The Preparation Of Reversible Thermochromism Microcapsule And Its Application On Wood-plastic Composites

This experiment added two types of reversible thermochromism material to prepare functional reversible thermochromism wood-plastic composite(WPC), and compared the performances with the pure WPC to research the applications of this reversible thermochromism WPC.Used urea resin as wall material, crystal violet lactone and heat sensitive rose red mixed with tetradecyl alcohol and bisphenol-A respectively as core material, utilized in-situ polymerization prepared two kinds of reversible thermochromism microcapsules. Used biological microscope, environmental scanning electron microscope, laser particle analyzer and so on to characterize two microcapsules microstructure, color-change time, color-change temperature range, grain size, heat aging resistance, organic solvent resistance, chemical stability resistance, fatigue resistance. The results showed that, the grain size of crystal violet lactone microcapsule was between 30-50 μm, the color-change temperature was between 40-52 ℃, the color-change was about 20 s; for the heat sensitive rose red microcapsule, the grain size was between 20-50 μm, the color-change temperature was between 30-42 ℃, the color-change was about 20 s; the two microcapsules was spherical particle, and color-change obvious and sensitive. Through the results of microstructure, grain size, color-change time and color-change temperature range, it can indicated that, the best way to prepare microcapsule was used tetradecyl alcohol as solvent of core material and the F/U value was 1.8. the microcapsules used this way had good heat aging resistance, organic solvent resistance, chemical stability resistance and fatigue resistance, but the strong base had a certain degree influence to it. In a word, the two types of microcapsules prepared by in-situ polymerization were reversible thermochromism microcapsules that practicable and good color-change consequence.Based on the best way to prepared a large number of organic reversible thermochromism microcapsule and added the microcapsule to prepare reversible thermochromism WPC. The physical and mechanical properties of reversible thermochromism WPC and pure WPC ware measured to compare the performance of three kinds of WPC. The results showed that, the color-change chromatism of two reversible thermochromism WPC were great, and compared with pure WPC, tensile property and bending property have increased significantly but impact toughness has few decreased. Because of the adding of microcapsule, the stiff flour ratio increased in WPC, so compared with pure WPC, the stickness and elasticity have a degree decreased, but have better nterfacial compatibility, this two reversible thermochromism WPCs were suitable for stiff environment. In all, this two reversible thermochromism WPCs were biomass composite with great color-change function.Through preliminary study of three kinds of color-change system(Co2+—tetradecyl alcohol system, bromophenol blue—Co2+—tetradecyl alcohol system, bromophenol blue—Mg2+—tetradecyl alcohol system) could get to know that, three kinds of color-change system could change color before and after heat, but after mixed with WPC, the color could not change anymore as temperature, so must modify the wood flour. by means of FTIR spectra of modified wood flour, when the temperature was 20 ℃, the solvent was normal hexane and the modifying agent was hydroxytrimethylsilane, the modification effect was best, the hydroxyl of wood flour could graft almost. Used the modified wood flour, LDPE and three kinds of color-change syetems to prepared reversible thermochromism WPC, only the composite with bromophenol blue—Co2+—tetradecyl alcohol system had the function of reversible thermochromism, and the interfacial compatibility of this reversible thermochromism WPC was better than pure WPC.