聚氨酯密封垫在变速箱中的应用

通常汽车、拖拉机变速箱的密封垫用丁腈橡胶制成。我们改用聚氨酯弹性体制成的密封垫 ,经使用收到了很好的效果 ,受到省内外有关大型汽车、拖拉机厂家的一致好评。由于该产品适合实验室和小型化工厂与汽车拖拉机制造厂配套生产 ,故聚氨酯树脂胶液 (预聚体 )的生产用 2 0 0 0ｍｌ左右的三口瓶或用 30 0～5 0 0ｍ3的反应釜及配套装置即可。1　主要原料聚醚多元醇 (或聚酯多元醇 )、ＴＤＩ、二甲苯、苯甲酰氯、炭黑、ＭＯＣＡ。2　制作工艺2 1　聚合反应根据设计好的预聚体中的异氰酸酯基 -ＮＣＯ的含量 ,将计量的聚酯 (或聚醚 )多元醇和二甲…     

水性超支化聚氨酯丙烯酸酯的合成及性能研究

以TDI、HPA、丁二酸酐、超支化聚酯为原料,合成了一种新型可紫外光固化的水性超支化聚氨酯丙烯酸酯,用FT-IR跟踪研究了合成过程基团的变化.测试了超支化预聚体水溶液粒径,结果表明该粒径随丁二酸酐含量的增加而减小.对固化膜的力学性能测试和热重分析测试结果表明,随着超支化聚氨酯丙烯酸酯中端丙烯酸酯基含量的增加,固化膜的热...     

聚氨酯预聚体分散体胶粒的形成与扩链

以聚丙二醇(PPG)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)、乙二胺(EDA)为原料合成了固含量40%的聚氨酯分散体。采用激光粒度分析仪测试了预聚体分散体胶粒形成和扩链过程中的平均粒径和粒径分布,透射电镜(TEM)表征了胶粒的形态结构。结果表明,预聚体分散体中可能存在理想胶粒、活性胶粒、可再分散胶粒,理想胶粒中的NCO处于胶粒内部,活性胶粒中的NCO处于胶粒的内部和表面;分散和扩链反应中活性胶粒之间的反应使胶粒粗化和呈双峰分布;提高预聚体nNCO/nOH、COOH%,预聚体分散体中活性胶粒增加;TEM显示聚氨酯分散体胶粒主要呈球形,部分呈不规则形态。     

聚氨酯预聚体分散体胶粒的形成与扩链EI北大核心

以聚丙二醇(PPG)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)、乙二胺(EDA)为原料合成了固含量40%的聚氨酯分散体。采用激光粒度分析仪测试了预聚体分散体胶粒形成和扩链过程中的平均粒径和粒径分布,透射电镜(TEM)表征了胶粒的形态结构。结果表明,预聚体分散体中可能存在理想胶粒、活性胶粒、可再分散胶粒,理想胶粒中的NCO处于胶粒内部,活性胶粒中的NCO处于胶粒的内部和表面;分散和扩链反应中活性胶粒之间的反应使胶粒粗化和呈双峰分布;提高预聚体nNCO/nOH、COOH%,预聚体分散体中活性胶粒增加;TEM显示聚氨酯分散体胶粒主要呈球形,部分呈不规则形态。     

1,5-萘二异氰酸酯的反应活性及预聚体制备EI北大核心CSCD

基于1,5-萘二异氰酸酯(NDI)的聚氨酯预聚物仅具有限的存储稳定性,为研究其原因,采用动力学实验和量化计算研究了NDI的反应活性。从结果看,NDI的活性不高于常见芳香族异氰酸酯4,4’-二苯基甲烷二异氰酸酯(MDI)和2,4-甲苯二异氰酸酯(TDI),甚至低于脂肪族的1,6-六亚甲基二异氰酸酯(HDI)。结合实验数据和文献分析,发现在NDI型预聚体合成中较高反应温度(120~130℃)会导致异氰酸酯与氨基甲酸酯的支化副反应,导致预聚体存放或浇注时凝胶失效。通过在合成过程中加入抑制剂磷酸的方法可以获得稳定耐储存NDI型聚氨酯预聚体,并且随着磷酸含量的增加,预聚体的相对分子质量和黏度以及后固化得到的聚氨酯弹性体的力学性能均有所下降。     

PAMAM树枝状大分子在水性聚氨酯合成中的应用研究

由异佛尔酮二异氰酸酯(IPDI)、聚醚多元醇(DL-2000D)、聚酯多元醇(CMA-244),二羟甲基丙酸(DMPA)、1,4-丁二醇、乙二醇合成含异氰酸酯基(—NCO)的聚氨酯预聚体,再令其与整代聚酰胺-胺(PAMAM)接枝,合成不同代数的树枝状水性聚氨酯。用红外光谱(FT-IR)、透射电镜(TEM)、激光粒度分析表征乳液粒径及其分散状态,用原子力显微镜(AFM)、水接触角表征其表观性能,分析胶膜的理化性能。结果表明,由相对分子质量较小的PAMAM(G2)改性所得的水性聚氨酯WPU-G2的水性聚氨酯耐水、耐热性能有了明显提高。     

新型聚氨酯固化剂的制备

以低分子聚酯多元醇为预聚体,与甲苯二异氰酸酯(TDI)及二苯基甲烷-4,4'-二异氰酸酯(MDI)合成了新型聚氨酯固化剂,研究了预聚体的性能、合成条件、MDI与TDI物质的量比对固化剂性能的影响.实验结果表明:当预聚体的羟值为125~155mgKOH/g,并且MDI与TDI物质的量比值为2.5,反应温度为75℃,反应时间为2h时,制得的聚氨酯固化剂性能最佳,用该固化剂配成的胶粘剂对PET/PE复合膜有很好的粘结性能.     

N,N-二甲基乙醇胺在本体消光型水性聚氨酯中的作用EI北大核心CSCD

本体消光型水性聚氨酯可以避免外加消光剂带来的弊端,是一种新型的功能性环保涂料。文中以异氟尔酮二异氰酸酯、聚己二酸丁二醇酯多元醇、二羟甲基丙酸(DMPA)、三羟甲基丙烷为预聚体原料,三乙胺和N,N-二甲基乙醇胺(DMEA)为中和剂,乙二胺基乙磺酸钠和水合肼为后扩链剂,采用预聚体分散法制备出水性聚氨酯(WPU)乳液。对不含DMEA的WPU样品系列与含有DMEA的WPU样品系列的消光性能进行了对比研究。结果表明,当DMEA的质量分数为1%时,不同DMPA用量的WPU乳液的平均粒径均保持在2100 nm左右,且粒径分布较窄,DMPA用量对其粒径和粒径分布影响不大;含有DMEA的WPU涂膜透过率相对有所降低,其表面凸起由球状颗粒紧密堆积而成,测得表面光泽度(60°)低于1。     

N,N-二甲基乙醇胺在本体消光型水性聚氨酯中的作用

本体消光型水性聚氨酯可以避免外加消光剂带来的弊端,是一种新型的功能性环保涂料。文中以异氟尔酮二异氰酸酯、聚己二酸丁二醇酯多元醇、二羟甲基丙酸(DMPA)、三羟甲基丙烷为预聚体原料,三乙胺和N,N-二甲基乙醇胺(DMEA)为中和剂,乙二胺基乙磺酸钠和水合肼为后扩链剂,采用预聚体分散法制备出水性聚氨酯(WPU)乳液。对不含DMEA的WPU样品系列与含有DMEA的WPU样品系列的消光性能进行了对比研究。结果表明,当DMEA的质量分数为1%时,不同DMPA用量的WPU乳液的平均粒径均保持在2100 nm左右,且粒径分布较窄,DMPA用量对其粒径和粒径分布影响不大;含有DMEA的WPU涂膜透过率相对有所降低,其表面凸起由球状颗粒紧密堆积而成,测得表面光泽度(60°)低于1。     

上海市合成树脂研究所推出水处理微生物包埋载体用PUA预聚体

上海市合成树脂研究所以多官司能度、水溶性聚醚多元醇和异佛尔酮二异氰酸酯(IPDI)进行预聚反应合成-NCO封端的聚氨酯(PU)预聚体,再和甲基丙烯酸羟乙酯(HEMA)反应合成含有双键的聚氨酯丙烯酸酯(PUA)预聚体。该预聚体流动性好,易乳化于水,     

干混工艺对PVC搪塑制品中纳米颗粒分布和性能的影响

通过增加室温混合阶段并优化关键工艺参数的方式改进了聚氯乙烯(PVC)搪塑粉料的传统混料工艺,针对粒径60~80nm的活性CaCO_3和粒径100~120nm的金红石型钛白粉等纳米颗粒,对比研究了新混料工艺和传统混料工艺对无机纳米颗粒均匀分散的影响,并定量分析了在室温混合阶段的不同工艺参数下PVC搪塑粉料的流动性和搪塑制品的力学性能及热稳定性。结果表明:优化后的干混工艺不仅有效提高了搪塑表皮中纳米颗粒分散均匀性和搪塑粉料的流动性,而且明显改善了搪塑表皮的断裂伸长率、热稳定性和耐热挥发损失性。     

四氯化钛水解法制备纳米氧化钛超细粉体

研究了改变溶液的酸碱度来控制ＴｉＣｌ４水解,制备锐钛上超细ＴｉＯ２纳米粉体的过程,采用ＸＲＤ,ＴＥＭ、ＳＡＥＤ和ＴＧ－ＤＴＡ等方法对所得粉体进行了表征,发现水解后的沉淀经真空干燥后,不用任何热处理,室温下即有锐钛矿相存在,其原始粒径约为３．８ｎｍ,粉体于４００℃煅烧２ｈ,可得到平均粒径为７ｎｍ的纯钛矿相纳米氧化钛粉体。     

双马来酰亚胺基体树脂的改性研究

本文报道用改性物B改善双马来酰亚胺/二胺预聚物溶解性的实验研究.结果表明,改性后的双马来酰亚胺/二胺基体树脂在低沸点、低毒性溶剂如丙酮中具有良好的溶解性,并且有足够的均相期,为湿法制作预浸料创造了有利条件.同时对树脂的固化反应、耐热稳定性及其复合材料在高温条件下(150℃、200℃)的层间剪切性能进行了研究.      

双马来酰亚胺基体树脂的改性研究

本文报道用改性物B改善双马来酰亚胺/二胺预聚物溶解性的实验研究.结果表明,改性后的双马来酰亚胺/二胺基体树脂在低沸点、低毒性溶剂如丙酮中具有良好的溶解性,并且有足够的均相期,为湿法制作预浸料创造了有利条件.同时对树脂的固化反应、耐热稳定性及其复合材料在高温条件下(150℃、200℃)的层间剪切性能进行了研究.     

Preparation of highly water-dispersible titanium-silicon binary oxide materials by sol-gel method

The preparation of highly water-dispersible titanium-silicon binary oxide materials was performed by the following two-stage sol-gel reactions. First, the mixture of titanium tetraisopropoxide and 3-aminopropyltrimethoxysilane was stirred in a mixed solvent of isopropyl alcohol and 0.5 mol/L methanolic hydrochloric acid at room temperature, followed by heating in an open system until the solvent was evaporated. Then, the aqueous solution obtained by adding water to the resulting product was heated in the open system until the water was completely reevaporated. The resulting product was dispersed well in water, and its aqueous dispersion was highly transparent and cut off UV light, confirmed by UV-Vis measurements. The solid product obtained by lyophilization of its aqueous dispersion was redispersed in water. The average particle size of the product was assessed to be < 10 nm by dynamic light scattering (DLS) in water and transmission electron microscopy (TEM) measurements, indicating that the product was a water-dispersible spherical nanoparticle. It was assumed that the water-dispersible property of the product probably originated from the TiO2/SiO1.5(CH2)3NH3 x Cl core/shell structure. In addition, highly transparent films can be prepared from the aqueous dispersion of the product, and these films also cut off the UV light, evaluated by UV-Vis measurements.     

Investigation of the decomposition reaction and dust explosion characteristics of crystalline benzoyl peroxides

The benzoyl peroxide (BPO) is widely used in the chemical industry. Many catastrophes have been caused by its thermal instability or reactive incompatibility in storage or thermal decomposition reaction. Thus, its hazard characteristics have to be clearly identified. First of all, the differential scanning calorimeter (DSC) is used to measure the heat of decomposition reaction, which can contribute to understanding the reaction characteristics of benzoyl peroxide. The accelerating rate calorimeter (ARC) is used to measure the rates of temperature and pressure rises of decomposition reaction, and then the kinetics parameters are estimated. Furthermore, the MIKE 3 apparatus and the 20-l-Apparatus are used to measure and analyze the dust explosion characteristics of benzoyl peroxide under room temperature and atmospheric pressure. Finally, Semenov's thermal explosion theory is applied to investigate the critical runaway condition and the stability criterion of decomposition reaction, and to build the relationship of critical temperature, convective heat transfer coefficient, heat transfer surface area and ambient temperature. These results contribute to improving the safety in the reaction, transportation and storage processes of benzoyl peroxide.     

低电阻率高性能PTCR陶瓷材料-汽车闭锁器马达过电流保护元件的制备

为满足汽车电器等低电压下的保护元件的需求,研制低电阻率高性能PTCR陶瓷材料已成为研究的热点．本工作采用通常的混合氧化物工艺制备了室温电阻率＜10Ω·cm,电阻率的突变达到10⁵的高性能PTCR热敏电阻陶瓷．并研究了原材料,固溶体的基方组成,各种添加物以及烧结工艺等对PTCR陶瓷性能的影响,特别注意了用液相方式添加施主和受主杂质在制备低电阻率的高性能PTCR陶瓷时起的更为有效的作用,对材料的化学组成,制备（烧结）工艺,显微结构和PTCR效应之间的关系进行了讨论．用本材料制备的元件能用于汽车闭锁器马达的过电流保护．     

提高脉冲LD测距系统测距能力的一种方法

从激光测距机的噪声构成分析入手,寻求提高脉冲 LD 测距机测距能力的方法。脉冲 LD测距系统的噪声主要包括热噪声、散粒噪声、背景噪声、暗电流噪声及放大器噪声。在一定的光功率、暗电流情况下,LD 测距的测距能力更容易受背景噪声的影响。研究表明,LD 测距系统中探测器偏压的变化只补偿温度变化,由此提出,在背景光照射较强时让背景噪声参与偏压调整从而抑制背景噪声的方案。实验结果证实,强背景下的信噪比提高 1 倍以上,测距能力提高 1 倍。     

Mechanical properties of polyhydroxybutyrate-hydroxybutyrate-hydroxyvalerate copolymer blends

Blends of polyhydroxybutyrate and its copolymers with hydroxyvalerate have been prepared. Under certain conditions of composition and temperature these blends can phase separate. It is shown that for freshly prepared samples, crystallization from a biphasic, rather than a homogeneous, melt leads to improvement in yield and fracture properties. However, during storage at room temperature, an ageing process occurs and the improvement in properties is largely lost.     

Preparation and characterization of mesoporous titania gel-monolith

This paper focused on the preparation and characterization of a pure TiO₂ monolith. The preparation method is based on the sol-gel technique using tetrabutyl titanate as precursors. By controlling the hydrolysis of tetrabutyl titanate and the rate of gel drying, transparent TiO₂ gel-monoliths are obtained at room temperature. The TiO₂ gel-monoliths prepared in this manner have a mean pore diameter about 4.4 nm, specific surface area 332.8 m^{2 g–1} and more than 57.6% porosity, especially, the TiO₂ gel-monoliths are not amorphous but crystalline, anatase phase. It retains a surface area and a porosity of about 90.5 m²g^–1 and 45.6%, respectively, after the heat treatment at 500 °C for 2 h. And XRD, TEM and N₂ adsorption isotherm analysis indicate that particle growth is the main influencing factor of the specific surface area and porosity from room temperature to 500 °C, but from the heat treatment temperature higher than 500 °C, the densification assisted by anatase to rutile phase transition become the main role to influence the specific surface area and porosity.