Ti(acac)2Cl2/AlEt2Cl(或AlEt2Cl-ZnCl2)催化剂催化丙烯腈聚合反应

研究了Ti(acac)2Cl2／AlEt2Cl催化丙烯腈聚合反应,分析了加入第三组分ZnCl2对聚合反应的影响,用^13C—NMR对聚合产物进行了表征,并探讨了聚合反应机理。结果表明,随着聚合温度的提高和聚合反应时间的增加,单体转化率增大,聚丙烯腈的分子量提高。当体系中n(AN)／n(Cat)超过一定量时,则得不到高聚物。体系中加入ZnCl2能明显提高单体转化率和产物分子量,并且产物的三单元规整结构含量明显增加。     

废腈纶水解物的制备与表征

腈纶经水解处理后可以制备出多种高附加值的产品，文中研究了聚丙烯腈碱法水解工艺的水解过程、水解程度，考察了水解工艺条件和水解配方对产物性能的影响。结果表明，m(PAN)／m(NaOH)／m(H2O)=1／0．6／5时，在95℃水解4h，得到含羧钠基、酰胺基等多种亲水性基团的均匀透明的无规共聚物水溶液。采用FT—IR、XRF、^13C-NMR等对产物进行了分析表征，进一步验证了试验结果。     

注射工艺参数对PC/ABS材料制品收缩与翘曲的影响

将计算机模拟注射成型过程和实验优化设计相结合,提供了一套经济有效便捷的方法对各工艺参数进行定量的统计分析。选用L27(3^13)正交表设计实验,通过研究注射速率来判断流动引起的收缩;计算模具温度、熔体温度、保压压力与保压时间来确定热诱导的收缩;研究浇口尺寸来判断剪切热对PC／ABS塑料制品收缩的影响程度。以洗衣机上盖为例,以Taguchi实验方法为设计准则安排CAE分析,在制品关键部位采集收缩翘曲量,通过对因素与水平进行的方差分析和直观分析,最后得出熔体温度和保压压力对PC／ABS塑料制件的收缩翘曲影响最大。     

新型含磷双马来酰亚胺／环氧树脂的合成与性能特征

通过双(3-氨基苯基)苯基氧膦的酰亚胺化制备了一种新型可溶性的含磷双马来酰亚胺单体：双(3-马来酰亚胺基苯基)苯基氧膦(BMIPO)。并用^1H核磁，^13C核磁及傅立叶红外光谱对其结构进行了表征。BMIPO树脂中含有五元酰亚胺环及高密度的苯基，使BMIPO树脂成为一种有着较高的玻璃化温度(Tg)、高起始分解温度及高氧指数的极好的阻燃剂。可以得到任意比例且不存在相分离的均相含磷双马来酰亚胺／环氧／4，4’-亚甲基二苯胺(DDM)固化树脂。由于BMIPO／DDM之间的反应速率比4，4’-双马来酰亚胺基二苯甲烷(BMIM)／DDM大，增大混合树脂中BMIPO／BMIM的比例，也就增加了后固化阶段重新交联的危害性，使得Tg值及热稳定性有所降低。BMI／环氧固化体系的热稳定性较环氧固化体系低，这是由于在BMIPO中引入膦基造成的，但其Tg值和阻燃性都明显比环氧固化体系高。混合物中BMIPO含量越高，阻燃性越好。     

化学氧化聚吡咯的结构及导电性的研究EI

通过元素分析、X射线光电子能谱(XPS)、富里哀变换红外光谱(FTIR)及固体^(13)C核磁共振(^(13)CNMR)等测试方法,对化学氧化聚吡咯的导电性及化学结构作了详细探讨。实验结果表明,在氧化态的聚吡咯中,平均每四个吡咯环带有一个负离子(Cl^-),大分子链上的正电荷分布在氮原子上,各吡咯环主要以α-α′相连接。经还原剂处理后,聚吡咯的电导率下降了7个数量级,这与大分子链上正电荷的变化有关。     

改性壳聚糖亲核一氧化氮供体的合成及释放性能

分别用二乙烯三胺、丙醛对壳聚糖的氨基进行改性,并与NO气体在甲醇钠／甲醇溶液中6×101．3kPa反应7d,得到两种改性壳聚糖／一氧化氮加成产物。采用FT-IR、UV、^1H—NMR和^13C-NMR对产物的化学结构进行了表征,并用Griess试剂法测定了其NO释放曲线。NO释放试验表明,增加改性壳聚糖亲核住点NH的数量可以显著提高NO负载量。CS／DETA／NO的NO最大释放量为1945nmol／mg,CS／PA／NO的NO最大释放量是1156nmol／mg。     

掺铒氧氟碲酸盐玻璃的上转换发光研究

研究了掺铒氧氟碲酸盐玻璃的吸收光谱和上转换发光光谱，分析了Er^3 离子在氧氟碲酸盐玻璃中的上转换发光机理．结果表明：通过975nm的激光二极管(LD)激发，在室温下同时观察到强烈的绿光(524和545nm)和红光(655nm)，分别是由于Er^3 离子^2H11／2→I15／2，^4S3／2→I15／2，和^4F9/2→I15／2跃迁．随PbF2含量增加，绿光的发光强度增加趋势较小，而红光的发光强度增加趋势大于绿光．上转换发光机理主要涉及能量转移和激发态吸收，强烈的绿光和红光激发都是由于双光子吸收过程．     

溶胶-凝胶法Pd／SiO2杂化材料的热稳定性和热分析动力学

采用溶胶-凝胶法，在甲基化改性SiO2溶胶中掺杂PdCl2，制备Pd／SiO2杂化材料，通过XRD、红外光谱、TG—DTG分析以及接触角测定，考察Pd／SiO2杂化材料在N2气氛中的热稳定性，用Coast—Redfern方程、Doyle方程，结合最概然机理函数的Malek推断法，求算Pd／Si02杂化材料在热分解过程中各阶段的热分析动力学三因子，结果表明，保持Pd／SiO2杂化材料疏水性的最适宜焙烧温度为350℃。在N2气氛中，Pd／SiO2杂化材料中-CH3的无机化过程包括4个阶段，各阶段具有不同的热分解动力学机理函数，其活化能分别为73．85、143．66、204．47和417．19kJ·mol-1，指前因子分别为1．20x10^12、2．27x10^13、8．50x10^11和1．03x10^20S-1。     

Er3+掺杂的MFT玻璃材料2H11/2、4S3/2→4I15/2荧光性质

计算了Er^3 掺杂的氟氧化物玻璃材料MFT的J－O参数,进而获得了一些能级间跃迁的跃迁几率、分支比、及寿命等数据,测量了室温下Er^3 的较强的两个绿色发射^2H11／2、^4S3／2→^4I15／2及红色发射^4F9／2→^4I15／2的激发光谱,观测了^2H11／2、^4S2／2→^4I15/2跃迁荧光强度随着温度的变化,测量了室温下这两筹这衰减曲线,计算了这两个能级的无辐射跃迁几率及量子效率。     

掺Er3+硅酸盐玻璃上转换发光特性研究

研究了掺Er^3＋硅酸盐玻璃的吸收光谱和上转换光谱，应用Judd-Ofelt理论计算了Er^3＋强度参数Ωλ（λ=2、4、6）、跃迁振子强度、自发辐射几率、荧光分支比．上转换光谱分析表明：在522、545、658nm处有较强的绿光和红光，分别对应于^2H11／2→^4I15／2、^4S3／2→^4I15／2、^4F9／2→^4I15／2的跃迁，发光曲线拟合斜率分别为1．67，1．94，1．76；上转换发光机制主要是激发态吸收和能量转换，且均为双光子吸收过程．     

新型聚氨酯防火涂料的阻燃抑烟性能研究

本文主要阐述了采用锥形量热仪法测试由聚磷酸铵(APP)/新型成炭剂(Carbonific)/聚氨酯(PU)清漆所构成的防火阻燃体系的阻燃、抑烟性能,并和聚氨酯(PU)清漆体系的性能进行对比,分析了该体系阻燃、抑烟的原因.     

Use of precipitated silica with silanol groups as an inorganic chain extender in polyurethane

In this study, novel polyurethane/silica (PU/SiO₂) hybrid materials, prepared without an external crosslinking agent, were developed via the chemical reaction between urethane groups of PU prepolymer and hydroxyl groups at the surfaces of silica. The added inorganic filler-silica thus played the dual roles not only inorganic chain extender but also reinforcing agent in the preparation of the hybrid. Two different blending methods, were compared with respect to the mechanical properties of the PU/SiO₂ hybrid materials: stirring mixing and three-roller shear mixing. The hybridization mechanism was confirmed using Fourier-transform infrared spectroscopy (FT-IR), solid-state ²⁹Si NMR spectroscopy and X-ray diffraction (XRD). The dispersion of silica particles in the PU matrix was investigated by scanning electron microscopy (SEM). Because of the shear effect of three-roller shear process, the size of the silica aggregates tended to be more uniform. The tensile strength and elongation at break of the PU/SiO₂ hybrid were 51 MPa and 590%, respectively, which represent increases of fourfold and 39% compared to those of neat PU. The thermogravimetric analysis (TGA) results for the PU/SiO₂ hybrids indicated greater thermal stabilities and lower decomposition rates after hybridization. This work contributes new insights into the preparation of high-performance PU/SiO₂ hybrids.     

Effects of organic chain length of layered zirconium phosphonate on the structure and properties of castor oil-based polyurethane nanocomposites

Three novel organic–inorganic hybrid molecules, layered zirconium phosphates or phosphonates, were synthesized. To study the effects of organic chain length of them on the structure and properties of polymer nanocomposites, the polyurethane/α-zirconium phosphate (PU/ZrP), polyurethane/zirconium 2-aminoethylphosphonate (PU/ZrAEP) and polyurethane/zirconium 2-(2-(2-(2-aminoethylamino)ethylamino)ethylamino) ethylphosphonate (PU/Zr(AE)₄P) nanocomposites were prepared, and characterized by Fourier Transform Infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing. It was revealed that morphological, mechanical, and thermal properties of these nanocomposites were strongly dependent on the organic chain length of the layered zirconium phosphonates. The results showed that the fillers with longer chain length exhibited better dispersion in the PU matrix. As expected, the mechanical properties and water resistance were improved with the increasing of organic chain length of fillers, which attributed to better interfacial adhesion between fillers and PU matrix.     

Preparation of polyurethane/poly(vinylidene fluoride) blend hollow fibre membrane using melt spinning and stretching

Melt spinning and stretching process was used to prepare polyurethane/poly(vinylidene difluoride) (PU/PVDF) blend hollow fibre membrane in this study. Rheological properties of melts of PU, PVDF and their blends were studied by observing their melting viscosity changing with shear rate and temperature. Morphologies of PU/PVDF blend hollow fibre membranes with different mass ratios were also observed by SEM and results showed that PU/PVDF mass ratio of 3:1 was relatively better condition for membrane preparation. The forming mechanism of the interfacial microvoids in PU/PVDF blends was also investigated and PU/PVDF blend hollow fibre membrane with water flux of ～2174 L m^?2 h^?1 was finally obtained under the pressure of 0·1 MPa.     

Effect of surface nature of carbonaceous nanosized fillers on properties of polyurethane based nanocomposites

Polyurethane (PU) composites containing uniformly dispersed nanosized and macrosized carbonaceous fillers (fullerene C60, fullerene soot, detonation nanodiamonds, and nanodiamonds soot) with loadings varying from 0.1 to 0.5?wt.% were prepared by in situ polymerization. The kinetics of PU synthesis catalyzed by dibutyltin dilaurate was studied as a function of amount of nanosized filler. It was found that the reaction is zero-order. The kinetics of the hard domain growth of the PU matrix was studied and described successfully using the two-parameter Avrami model for isothermal crystallization. It was found that the growth of polymers induces athermal primary nucleation for hard domain growth, and that nanosized fillers do not change the nucleation mechanism. Our results show that the mechanical strength of PU composites increases in the presence of all types of nanoparticles under study. This can be related to the antiplasticization effect of the nanoparticles on the polymer matrix. The dielectric spectroscopy demonstrated that T_g values of the composites increase in comparison with neat PU. However, the effects of hydrophilic/hydrophobic properties of nanoparticles on the secondary relaxations are not obvious Microphase separation in these nanocomposites was studied using FTIR spectroscopy, but no effect of surface properties of the nanoadditives on this phenomenon has been observed.     

Synthesis and characterization of thermoplastic polyurethane/montmorillonite nanocomposites produced by reactive extrusion

The novel polyurethane/montmorillonite (PU/MMT) nanocomposites based on poly (propylene oxide) glycol (POP), 4,4′-diphenymethylate diisocyanate (MDI), 1,4-butanediol (1,4-BD) and MMT has been synthesized using a one-step direct polymerization-intercalation technique by twin-screw extruder. Its structure and thermal properties are characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and High-resolution electron microscopy (HREM), Fourier-transform infrared spectroscopy (FTIR) and Thermogravimetry analysis (TGA), respectively. The results of XRD and HREM analyses show that the silicate layer is well dispersed in PU matrix and this mesostructure can be considered as a delaminated nanocomposites. The TGA analysis indicates that the thermal stability properties of the PU/MMT nanocomposites are increased slightly compared with the pristine PU, due to the increase of the char residue. The mechanical and flammability performances are examined by electronic Universal Tester and Cone calorimetry, respectively. The layered silicate, which acts as a high aspect ratio reinforcement, enhances tensile strength of the PU. Specifically, there is a 25% increase in the tensile strength of PU nanocomposites containing 4 wt.% MMT compared with that of pristine PU. However, the elongation at break of PU/MMT nanocomposites is lower than that of pristine PU. The loading of MMT leads to the remarkably decrease of heat release rate (HRR), contributing to the improvement of flammability performance.     

预聚法制备聚氨酯/分子筛复合材料及表征

采用预聚法制备了聚氨酯(PU)/沸石分子筛(zeo lite 13X)复合材料,并利用XRD、DSC和TG等手段表征了复合材料的晶态、硬链段的结晶及熔融温度、材料的耐热性能。结果表明,随着沸石分子筛在体系中加入量的增大,PU/13X复合材料的硬链段结晶度减小,而硬链段和软链段之间的混乱度增大,硬链段的结晶形态发生改变,晶面间距增大。力学性能测试表明,分子筛添加量小于7%时,拉伸强度和撕裂强度明显提高。     

聚氨酯改性TDE-85/E-51环氧树脂的固化反应机理

以混合芳胺为固化剂,通过聚氨酯(PU)对4,5-环氧环己烷-1,2-二甲酸二缩水甘油酯(TDE-85)与二酚基丙烷缩水甘油醚(E-51)环氧树脂的混合树脂体系(EP)的改性,制备得到了一种高性能聚氨酯改性环氧树脂(PU/EP)。通过对材料样品结构的红外光谱表征,探讨了PU/EP的固化反应机理。研究结果表明,PU预聚体与1,4-丁二醇(1,4-BDO)及三羟甲基丙烷(TMP)发生了扩链、交联反应得到PU交联聚合物网络,TDE-85/E-51环氧树脂与混合芳胺固化剂反应生成了交联环氧聚合物。EP与PU之间存在的化学接枝、交联反应,提高了EP与PU之间的相容性及共混程度。     

聚氨酯改性聚乳酸/蒙脱土复合材料的制备与表征

采用溶液共混法,用聚氨酯(PU)和蒙脱土(MMT)对聚乳酸(PLA)进行改性.通过综合热分析(TGA＆DSC)、红外吸收光谱(IR)以及力学测试(FP)对改性聚乳酸(PLA)的性能进行了表征.结果显示,聚氨酯和蒙脱土与聚乳酸均有较好的相容性,复合材料的稳定性较好,而且聚氨酯/蒙脱土/聚乳酸复合材料较纯聚乳酸的力学性能有了较明显的提高,强度和韧性均较好.     

气相二氧化硅的异氰酸酯改性及其对浇注型聚氨酯弹性体力学性能的影响

为了改善气相二氧化硅(FS)/浇注型聚氨酯(PU)体系成型流动性,在制备预聚体的过程中,采用2, 4-甲苯二异氰酸酯(TDI)进行改性获得异氰酸酯改性的二氧化硅(NCO@FS),通过原位聚合法制备了NCO@FS/PU弹性体复合材料。采用FTIR、XPS及动态接触角对NCO@FS及FS进行了表征。结果表明：FS的表面羟基与TDI的-NCO基团发生反应生成了氨酯基(-NHCOO),改善了FS与PU间的界面相容性及界面结合。复合材料中NCO@FS质量分数为1.5wt%时,NCO@FS/PU复合材料的拉伸和撕裂强度分别为57 MPa和110.5 kN/m,比纯浇注型PU分别提高了31.6%和23.6%;玻璃化转变温度由3.4℃下降到-11.2℃,损耗因子tanδ由0.59下降到0.46。异氰酸酯改性FS适合制备FS增强浇注型聚氨酯复合材料。