Study On The Gluing Shear Properties Of Carbonized Bamboo/Larch Glue

Larch is a kind of fast-growing wood with rich resources,but its mechanical properties are relatively poor.Bamboo has excellent bending and tensile strength,but the density is large and the diameter is small,the utilization rate is low,and the large wooden structural members made of it are too heavy Therefore,the bamboo plywood made of bamboo and wood exhibits superior mechanical properties.However,there is still a lack of systematic research on the factors affecting the gluing performance of bamboo-wood glued materials,such as texture,knots,etc.and their failure mechanisms.In this paper,carbonized bamboo and larch are used as materials,and the influencing factors of bamboo pine glued material's gluing performance are deeply explored,and the gluing process is optimized on this basis.In order to reduce the dispersion of the glued shear strength value of the glued lumber,the method of inserting the round bar tenon without glue to enhance the glued shearing performance of the bamboo-pine glued lumber provides technical support for the preparation and structural optimization of the high-strength new bamboo-wood glued lumber.1.The paper firstly tested the gluing properties of glued materials prepared with different types of adhesives.The results showed that:the gluing properties of the glued materials prepared by pHenolic resin adhesives meet the requirements of international standards,the shear strength can reach 6.5 MPa,and the wood breakage rate can reach 90%.In this paper,the effects of different surface roughness,different moisture content,bamboo green side,vermillion side,wood diameter section and chord section on the adhesion of bamboo-wood composite materials are deeply studied.Tests show that wood and bamboo are sanded with 60 mesh and 100 mesh sandpaper respectively,and the moisture content is about 5%?10%.The bonding performance of the composite material prepared by the bamboo green side-string cut surface assembly method is the best.The average shear strength can reach 6.7 MPa,and the wood breaking rate is over 90%.Since the roughness of the bonding surface affects the degree of wettability of the adhesive to the material,the smaller the surface roughness of the material,the worse the bonding performance.The different dry shrinkage and swelling coefficients of wood and bamboo cause the shear strength of the glue layer to decrease with the increase of the moisture content of the two materials.2.By changing the angle between bamboo and wood texture,the effect of different texture directions on the gluing performance of the gluing material was studied.The results show that the relationship between the angle formed by bamboo and wood texture is an important factor affecting the shear strength.The shear strength of the adhesive layer of the two materials with an angle of 0° along the grain assembly method is higher than that of 30°,45°,60° angle assembly and 90° vertical assembly.The shear strength can reach 6.72 MPa,and the wood is broken.The shear strength of the laminated lumber with the texture angles of 30°,45°,60° and 90°is 42.4%and 45.1%lower than that of the glued lumber with the 0° along the grain.,49.0%and 52.1%,the shear strength of the glued lumber showed an exponential decline trend with the increase of the angle formed by the texture of the two materials;in addition,for the glued lumber made of larch and carbonized bamboo,the shear strength and the wood breakage rate Shows a linear positive correlation.3.According to the research on the factors that affect the gluing performance of bamboo and wood glued materials,the gluing process of the glued materials is further optimized.Using phenolic resin as the adhesive,the influence of phenolic resin's sizing amount,hot pressing pressure,hot pressing time and hot pressing temperature on the bonding performance was investigated through single factor tests.The range of each factor was determined and the orthogonal test was carried out to obtain the best The bamboo-pine gluing process parameters.The test results show that when the sizing amount is 220 g·m-2,the hot-pressing pressure is 3.5 MPa,the hot-pressing time is 15 min,and the hot-pressing temperature is 130?,the bonding performance of the composite is the best.4.The presence of pine joints on the glued surface has a significant effect on the bonding performance of the composite material,while the effect of the bamboo is not significant.The bonding performance of composite materials decreases with the increase of the pine joint diameter,and the shear strength and the size of the pine joint diameter show a curve correlation.In the test of the influence of the round bar tenon connector on the shear strength of the bamboo-wood composite material,it is found that the round bar tenon with a diameter of 12 mm is baked to dryness,the round bar tenon and the mortise are interference fit,and no glue is inserted into the round bar tenon,The average shear strength of the specimen reaches 7.79 MPa,which is 15.9%higher than that of the specimen without a round bar tenon.Experiments prove that the insertion of the round bar and tenon has played an optimizing effect on the composite structure.Through the above experiments,the preparation process of bamboo-wood composite material and the influencing factors of bamboo-pine glued material's gluing performance are analyzed in detail,and the key technology of bamboo-wood composite material preparation and structural optimization is obtained.It is the engineering glulam of larch and carbonized bamboo in my country.The production preparation provides reference and basis.