人造板甲醛释放规律、机理及处理方法研究

发布时间：2018-08-31 12:51

【摘要】：采用甲醛检测仪、有机气体检测仪等测试了桂林、南宁、柳州等广西典型城市的居室和公共场所的甲醛、总挥发性有机物(TVOC)浓度,运用Airpak软件模拟了典型污染源人造板在室内的甲醛浓度分布；在环境测试舱中研究了温度、湿度、换气率、装载率、板材种类及厚度等因素对人造板甲醛释放的影响规律；运用双指数衰减模型、迭代法计算人造板的甲醛可释放量和释放特征参数,并结合传质理论建立人造板的甲醛释放预测模型；采用正交试验法研究了人造板甲醛去除工艺、脲醛树脂胶改性方法,采用热重分析仪(TG-DTG)、差示扫描量热仪(DSC)等研究了人造板脲醛树脂(UF)胶的热解动力学、热力学。主要结论如下：(1)桂林市典型居室内甲醛和TVOC污染程度依次为：书房卧室客厅厨房,最高浓度分别达0.898mg/m3、1.532mg/m3;南宁市典型居室的甲醛污染程度依次为：书房卧室客厅,TVOC污染程度依次为：卧室书房客厅,最高浓度分别达0.901 mg/m3、 0.673mg/m3;在公共场所中,柳州市、桂林市商场内的甲醛、TVOC浓度较高,最高浓度分别为0.268 mg/m、0.713 mg/m3,0.276 mg/m3、0.805 mg/m3。(2)室内的甲醛扩散方式主要有自由扩散、湍流作用和空气对流等,室内甲醛的浓度分布与污染源、气流等直接相关,中间过道附近的甲醛浓度均低于国家标准,在床下方的成人坐姿呼气区、站姿呼吸区以及床上方的卧姿呼吸区域的甲醛浓度均超过国家标准,最高浓度分别达到0.198mg/m3、0.177 mg/m3、0.171 mg/m3,模拟值与实测值的最大误差为9.6%。(3)刨花板、胶合板、密度板、大芯板、实木板的甲醛释放过程可分为快速释放、缓慢释放、释放饱和三个阶段,释放的甲醛浓度随着环境温度、湿度、厚度和装载率的增加而增加,随着换气率的增加而降低,最高浓度分别为0.428 mg/m3、0.377 mg/m3、0.345 mg/m3、 0.213 mg/m3、0.023 mg/m3。(4)甲醛在人造板内部的扩散系数D随着环境温度、湿度或换气率的增加而增加,气／源界面的分配系数K随着环境温度、湿度的增加而减小；刨花板、胶合板和密度板的甲醛释放预测模型拟合的浓度与实验值的最大误差分别为15%、20%、12%。(5)影响人造板甲醛去除效果的强弱次序为：处理温度换气速率处理时间相对湿度；最优去除工艺为：处理温度、换气速率、处理时间、相对湿度分别为95℃、16.8 m3/h、6d、35%RH,经此工艺处理后的甲醛去除率为63.2%,且对板材力学性能影响很小。(6)改性剂对UF胶甲醛释放量的影响顺序为：皂土苯酚二环己基碳二亚胺甲基甲基硅油；最佳改性工艺为：皂土、甲基硅油、二环己基碳二亚胺、苯酚的添加量分别为10%、10%、3%、3%,经该工艺改性后UF胶的甲醛释放量降低了50.7%,其热稳定性、胶合强度、耐水性等均有所提高。(7)改性前后的UF样品在103～198℃的失重率分别为14.3%、9.5%,在200～330℃的失重率分别为47.8%、46.1%,热失重率在35%～60%区间内的平均活化能分别为222.292kJ/mol、261.569 kJ/mol,指前因子1gA分别为23.744 s-1、30.264 s-1,△H、△S、△G分别为217.72 kJ/mol、196.23 J/(mol-K)、109.84 kJ/mol,284.97 kJ/mol、350.07 J/(mol-K)、93.22 kJ/mol。
[Abstract]:Formaldehyde and total volatile organic compounds (TVOC) concentrations in rooms and public places of Guilin, Nanning, Liuzhou and other typical cities in Guangxi were measured by formaldehyde detector and organic gas detector. The indoor formaldehyde concentration distribution of wood-based panels was simulated by Airpak software. Formaldehyde emission from wood-based panels was predicted by double exponential decay model and iteration method, and the prediction model of formaldehyde emission from wood-based panels was established based on mass transfer theory. The pyrolysis kinetics and thermodynamics of wood-based panel urea-formaldehyde resin (UF) adhesive were studied by TG-DTG and DSC. The main conclusions are as follows: (1) The pollution degree of formaldehyde and TVOC in typical living rooms of Guilin is in turn as follows: study bedroom living room kitchen, the highest concentration is 0.898mg/kg, respectively. M3,1.532mg/m3; Nanning typical room formaldehyde pollution degree in turn: study bedroom living room, TVOC pollution degree in turn: bedroom study living room, the highest concentration of 0.901 mg/m3, 0.673 mg/m3; in public places, Liuzhou, Guilin shopping mall formaldehyde, TVOC concentration is higher, the highest concentration is 0.268 mg/m, 0.713 mg/m3, 0.713 mg/m3, respectively. 276 mg / m3,0.805 mg / m3. (2) The main indoor formaldehyde diffusion modes are free diffusion, turbulence and air convection. The indoor formaldehyde concentration distribution is directly related to pollution sources and airflow. The formaldehyde concentration near the middle passageway is lower than the national standard. The maximum concentration of formaldehyde was 0.198 mg/m3, 0.177 mg/m3 and 0.171 mg/m3, respectively. The maximum error between simulated value and measured value was 9.6%. (3) The formaldehyde release process of particleboard, plywood, density board, large core board and solid wood board can be divided into three stages: rapid release, slow release and saturation release. The aldehyde concentration increases with the increase of ambient temperature, humidity, thickness and loading rate, and decreases with the increase of air exchange rate. The highest concentrations are 0.428 mg/m3, 0.377 mg/m3, 0.345 mg/m3, 0.213 mg/m3, 0.023 mg/m3, respectively. (4) The diffusion coefficient D of formaldehyde in the wood-based panel increases with the increase of ambient temperature, humidity or air exchange rate. The maximum errors between the predicted concentrations of formaldehyde emission from particleboard, plywood and density board and the experimental values were 15%, 20%, 12%. (5) The order of influencing formaldehyde removal efficiency of wood-based panels was: the relative humidity of treatment temperature and air exchange rate of treatment time; The optimum removal process is as follows: treatment temperature, air exchange rate, treatment time, relative humidity is 95, 16.8 m3/h, 6 days, 35% RH, and the removal rate of formaldehyde is 63.2%. The effect of modifier on formaldehyde emission from UF glue is in the order of bentonite phenol Dicyclohexylcarbodiimide methylsilane. The optimum modification process is bentonite, methyl silicone oil, dicyclohexyl carbodiimide, phenol 10%, 10%, 3%, 3%, respectively. The formaldehyde emission of UF adhesive is reduced by 50.7%, and its thermal stability, bonding strength and water resistance are all improved. (7) The weight loss of UF samples before and after modification is 14.3% at 103 ~ 198 C, respectively. The average activation energiwere 222.292kJ/mol, 261.569 kJ/mol, 261.569 kJ/mol, and the pre-exponentfactor 1gA were 23.744 s-1, 30.264 s-1, Delta H, Delta S, Delta G were 217.72 kJ/mol, 196.23 J/ (mol-K), 109.84 kJ/mol mol, 284.97 kJ/mol, 284.97 kJ/mol, 284.97 kJ/mol, kJ/mol, 28 4.97 kJ/mol, kJ/mol, 30.97 kJ/mol, 1 gA were 23.744 s-1, 30.264 s-1, 30.264 s-1, 93.22 kJ/mo L.
【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU531;X51

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