A Survey of Rheological Properties of One-Component Epoxy Adhesives

Flow characteristics of seven commercially available one-component epoxy adhesive pastes were measured using a controlled shear stress rheometer and a controlled shear rate rheometer over a temperature range from 5°C to 60°C. Combining data obtained from both controlled rate and controlled stress experiments over a wide range of shear rates, we observed Newtonian flow (shear stress proportional to shear rate) at very low shear rates, a plateau “shear thinning” region at intermediate shear rates, and a second region of linear dependence of shear stress on shear rate at high shear rates. The adhesive pastes exhibited a very broad range of rheological behavior. Two flow parameters important to adhesive application technology, the plastic viscosity and the apparent yield stress, were measured for each adhesive. The plastic viscosity ranged from 11.6 to 329.5 Pa. s; the apparent yield stress ranged from 56.2 to 413 Pa. The temperature dependence of the rheological parameters of the epoxy adhesive pastes was also determined. The results are reported as the activation energies, E_η and E_σ , of plastic viscosity and apparent yield stress, respectively. The apparent yield stress of each adhesive paste was much less sensitive to changes in temperature than was the plastic viscosity. This suggests that the processing characteristics are likely to show qualitative as well as quantitative changes with temperature.     

硅微粉对水泥浆体流变性能的影响

运用水化热测定仪、流变仪、以及Dinger-Funk紧密堆积等方法,研究了硅微粉掺入水泥中对复合浆体的流变性能的影响,比较了不同硅微粉掺量对复合浆体的早期水化放热、紧密堆积程度、屈服应力和塑性粘度的作用.结果显示:硅微粉取代水泥后,降低浆体水化热放热量,提高了体系紧密堆积程度;Bingham流体仍适用于硅微粉-水泥复合浆体,取代5%、10%、15%水泥的复合浆体,屈服应力和塑性粘度在0、60 min时都小于纯水泥浆体,并且取代10%水泥的复合浆体,其屈服应力和塑性粘度在0、60 min时都最小,流变性能最好.     

聚硅氧烷侧链高分子液晶电流变液体的性能研究

研究聚硅氧烷侧链高分子液晶配制成电流变液体的电流变效应 ,以获得高性能的电流变液体 ,应用德国RV2 0电流变仪测试性能。结果表明 ,该电流变液体 5 2℃ ,电场强度由零增至DC 2 0 0 0V/mm ,剪切速率为 30 0s-1时 ,剪切应力由 2 0 0Pa增至 5 4 0 0Pa ,表观黏度由 2 0 0mPa·s增至 10 0 0 0mPa·s;剪切速率为 4 0 0s-1时 ,剪切应力由 2 0 0Pa增至 6 30 0Pa,表观黏度由 2 0 0 0mPa·s增至 76 0 0mPa·s ;剪切速率为 5 0 0s-1时 ,剪切应力由 2 75Pa增至 6 80 0Pa,表观黏度由5 0 0mPa·s增至 90 0 0mPa·s。 77℃时 ,同样条件下 ,剪切速率为 5 0 0s-1时 ,剪切应力达 80 0 0Pa,具有更高的剪切应力 ,说明温度适应性较强。     

减水剂的加入时间对新拌水泥浆体流变性能的影响

研究了三聚氰胺甲醛磺酸盐(MFS)减水剂的掺加时间对普通硅酸盐水泥浆体在初始120 min的水化时间内流变性能的影响,研究中MFS的后掺时间为0 min、5 min、10 min、15 min、20 min和25 min。检测了在不同减切速率(3～147 s-1)下水泥浆体水化30 min和120 min时的剪切应力和表观粘度。测定了水化120 min后的水泥浆体的Ca2+浓度和化学结合水。结果表明:推迟减水剂的后掺时间降低了水泥浆体在120 min内的屈服应力和表观粘度,减水剂MFS的最佳后掺时间为10～15 min。     

聚碳硅烷流变性能的研究

采用 Instron毛细管流变仪 ,研究了不同温度下聚碳硅烷的流变性。结果表明 ,聚碳硅烷为典型的切力变稀流体 ,而且由牛顿流动向“切力变稀”流动的临界切变速率随温度升高而增大。其粘度温度关系基本满足 Arrhenius方程 ,粘流活化能很高 ,表观粘度随温度升高下降显著 ,为了提高纺丝的稳定性 ,必须严格控制纺丝温度     

絮凝氧化铁悬浮液流变性质研究

应用LVDV-Ⅲ+型可编程流变仪测定了微米级氧化铁悬浮液絮凝处理后的流变特性,考察因素包括悬浮液固相质量浓度、pH值、絮凝剂添加量、搅拌速度。结果表明,悬浮液浓度不同,其流变性能也表现出不同,在相同剪切速率下,高质量分数悬浮液的表观粘度和剪切应力都大于低质量分数悬浮液的表观粘度和剪切应力;pH对絮凝悬浮液流变性有重要的影响。絮凝悬浮液粘度随pH的增加先增大后减小,絮凝剂聚合氯化铝添加量为80 mg的条件下,pH=6.14时表观粘度最大;絮凝剂浓度的不同,对于悬浮液流变性能的影响也不同,在相同剪切速率下,添加高浓度絮凝剂悬浮液的表观粘度和剪切应力都大于添加低浓度絮凝剂悬浮液的表观粘度和剪切应力,增加絮凝剂浓度对提高悬浮液粘着性能具有积极意义;对悬浮液搅拌强度不同其流变性能也表现出不同,在相同剪切速率下,悬浮液的表观粘度和剪切应力随着测试前对它搅拌强度的增加表现出先增大后减小。     

基于稳态流变测试的水泥浆体剪切模式研究

采用RHEORIAB QC型旋转黏度计测定不同剪切方式下水泥浆体稳态流变曲线,并用修正宾汉姆流变模型对其进行拟合,研究了剪切方式对水泥浆体稳态流变测试的影响.结果表明:预剪切对水泥浆体动态屈服应力和塑性黏度影响不大.恒定剪切变形速率小于、等于、大于、偏大于水泥浆体结构抗剪切破坏能力时,剪切应力随时间分别先线性增加接着保持同一值、直接保持恒定值、先减小接着保持同一值、轻微增加后达到平衡.随剪切速率增加,水泥浆体在0.1～100 s-1、100～400 s-1、400～600 s-1三个区段依次呈现出剪切变稀、宾汉姆流体、剪切增稠的流变行为.剪切速率变化范围向剪切变稀或剪切增稠段移动,水泥浆体动态屈服应力减小、塑性黏度增大;单个剪切速率的剪切时间越长,水泥浆体动态屈服应力、塑性黏度均越小.     

Influence of time addition of superplasticizers on the rheological properties of fresh cement pastes

It is well known that the fluidity and the fluidity loss of fresh cement pastes are affected by the kind and the time of addition of organic admixtures. The influence of the time addition of two chemical admixtures, namely, melamine formaldehyde sulfonate (MFS) and naphthalene formaldehyde sulfonate (NFS), on the rheological properties of ordinary Portland and sulfate-resisting cement pastes through the first 120 min of hydration was investigated. The admixture addition was delayed by 0, 5, 10, 15, 20, and 25 min. Shear stress and apparent viscosity of the cement pastes were determined at different shear rates (3-146 s⁻¹) and hydration times of 30, 60, 90, and 120 min. The concentration of Ca²⁺ and the combined water content of the cement pastes were determined after 120 min. Yield stress and plastic viscosity values were also determined by using the Bingham model. The results show that an increase in the addition time of the admixture reduces the shear stress, the yield stress, and the plastic viscosity of the cement pastes at the early ages (15 min) as well as at later early ages (120 min). The optimum delaying time of admixture addition is found to be 10-15 min. This time does not depend on the cement and superplasticizer type.     

PVC通信电缆绝缘料流变行为的研究

本文采用毛细管流变仪对聚氯乙烯电缆料的加工流变性能进行了研究，分析并讨论了影响ＰＶＣ流变性能的各种因素。结果表明：在试验温度下，增塑ＰＶＣ的剪切应力均随剪切速率的增加而增大，但当剪切速率增加到一定程度后，剪切速率对剪切应力的影响变小；改性剂ＰＭ－１的加入可以大大降低在相同剪切速率下的剪切应力。改性剂ＰＭ－１使电缆料的剪切敏感性减小，牛顿性增强。虽然ＰＭ－１不能改变临界剪切应力值，但却使当临界剪切应力相应的熔体粘度减小，即临界剪切速率增大，这在实际生产过程中是十分有用的，即可以提高挤出速度而不致于产生熔体破裂。分子量减小，熔体表观粘度明显减小。熔体表观粘度随温度的升高而逐渐减小。     

进口聚苯硫醚树脂流变性能的研究

采用毛细管流变仪研究了日本聚苯硫醚(PPS)树脂的流变性能。结果表明:随着剪切速率的增加,PPS的表观粘度降低;当温度升高时,PPS的表观粘度也降低;剪切速率越高,温度对剪切速率的影响越小;随着温度的增加,非牛顿指数增加且趋近于1,PPS熔体为假塑性流体;PPS的粘流活化能随着温度的增加而减小;此外,随着温度的增加,结构粘度指数减小。     

Effects of sucrose on the rheological behavior of wheat starch pastes

The rheological properties of starch–water–sucrose pastes have been determined under steady and oscillatory shear conditions. The results show that the effect of sucrose at concentrations of less than about 20% w/w is to increase the apparent viscosity, yield stress, dynamic viscosity, and dynamic rigidity. At higher surose concentrations the yield stress and dynamic rigidity tend to zero while values of the dynamic viscosity and apparent viscosity are reduced compared with controls. Sucrose causes the dispersed gel particles in pastes to change volume, and it is suggested that this is one of the factors responsible for the observed effects of sucrose on rheological behavior.     

凝聚剂对氧化铁悬浮液流变性的影响

应用LVDV-Ⅲ+型可编程流变仪测定了凝聚剂对氧化铁悬浮液的流变特性的影响。实验结果表明,高价凝聚剂对于悬浮液颗粒的凝聚能力要比低价凝聚剂更加明显;随着凝聚剂浓度的增加,悬浮液颗粒的凝聚程度也相应增加;凝聚剂种类的不同,对于悬浮液流变性能的影响也不同,高价凝聚剂对于悬浮液流变性能的影响比低价凝聚剂大。在相同剪切速率下,添加高价凝聚剂悬浮液的表观粘度和剪切应力都大于添加低价凝聚剂悬浮液的表观粘度和剪切应力;凝聚剂浓度的不同,对于悬浮液流变性能的影响也不同。在相同剪切速率下,添加高浓度凝聚剂悬浮液的表观粘度和剪切应力都大于添加低浓度凝聚剂悬浮液的表观粘度和剪切应力,增加凝聚剂浓度对提高悬浮液粘着性能具有积极意义。     

Experimental study of rheological properties of solid propellant slurry at low-shear rate and numerical simulation

The steady state rheological properties of a three-component hydroxyl-terminated polybutadiene binder (HTPB) solid propellant slurry at low shear rate were investigated using a rotational rheometer. The data were analyzed and the rheological characteristics of the slurry were determined. The effect of shear rate on apparent viscosity and shear stress as well as the viscosity–time effect of the slurry were also analyzed. Herschel–Bulkley (H-B) model was applied for the simulation of the flow process of a two-dimensional container using CFD Ansys-polyflow software. Experimental results showed that solid propellant slurry had yield pseudoplasticity. Yield characteristics were determined based on the fact that when shear stress was greater than yield stress, the slurry began to flow and the relationship between shear stress and shear rate obeyed power law function. Simulation results further verified the correctness of experimental results.     

固相缩聚半芳香透明聚酰胺的流变性能

采用毛细管流变仪对固相缩聚半芳香透明聚酰胺(Semi-AromaticTransparent Polyamide,简称SATPA)的流变性能进行了研究。研究结果表明:固相缩聚SATPA熔体属假塑性流体,非牛顿指数随剪切速率的增大而减小;表观黏度随温度、剪切速率和剪切应力的升高而降低。随着剪切速率的增大,黏流活化能减小,表观黏度对于温度的敏感性减弱。     

丙烯腈-苯乙烯-丙烯酸酯共聚物的流变性能

用毛细管流变仪测试了丙烯腈-苯乙烯-丙烯酸酯（ASA）树脂的表观黏度、黏流活化能、非牛顿指数等流变参数,讨论了剪切速率、剪切应力、温度对ASA的表观黏度的影响,研究了黏流活化能与剪切速率的变化规律。结果表明,随着温度升高, 共聚物的表观黏度下降,非牛顿指数增大;随着剪切速率的增大,树脂的黏流活化能降低;其非牛顿指数n小于1,说明ASA是典型的假塑性流体。     

Rheological and solid wall boundary condition characterization of unvulcanized elastomers and their compounds

An extensive fundamental investigation of the rheological properties and solid wall boundary condition shear stress of elastomers and elastomer–carbon black compounds has been carried out. The elastomers were an emulsion butadiene–styrene copolymer (SBR 1500) and a polybutadiene. Shear flow rheological properties were measured using a newly designed sandwich rheometer, in both constant shear rate and creep modes as well as in a capillary rheometer. A constant elongation rate rheometer for elastomers was developed. Stress relaxation measurements were also carried out in the sandwich rheometer. The shear viscosity of the gum elastomers exhibits a constant very high shear zero viscosity (8 × 10⁸ Pa.s for SBR 1500 at 100°C) and decreases with increasing shear rate. The compounds exhibit yield values of similar magnitude to carbon black compounds of molten plastics. Only the SBR 1500 and its compounds were studied in the elongational flow mode. It was not possible to achieve a steady state in these experiments. An apparatus for measurement of shear stress as a function of velocity (shear rate) at a specified pressure was developed. The instrument, which we call a friction tester, was used not only to determine wall shear stress but to investigate the regime of flow and potentially determine conditions for the onset of slip. Evidence of changing flow regimes were found, and the implications discussed.     

Rheological behaviour of copoly(ethylene/octene) elastomer compunds: Effect of blowing agent and precipitated CaCO3 filler

Abstract

An experimental study of the rheological behaviour of ethylene/octene copolymer compounds in extrusion containing blowing agent has been carried out. The cell morphology development was studied using scanning electron microscopy. Rheological properties of unfilled and precipitated CaCO₃ filled systems with various blowing agents, extrusion temperatures, and shear rates were studied using a capillary rheometer. The total extrusion pressure, apparent shear stress, apparent viscosity, and die swell of the unfilled and CaCO₃ filled compounds were also determined and the effect of blowing agent on the rheological properties of the compounds studied. It was observed that there is reduction of stress and viscosity with blowing agent loading. Incorporation of blowing agent led to decreased shear thinning behaviour resulting in an increase in the power law index. The viscosity reduction factor of the unfilled compound was found to be dependent on the concentration of blowing agent, the shear rate, and the temperature.     

Rheological Characteristics of Short Nylon-6 Fiber Reinforced Styrene Butadiene Rubber Containing Epoxy Resin as Bonding Agent

ABSTRACT

The rheological characteristics of short Nylon-6 fiber–reinforced Styrene Butadiene rubber (SBR) in the presence of epoxy resin–based bonding agent were studied with respect to the effect of shear rate, fiber concentration, and temperature on shear viscosity and die swell using a capillary rheometer. All the composites containing bonding agent showed a pseudoplastic nature, which decreased with increasing temperature. Shear viscosity was increased in the presence of fibers. The temperature sensitivity of the SBR matrices was reduced on introduction of fibers. The temperature sensitivity of the melts was found to be lower at higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity of the composites increased with shear rate. In the presence of epoxy resin bonding agent the temperature sensitivity of the mixes increased. Die swell was larger in the presence of bonding agent.     

定向碳纳米管/高密度聚乙烯复合材料体系流变行为的研究

对定向碳纳米管进行酸化处理以后，采用机械共混法制备了定向碳纳米管／高密度聚乙烯复合材料，利用毛细管流变仪研究了高密度聚乙烯和定向碳纳米管／高密度聚乙烯复合材料的流变行为．讨论了剪切应力、剪切速率、温度以及定向碳纳米管的加入对体系流变行为的影响。结果表明：高密度聚乙烯和定向碳纳米管／高密度聚乙烯复合材料都属于假塑性流体．高密度聚乙烯的非牛顿性要大于定向碳纳米管／高密度聚乙烯复合材料；随剪切速率和剪切应力的增大及温度的升高．熔体表现粘度均减小；随着定向碳纳米管含量的增加，定向碳纳米管／高密度聚乙烯复合材料的表观粘度先减小后增大。     

Development and characterization of hydrocarbon polyol polyurethane and silicone magnetorheological polymeric gels

Magnetorheological polymeric gels (MRPG) have been developed for use in semi‐active magnetorheological fluid (MRF) dampers and other magnetorheological (MR) devices. The novel MRPGs are prepared by suspending iron particles in polymeric gels. Off‐state (i.e, no applied magnetic field) viscosity and settling behavior can be controlled through the selection of polymeric gels. In this study, tunable rheological properties were investigated with a piston‐driven flow type rheometer with a shear rate varying from 20 s^?1 to 6,000 s^?1. Silicone MRPG (with 84.5 wt % iron particles) has controllable viscosity and a high shear yield stress over a wide range of shear rates. Silicone MRPG (79.5 wt % iron particles) has the lowest viscosity of those studied. Polyurethane MRPG has the lowest settling rate. The order of addition of magnetic particles and polymer during the polymerization process affects the MRPG final off‐state apparent viscosity (80% increase in apparent viscosity for silicone MRPG polymerized after adding iron particles). This indicates that polymer gels modify the surface properties of the magnetic particles, causing interaction among particles. The dynamic shear yield stress is higher for fluids with better dispersion stability. Polyurethane MRPG, which has the lowest settling rate, has a high dynamic yield stress (23 kPa at 350 mT). Both dynamic and static shear stress values of the MRPGs were found to be similar in magnitude (5–8 kPa at 120 mT for silicone MRPG with 84.5 wt % iron particles and polyurethane MRPG), indicating that MRPGs can provide consistent performance in devices. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1176–1182, 2004