LF-1型低毒脲醛树脂的固化和固化反应动力学

本文通过热分析研究了脲醛树脂的催化固化反应。比较了几种固化剂的性能,选择有效的固化剂,确定最佳固化条件以及判断树脂的固化深度。反应动力学研究结果表明,脲醛树脂的固化过程可用自加速型反应机制描述,固化反应动力学模型为:da/dt=3.685×10~(13)e~(-92110/(RT))α~(0.8)(1-α)~(1.2),活化能E=92.11kJmol~(-1),前置因子A_0=3.685×10~(13)min~(-1)。     

Condensation reactions of phenolic resins III: self-condensations of 2,4-dihydroxymethylphenol and 2,4,6-trihydroxymethylphenol (1)

This study reexamined the kinetics of the condensation reactions of hydroxymethylphenols with the purpose of elucidating the reaction mechanisms. This report discusses experimental results on the self-condensations of 2,4-dihydroxymethylphenols (2,4-DHMP) and 2,4,6-trihydroxymethylphenol (THMP), focusing on the order of reaction. The relations between the initial rates of reaction and the initial concentrations of reactants were investigated. Results quite different from those of previous reports were obtained. The order of reaction of the selfcondensation of 2,4-DHMP was found to be 1.1, which did not change with the alkali/2,4-DHMP molar ratio. The order of reaction of the self-condensation of THMP was found to vary with both the concentration of THMP and the alkali/THMP molar ratio. In the region of THMP concentrations above 1.5mol/l, the order of reaction was confirmed to be 2.0, which did not change with the alkali/THMP molar ratio. In the region of THMP concentrations below 1.0mol/l, the order of reaction varied with the alkali/THMP molar ratio, showing fractional numbers of 1.2–1.6. These results indicate that unimolecular reaction(s) and bimolecular reaction(s) take place simultaneously as the ratedetermining step in the condensation reactions of 2,4-DHMP and THMP and that the reaction mechanism changes with the species of reactant and, in some cases, with the reaction conditions.Part of this study was presented at the Wood Adhesives 2000 symposium, South Lake Tahoe, Nevada, USA, June 2000     

Application of a modified rate equation to the acetylation of wood

A modified rate equation, in which the diffusion of reagent was taken into consideration, was proposed and applied to results reported previously for the acetylation of wood. The equation was fitted more successfully to the prolonged as well as the early stage of the reaction than a common first-order rate equation. Although the conclusions were virtually unchanged, the reliability was enhanced because reaction parameters such as the rate constant, ultimate extent of the reaction, and activation energy calculated for the modified equation were based on much more data than those reported previously. The equation proposed here may be applicable not only to acetylation but to other chemical modifications of cellulosic materials in heterogeneous systems.     

AlH2P3O10·2H2 O（Ⅰ）对水中Ni^2＋的吸附动力学和热力学研究

采用静态吸附法研究Al2O3-P2O5-H2O反应体系产物三聚磷酸二氢铝Ⅰ型二水物[AlH2P3O10.2H2O（Ⅰ）]吸附水中Ni2＋的动力学和热力学。考察了温度、浓度、粒径、pH和搅拌速度对吸附过程的影响,通过不同温度下的吸附等温热力学性能的变化,计算了吸附焓、吸附熵和自由能。结果表明,在试验范围内,AlH2P3O10.2H2O（Ⅰ）对Ni2＋的吸附符合Langmuir吸附等温方程式,过程受颗粒扩散控制,反应级数为1.88,298.15 K时的热力学数据为：Ea=11.561 kJ/mol,ΔH=35.75 kJ/mol,ΔS=190.58 J/（mol.K）,ΔG=-21.07 kJ/mol,吸附为自发的吸热过程,其吸附动力学总方程为：1-2/3x-（1-x）2/3=0.36r02C01.88exp（-11 561/RT）。     

L-苏氨酸摇瓶发酵动力学研究

对L-苏氨酸摇瓶发酵过程和发酵动力学进行了研究。基于实验结果,经非线性拟合和优化,得到了最佳的模型参数值,最终确定了能够很好的表征实际发酵过程中菌体细胞生长、产物L-苏氨酸形成以及基质总糖消耗的3个动力学方程。并对试验数据与模型进行了比较,结果拟合良好,说明此模型较好地反映了发酵过程及其动力学机制。     

基于SLMD的生物质热解动力学预测模型

采用单纯形格子混合设计法(SLMD)对纤维素、半纤维素和木质素3种生物质组分进行复配优化设计,并在综合热分析仪上进行了热解试验。分析了3组分混合热解特性,建立了由生物质3组分比例直接计算动力学参数的预测模型,对模型进行了试验验证。结果表明:纤维素热解反应级数较低(1.20),活化能较高(134.50 k J/mol),指前因子较大(3.49×1012s-1),热解较为迅速与剧烈;半纤维素和木质素热解的反应级数较高(1.30、1.32),活化能较低(33.51、19.98 k J/mol),指前因子较小(9.43×103、107 s-1),热解较为缓慢;3组分在混合热解中对动力学参数存在交互影响,纤维素对活化能和指前因子的影响较为显著,而半纤维素与木质素对反应级数的影响较大;动力学参数预测模型精度较高,可有效预测生物质热解动力学参数。     

阴离子交换树脂对米糠植酸的吸附解吸性能

通过静态和动态试验研究了6种阴离子交换树脂对植酸的吸附与解吸性能.结果表明,D201树脂对植酸的吸附交换作用较好,且在pH值为2.2时吸附能力最强,静态吸附量达到94.54 mg/g,1.5 mol/L的NaOH溶液利于植酸解吸;Freundlich吸附等温方程可以较好地描述D201树脂对植酸的等温吸附,表明吸附在常温下进行即可;D201树脂对植酸的吸附过程符合Lagergren一级速率方程,表观吸附速率常数k与植酸起始植酸浓度呈负相关关系,与温度呈正相关关系.在D201树脂对植酸的动态吸附与解吸过程中,层析柱管径、上样液浓度、上样液流速和洗脱剂流速对吸附与解吸效果影响较大.     

车辆AMT离合器离散变结构控制

以车圆舞曲机械式自动变速系统（AMT）的离合器液压执行机构为研究对象，建立系统非线性动力学模型。进一步应用基于微分几何的反馈线性化方法，将原非线性系统等价为完全可控型线性化模型。在此基础上设计了离散变结构控制器，并且证明了离散变结构系统的稳定性，实验结果证明，这一控制器跟踪精度高，并且对系统的非线性和不确定性表现出很强的鲁棒性。     

超声波降解苹果汁中展青霉素动力学研究

为了掌握超声波降解苹果汁中展青霉素的动力学特性,在前期超声波降解苹果汁中展青霉素的研究基础上,利用拟一级反应动力学方程对超声波影响因素中超声波功率、频率及温度降解苹果汁中展青霉素的试验数据进行拟合,确定相关参数,进一步建立各影响因素降解速率常数与相关影响因子之间的关系方程。结果表明:超声波功率对苹果汁中展青霉素的降解符合拟一级反应方程,超声波功率为490 W时,降解率最大;功率降解速率常数kP与超声波功率的方程为kP=6×10-5P-0.011 7。超声波频率对展青霉素的降解符合拟一级反应方程,超声波频率为45 k Hz时,降解率最大;频率降解速率常数kf与超声波频率f的关系方程为kf=-8×10-4f2+0.111 9f-2.512 6。温度对苹果汁中展青霉素的降解符合拟一级反应方程,温度为30℃时,降解率最大;温度降解速率常数kT与温度T的关系方程为kT=-1×10-4T2+0.006 1T-0.076 9。     

几种磷矿粉中磷和钙溶出动力学特性

采用间歇实验方法，研究4种磷矿粉在1M NH4OAC（pH4.8）酸性溶液中磷和钙溶出动力学规律，结果表明：磷矿粉中磷的溶出分为2个阶段，0~30min为快反应过程，30min后为慢反应过程，它能较好地符合Elvoich方程，磷的溶出速率（b）与枸溶性磷含量有较好的相关性，主要受磷矿粉中SiO2和碳酸钙含量的影响，枸溶性磷含量愈高，磷的溶出速率愈大，溶出磷的浓度也愈高。磷矿粉中钙的溶出也符合Elvoich方程，且与游离的碳酸钙含量有关，与其他磷矿粉不同，在PR1中钙的溶出浓度较高，很可能来自于碳酸钙的溶解。因而，磷矿粉不仅可以提供磷素营养，还提供植物生长所需的钙素营养。