| Recombinant bamboo is the first composite material successfully developed in China with independent intellectual property rights,which has wide applications in outdoor furniture,indoor and outdoor flooring,and building structure materials.This process has problems such as high energy consumption and low efficiency,which increase the production cost of recombinant bamboo.Moreover,the mechanism of heat migration and adhesive curing in the hot pressing process is still unclear,which seriously restricts the market competitiveness of recombinant bamboo products and the large-scale development and utilization of bamboo resources in China.In this paper,we investigate the curing law of phenolic resin adhesive in the hot pressing process of recombinant bamboo,reveal the heat migration mechanism in the hot pressing process of recombinant bamboo,obtain the heat migration and adhesive curing model in the hot pressing process of recombinant bamboo,and provide the theoretical basis for optimizing the hot pressing process of recombinant bamboo.Based on the content of the above research,the paper draws these conclusions as follows.(1)Using TG-DSC,SEM and other characterization means and mathematical statistical analysis methods,the effect of moisture and temperature on the curing of phenolic resin was systematically studied,the results show that:restricting the evaporation of water in the phenolic resin solution,the phenolic resin will be cross-linked curing,the unevaporated water exists between the cured phenolic resin molecules,the hardness and strength of the cured phenolic resin is lower,the microstructure is more rounded,the adsorption sites The cured phenolic resin has higher hardness and strength,rougher microstructure,and more adsorption sites,which is conducive to the full combination of phenolic resin and bamboo material.This model provides a theoretical basis for the quantitative characterization of phenolic resin curing during the hot pressing process of recombinant bamboo.(2)Using the hot pressing machine,physical inverse problem algorithm and mathematical statistical analysis method,the effect of hot pressing temperature and hot pressing pressure on the thickness and porosity of the slab in the hot pressing process of recombinant bamboo was systematically studied.The results showed that the thickness of the recombinant bamboo slab showed a non-linear increasing trend with the increase of temperature and pressure under different hot pressing temperature and hot pressing pressure conditions,and the model of the variation of the porosity of the slab with temperature and pressure in the hot pressing forming process of recombinant bamboo was constructed,which provided the basic data for the quantitative study of the variable porosity on heat transfer and the curing law of phenolic resin adhesive.(3)Based on Fourier’s law of thermal conductivity and energy conservation equation,combined with phenolic resin temperature curing model and porosity change model,a model of heat transfer and adhesive curing of recombinant bamboo thermoforming was constructed to quantitatively characterize the heat migration and phenolic resin curing law in the recombinant bamboo thermoforming process,and the results showed that the heat transfer model can more accurately respond to the heat transfer and cooling process in the recombinant bamboo thermoforming process.Based on this model,the hot pressing process of recombinant bamboo with different thickness and temperature was obtained,and 15mm and 25mm thick recombinant bamboo were selected for hot pressing process testing.The model can provide some scientific basis and theoretical support for the optimization of the recombinant bamboo hot pressing forming process. |
