LLDPE/纳米ZnO复合材料熔体流变性的研究

将纳米ZnO(或改性纳米ZnO)与LLDPE经Brabender挤出机熔融共混制备了LLDPE/纳米ZnO复合材料,采用毛细管流变仪和HAAKE转矩流变仪研究了该复合材料的熔体流变性能,讨论了纳米ZnO、改性纳米ZnO及KH550偶联剂含量对LLDPE熔体流变性能的影响。结果表明:少量纳米ZnO的加入略提高了LLDPE的表观黏度、黏流活化能和熔体的平衡转矩,改性纳米ZnO复合材料的表观黏度比未改性纳米ZnO复合材料的略低。     

Effect of polyethylenimine on the dispersion and electrophoretic deposition of nano-sized titania aqueous suspensions

The dispersion and electrophoretic deposition (EPD) behavior of an aqueous suspension of nano-sized titania particles stabilized with a dispersant of polyethylenimine (PEI) were systematically investigated. The adsorption behavior of PEI on the titania surfaces indicated a high affinity adsorption of PEI at a high pH value while a low affinity adsorption was observed at a low pH value, which is consistent with the viscosity behavior of the suspension. The influences of the suspension pH, the added amount of PEI and the salt addition on the electrophoretic deposition behavior of the suspensions were studied.     

油基纳米氧化锌分散浆的制备及其流变特性

选用硬脂酸钠对ZnO进行表面湿法改性，以环十五硅氧烷硅油为溶剂，PEG-10聚二甲基硅氧烷为分散剂，通过机械球磨法制备了纳米ZnO分散浆。利用水接触角、热重、TEM和FTIR对纳米ZnO粉体进行表征。结果表明，硬脂酸钠改性后，粉体具有疏水性，且硬脂酸钠最佳包覆量为6%（以ZnO的质量计，下同）。硬脂酸钠包覆量为6%的疏水性纳米ZnO粉体，包覆层厚度约为2 nm，此时水接触角最大为145.4°。模拟防晒乳液的防晒性能测试中，纳米氧化锌分散浆的紫外屏蔽性能显著优于粉体。流变特性测试表明，分散浆为假塑性流体，流动曲线符合Ostwald-de Wale幂律方程，具有剪切稀化特性；分散浆的黏度低，触变性小，储存稳定性高；温度升高，黏度降低，配方生产中对温度的敏感程度较小 。     

A facile solid-state heating method for preparation of poly(3,4-ethelenedioxythiophene)/ZnO nanocomposite and photocatalytic activity

Poly(3,4-ethylenedioxythiophene)/zinc oxide (PEDOT/ZnO) nanocomposites were prepared by a simple solid-state heating method, in which the content of ZnO was varied from 10 to 20 wt%. The structure and morphology of the composites were characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The photocatalytic activities of the composites were investigated by the degradation of methylene blue (MB) dye in aqueous medium under UV light and natural sunlight irradiation. The FTIR, UV-vis, and XRD results showed that the composites were successfully synthesized, and there was a strong interaction between PEDOT and nano-ZnO. The TEM results suggested that the composites were a mixture of shale-like PEDOT and less aggregated nano-ZnO. The photocatalytic activity results indicated that the incorporation of ZnO nanoparticles in composites can enhance the photocatalytic efficiency of the composites under both UV light and natural sunlight irradiation, and the highest photocatalytic efficiency under UV light (98.7%) and natural sunlight (96.6%) after 5 h occurred in the PEDOT/15wt%ZnO nanocomposite.     

载银纳米氧化锌在聚丙烯腈原液中分散性能的研究

采用新型的载银纳米氧化锌(纳米ZnO/Ag)抗菌剂,通过正交实验,以最佳工艺制备其水相悬浮液,并用硅烷偶联剂修饰。将修饰后的纳米ZnO/Ag悬浮液加入到聚丙烯腈原液(NaSCN溶液)中共混,得到透明的聚丙烯腈共混原液。采用Zeta纳米粒度与电位分析仪、热台偏光显微镜、扫描电镜、透射电镜、红外光谱等仪器测试了纳米ZnO/Ag微粒在聚丙烯腈原液中的分散性能;用流变仪研究了共混原液的流变性能。     

纳米氧化锌在天然橡胶发泡中的活化作用

以天然橡胶(NR)为基体,偶氮二甲酰胺(AC)为发泡剂,比较了纳米氧化锌和普通氧化锌对NR纯胶和NR混炼胶发泡的活化作用,并研究了纳米氧化锌对NR发泡胶料硫化的影响。结果表明,粒径较小且分布均匀的纳米氧化锌无论是在NR纯胶还是在NR混炼胶中,都能使AC的分解峰值温度低于用粒径较大的普通氧化锌活化时AC的分解峰值温度,且随着纳米氧化锌用量的增加,AC的分解峰温逐渐下降;在NR发泡胶料中,2份纳米氧化锌可达到甚至超过5份普通氧化锌的硫化效果。     

纳米ZnO/PP及ZnO/CaCO_3/PP复合材料的性能研究

纳米氧化锌(ZnO)与聚丙烯(PP)通过熔融共挤制得了ZnO/PP纳米复合材料.研究了ZnO/PP纳米复合材料的力学、流变学性能与纳米ZnO添加量之间的关系;同时制备了ZnO/CaCO3/PP三元纳米复合材料并对其进行了机械性能和制备成本分析.结果表明,ZnO/PP纳米复合材料的熔体质量流动速率较纯PP有较大程度的提高;纳米CaCO3的加入不但可以降低生产成本,而且可以显著改善体系的冲击韧性;材料的拉伸破坏属于韧性断裂过程.     

Colloidal dispersion of nano-scale ZnO powders using amphibious and anionic polyelectrolytes

This article describes the dispersion of aqueous suspensions containing nano-scale ZnO powder by utilizing a hybrid of chemical dispersant and mechanical mixing/grinding process. The chemical dispersants included anionic or amphibious polyelectrolytes, i.e., sodium salt of polymethylacrylic acid (PMAA-Na) or polyacrylamide/(α-N, N-dimethyl-N-acryloyloxyethyl) ammonium ethanate (PDAAE). The optimum critical concentrations for each dispersants to achieve the lowest viscosity, smallest final sediment volume and particle size (d₅₀) for the nano-ZnO suspensions, 3 wt.% for PMAA-Na and 5 wt.% for PDAAE, were identified. The finely dispersed nano-ZnO powders were transferred to prepare sputtering target. The root-mean-square roughness (R_RMS) of thin films deposited by utilizing such a target was found to be 2.05 nm, which was lower than the R_RMS of the film (≈27.57 nm) deposited by using a commercial ZnO target comprised of micro-scale granules.     

TiO_2/ZnO超细粉体共混改性PET的流变性能

将改性的二氧化钛/氧化锌(TiO2/ZnO)超细复合粉体应用于聚对苯二甲酸乙二醇酯(PET)的共混改性,研究了改性PET的流变性能及其纤维的力学性能。结果表明:改性PET共混物为非牛顿假塑性流体,其表观粘度随剪切速率的增大而减小;随着超细粉体含量增大,改性PET共混物非牛顿流动指数下降,熔体粘度对温度的敏感性增大,流变性能改善;当超细粉体质量分数为5%时,改性PET共混物粘流活化能可达81.5 kJ/mol;随着超细复合粉体添加量增大,改性PET纤维断裂强度下降。     

硫化体系对氯化丁基橡胶/尼龙12动态硫化胶性能的影响

研究了氧化锌、N,N’-间苯撑双马来酰亚胺(HVA-2)/氧化锌和1,3-双柠糠酰亚胺甲基苯(PK 900)/氧化锌3种硫化体系下氯化丁基橡胶(CIIR)/尼龙(PA)12混炼胶的硫化特性及CIIR/PA 12动态硫化胶(TPV)的物理机械性能和微观相结构,并考察了PK 900与氧化锌不同配比对CIIR/PA 12TPV物理机械性能、流变性能及微观相结构的影响。结果表明,PK 900/氧化锌的硫化速率介于氧化锌和HVA-2/氧化锌两者之间,由其制备的TPV橡胶相粒径为1～2μm,均匀分布在树脂相中,物理机械性能最优;固定PK 900用量为3份时,随着氧化锌用量的减少,CIIR/PA 12 TPV的拉伸强度、扯断伸长率和100%定伸应力均呈现先增大后减小的趋势;当PK 900/氧化锌(质量比)为3/5时,CIIR/PA 12TPV的物理机械性能最佳,且呈现低剪切速率高黏度、高剪切速率低黏度的特性。     

Preparation of nano-ZnO/PMMA composite particles via grafting of the copolymer onto the surface of zinc oxide nanoparticles

The grafting of polymers onto the surface of zinc oxide nanoparticles and radical copolymerization of methyl methacrylate (MMA) and methacrylic acid (MAA) were investigated. The copolymer chains encapsulating nanoparticles were anchored onto the surface of nano-ZnO through reactions of carboxyl groups with ZnO. Grafting percentage and grafting efficiency of composite particles were investigated by employing thermogravimetric analysis (TGA). FT-IR and ¹³C NMR showed that there existed a strong interaction at the interface of nano-ZnO and copolymer, which implied that the copolymer chains were grafted onto the surface of ZnO nanoparticles. Nano-ZnO being encapsulated by copolymer was confirmed by using transmission electron microscopy (TEM). Additionally, TGA plots showed that the presence of ZnO nanoparticles improved the thermal stability of copolymer to a certain extent. Another important finding is the copolymerization and grafting reaction did not alter the crystalline structure of the ZnO nanoparticles according to the X-ray diffraction patterns. It can also be seen from scanning electron microscope (SEM) that grafted polymer chains on nanoparticles interfere with the aggregation of ZnO nanoparticles in polymer matrix and improve their compatibility with the polymeric matrix.     

纳米氧化锌在氯丁橡胶中的应用研究

用电子显微镜观察了纳米氧化锌的形貌、尺寸，研究了纳米氧化锌在氯丁橡胶胶料中作硫化剂时对胶料物理机械性能的影响，并选用普通氧化锌，国外某品牌氧化锌进行对比。结果发现，当纳米氧化锌与普通氧化锌用量同为5份时，含纳米氧化锌胶料的某些物理机械性能指标有提高，当纳米ZnO用量减至3份时与5份普通ZnO的力学性能相当。充分显示了纳米材料的尺寸效应，应用纳米氧化锌可以提高产品的力学性能，并能降低成本，具推广应用价值。     

Rheological properties of hydrolyzed polyacrylonitrile-grafted cellulose

The rheological properties of aqueous dispersions of hydrolyzed polyacrylonitrile-grafted cellulose (H-CPAN) have been investigated. The experimental results are consistent with the idea that the elementary particle is a rigid cellulose protofibril stabilized in suspension by associated polyelectrolyte side chains (polyacrylamide–polyacrylic acid copolymer grafts). The behavior of intrinsic viscosity with electrolyte concentration, the concentration depependence and shear dependence of the viscosity and of the steady-state and dynamic shear moduli are qualitatively explained on this basis.     

高分子稀溶液中溶剂对分子特性与流变性能的影响

本文研究了不同溶剂对离子性和非离子性高分子稀溶液的分子构型和流变性能的影响.在部分水解的聚丙烯酰胺水溶液中加入无机盐,测量并计算了分子扩张因数,特征粘度与盐浓度、盐离子价数、溶液pH值的关系.同时使用不同的有机溶剂测量聚丁烯溶液的Maxwell模型松弛时间和分子扩张因数.研究表明,高分子稀溶液可藉调整溶剂性质的方法以达到期望的流变特性.     

碱溶性羟乙基纤维素在复合溶剂体系中的流变性能

使用平行板流变仪,以氢氧化钠/硫脲/尿素/水溶液作为碱溶性羟乙基纤维素(HEC)的复合溶剂,研究了HEC在该溶剂体系中的流变性能,并考察了剪切速率、温度及溶液浓度对溶液的非牛顿指数、结构黏度指数及黏流活化能的影响。结果表明:溶液属于切力变稀型假塑性流体,随溶液温度下降及浓度增加,溶液的表观黏度和结构黏度指数增大,非牛顿性增强;该溶液的黏流活化能随着剪切速率的增加而下降。     

MC尼龙6/纳米ZnO复合材料的研究

采用硅烷偶联剂KH-550修饰纳米ZnO,制备了MC尼龙6/纳米ZnO复合材料。力学性能测试表明,当纳米ZnO质量分数为1%时复合材料的力学性能最优,拉伸强度比纯MC尼龙6提高25.6%,断裂伸长率提高165.6%,简支梁冲击强度提高70.1%,这说明纳米ZnO可起到同时增强增韧的作用。扫描电子显微镜分析表明,纳米ZnO质量分数为1%时,纳米ZnO在MC尼龙6基体中分散最好,达到了纳米级分散;由X衍射分析发现,纳米ZnO没有改变MC尼龙6的结晶形态,纳米ZnO质量分数为1%时复合材料的结晶形态结构优越。     

Effects of dispersant concentration and pH on properties of lead zirconate titanate aqueous suspension

Lead zirconate titanate (PZT) aqueous suspensions were prepared at 60 wt.% solids loading using a commercial ammonium polyacrylate (APA) dispersant. Effects of the dispersant concentration on rheological behavior, dispersion and stability of PZT aqueous suspensions were investigated by means of zeta potential, viscosity and sedimentation height measurements. The results showed that, under suitable conditions, APA dispersant promoted particle dispersion and stabilization in PZT aqueous suspensions. For 60 wt.% solids loading suspensions, the dispersant concentration yielding the lowest viscosity was 0.5 wt.% based on PZT powder dried weight basis. Effects of pH on particle dispersion in the suspensions prepared with APA were studied by laser light scattering technique and scanning electron microscopy. The results showed an improvement in particle dispersion for the alkaline condition, which led to relatively low viscosity and highly stable suspension. Possible particle stabilization mechanisms at various pHs were discussed based on dissociation of the dispersant in water, polymer conformation and adsorption behavior of the dispersant on the particle surface.     

Electrophoretic deposition of ZnO–CeO2 mixed oxide nanoparticles

ZnO–CeO₂ nanoparticles were synthesized by microwave combustion and deposited by electrophoretic deposition (EPD). The effect of using two different alcohols, ethanol and methanol, was investigated on EPD behavior and morphology of deposited film. Moreover, the effect of concentration of nanoparticles and applied voltage on the mass of deposit and the variation in the current density were investigated. With a change in the alcohol type, the surface morphology of deposition changed and some voids were observed on the deposition surface in ethanol. In all cases, with increasing concentration of nanoparticles in suspension, the number of developed cracks increased. Besides, a rise in voltage led to an increase in the number of cracks. The EPD processes in ethanol and methanol suspension were simulated over time using different zero boundary conditions. Hemi‐spherical morphology was seen for the nanoparticles deposited in ethanol. This kind of growth was simulated based on the changes in electrical field.     

The rheological properties of shear thickening fluid reinforced with ZnO of different friction characteristics

The viscosity of shear thickening fluid (STF) changes significantly with low concentrations of additives. However, existing research has suggested that there has not been any consistent enhancement mechanism of additives. The possible reason for this research gap is that existing research has focused on the effect of the shape and content of additives on shear thickening (ST) performance, whereas the friction characteristics of additives on ST performance have not been considered. Accordingly, nanoparticle-enhanced STF with various friction characteristics of ZnO was synthesized in this study to investigate the enhancement mechanism of additives. The aspect ratio of ZnO with different shapes was obtained through SEM analysis. The friction characteristics of ZnO were examined. Lastly, the rheological behavior of reinforced STFs was evaluated. The results indicated that ST performance was enhanced compared with that of neat STF, which was significantly dependent on the friction characteristics of ZnO.     

羟丙基纤维素溶液的流变性能

采用ARES-RFS流变仪测定了羟丙基纤维素溶液的流变性能,考察了温度、溶液浓度、醚化剂量对溶液流变行为的影响,并得到了溶液的非牛顿指数、黏流活化能及结构黏度指数。结果表明:羟丙基纤维素溶液属于假塑性流体,随温度升高、浓度降低、醚化剂用量的增加,该溶液的表观黏度降低,非牛顿指数增大。