Study On UF Thermal Response Characteristics With Several Waste Wood And Manufacturing Technologies Of Medium Density Fiberboard

While wood-based panel industry in China is highly developed, the supply of forest protection and wood reduction to promote our timber supply have become increasingly conspicuous, and shortage of materials has become a bottleneck in the development of wood-based panel industry. In real-life, a large number of waste wood is low used, or even idle, not only a waste of resources, but polluting environment. If recycling–using waste wood , not only as sources of raw materials, to some extent alleviated the pressure with shortage of timber resources in China, but also to change the traditional mode of one-way wood consumption, recycling economy development model of buildingresource-saving and environment-friendly society have important practical significance. This thesis maks the three remaining properties of forest, agricultural residues (vine) and pharmaceutical residues (Caulis Erycibes ) for experiment object with now rich in resources and difficultly used, researches the basic properties of different materials, process parameters of UF fiberboard , discusses the possibility of PMDI adhesive for fiberboard ,and compares the different materials properties of medium density fiberboard, the results are as follows:1) In fiber preparation process, as Cunninghamia lanceolata material containing much bark component, requires a lower discrotation speed, broken veneer prone to blocking screw feeder, the vine and Caulis Erycibes facing greater resistance during thermo grind; Block, Cunninghamia lanceolata and mixed 2 fiber screening value are relatively poorer, the rest equivalent.2) The pH value and buffer capacity of different material fiber are much different, and its buffering capacity with pH has no significant correlation. Obtained by DSC thermal analysis: the addition of curing agent ammonium chloride significantly promoted the UF resin gelation, and along with the increase of dosage, UF resin curing temperature decreased; adding different materials wood flour to UF resin on the DSC curves influences the second endothermic peak temperature more significantly than the exothermic peak temperature, but glue-like adding wood flour required higher curing temperature than no adding, delayed curing. Exception for Caulis Erycibes and Cunninghamia lanceolata, Cunninghamia lanceolata rich in bark led to the lowest pH value, whereas Caulis Erycibes inclusion of more complicated ingredient, pending further study.3) From physical and mechanical properties of fiberboard with different processing conditions , optimum process parameters of UF fiberboard: pressing temperature 165℃, the pressing time for the 20s/mm, curing agent 1%, glue content 12%, density 0.75 g/cm3, amongly, the choice of different levels of adhesive has great impact on the strength. Beside ,wax powder applied directly on the plate to improve water resistance less effectively than Wax emulsion form.4) Comparing the physical and mechanical properties of UF fiberboard, mixed 3 fiber has the best performance, wood block , mixed 2and 1 have better performance, broken veneer, Cunninghamia lanceolata and vine followed, caulis erycibes worst. Comparison the properties of non-formaldehyde fiberboard: mixed 3 fiber has the best performance, wood block and broken veneer better, vine, mixed 1 and2 followed , Cunninghamia lanceolata and Caulis Erycibes worst.5) Comprehensive assessment of fiber quality and performance of fibeeboard: Caulis Erycibes material is not suitable for two kind fiberboard material used alone, Cunninghamia lanceolata material not suitable for a non-formaldehyde fiberboard material used separate, but can be used in accordance with high quality materials by mixing and matching to use a certain proportion so as to enhance the level of board, the performance of mixed 3 fiberboard has proved its feasibility in experiment.6) The IB, MOR improvement of board while PMDI glue dosage and density increasing, while 24hTS decreasing of board. In addition, compared with UF, the physical and mechanical properties as PMDI adhesive for waste wood fiberboard are significantly improved .And in the case without waterproof agengt , the performance of block fiberboard under 6% PMDI glue dosage and 0.7g/cm3 can achieve the national standard of requirements, so the adhesive selected PMDI has its obvious advantages.