Study On The Mechanism Of Bamboo Split Into Fibers By Mechanical Method

Natural bamboo fibre, whose morphogenesis is close to bast-fibre, is processed directly by bamboo.It is an excellent material for textile fiber, for its particular anti bacterial, order resistant and breathable properties. Besides, natural bamboo fiber is an ideal substitute of fibre reinforced composite material,since it owns excellent specific strength and specific stiffness, and its specific strength and specific modulus approach the level of GF.At present,research on production methods of natural bamboo fibre is mainly divided into two categories: biochemical ones and physical ones. With physical methods, bamboo chips are under forces like heat, pressure and mechanical force to cause bamboo being destroyed. Then fibre is produced after fibre and colloid are debonded and peeled. The fundamental theories for explaining fibre separating mechanism are relaxation theory and extrusion-slippage mechanism. These two theories are widely accepted for explaining separating mechanism of staple fibre by defibrator. However, separating technologies for macrofibre are immature. The defibering method splitting method are still in experimental research stage. Correspondingly, fundamental theory work in bamboo macrofibre is even more backward. Especially the research on mechanism of mechanical type for producing bamboo has no systematic theory. All above mentioned are unsolved critical technological problems.To the above problem, this paper theoretically studies the mechanism of natural bamboo fibre production via bamboo wood mechanically splitting to build a theory system of fracture and make fiber of fibre matrix interface vertically under alternating loads in the viewpoint of mesomechanics.Furthermore, by qualitative analysis of bamboo wood property and influence law of load pattern on bamboo wood splitting quality, and quantitative analysis of new methods on bamboo wood property modification,this paper proposes a new technology on bamboo wood splitting via softening . The details include:1. From that bamboo wood has the structural characteristic of unilateral macrofibre reinforced composite material, the mechanical mechanism of bamboo wood mechanical splitting in the macroscopic view and microcosmic view is discussed, respectively.2 . With the fourth strength criterion, i.e., the energy strength criterion, this paper evades the complex problem of bamboo wood being destroyed under loading stress and builds a microcosmic model of bamboo wood interface debonding. A quantitative analysis on the relationship among bamboo wood matrix destroying and removing effect, external loading and bamboo chip elasticity modulus is also illustrated.3 . This paper launches the research on new technologies of green and environment-protected biochemical bamboo wood property modification.4. This paper studies the splitting effect of bamboo fibre and matrix under different forces.5. Some initial exploration is done on bamboo continuous making fiber orientational technology.Through analysis, we can obtain the following concluding statements.1) The mechanism of making fiber by mechanical method is: In microscomic view, interface between bamboo fibre and matrix causes debonding to form initial flaw under mechanical load. Then under continuous load, bamboo wood flaw expands vertically along with fibre until fibre and matrix become separated completely.2) From energy strength criterion, with J1c integral method, the microscomic mechanical model of bamboo fibre matrix interface debonding is built. The bamboo wood matrix interface debonding condition is:3) With the continuous loading of applied load, the energy provided is larger than the energy needed for destroying bamboo chip matrix. Then, bamboo fibre and matrix separate. Besides, when Em/Ef?0, it is easier for interface debonding, which means that bamboo wood appears easy to making fiber.4) The bamboo wood biochemical softening experiment shows that biochemical modification of bamboo wood is superior to the chemical one. For hemicellulase biological softening technology, the best condition is with processing temperature 50? , hemicellulase density 2.0g/L, pH value 6, and processing time 7 hours. The residual gum content of obtained bamboo wood is 36.86%, and the compression strength perpendicular is 886.875kPa. The obtained bamboo wood is gray-white and loose.5) The research on splitting effect of bamboo fibre and matrix under different applied force is performed. The result shows that bamboo wood vertical drawing is not efficient for fibre splitting. The lateral compression and fatigue rupture are good for bamboo fibre interface debonding.6) Making fiber by mechanical method establishes foundation for bamboo fibre production mechanization.