Study On The Technology Of Corn Stalk Skin Flake/Wood Particle Composite

This study is focused on the technology of corn stalk skin flake/wood shaving composite, which is using urea-formaldehyde (UF) resin modified by isocyanate (PMDI) as the adhesive. The mixing characteristic of the two kinds of raw material, corn stalk skin flakes and wood shavings, was studied. The effects to the mixing characteristic and properties of the composite, which were brought by two kinds of forming, mechanical forming and air forming, and the vibration caused by the transportation of the mats, were all discussed in this article. The effects of material mixture ratio, glue content, hot-pressing temperature, and hot-pressing time on the physical and mechanical properties of the composite were studied by orthogonal experiment method. The adhesive characteristic of the composite was analyzed by scanning electron microscope (SEM), the thermo mechanical property of the composite was analyzed by dynamic mechanical analysis (DMA) and the thermo stability property of the composite was analyzed by thermo gravimetric analysis (TGA). The single factor experiments of the material mixture ratio and glue content were carried out respectively according to the results of the orthogonal experiment, and an ideal technology of the composite was got finally.The results show that:after being mechanical formed and air formed, the material mixture ratios of different positions of the mats were all different. The vibration caused by the transportation of the mats would also make the material mixture ratios of different positions in the direction of the thickness of the mats different; The effect of the material mixture ratio on two hours thickness swelling (2hTS) and modulus of rupture (MOR) is highly significant, the effect of glue content on2hTS, internal bond strength (IB), and modulus of elasticity (MOE) is highly significant, the effect of hot-pressing temperature on MOR and MOE is highly significant. Compared with the corn stalk skin flakes, the wood shavings bond with each other better, and the thermo dynamic performance and the thermo stability are better. The properties of the composite would improve as the content of wood shavings increased or the glue content increased. A carbonization phenomenon would appear on the surface of the composite as the hot-pressing temperature and hot-pressing time kept rising.The results of the technology optimization of the composite are as follows:the ratio of corn stalk skin flake to wood shaving is3:7, glue content is12%, hot-pressing temperature is150℃, and hot-pressing time is4.5min. In this process, the physical and mechanical properties of the composite will meet the requirements of the relevant National Standard.