水性聚氨酯分散体流变学特性

流变学理论与水性聚氯酯合成和使用都有非常紧密的联系,但关于水性聚氯酯流交学国内观注很少,故此对水性聚氯酯流变学特性理论方面进行了较为深入的理论总结.     

Nanoparticles of Magnetite in Polymer Matrices: Synthesis and Properties

This review covers publications on magnetite nanoparticles in polymer matrix, especially in humic acids, which are very interesting, widespread natural polymers. Of special attention was the influence of synthetic conditions on the structure and physicochemical properties of magnetic nanomaterials as well as their potential in environmental applications as sorbents. Nanoparticles of Fe₃O₄ in polymer matrix as promising materials for environmental applications have been in the focus of a great number of studies due to their properties. The modification of magnetic nanoparticles by humic acids leads to increase the sorption properties of such composites and stabilization of magnetite nanoparticles, inhibiting their agglomeration. Thus, humic acids on the one hand, can be used as effective stabilizers for magnetoactive nanoparticles, and on the other hand, keep their protective properties towards ecotoxicants.     

Properties of Waterborne Polyurethane/Clay Nanocomposite Adhesives

A series of waterborne polyurethane (WBPU)/clay nanocomposite dispersions using two different organically modified clays, namely Cloisite 15A and Cloisite 30B, were prepared. It was found that the properties of WBPU/clay nanocomposites were highly dependent on both the clay content and the clay surface characteristic (hydrophilic/hydrophobic). A WBPU/clay nanocomposite dispersion with a higher clay content showed a less negative zeta potential. A lower zeta potential for dispersion with Cloisite 30B compared to Cloisite 15A was observed indicating a higher stability of the dispersion. The tensile strength, Young's modulus and adhesive strength of WBPU/clay nanocomposite containing Cloisite 30B were also higher than those of nanocomposite containing Cloisite 15A. The optimum clay contents, with respect to these properties, for nanocomposites with Cloisite 15A and Cloisite 30B were found to be 2 wt% and 3 wt%, respectively.     

纳米改性水性聚氨酯的制备与性能研究

对纳米SiO2和TiO2进行了TDI(HDI)和PEG的接枝改性,并采用共混法制备了纳米改性水性聚氨酯乳液,电镜观测表明改性后的纳米粒子在乳液中分散均匀,无团聚现象。纳米粒子改性后的水性聚氨酯乳液力学性能比未改性前得到改善和提高,纳米粒子添加量为0.5%时,水性聚氨酯乳液的力学性能最佳,同时吸水率降低了70%,添加的纳米粒子对290~400 nm的紫外光有吸收。     

丙烯酸改性芳香族聚醚聚氨酯水分散体的结构与性能

利用丙烯酸酯对聚氨酯进行改性是提高聚氨酯综合性能的主要手段之一。通过预聚聚合的方法,合成了综合性能良好的聚氨酯乳液。研究表明:聚合温度与时间影响聚氨酯粒子的形态与结构,丙烯酸酯的接枝改性使聚合物成膜后微区结晶现象减弱。控制合适的工艺条件制备得到耐水性及良好力学性能的改性聚氨酯乳液。该聚合物乳液可替代传统的溶剂型聚合物,应用于室内木材、塑料及金属的涂覆,环境效应明显。     

磺酸型水性聚氨酯分散液的制备方法与性能

叙述了磺酸型水性聚氨酯分散液的分散性、固含量以及胶膜性能,除与低聚物二元醇、二异氰酸酯、扩链剂种类及合成工艺有关外,与磺酸根在聚氨酯大分子中的引入方式密切相关.从磺酸根不同引入方式,即磺酸根是从链端引入还是在链上引入,链上引入又分软段引入和硬段引入,详细介绍了不同引入方式和制备磺酸型水性聚氨酯分散液的工艺及性能.     

HDI三聚体改性聚氨酯水分散体的合成与性能

采用己二异氰酸酯(HDI)三聚体(HT)合成交联改性聚氨酯水分散体(HPUD),考察了HT添加量对HPUD涂膜的耐水性、耐溶剂性、表干时间、硬度、光泽以及交联度的影响。通过粒径分布仪、热重分析仪(TGA)和傅立叶变换红外光谱仪(FTIR)分别对HPUD乳液贮存过程中粒径的变化、涂膜热稳定性与分子结构进行表征,结果发现,引入质量分数5%～10%的HT可提高聚氨酯涂膜的表干速率和交联度,当w(HT)=10%时,HPUD涂膜具有最佳的综合性能,涂膜表干时间为45min,交联度为80%,吸醇率为78%,吸水率为7%。同时还发现,HPUD涂膜硬度上升速率较快,但最终硬度较未改性聚氨酯水分散体(PUD)有所降低;粒径分析表明,当w(HT)≥20%时,HPUD贮存过程中乳液粒径增大,贮存稳定性下降;TGA分析表明,HPUD涂膜具有较好的热稳定性。     

聚氨酯水分散体结构与性能的关系研究

以聚四氢呋喃、甲苯二异氰酸酯、二羟甲基丙酸为主要原料合成了WPUD.并采用红外光谱对WPUD分子结构作了表征,同时对分散体的性能进行了测试和分析.结果表明,DMPA用量是影响水分散体性能的主要因素.DMPA影响分散体的形态、稳定性、吸水率、平均粒径.随着DMPA含量的增加,水分散体稳定性提高、吸水率增加.当DMPA的质量分数由0.014％增加到13.57％时,透光率从0.003％提高到88.88％.并研究了聚氨酯硬段和软段的含量对涂膜基本性能的影响,随着硬段含量增加,铅笔硬度有所提高,软段含量增加,柔韧性提高.另外,残留溶剂是影响水分散体稳定性的另一个重要因素,当分散体中残留溶剂含量增加时,稳定性降低.     

酮亚胺对水性聚氨酯性能的改进

用丙酮分别和乙二胺、己二胺反应制备酮亚胺,并以其作为潜伏性扩链剂改善水性聚氨酯(PU)的性能。研究了酮亚胺以不同方式、加量对水性PU漆膜的厚度、硬度、耐水性、耐酸性、热稳定性和机械性能的影响。结果表明,采用丙酮缩乙二胺扩链的水性PU乳液的漆膜的耐水性优于用丙酮缩己二胺和用水扩链的PU乳液的漆膜,且加入过量的酮亚胺扩链效果较好,但其热稳定性并没有得到明显提高。     

工艺参数对水性聚氨酯分散体性能的影响

以甲苯二异氰酸酯(TDI)、自制聚酯二元醇为主要原料合成了水性聚氨酯分散体(WPUD),研究了投料方式、反应温度和反应时间、中和方式、乳化温度等工艺参数对NCO含量及WPUD性能的影响.结果表明,采用两步投料法,第一步温度控制在65～70 ℃、反应1 h,第二步温度控制在70～75℃、反应3 h;采用前中和工艺、乳化时...     

硅烷改性水性聚氨酯分散液的合成与性能研究

以二羟甲基丙酸(DMPA)为亲水单体,甲苯二异氰酸酯(TDI)、聚醚二元醇(N210)为原料,丁二醇为扩链剂,三乙胺(TEA)为中和剂合成水性聚氨酯.采用有机硅烷对水性聚氨酯进行改性,研究了有机硅烷、亲水单体的用量对改性水性聚氨酯外观稳定性及涂膜性能的影响.结果表明:适量的有机硅烷的引入可以有效改善水性聚氨酯的耐水性、附着力以及硬度.当硅烷加入量为0.6%,改性水性聚氨酯的吸水率为5.5%,为未改性水性聚氨酯膜吸水率的1/6.     

MDI型水性聚氨酯乳液的合成及性能研究

以二苯基甲烷二异氰酸酯、聚酯二醇、二羟甲基丙酸等为原料合成了水性聚氨酯预聚体,用三乙胺中和制备了水性聚氨酯的透明乳液.通过FT-IR、TEM、拉力机等测试手段对所制水性聚氨酯进行了形貌观察、力学及耐水性测试.结果表明,当n(-NCO):n(-OH)比值为1.8～1.9,DMPA含馈在6.5%～7%,中和度在100%～120%时可制得性能稳定的水性聚氨酯乳液,若在乳化阶段用乙二胺进行扩链,则胶膜的吸水率会进一步降低至4%.     

Preparation of Shape Memory Polyurethane/Hydroxyapatite Nanocomposite Scaffolds by Electrospinning Method and Investigation of Their Microstructure and Physical-Mechanical Properties

ABSTRACT

A facile method was used for fabricating in-situ-polymerized shape memory polyurethane (PU) hydroxyapatite (HA) nanocomposite scaffolds through electrospinning. The chemical structure and hydrogen bonding index (HBI) content were investigated using Fourier transform infrared spectroscopy. The crystalline morphology was analyzed by X-ray diffraction patterns. Differential scanning calorimetry was conducted to determine the glass transition temperature (T_g ) and degree of crystallinity. The results revealed that HA nanoparticles provide significant reinforcement of PU. Furthermore, incorporation of HA nanoparticles improved the shape memory properties of nanocomposites. The effect of HA nanoparticles on PU/HA electrospun fiber diameter, porosity, mechanical, and shape memory properties were examined.     

基于醛酮树脂的聚氨酯分散体的涂膜性能研究

以二羟甲基丁酸(DMBA)和新型聚氧乙烯醚作为亲水单体,以聚己二酸新戊二醇酯(PNA)、醛酮树脂、异佛尔酮二异氰酸酯(IPDI)为主要原料,采用预聚体法合成了阴/非离子型聚氨酯分散体(PUD),并以此为主要组分制备了水性涂料。研究表明,醛酮改性的聚氨酯分散体具有较小的粒径和较低的黏度,耐热性良好,适用于涂料产品;当亲水基团含量为25 mmol/100 g,醛酮树脂含量为40%,n(—NCO)∶n(—OH)=1.3时涂膜的综合性能最好,涂膜硬度可达4H,且涂膜附着力、柔韧性、耐冲击性和耐水性优异。     

A Study on Polyurethane Hybrid Nanocomposite Foams Reinforced with Multiwalled Carbon Nanotubes and Silica Nanoparticles

Multifunctional polyurethane foams reinforced with multiwalled carbon nanotubes and silica nanoparticles enhanced specific properties. We studied the effects of nanoparticle addition into polyurethane on mechanical properties and thermal stability by means of tensile, Charpy impact, hardness tests, and thermogravimetric analysis. Nanoparticles added to polyurethane are multiwalled carbon nanotubes, two types of silica nanoparticles, and multiwalled carbon nanotube/spherical silica as hybrid filler. Hybrid polyurethane/spherical silica/multiwalled carbon nanotube nanocomposite with the constant overall content of 0.75?wt% showed higher tensile strength, hardness, and thermal stability than either of nanoparticles at this content, which approves a synergistic effect between multiwalled carbon nanotubes and silica nanoparticles.     

Tracer Dispersion in Stirred Tank Reactors: Asymptotic Properties and Mixing Characterization

This article addresses the characterization of dispersion and homogenization phenomena in stirred vessels through the analysis of dispersion curves that can be obtained experimentally by means of conductivity measurements. New insights on mixing conditions can be achieved from the analysis of the qualitative and asymptotic properties of tracer dispersion curves. The results obtained are interpreted in the context of the spectral approach to the advection‐diffusion equation. It is shown that any flow model aimed at reproducing the experimentally determined dispersion curves must be at least two‐dimensional. Convection‐enhanced dispersion associated with the spectral structure of the advection‐diffusion equation is addressed.     

Properties of Waterborne Polyurethane/CNT Nanocomposite Adhesives: Effect of Countercations

Two series of waterborne polyurethane (WBPU)/carbon nanotube (CNT) nanocomposites were prepared with various CNT contents (0–1.50 wt%). We used a metal-hydroxide (copper hydroxide, Cu(OH)₂) and amine (triethylamine, TEA) as the countercation in the nanocomposites. The interaction of the countercations with the CNTs in the nanocomposite was characterized by TEM, and the interaction effects on the properties, such as the glass transition temperature (T_g), storage modulus, tensile strength, Young's modulus and adhesive strength, were investigated. The CNTs were homogeneously (optimum) dispersed at concentrations of up to 1.25 and 1.00 wt% for the metal-hydroxide and amine series, respectively. At the optimum CNT content, the tensile strength and adhesive strength were maximized in each series. However, the adhesive strength of the WBPU/CNT nanocomposite with the metal-hydroxide countercation was less affected than with the amine-countercation after immersing the adhesive bonded nylon fabrics in water (for up to 48 h).     

聚醚软段对光固化水性聚氨酯纳米复合乳液性能的影响

分别以聚氧乙烯-聚氧丙烯-聚氧乙烯(PEO-PPO-PEO)、聚丙二醇(PPG)和聚四氢呋喃均聚醚二醇(PTMG)为聚醚组分,通过丙酮法合成光固化水性聚氨酯(WPU)/二氧化硅(Si O2)纳米复合乳液。研究了聚醚组分对复合乳液粒径、复合膜微观结构和动态力学性能的影响。研究表明,聚醚软段的不同结构对WPU及其纳米复合乳液的粒径、纳米Si O2的分散性以及纳米复合膜的微结构和动态力学性能有较大影响。改变聚醚二元醇的结构,可调控WPU纳米复合膜的微结构和性能。     

表面活性剂对镀镍液中SiO2纳米颗粒分散的影响

电镀溶液中纳米颗粒的分散是复合镀技术中需要解决的首要问题,以十六烷基三甲基溴化铵和聚乙二醇-10000为分散剂,对镀镍溶液中的SiO2纳米颗粒进行改性.通过沉降实验对表面改性后的SiO2纳米颗粒悬浮液的稳定性进行了比较分析.结果表明,当十六烷基三甲基溴化铵和聚乙二醇-10000在悬浮液中的质量浓度分别为2g/L和1.5g/L时,SiO2纳米颗粒能够均匀悬浮,稳定分散.     

Influence of Copper Nanoparticles Concentration on the Properties of Poly(vinylidene fluoride)/Cu Nanoparticles Nanocomposite Films

In this study, the nanocomposite films of polyvinylidene fluoride/copper nanoparticles were prepared by mixing of copper nanoparticles in a solution of dimethylformamide and polyvinylidene fluoride. The prepared nanocomposites were investigated by fourier transform infrared spectroscopy and X-ray diffraction techniques, showed an obvious α- to β-phase transformation compared to pure PVDF. Scanning electron microscope micrographs showed spherulitic crystal structure of PVDF. The spherulitic morphology of the pure PVDF is maintained for the PVDF nanocomposites; the size of the spherulites decreased by increasing weight fraction of copper nanoparticles. The optical band gap values deduced from the UV–Visible absorption spectra were found to reduce from 4.77 eV in pure PVDF to 3.2 eV after embedding 1 wt% of copper nanoparticles. The surface resistivity values were decreased with increasing copper nanoparticles content. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to pure PVDF.