to meet the requirements of textile fibers,but also cannot meet the requirements for preparing composite materials and weaving.Material requirements.Based on the above reasons,Yao Wenbin et al.proposed a device and method for fabricating delamination and fiber formation of bamboo.This method fully utilizes the uneven distribution of fibers along the wall thickness direction of bamboo,forcing the bamboo sheet to be bent,squeezed and pulled.The combination deformation of the extension causes the geometrical nonlinear large deformation of the bamboo sheet to realize the crack in the fiber and the matrix structure of the bamboo material,and the detachment and separation of the fiber and the matrix,the bamboo fiber bundle is extracted,and the production is performed.The process is simple and easy,and the production process is environmentally friendly and non-polluting,and the bamboo structure can be uniformly deformed by extrusion and bending,so that the obtained bamboo fiber(bundle)has good elasticity,good toughness,and fine fiber fineness and uniformity.In this paper,on the basis of the aforementioned fiber opening device and method,the paper developed a bamboo sliver uncoiling and delaminating experiment machine,which,based on the characteristics of non-uniform biological structure and anisotropy of bamboo,made the softened bamboo sliver directly separate the natural long bamboo fiber with better physical performance through the large bending uncoiling deformation back stretch fiber forming method.Through the horizontal grain bamboo radial bending test and combining with the fiber volume fraction,establish bamboo macro mechanical properties and the relationship between the fiber volume fraction provide the basis for open fine mechanics model is set up,through the establishment of interlayer debonding failure strain model,the interface debonding and the matrix damage mechanics model for bamboo folding counter loop layer fiber forming conditions,and through the test to determine the best softening technology,fiber and bamboo material performance parameters,to reveal the law of the open bamboo fiber.The main research contents and achievements are as follows:(1)Through the bending test of the transverse grain of bamboo with different ages,positions and levels,assisted by the microscopy and image automatic recognition processing technology.The mechanical properties of fiber and matrix are calculated by mixing law.The characteristics of bamboo composites reinforced with unidirectional fiber are determined.(2)Taking bamboo as a natural unidirectional fiber reinforced composite material,the research method of composite material is adopted to conduct theoretical analysis on the damage and damage process of bamboo material.The mechanical model of inter-layer debonding failure was established according to the bamboo layer and structure,and the strain energy release rate analysis method and shear-lag method were used to construct the model of fiber and matrix interface debonding and matrix failure.The three models systematically reveal the mechanism of bamboo strip delamination and provide technical support for the experimental study of bamboo roll over and reverse.(3)Through experiments,the influencing factors of unfurling and delamination of bamboo sheets were investigated,and the effects of softening conditions,rolling radius,different bamboo species and different parts on the separation and fibrosis of bamboo were analyzed.The experimental results showed that 3% alkali concentration and 4mm rolling radius were conducive to the extraction of bamboo fibers with good physical performance,and the extracted bamboo fibers were 84%,144.3 ?m,43.5 ?m and 32.1MPa,respectively.The bamboo tip with higher fiber content can reduce the matrix structure on the fiber surface and thus improve the fiber physical indexes.The average separation degree,fineness and tensile strength of the fiber extracted from the bamboo tip were increased by 30.7%,34.1% and 21.1% respectively compared with the bamboo root.Among the three kinds of bamboo,the average fiber separation degree of Phyllostachys heterocycla is 78.3% higher than that of Neosinocalamus affinis and Dendrocalamus membranceus Munro 62.7% and 56.6% In contrast,the average fiber fineness of Neosinocalamus affinis and Dendrocalamus membranceus Munro was 143.7?m,while that of mj was 158.7?m,which was superior to that of mj.The biological differences among the bamboo species resulted in different arrangement modes of the single fiber,which affected the tensile strength of the bamboo fiber bundles.The average tensile strength of the bamboo fiber bundles of Phyllostachys heterocycla,Neosinocalamus and Dendrocalamus membranceus Munro were 27.3,23.7 and 23.0MPa,respectively.