Research On Broussonetia Papyrifera Homogeneous Particleboard

Forest resources are scarce in our country. Many artificial board factories are confronted with the shortage of materials now. Exert great efforts in developing fast-growing forest is one of the effective methods to resolve the contradiction of the demand for the woods exceeds the supply in China. Broussonetia papyrifera is abound in natural resourses, with fast growth, high suitability, adverse conditions and high economic benefit. It is a new species of resources which reliece the raw materials shortage of artificial board. The differences between surface layer and core layer in homogeneous particleboard decreased. The board with high performance and even-textured is widely used. It is a new product with strong vitality and development prospect in particle board. Therefore, it is very actual value to study on the new research of broussonetia papyrifera homogeneous particleboard in China artificial board industry.In this paper, broussonetia papyrifera was used to make homogeneous particleboard. The chemical constituents and particle shape of broussonetia papyrifera, reinforcement mechanism of MUF was studied. The optimum process parameters were determined through orthogonal experimental design method. Each main parameter impacted on its mechanical characteristics, performance test and mechanism discussion was studied, providing the theory basis for the production of the product.It analysed the chemical constituents, particle shape and screening of broussonetia papyrifera. The results shown that holocellulose of xylem was 84.01%, holocellulose of phloem was 79.04%, cellulose of xylem and phloem was about 42%, Klason lignin of xylem was 17.63%, Klason lignin of phloem was 11.69%. Average length of fibre was 0.9mm, average width of fibre was 23μm, length-width ratio was 37:39, cell wall thickness-lumina was 0.33. The fiber was belong to medium size. Average thickness of shavings was 0.3mm, core layer thickness was 0.45mm～0.9mm, surface layer thickness was 0.20mm～0.45mm, so it was feasible for broussonetia papyrifera to make homogeneous particleboard.The results of testing surface wetting properties of MUF by JC2000A contact angle measurement show: shavings in close contact with the MUF can form the strong bond strength. The effects of the contents of different curing agents on the curing of the modified resin were also investigated by means of DSC. The results indicated that even in the heat under the certain time can be guaranteed the degree of cure when the content of curing agent was 1%. Therefore, in the experiment, in order to ensure the cure rate, the content of curing agent of surface layer was 1%, the content of curing agent of core layer was 1.5%.The optimum technology condition was obtained by orthogonal tests. The results were as followes: hot pressure 2.5MPa, pressing temperature 160℃, pressing time 36s/mm, surface moisture content 15%, glue content (surface layer: core layer) 12%: 8%, bark content 5%. The performance of homogeneous particleboard was test by GB/T17657-1999"Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels". Main physical and mechanical properties were as followes: MOR is 17.2MPa, MOE is 2465MPa, TS is less than 8.0%, IB is 1.24MPa. According to GB/T4897-2003"Particleboard", the main physical and mechanical properties of homogeneous particleboard manufactured can fulfill quality requirements was better than particleboard.The FTIR research shows, broussonetia papyrifera homogeneous particleboard has absorption peak at 2921 cm-1, 1736 cm-1, 1417 cm-1, 1070cm-1. The results indicated that after crushing, the surface chemical structure has not been changed too much and the number of free hydroxyl has been increased, which help to improve the bond performance between raw materials and adhesive.R-ray densitometer analysis show that: The average density 883 kg/m3, the maximum surface density 912kg/m3, most low-density core layer 849kg/m3, core layer density distribution has no obvious low point, the minimum core layer density was 96% of average density. After sanding, the broussonetia papyrifera homogeneous particleboard can be divided into upper and lower surface and core, and the slab center along the sides were symmetrical. By perforation method, the result shows that formaldehyde emission is up to E1 standard in Europe. Broussonetia papyrifera homogeneous particleboard is a green environmentally product.