The Study Of Nano-CaCO₃/Fast-growing Poplar Composite And Preparing Building Templates

The development of inorganic nanometer material technology opened up a new development space and new opportunities for the functional improvement for wood composite technology. The inorganic nanometer materials are able to improve inferior woods, with the same time keeping their inherent performances, such as the visual properties of the lumber and processing properties, and gift wood new excellent functions, such as the physical and mechanical performances of wear resistance, hardness and rigidity etc., which improves the utilization rate and application spaces of inferior woods. Based on these aspects and ideas, this research puts forward that nano-material powders by means of the carrier of high polymer materials are impregnated by the vacuum impregnation into the fast-growing poplar, which may play the role of excellent nano-material properties (by means of the solidify of polymer material) to improve the performances of the fast-growing poplars. This paper intends to make full use of the excellent performances of nanometer calcium carbonate, with the advantages of high quality performances, low cost, avirulent insipidity, high quality packing, reinforcing agent, and the sources advantage of fast-growing poplars, researching and developing the new wood and inorganic nanometer composites with the fast-growing poplar as the matrix, nanometer calcium carbonate as the packing, with the aid of the organisms of phenolic resin, and attempt to prepare a new and widespread building template by using the kind of composites. Main contents and results are as follows:(1)We synthetized phenolic resin (PF) with water-soluble and thermosetting adhesive as the middle medium during compositing, and the solution of CaCl2and (NH4)2CO3happen the metathesis to product the nano-CaCO3in the system of homemade PF, and the PF-CaCO3prepolymerization body are impregnated into the fast-growing poplar veneers by the vacuum impregnation to prepare the nano-CaCO3and poplar composites. Through the experiment of the metathesis reaction added time, we found that with the time delay, the stability of PF-CaCO3prepolymerization body were strengthened gradually, and CaCO3nanoparticles got smaller then. The better time of adding the metathesis reaction was after160mins by some experiments. Through observation of the transmission electron microscopy (TEM), electronic scanning electron microscope (SEM) and the research and exploring of FTIR Spectrometer analyses (FTIR), Energy spectrum analysis (EDXA), and the differential scanning calorimetry (DSC)/thermal gravimetric analysis (DSC/TG), it was obvious that the impregnate effects and the high thermal stability of sample colloid and dipped veneers were added3%CaCl2and4.5%(NH4)2CO3solution accounted for1%of the total phenolic resin. In the PF-CaCO3system, the calcium carbonate gained is nanometer and cube. Nanometer calcium carbonate powder size is growing with the increase of CaCl2mass percentage and separated and reunited, it was found that prepolymer PF-CaCO3were controlled into the lumen and the veneer hardness, weight gain were effected with the increase of CaCl2mass percentage.(2) First, CaCO3nanoparticles about50nm in size and cube-shaped were prepared using the metathesis method (the reaction of CaCl2and (NH4)2CO3). In this segment the modification additive was BS-12, which was able to improve speed crystallized in the process of the early response, restraining the growth of the crystal to the vision, controlling the grow direction of the crystal, and inhibiting the morphology and size of the products in the later period. The BS-12additive could modify the surface of CaCO3nanoparticles, and changed the surface properties of CaCO3nanoparticles. The optimized parameters of preparation about CaCO3nanoparticles was the solution of250ml,0.3mol/L CaCl2,2.5ml BS-12additive, mixing,then adding the same molar mass of the solution of (NH4)2CO3,suction filtering, rectisol and water scrubbing, finally drying.(3) Nano-CaCO3and fast-growing poplar composites were prepared by the sol-gel method. The nano-CaCO3prepared by the metathesis method of (2), and as the carrier, homemade PF were combined to form the colloid, which impregnated the poplar veneers by the vacuum impregnation. Through the sample characterization methods, we concluded that the size of CaCO3was obviously lower with the increase of the BS-12additive, and the solution dispersion of CaCO3nanoparticles was increased. Thermal stability was better than not adding the BS-12into the composite materials. When the addition of the BS-12was2.5ml, the sol effect was better, transparent, uniform, and massive gel is formed in the system of the poplar veneer, whose WPG of the impregnated veneer by the vacuum impregnation and the sol-gel method was to148%, with infiltrating effect obvious, and the hardness was better than other impregnated veneers.(4)The nano-CaCO3and fast-growing poplar composites were prepared by the diffusion method. The optimized technological parameter is that5%CaCl2solution,7%(NH4)2CO3solution, and0.5%BS-12. The process was simpler, and able to keep their inherent performances, such as the visual properties and environics properties of the lumber. Because of the less addition, CaCO3prepared was less, leading to lower WPG, but the antiseptic effect was better and the composite material had the hydrophobic, hardness was higher than native poplar veneer. The result indicates the gap filling of inorganic calcium carbonate increased the hardness of the poplar veneer, realizing the purpose of optimizing inferior woods.(5) According to GB/T17656-2010national standard, we prepared the building templates by three methods (PF-CaCO3, Sol-gel, Diffusion) and tested their physical and mechanical performances, and meeting and exceeding national standards. The optimum hot-pressing process:hot pressing-pressure for3Mpa, hot pressing time for12min, hot-pressing temperature140℃, hot pressing for the segmentation type. The MOR (106.39Mpa) and IB (1.6Mpa) of building templates by poplar veneers dipped by the PF-CaCO3prepolymer method were better than the other two methods. The MOE (10.34Gpa) and TS (2.19%) of building templates by poplar veneers dipped by the diffusion method was the best in these treatment methods. Through the differential scanning calorimetry (DSC)/thermal gravimetric analysis (DSC/TG), the thermal stability composite building template according to the good or bad sort is PF-CaCO3prepolymer method, diffusion method and sol-gel method. Comprehensive comparing, the performances and precess of the builing template by PF-CaCO3prepolymer method are better than other methods.