Dependence of intrinsic viscosity and molecular size on molecular weight of partially hydrolyzed polyacrylamide

As a typical water-soluble polymer, ultra-high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (R_g) and hydrodynamic radius (R_h) were less documented due to their high viscosity in aqueous solution. In this work, the molecular structure of five UHMW-HPAM samples with different MW was elucidated by ¹H and ¹³C NMR spectroscopy, and their solution properties were characterized by both static and dynamic light scattering. It is found that all the second virial coefficient (A₂) values are positive and approaching zero, indicating of a good solvent of 0.5 M NaCl for UHMW-HPAM. The weight-average molecular weight (M_w) dependence of molecular size and intrinsic viscosity [η] for these series of HPAM polymers with MW ranging from 4.81 to 15.4 × 10⁶ g·mol⁻¹ can be correlated as R_g = 3.52 × 10⁻²M_w^0.51, R_h = 1.97 × 10⁻²M_w^0.51, and [η] = 6.98 × 10⁻⁴ M_w^0.91, respectively. These results are helpful in understanding the relationship between molecular weight and coil size of HPAM polymers in solution, and offer references for quick estimation of molecular weight and screening of commercial UHMW-HPAM polymers for specific end-users.     

含侧氨基聚二甲基硅氧烷MHS方程的订正

通过测定含侧氨基聚二甲基硅氧烷聚合物的数均分子量和特性粘数,对MHS方程中的常数K和α进行了订正,得到的MHS方程表述为:[η]=3.21×10-4Mn0.66。     

DSC法研究高粘度超有光聚酯切片的等温结晶

采用差示扫描量热法（DSC）对自制不同特性粘数的超有光聚酯切片进行结晶行为研究。分析结果表明：特性粘数增加,冷结晶温度Tc升高,熔融结晶温度Tmc降低,即结晶变慢;等温结晶行为较好地符合了Avrami方程。在同样的结晶温度下,特性粘数升高,半结晶周期t1/2增加,结晶变慢;相同时间内随着聚酯样品特性粘数的升高,结晶速率变慢。     

Polymer molecular weight,zero shear viscosity,steady state compliance and binary blending law

Viscoelastic properties of binary blends of polystyrenes with a narrow distribution of low and high molecular weights (M₂ > M₁ > M_c) were examined. By combining the theoretical work of Montfort et al., Kurata, and Schausberger, a binary blending law was developed and was used to calculate the zero shear viscosity and steady state compliance of the blend of two monodisperse polymers. The blending law was also used to calculate the molecular weight distribution of a polydisperse polymer. The calculated results were compared with those obtained from viscoelastic ] and GPC measurements, with good agreement.     

超高相对分子质量聚乙烯特性黏数的测试方法

采用毛细管黏度计法测定超高相对分子质量聚乙烯(UHMWPE)的特性黏数([η]),对[η]的准确测定的影响因素进行了探讨。结果表明:以十氢萘为溶剂,使用前进行蒸馏提纯;在配制UHMWPE溶液时,加入质量分数为0.2%的抗氧剂1010,按预溶胀、溶胀、溶解3步骤进行溶解,溶解温度150℃,溶解时间0.5 h,配制UHMWPE溶液浓度为100~600 mg/L;严格控制温度(135±0.2)℃,所测UHMWPE的[η]平行性较好,相对标准偏差为1.08%。     

PET特性黏度分析离群值的判定方法

结合PET生产检验实例,使用方差分析发现特性黏度数据之间存在显著性差异,而使用国标中离群值检验判别法发现离群值的判定结论相反,在结论矛盾的基础上分析指出应正确识别系统误差及随机误差,合理应用各种检验方法,同时指出离群值判定方法与方差分析的结合使用有助于提高离群值判定的科学准确性。     

聚酯特性粘数测试方法的比较

阐述了相对粘度仪法和传统玻璃毛细管粘度仪法的测试原理，实验验证了Y501相对粘度仪和LAUDACD30粘度仪测试结果的差异性。结果表明其差异性不大，相比LAUDACD30粘度仪，5（501相对粘度仪的测试精度及自动化程度更高、有利环保，更具有实用性和快捷性。     

氯化聚丙烯甲苯溶液的特性黏数及其黏均分子量

分别用乌氏黏度计和旋转黏度计测定了氯化聚丙烯甲苯溶液的特性黏数和黏度,把特性黏数和黏度进行关联,发现ηsp/C与浓度C(ml/g)的关系用多项式ηsp/C=[η]+k1[η]2C+k2[η]2C2拟合,可以得到很好的结果。并且用特性黏数和Mark-Houwink方程求出了不同氯化聚丙烯(CPP)的黏均分子量。     

Molecular weight and the Mark‐Houwink relation for ultra‐high molecular weight charged polyacrylamide determined using automatic batch mode multi‐angle light scattering

This study presents an automatic batch mode (i.e., off‐line) multi‐angle light scattering (MALS) method for the molecular weight (MW) determination of ultra‐high MW (UHMW) polyacrylamide (PAM) homopolymer and acrylamide copolymers. This method combines a MALS detector with a sample dilution and injection device that automatically delivers a concentration gradient from a stock solution. The automation makes it practical to use the batch MALS method for routine MW analysis of UHMW polymers. The automatic batch MALS analyses of a series of poly(sodium acrylate‐co‐acrylamide) (30:70 mol %) in 1.0M NaCl show a non‐linear Mark‐Houwink relation in the MW range of 1.2 × 10⁶ to 12.6 × 10⁶ g mol^?1. The entire molecular weight range can be fit with a quadratic relation or two linear equations, one for molecular weight up to 5.3 × 10⁶ g mol^?1 and the other from 5.3 × 10⁶ to 12.6 × 10⁶ g mol^?1. The non‐linear Mark‐Houwink relation suggests that the extrapolation of the Mark‐Houwink equation beyond the measured MW range into the UHMW regions can significantly overestimate the MW of the UHMW polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43748.     

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     

A new analytical method to calculate intrinsic viscosity and viscosity constants of polymer–solvent systems

Experimental viscosities were measured by Schott Gerate viscometer at 30 °C for polystyrene–chloroform and polycaprolactum–benzene systems. These data were analyzed by a newly developed analytical method to calculate intrinsic viscosity and viscosity constants. The analytical method was compared with the graphical as well as the least squares methods and the new analytical method is better than the graphical method because it avoids personal errors that might arise in reading the intercept and slope values from the reduced viscosity versus concentration plots. Furthermore, the analytical method is as effective as the least squares method, but provides better insights while choosing the experimental viscosity values. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 283–290, 2002     

无机盐对两性聚丙烯酰胺特性粘度的影响

用红外吸收光谱对两性聚丙烯酰胺结构进行了表征,表明分子链上丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(MADQUAT)和丙烯酰胺基甲基丙磺酸钠(NaAMPS)链节的存在。随后研究了NaCl、CaCl2浓度及pH值对不同阴阳离子度的聚合物特性粘度的影响。结果表明,AM-MADQUAT-NaAMPS共聚物特性粘度受CaCl2浓度影响较NaCl大,但总的来说耐盐性比单性离子聚合物好,且其特性粘度在很大范围内(除等电点附近)不受pH值的影响。     

聚酯切片特性粘度分析的误差来源

叙述了在落实聚酯切片特性粘度国家标准的过程中出现的一些问题 ,讨论了特性粘度分析误差的主要来源于测试仪器、所用试剂、过滤设施等 ,并提出了解决办法。     

Differences in the molecular weight and the temperature dependences of self-diffusion and zero shear viscosity in linear polyethylene and hydrogenated polybutadiene

Within the context of a generalized coupling model we can support the hypothesis that, while the mode of relaxation for self diffusion (D) and shear flow (η) are the same, the entanglement interactions are different. We assume that there are two distinct coupling parameters n_D and n_η for self diffusion and shear flow respectively. The model predicts the molecular weight and temperature dependences to be scaled by the relevant coupling parameters as:

for melts with Arrhenius temperature dependences. We have found that n_n=0.43 and 0.42 for polyethylene (PE) and hydrogenated polybutadiene (HPB) which scale η as M^3.5 and M^3.4. Also the apparent flow activation energies $\text{E1}{}_{\mathrm{a}}$ of 6.35 kcal mole^?1 for PE and 7.2 kcal mol^?1 for HPB scale to primitive activation energies E_a of 3.6 and 4.2 kcal mole^?1 for PE and HPB respectively. On the other hand the M^?2 dependence of D results in n_D=1/3. Then the reported activation energies for self-diffusion in PE and HPB of 5.49 and 6.2 kcal mole^?1 scale to primitive activation energies of 3.7 and 4.1 kcal mole^?1, respectively.     

聚酯的特性黏度与聚合度

通过测定的聚酯特性黏度计算确定其聚合度是聚酯生产控制的关键环节 ,为此列举了目前国内厂家测定聚酯特性黏度的几种不同溶剂体系及其特性黏度的计算方法 ,并通过介绍质量比为 3 / 2的苯酚 四氯乙烷溶剂体系的特性黏度与分子质量的关系式 ,着重说明通过特性黏度计算聚酯聚合度的方法。     

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。     

聚合物特性黏度称重增浓外推测试新方法

根据黏度测量基本原理建立了聚合物稀溶液特性黏度测试新方法——称重增浓外推法。使用这种方法测定了一系列刚性链大(键共轭结构聚合物的特性黏度,其比浓黏度ηsp/c以及比浓对数黏度In(ηr/c)分别与浓度的关系曲线均呈现良好的线性关系。和传统的稀释外推法以及单点法如Maron法、Solomon-Ciuta法和算图法相比,称重增浓外推法具有数据可靠、准确、低有机溶剂消耗和操作连续省时等优点。     

An alternative method for evaluation of intrinsic viscosity

An alternative method for determination of intrinsic viscosities is described which evolves from the application of l'Hǒpital's rule to the expression defining the intrinsic viscosity. The method yields independent evaluations of the intrinsic viscosity and does not involve extrapolation beyond the range of experimental data or rely on a theoretical expression associated with such extrapolations. The application of the method is illustrated and comparisons are included with the results obtained by traditional approaches.     

熔体流动时间法测定PBT树脂特性粘数的研究

开发了一种新的特性粘数分析方法 ,该方法采用熔体流动时间计算特性粘数 ,与经典特性粘数分析方法有很好的相关性且具有分析时间短、费用低、无污染等优点。     

测试条件对瓶级聚酯切片特性黏度的影响

比较了GB T1793 1 1999标准、ISO162 8 5 :1998和ASTM460 3 96标准的测试条件。按照GB T1793 1 1999中规定的 2种方法对样品的特性黏度进行测试。试验了溶剂体系、测试温度、计算公式及黏度计毛细管直径对黏度测试结果的影响。瓶级聚酯切片标准样品在质量比为 1 1的苯酚 邻二氯苯溶剂中测试的特性黏度结果比在质量比为 3 2的苯酚 /四氯乙烷溶剂中的结果高 0 .0 5 ;在 2 5℃与 3 0℃下测试的结果相差 0 .0 13左右 ;用 2个计算公式得出的特性黏度结果有明显差异 ;而黏度计毛细管的直径影响不大 ,d为 0 .84～ 0 .95mm能满足试验精度要求。但毛细管直径选定后 ,不要轻易改变 ,以确保系统误差稳定。