Study On Resin Infiltration Flow Process Under Vacuum Assisted Molding Of Plant Fiber

Vacuum assisted resin transfer molding(VARTM)is an advanced biomass liquid molding technology.As an advanced biomass molding technology with low cost and excellent performance in the world,it has solved the high cost of traditional molding technology.A series of problems such as high energy consumption and serious pollution.The research on the preparation of plant fiber products based on VARTM molding technology makes full use of many advantages such as high specific strength,renewable utilization,light weight and low price,and wide range of sources.It has become a hot spot in the research and application of new fields.There are many factors affecting the quality of VARTM molded products.The quality of the products is not only related to the properties of the resin matrix and the fiber reinforcement,but also depends on the combination of the resin matrix and the fiber reinforcement.In order to explore the infiltration flow law of resin under vacuum assisted molding,the resin infiltration process of porous fiber in flax fiber was studied.Based on Darcy's law,the resin infiltration model under vacuum assisted resin transfer molding technology was established.The characterization of the wetting properties of flax fiber by resin was discussed.The method of improving the infiltration performance of flax fiber by resin was discussed.The theoretical calculation formula of permeability value was derived and the one-dimensional unidirectional permeability value and two-dimensional diameter of a flax fabric were measured experimentally.To the permeability value.The results show that the one-dimensional unidirectional permeability value of the flax fiber sample is between the two-dimensional radial long and short axis permeability values.Based on the fluid mechanics theory of resin flowing in flax fiber porous medium,the simulation of resin flow process under vacuum assisted molding of plant fiber was carried out.The three process parameters such as vacuum pressure,resin viscosity and presence or absence of flow guiding medium were investigated.The effect of the resin flow process.The results show that as the vacuum pressure inside the cavity increases,the resin filling flow infiltration time becomes shorter.Resin viscosity is an extremely important process parameter in VARTM molding technology.It has a significant effect on the resin filling flow process.The low viscosity resin has very Good fluidity;good flow of resin under the condition of diversion medium,short filling time,and straightness of resin filling front curve,good wettability.In order to study the influence of gravity effect on the resin wetting flow process during VARTM molding process,flax fiber was selected as the reinforcement and epoxy resin was used as the matrix material.The linen fiber resin base layer was prepared by vacuum assisted resin transfer molding(VARTM)molding technology.The plywood was used to record the filling time of the resin under different resin flow inclination angles,and the tensile and bending properties of the plywood of the workpiece were tested.The results show that the filling time increases with the increase of the resin flow inclination angle(from-90°to 90°).With the increase of the resin flow inclination angle,the tensile strength and tensile modulus of the laminate are The bending strength,the flexural modulus,and the like are all increased.In the failure mode of tensile failure of the laminate,the main fiber failure includes flax fiber pull-out and flax fiber breakage;under the failure mode of the bending failure of the laminate,the lining breakage and matrix cracking of the flax fiber are mainly carried out.