Study On The Manufacture And Performance Of Composites Consisted Of Veneer And Straw Board For Environmental-friendly Floor

The crop straw resources are very rich in our country. However, most of them are dumped or incinerated, not only a waste of resources also a huge cause of atmosphere pollution. Therefore, it is of great practical significance to develop and use adequately the straw resources. In this paper, with rice straw and inorganic adhesive as testing material, the straw board was manufactured by using cold forming process. The effect of glue-straw ratio, raw material forms, density and structure on the the physical and mechanical properties of the straw board were systematically studied. Then the straw board was treated with veneer to develop two structures of floor by hot pressing process. The influence of glue spread, hot pressing temperature, hot pressing time and hot pressing pressure on the straw board were researched by single factor and orthogonal experiment method, in order to achieve the optimization of process used to manufacture the veneer-straw board composites for floor environmentally. At the same time, the combustion performance and thermal conductivity of the composites were evaluated by the use of cone calorimeter (CONE), thermal conductivity. While the bonding interface morphology between veneer and straw board was observed by scanning electron microscope(SEM).The main conclusions of this study are as follows:(1) The effect of glue-straw ratio, raw material forms, density on the mechanical properties of the physical straw board were significant. With the increasing of glue-straw ratio, the MOR and MOE of straw board increased first and then decreased, while the IB showed a rising trend and TS was a downward trend. In the same amount of glue, the MOR and MOE of coarse material were better than those of fine material and mixture material, while the IB and 2hTS of mixture material are the bestest of the three different of raw material forms. The regression equations between the density and the MOR, MOE, IB and TS of straw board were y=19.148x-2.9411, y=3711.495x-343.1512, y=1.902x-1.0521 and y=-2.336x+4.7060. It also could be concluded that the properties of a single layer structure were better than those of a three-layer structure of straw board.(2) It was concluded from the single factor test and orthogonal optimization test that with the glue spread of 300g/m2, hot pressing temperature of 120℃, hot pressing time of 18min and hot pressing pressure of 1.8MPa as process parameters, the physical and mechanical properties of the composites consisted of veneer and single flame resistant core layer of straw board were the best. While the moisture content, MOR, MOE, IB,2hTS, SB of the composites were respectively 8%,49.2MPa,5600MPa, 1.15MPa,1.56%,0.96MPa. And the III and the II types of bondline delamination of composite were not stripped.(3) It could be also found that with the glue spread of 300g/m2, temperature of 120℃, time of 18min and pressure of 1.8MPa as process parameters, the physical and mechanical properties of the composites consisted of veneer and double flame resistant core layer of straw board were the best. While the moisture content, MOR, MOE, IB, 2hTS, SB of the composites were respectively 8.8%,53.4MPa,6120MPa,1.25MPa, 2.02%,0.94MPa. And the III and the II types of bondline delamination of composite were not stripped under the optimal condition.(4) Compared to the composites with single core layer of straw board, the thermal conductivity of the straw board increased by 3.4%, while the composites with double core layer of straw board reduced by 21.7%. The heat release rate(HRR), pk-HRR, total heat release(THR), smoke production rate(SPR), total smoke production(TSP) and mass loss rate(MLR) were all obviously lower than those of plywood. The heat release rate(HRR), pk-HRR, total heat release(THR), smoke production rate(SPR), total smoke production(TSP) and mass loss rate(MLR) were all obviously lower than those of plywood. It could be concluded that there were three destructional forms of composites samples treated with static bending, which were respectively fracture type, shear type and mixed type that was the main damage of hybrid. The adhesive could penetrate into the porous structure of veneer to form mechanical fitting or form a chemical connection with polymer composition of the cell wall, under hot pressing process with suitable amount of adhesive. Which was good for growth of the mechanical strength and dimensional stability of the interface layer of composites.