Development Of Multifunctional Plastering Gypsum

Modern life and architectural decoration require that the gypsum plaster be multifunctional in terms of ecological environmental protection and hygiene,and mosquito repellent,fresh air,waterproof and other aspects should be paid more and more attention.This dissertation focuses on the research of plastering gypsum in repelling mosquitoes,degrading indoor formaldehyde,and waterproof.The purpose of this paper is to develop repellent plaster,formaldehyde-removing plaster and waterproof plaster,and the details are as follows:1.Use?-hemihydrate gypsum as raw material to obtain mosquito-repellent plaster by adding microcapsules.Mosquito repellent microcapsule were prepared by complex coacervation,which used gelatin,arabic gum and wormwood essential oil as raw materials,scanning electron microscopy were used to characterize microstructure of the products prepared by the best conditions,the optimal process parameters were determined.The results show that the emulsification stirring intensity 1500 r/min,stirring time is 45 minutes,Complex coacervation stirring speed 900 r/min,complex coacervation time is 40 minutes,curing with tannic acid,tannic acid concentration1.5 g/g gelatin,the curing time is 80 minutes,the alkalization processing 10 minutes under pH value 8.0 and temperature of below 10?,the microcapsule yield is 60.5%and the coating rate is87.94%which is the best,the average size is about 5 um,When the addition of microcapsules accounted for 3%of the quality of wall plaster,The initial mosquito repellent rate of wall plaster is 94%,and the mosquito repellent rate still at more than86%after wall plaster is shelved in the open air for 75 days.2.Based on?-hemihydrate,gypsum plaster with the function of methanal decompasing coul be obtaind by adding photocatalyst.The photocatalyst is a modified catalyst with TiO₂ as the main body in the sharp state,urea and lanthanum nitrate as the modifier,and loaded with tourmaline.The structure and properties of the modified catalyst were characterized by XRD,UV-Vis,and SEM.and the degradation efficiency of formaldehyde after the addition of the modified catalyst in the gypsum plaster was discussed.The optimal formula was N doping amount5%,La doping amount 1%,tourmaline 10%,the best effect,the average particle size is about 11.7 nm,the degree of crystallization is very good,mainly anatase structure.The spectral response and degradation efficiency of TiO₂ in the visible range were increased.When the amount of 5%N-1%La-TiO₂/10%tourmaline catalyst was 2%,the formaldehyde removal rate of the plasterboard was 93.4%.Good and economical,and lasting,the removal rate was 87.2%after five months.3.Waterproof plastering gypsum was prepared by adding different waterproofing agents,and its moisture resistance in wet environment was tested,and its mechanism was studied.The results showed that the best water repellent was emulsified stearic acid.When the addition amount was 7%,the water absorption rate of plastered gypsum board under the air humidity of 98%±2%within 24 hours was 0.57%.Stearic acid will wrap the gypsum,change the surface properties of the gypsum,change from hydrophilic to hydrophobic,and at the same time can reduce the gap between the gypsum crystal and the crystal to a certain extent and reduce the internal density of the gypsum by increasing the internal density of the gypsum.Its water absorption rate.