Studies on Wool Wax III: Effect of Wool Wax and Certain Wool Wax Derivatives on the Rheological Behaviour of Vaseline

Wool wax and certain wool wax derivatives are investigated as regards their effect on the rheological behaviour of a hydrocarbon ointment base (vaseline). The rheological parameters considered are: flow pattern, structural viscosity, yield value, plastic viscosity, coefficients B and M of thixotropic breakdown and structural recovery. Evidence is provided for marked changes of the rheological characteristics of the system in presence of any of the investigated materials. A discussion of the different effects is presented.     

Effect of Beeswax on the Rheological Characteristics of Soft Paraffin

The effect of beeswax on the rheological characteristics of soft paraffin was investigated. The rheological parameters considered were the flow pattern, structural viscosity, yield value, plastic viscosity, coefficients B and M of thixotropic breakdown and structural recovery. Evidence is presented to show that beeswax affects markedly the rheological characteristics of soft paraffin.     

Interactions in aqueous polypeptide derivative/surfactant systems

Summary A new class of compounds of water-soluble polypeptide derivatives have been synthesized and the interactions with the anionic surfactan sodium dodecylsufate (SDS) studied by rheological and light scattering investigations. The viscosity of the aqueos polypeptide solution passes through a distinct maximum with increasing surfactant concentration. This behaviour, so far only known for hydrophobically modified cellulose derivatives, can be explained by a formation and decay of polymer surfactan networks. The changes caused by microscopic structural parameters through surfactant adsorption are observed by dynamic light scattering and can be correlated with the macroscopic behaviour of the solutions.     

UHMWPE／UHMWPP冻胶体系的流变行为研究

研究了超高相对分子质量聚丙烯（UHMWPP）的加入对超高相对分子质量聚乙烯（umfwPE）冻胶体系粘性行为、非牛顿指数、结构粘度指数的影响。结果表明：UHMWPP在UHMWPE／UHMWPP共混体系中起到了润滑剂的作用,使体系的表观粘度降低,非牛顿指数升高,结构粘度指数下降。其中,UHMWPP添加量为5％时,冻胶体系的可纺性最佳。     

Studies on Wool Wax I: General Rheological Behaviour

Woll waxes were studied for their general rheological behaviour as a function of breed of animal and geographical locality. The rheological parameters studied included flow curve, structural viscosity at low as well as at high levels of shear, yield value, and plastic viscosity. The influence of temperature on these parameters was also considered.     

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。     

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。     

竹炭改性聚酯流变性能研究

采用博力飞黏度计测试竹炭改性聚酯熔体的流变性能,对其黏度、非牛顿指数、结构黏度指数进行分析。结果表明:竹炭改性聚酯表现为切力变稀流体,竹炭母粒的加入明显降低了纯聚酯的非牛顿指数,且使结构黏度指数较大幅度提高,可加工性降低,在挤出成型加工的剪切速率范围内(γ=103~104 s-1),熔体黏度较为稳定因,此适当降低成型温度有利于挤出成型的稳定性。     

聚苯硫醚流变行为研究

采用高压毛细管流变仪研究了进口聚苯硫醚(PPS)树脂的流变性能,分析了剪切速率、温度对PPS树脂流变行为的影响。结果表明,PPS树脂的非牛顿指数均小于1;在低剪切速率下,PPS树脂的表观黏度对温度的依赖程度高于高剪切速率下的依赖程度;PPS树脂的黏流活化能随剪切速率的增加呈减小趋势,其结构黏度指数随温度升高而减小。     

凝胶纺三元聚丙烯腈原液的流变行为

研究了聚丙烯腈／二甲基亚砜／水三元纺丝原液在不同的含水量、聚丙烯腈浓度和温度下的流变性能,获得了零切粘度,表观粘度,非牛顿指数和结构粘度指数对于原液含水量、聚丙烯腈浓度和温度的依赖关系。该溶液是一种剪切变稀的非牛顿流体。随着含水量的增加,零切粘度、表观粘度和结构粘度指数增加,非牛顿指数下降。随着聚丙烯腈浓度的增加,原液的袁观粘度和结构粘度指数增加,非牛顿指数下降。原液的流动性和可纺性随温度提高而增加。     

聚乳酸熔体流变性的研究

研究了聚 L -乳酸熔体的流变性 ,并与 PET熔体流变性进行了比较 ,发现聚 L -乳酸流体为切力变稀流体 ,当温度达 2 2 5℃ ,流动曲线上出现了第二牛顿区 ;粘流活化能高达 12 3k J/m ol;随着熔体温度的增大 ,其流动曲线下移 ,表观粘度下降 ,非牛顿指数增大 ,在 2 0 5～ 2 15℃区域内上升速率较大 ,其结构粘度指数变小 ,同时特性粘数的下降高达 39%。     

高浓度超高相对分子质量聚乙烯冻胶流变行为的研究

应用Rosand RH7D型双料筒毛细管流变仪,研究了以白油为溶剂的高浓度超高相对分子质量聚乙烯(UHMWPE)冻胶的流变特性,以及冻胶浓度、温度对高浓度冻胶的流变曲线、非牛顿指数和结构黏度指数的影响。结果表明:高浓度UHMWPE冻胶属于宾汉流体,不同浓度的UHMWPE冻胶非牛顿指数随温度的升高先增大后减小,结构黏度指数随UHMWPE冻胶浓度及温度的增高而减小。     

Influence of intermolecular interactions on the melt rheology of a propylene–acrylic acid copolymer and its salts

Ionomers based on propylene–acrylic acid copolymer have been prepared and their rheological behavior studied. With different cations the melt viscosity at any shear rate increases as tributylamine salt < acid < zinc salt < sodium salt. Similarly, the activation energies for viscous flow follow the order polypropylene ～ tributylamine salt < acid ～ zinc salt < sodium salt. These results are a consequence of intermolecular interactions between salt groups for the metal acrylate derivatives and hydrogen bonding for the acid derivatives. Strong ionic interactions are absent in the tributylamine salt because of steric hindrance of the bulky amine substituents. The glass transition temperatures for these materials were equivalent. The elastic properties of these polymers follow a similar trend as does the viscosity.     

Effect of Polymerization Conditions on the Rheological Behavior of Acrylic Polymer Solutions with 1-Butyl-3-Methylimidazolium Tetrafluoroborate as Solvent

Rheological behavior of concentrated acrylic polymer/1-butyl-3-methylimidazolium tetrafluoroborate (PAN/[BMIM]BF4) solutions, which were prepared by the radical copolymerization of acrylonitrile (AN) and methylate (MA) in ionic liquid, is reported. The effect of copolymerization conditions on the rheological behavior of the solutions is discussed in detail. The shear viscosity and structural viscosity index, Δη, increases while the non-Newtonian index, n, decreases with increasing polymer concentration as the copolymerization time increases, and decreases with decreasing initiator concentration. It is shown that the rheological behavior of PAN/[BMIM]BF₄ can be directly controlled by varying copolymerization conditions.     

Effect of the vinyl concentration on the structural and rheological characteristics of peroxide‐modified high‐density polyethylenes

The effect of the hydrogenation of the terminal vinyl groups on the peroxide modification and rheological properties of high‐density polyethylene (HDPE) was investigated. The aim of the study was to determine exclusively the effect of the terminal vinyl groups on the peroxide crosslinking and rheological properties of HDPE with one polymer type. This was achieved by hydrogenation of the terminal vinyl groups of a commercial HDPE to obtain an identical material from a structural point of view, which differed only in the nature of the terminal unsaturations, and the comparison of its level of peroxide crosslinking with that of the original polymer. Hydrogenated and unhydrogenated polymer samples were modified at 170°C with different amounts of organic peroxide ranging from 125 to 5000 ppm. Changes in the molecular structure were determined by Fourier transform infrared spectroscopy, size exclusion chromatography, and rheological measurements. Hydrogenation of the terminal groups of the original polymer significantly reduced the rate of modification or crosslinking. The dynamic viscosity and elasticity increased with the level of peroxide modification. Unhydrogenated samples exhibited rapid increases in viscosity and elastic modulus, whereas their hydrogenated counterparts required about 500% of the amount of peroxide needed for the unhydrogenated sample to attain similar structural changes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

超高相对分子质量聚乙烯冻胶的流变行为研究

研究了超高相对分子质量聚乙烯(UHMWPE)冻胶的流变特性,以及温度、相对分子质量对冻胶 的lgη_a-lgγ流动曲线、非牛顿指数和结构粘度指数的影响。结果表明:UHMWPE冻胶属于宾汉流体,具 有明显的非牛顿性,结构粘度指数随UHMWPE相对分子质量的增大而增大,随冻胶温度的升高而降低。     

纤维素纳米晶体对壳聚糖纺丝原液流变行为的影响

首先将纤维素纳米晶体(CNC)悬浮液进行超声分散,然后与壳聚糖乙酸溶液进行高速搅拌共混,制备不同CNC含量的壳聚糖-CNC共混均匀溶液。采用平板式旋转流变仪研究了CNC含量对壳聚糖溶液流变行为的影响。测试结果表明:壳聚糖-CNC共混溶液表现为非牛顿流体行为;黏度随温度的上升而下降,但在高剪切速率范围内,温度对黏度的影响不再明显;随着CNC含量的增加,壳聚糖溶液的表观黏度增大,对剪切速率的敏感性增强,同时非牛顿指数和黏流活化能降低;共混原液的结构黏度指数随CNC含量减少以及温度升高而降低;壳聚糖-CNC共混溶液储能模量和损耗模量的交叉点随温度的升高向高频区移动,随CNC含量的增加向低频区移动,溶液流变规律基本符合Cox-Merz规则。     

聚丙烯腈/凹凸棒土纺丝溶液的流变行为

将纳米凹凸棒土(AT)加入聚丙烯腈(PAN)/二甲基亚砜(DMSO)纺丝溶液中,用平板流变仪研究了温度、AT含量对纺丝溶液流变性能的影响。结果表明:随着AT含量的提高,纺丝溶液的表观黏度及结构黏度指数降低,非牛顿指数和粘流活化能增大。     

A study of rheological properties of cellulose diacetate in acetone solution at low and high shear rates

The rheological properties of cellulose diacetate (CDA) with different intrinsic viscosity (IV) and different concentration in acetone solutions were studied at low and high shear rates. The zero-shear viscosity increased and the structural index increased, when the IV of CDA was increased or the acetone solution concentration was increased. Evidence suggested that a sulfate structure may be forming. It is shown that the increase of hemicellulose and sulfur content is associated with an increase of chain entanglements between CDA molecules and the abnormal increase of solution zero-shear viscosity. At a high shear rate, the correlation curve between inlet pressure drop and solution concentration obtained by Bagley method analysis shows an inflection point, which appears to be the critical concentration at which the cellulose diacetate molecular chains in the solution form a long range entangled elastic network. After the concentration exceeds a certain range of above critical points, the entanglement of the molecular chains in the solution is significantly enhanced. The zero shear viscosity inflection point concentration calculated by the rheological curve with low shear velocity and the inlet pressure drop inflection point concentration calculated by the capillary rheological calculation have good consistency.     

Anomalous rheological behavior of polyethylene melts in the gross melt fracture regime in the capillary extrusion

During the capillary extrusion with several different polyethylenes, we observe an abnormal rheological behavior. The nominal viscosity of polyethylene melt in the gross melt fracture regime does not change with a temperature. All polyethylenes tested show same behaviors. More interestingly, the nominal viscosity in the gross melt fracture regime shows even no molecular weight dependency when PEs have similar molecular structures (degree of branching and co-monomer content). From various experiments, we conclude that this abnormal phenomenon is relevant to the structural change with the melt temperature.