未硫化橡胶门尼粘度测量不确定度的评定

通过门尼粘度检测整个过程进行不确定评定度分析,找出引起不确定度产生的因素。评定确认:转子上、下面空隙以及转子转速是影响结果的最主要因素,转子厚度、转子侧面空隙引入的不确定度也应引起重视。此方法对用圆盘剪切粘度计进行未硫化橡胶门尼粘度测定的不确定度评定具有借鉴和参考作用。     

丁二烯橡胶门尼粘度测量不确定度的评定

以丁二烯橡胶样品测定门尼粘度,评定其门尼粘度测量不确定度的来源,依据JJF1059-1999对门尼粘度测试过程中的测量不确定度分量进行了分析和评定。该测量过程中所产生的不确定度主要由测量的温度、标准物质的不确定度所决定。丁二烯橡胶样品测量结果表示为ML（1＋4）100℃（45.7±0.8）。     

胶粘剂剪切冲击强度测量结果的不确定度评定

依据GB／T6328—1999《胶粘剂剪切冲击强度试验方法》，以丙烯酸酯胶粘剂为饲，选用悬臂粱冲击试验机进行剪切冲击试验，分析了胶粘剂剪切冲击强度测量结果的不确定度的来源，计算了合成标准不确定度和扩展不确定度。     

文昌油田原油运动粘度测量不确定度评价

用标准方法《石油产品运动粘度测定法和动力粘度粘度计算法》（GB/T265—88）检测文昌油田原油运动粘度,应用测量不确定度评定理论,分析了此方法不确定度的重要来源,计算得出本方法的相对不确定度,U（P=99.7%）=3．5％。结果显示文昌油田运动粘度的主要来源于测试温度波动引起试样粘度变化而产生的不确定度,同时粘度计常数和仪器测试时间所引起的相对不确定度对总不确定度也有重要的影响。     

车用柴油运动粘度测量不确定度的评定与表示

根据平氏粘度计测量粘度的原理及计算公式,对车用柴油的运动粘度进行测量,在测量过程对影响测量结果的不确定度进行分析,评定结果合成标准不确定度为0.025 mm~2·s~(-1),扩展不确定度为0.053 mm~2·s~(-1)。结果表明:粘度计、温度变化、倾斜角度的不确定度分量对合成标准不确定度影响较大。     

火焰原子吸收法测定空气中锌的不确定度评定

以AAS法测定空气中锌为例,应用数理统计学中最小二乘法建立回归方程,在回归方程基础上建立数学模型,针对整个分析过程找出不确定度的来源,并加以评定分析。     

润滑油运动粘度测定结果不确定度的评定

由于润滑油产品中的运动粘度指标对各类滴水润滑油的分类起着决定作用,科学准确地获得润滑油的运动枯度测量结果,以便用户正确选择合适品种的润滑或参与国际贸易检测结果的比较,我们依据JJF-1059—1999《测定不确定度评定与表示》及GB/T265-1988《石油产品运动粘度测定法和运动粘度计量法》,按经验方法的评定程序,分析了润滑油运动粘度测量结果不确定度的来源,建立了相应的数学模型,利用标准物质对不确定度的分量进行评估,获得润滑油在100℃时运动粘度的扩展不确定度：U=0．54％．     

润滑油运动粘度测量结果不确定度的研究

本文对煤制油分公司购进的润滑油运动粘度进行了分析,着重研究了影响测定结果的各种不确定度的来源,根据一系列分析数据及参考数值计算出了不确定度的大小。研究表明,通过计算不确定的大小能够有效找出影响分析结果的各种因素,提高了分析结果的准确度和可靠性。     

粘度法测定药用聚乙二醇分子量的不确定度评定

粘度法测定了聚乙二醇的相对分子质量,并对测定结果的不确定度进行了分析和评定。通过对测定过程中的各种不确定度分析,得到了测定结果的不确定度主要由溶液配置过程中的容量瓶体积和移液管体积引入的不确定度组成,其他方面的组成较小,在实际评定中可以忽略。     

乙丙橡胶门尼粘度标准物质定值不确定度的评定

以乙丙橡胶为门尼粘度标准物质定值样品,评定其门尼粘度测量不确定度的来源,依据JJF 1059—1999对门尼粘度定值样品的不确定度分量进行了分析和评定。研制的乙丙橡胶门尼粘度标准物质,影响不确定度评定的因素有仪器测试时的温度和转速、各实验室定值测量的重复性、样品的均匀性、样品的稳定性。经过评定,乙丙橡胶门尼粘度标准物质在ML100℃(1+4)、ML100℃(1+8)条件下测定的不确定度分别为0.5和0.4,标称值分别为42.4±0.5和40.4±0.4。     

High shear strain rate rheometry of polymer melts

The rheology of a range of polymer melts has been measured at strain rates above those attained during conventional rheometry using an instrumented injection molding machine. Deviations from shear thinning behavior were observed at high rates, and previously unreported shear thickening behavior occurred for some of the polymers examined. Measured pressure and volumetric throughputs were used to calculate shear and extensional viscosity at wall shear strain rates up to 10⁷ s^?1. Parallel plate rheometry and twin bore capillary rheometry were used to provide comparative rheological data at low and medium shear strain rates, respectively. Commercial grades of polyethylene, polypropylene, polystyrene, and PMMA were studied. Measured shear viscosity was found to follow Newtonian behavior at low rates and shear thinning power law behavior at intermediate strain rates. At shear strain rates approaching or above 10⁶ s^?1, shear viscosity reached a rate‐independent plateau, and in some cases shear thickened with further increase in strain rate. A relationship between the measured high strain rate rheological behavior and molecular structure was noted, with polymers containing larger side groups reaching the rate‐independent plateau at lower strain rates than those with simpler structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

用旋转剪切法测量聚合物熔体零切粘度时应注意的几个问题

本文研究了不同测试条件下用旋转剪切法测量聚合物熔体零切粘度值的变化规律,并通过比较旋转剪切法所得数据与蠕变法及动态法数据,得出对于均聚物或均相共混体系零切粘度的测量,旋转剪切法与蠕变法及动态法同样适用。     

双毛细管黏度测试法的应用

介绍了双毛细管黏度法对聚酯特性黏度的测试。通过测试结果分析,认为双毛细管黏度法,具有较好的准确性、分析快速、连续性强、重现性好、安全环保的特点。     

Comparison of relative viscosity measurement of polyvinylpyrrolidone in water by glass capillary viscometer and differential dual‐capillary viscometer

The relative viscosity (RV) of polyvinylpyrrolidone (PVP) with different molecular weights was measured with a glass capillary viscometer and with a differential dual‐capillary viscometer in water at different concentrations. For the differential dual‐capillary viscometer, RV increases with a decreasing flow rate, especially for high molecular weight PVP at a 1% concentration. A good agreement in the RV between the two methods can be obtained for PVP with different molecular weights and at various concentrations if an appropriate flow rate is selected for the differential dual‐capillary viscometer. Special precaution is needed when using the differential dual‐capillary viscometer to measure the viscosity of a pure solvent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1312–1315, 2002     

Energy‐based predictive criterion for LCP fibrillation in LCP/thermoplastic polymer blends under shear

This article relates the fibrillation of liquid crystalline polymer (LCP) under shear in its blend with a thermoplastic polymer (TP) to the relative rate of energy utilization in the LCP and TP phases. The development of a criterion based on the energy relationship for predicting LCP fibrillation in the blend is discussed. The formation of LCP fibers in the blends of LCP with polycarbonate (PC), polyethylene naphthalate (PEN), high‐density polyethylene (HDPE), polypropylene (PP), and silica‐filled polypropylene (PP) was studied to validate the criterion and to demonstrate its applicability. For all the blends, viscosity data were obtained by using a capillary rheometer, which was subsequently used to estimate the rate of energy utilization in the LCP and the matrix phases. The predictions based on the proposed criterion were verified through the morphological investigations carried out on the extrudates obtained from the same capillary experiments. The energy‐based criterion was easy to implement, could account for the effect of variable LCP concentration and fillers in the blend, and could provide reliable predictions for a variety of LCP/TP blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3314–3324, 2003     

The dependence of shear and elongational viscosity on the molecular weight of poly(vinylidene fluoride)

The dependence of shear and elongational viscosity on the molecular weight of poly(vinylidene fluoride) has been studied using a capillary rheometer. The elongational viscosity was evaluated based on Cogswell's method with two types of capillaries: capillary length (L)/capillary diameter (D) = 10 mm/1 mm and L/D = 0 mm/1 mm. We used the ratio P₀/P_L that indicates the contribution of elongational flow to the total flow involving both the shear and elongational flows. P_L and P₀ are the pressure losses in the capillary and the converging flows, respectively. P₀/P_L increased with molecular weight and shear rate. This corresponds to decreasing the number of entanglements of molecular chain under a large displacement, especially high shear. Thus, we suggest using P₀/P_L as the parameter of the entanglement interaction on the molecular chain under a large displacement. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2381–2384, 1999     

Melt shear viscosity of PP/Al(OH)3/Mg(OH)2 flame retardant composites at high extrusion rates

The melt apparent shear viscosity (η_a) of polypropylene (PP) composites filled with aluminum hydroxide [Al(OH)₃] and magnesium hydroxide [Mg(OH)₂] was measured by means of a capillary rheometer under experimental conditions of temperature ranging from 180 to 200°C and apparent shear rate varying from 10 to 2 × 10³ s⁻¹, to identify the effects of the filler particle content and size on the melt viscosity. The results showed that the melt shear flow of the composites obeyed the power law and presented pseudoplastic behavior. The dependence of η_a on temperature was consistent with the Arrhenius equation. The sensitivity of η_a for the composite melts to temperature was greater than that of the unfilled PP, and weakened with increasing apparent shear rate. The η_a increased linearly with an increase of the weigh fraction of the flame retardant, especially in the low apparent shear rate region. The η_a of the composites decreased slightly with an increase of particle size of flame retardant. Moreover, the variation for the η_a with particle size of flame retardant was much less than with apparent shear rate under these test conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Viscosity of polydimethylsiloxane gum: Shear and temperature dependence from dynamic and capillary rheometry

The rheology of Dow Corning polydimethylsiloxane gum (PDMS/silicone gum) was studied over a time range of 10^?2 to 10⁵ s^?1 and a temperature range of 23–150°C using both capillary and dynamic rheometry. A low shear Newtonian region is observed at room temperature below 0.01 rad/s (increasing to 0.1 rad/s at 150°C) for which an Arrhenius activation energy for a viscous flow of 13.3 kJ/mol was determined. The Cox–Merz rule for merging of shear and complex viscosities is found to be valid up to 10 s^?1. Viscosity is found to be independent of temperature above 100 s^?1, where terminal power‐law flow is encountered. This is exhibited in the dynamic data as equal plateau moduli for the various temperature curves. Gross wall slippage is seen in capillary flows above approximately 100 s^?1, corresponding to a stress value of 70–100 kPa. Slip‐stick (spurt) flow is not observed. The viscosity data are best fitted by the Carreau–Yasuda model with a fitting parameter a of 0.7, a power‐law index n of 0.05 (low because of slip effect), and a zero shear viscosity of 32 kPa s at 23°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2533–2540, 2002     

Iosipescu shear deformation and fracture in model thermoplastic polyolefins

Shear deformation and fracture behaviors in polypropylene (PP)‐based model thermoplastic polyolefins (TPOs) were investigated with the Iosipescu shear test. The shear deformation process was monitored in situ via video camera to obtain experimental shear stress–strain curves of model TPOs. Shear fracture mechanisms were studied with optical microscopy and scanning electron microscopy. Macroscopically, the cracks in neat PP propagated along the maximum shear plane, which indicated that mode‐II shear failure existed in neat PP. Microscopically, it was shown that shear fracture initiated in the form of partial, discontinuous inclined microcracks that later coalesced and formed the final continuous crack. The incorporation of rubber in PP could transform the shear fracture process into a stretching process in the shear damage zone. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3201–3214, 2001