聚酯二元醇合成聚氨酯丙烯酸酯复合乳液的研究

以异佛尔酮二异氰酸酯(IPDI)、自制聚酯二元醇、二羟甲基丙酸(DMPA)和甲基丙烯酸甲酯(MMA)、苯乙烯(St)、丙烯酸丁酯(BA)为主要原料,合成了聚酯型聚氨酯丙烯酸酯(PUA)复合乳液,研究了不同相对分子质量的聚酯二元醇、聚氨酯制备时不同NCO/OH比值、添加三羟甲基丙烷(TMP)含量、及合成PUA时不同PU/PA的比值对最终制备的聚氨酯丙烯酸酯复合乳液及涂膜性能的影响。结果表明:1500～2000相对分子质量的聚酯二元醇:在TMP添加量为2%、NCO/OH为1.6～1.8,PU/PA以4︰6合成出的PUA,有着较好的制备稳定性和贮存稳定性,其涂膜硬度、耐水性和耐醇性较好。     

3,5-二甲基吡唑封闭型水性异氰酸酯固化剂的合成及应用

用异氰酸酯三聚体与二羟甲基丙酸(DMPA)先进行扩链反应,蒋用3,5-二甲基吡唑(DMP)将剩余的异氰酸酯基封闭,然后用二甲基乙醇胺(DMEA)中和成盐,制得可水分散型封闭异氰酸酯固化剂(WBI),并讨论了封闭比例[n(-H)∶n(-NCO)]、DMPA用量、反应温度、反应时间对制备水分散型封闭异氰酸酯固化剂的影响.采用傅里叶变换红外光谱(FT -IR)和差示扫描量热法(DSC)对封闭固化剂的结构进行了表征及分析,结果表明得到了预定结构产物,并且制备的封闭型多异氰酸酯固化剂可在较低温度( 130～ 150℃)实现解封.用合成的封闭异氰酸酯与环氧改性丙烯酸树脂制备了水性玻璃烘烤涂料,并对涂膜性能作了初步探讨.     

两步法制备高性能水性树脂及其在烘烤型水性涂料中的应用

结合溶液聚合和乳液聚合的优点,采用两步聚合法合成了一种水性羟基丙烯酸树脂,所制备的水性树脂外观良好,黏度适中。动态光散射结果表明所合成的水性乳液平均粒径为122 nm,粒径分布均匀。利用傅里叶红外光谱(FT-IR)对合成水性树脂的结构进行表征,结果表明得到了预定结构的产物。差示扫描量热仪(DSC)表明两步聚合的产物的玻璃化温度均为30℃左右,与实验设计相符合。利用所合成的水性羟基丙烯酸树脂与氨基树脂R-717配制烘烤型水性清漆,FT-IR谱图验证了固化反应的发生。固化后的水性清漆性能测试结果表明,漆膜光泽高、硬度高、附着力好,耐冲击性能优异,耐水性和耐乙醇性较好,与国外同类产品制得的清漆性能相当,可应用于车架、机械零部件及卷尺等工业防腐装饰领域。     

Activity improvement of Pt/C catalysts by adding CeO2 nanoparticles

Carbon-supported platinum catalysts were prepared by NaBH4 reduction of metal precursors and the CeO2 nanoparticles were pre-pared by citric acid sol-gel method.The structure and morphology of two kinds of nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM),respectively.The Pt particles were uniformly dispersed on the carbon surface and showed the rod-like morphology.The CeO2 was spherical in shape.The appropriate amount of CeO2 nanoparticles was added into Pt/C sys-tems to improve activity of the catalysts.Several electrochemical techniques such as cyclic voltammogram (CV),chronoamperometry (I-t) and electrochemical impedance spectroscopy (EIS) were used to investigate the properties of CeO2-Pt/C catalysts for methanol electrooxidation in 1 mol/L CH3OH+0.5H2SO4 aqueous solutions.The results revealed that compared with Pt/C catalysts CeO2-Pt/C exhibited a higher activity and stability for methanol electro-oxidation.Moreover,the effect of CeO2 content on the activity of Pt/C catalysts was discussed in detail.     

塑料薄膜用作水稻田埂

据文献介绍,美国加利福尼亚州试验站于一九五九年开始研究用塑料薄膜代替水稻田的土埂。在美国,水稻田的土埂一般底宽达1.5米,顶宽1.2米,高0.5米,占用总水田面积的2～7%。修筑土埂时需用两台拖拉机牵引一台筑埂器。试验塑料薄膜田埂的制作过程如下:     

反渗透过程的浓度极化及其传质系数测定

The relationship between osmotic pressure difference across the membrane and mass transfer coefficient is developed in this paper. On the basis of this relationship, a method for measuring mass transfer coefficient by using experimental data on reverse osmosis is established. Pitzer's equations are used to calculate osmotic pressure differences in order to assure accuracy of results. Under the conditions of constant operating pressure and bulk flow, mass transfer coefficient is scarcely affected by membrane structure, but decreases slightly with increasing feed concentration. The solute concentration in the polarization layer is calculated by using the measured values of mass transfer coefficient. Polarization layer concentration increases with augmentation in bulk concentration. However, their difference increases with increasing bulk concentration until a maximum difference is reached, and then decreases. Mass transfer coefficient increases with higher velocity of bulk flow. If mass transfer coefficient is so large that the ratio(PwΔπσ/k)becomes very small, polarization could be neglected.     

传热传质学课程教学内容及方法的探索与实践

“热质交换原理与设备”与“传热学”是建筑环境与能源应用工程专业（以下简称“建环”）两门重要的专业基础课,且均存在涉及面广、理论实践性强、学习难度较大等问题。在2019年合肥工业大学全面调整包括建环专业在内的培养方案和人才培养能力,且要求大量压缩专业课学时的背景下,尝试将原本开设的两门课合并为一门“传热传质学”。基于两门课主流教材内容,细致地整理了传热传质学的教学内容及学习重难点,整合删减了原有两门课重复陈述的知识点。利用智慧教学平台“雨课堂”及网络在线MOOC资源,构建了以学生为主体的线上线下混合启发式教学模式,并丰富了课程考核方式。通过教学内容及方法的探索与实践,使得在有限的课内学时,取得良好的教学效果。     

SnO2/还原氧化石墨烯/聚吡咯三元复合物的合成及其电化学电容性能

采用两步法制备出均匀分散的SnO2/还原氧化石墨烯(SnO2/RGO)二元复合物,再以二元复合物为模板,通过化学氧化法聚合吡咯(Py)单体,制备出SnO2/还原氧化石墨烯/聚吡咯(SnO2/RGO/PPy)三元复合材料。利用红外光谱(FTIR)、X射线衍射(XRD)和场发射扫描电镜(FESEM)对复合材料结构和形貌进行物性表征,利用循环伏安、恒电流充放电和交流阻抗对复合材料进行电化学性能研究,并讨论了不同含量的PPy对复合材料的结构和性能的影响。结果表明,所合成的三元复合材料的比电容随PPy含量的增加而增大,最大达到305.3F/g。三元复合物电容性能增强源于SnO2、RGO与PPy三者的相互协同作用,以及材料层状结构和大的比表面积。     

配网电力电缆故障探测的新方法探讨

论文分析了传统配网电力电缆故障探测方法的不足和缺点，提出了利用高频感应法及红外热象技术两种新方法来进行故障探测，高频感应法较之音频感应法有许多优点，而红外热象技术的先进性使其有很大发展潜力，是值得采用的电缆故障探测新方法。     

大连市城市水资源现状供需关系的初步分析

大连市位于辽东半岛的南端,濒临黄、渤海,是全国十四个开放城市之一。按流域分区,处于碧流河与复州河两流域之间的区间地带,(以下简称“区间地带”)。现状供需关系分析,以1980年为代表年,该年大连市供水,主要以“区间地带”地表迳流和地下水为水源。该“区间地带”集水面积3.864方公里,