环氧基封端聚二甲基硅氧烷的特性粘数与摩尔质量的关系

采用端基分析法测定了环氧基封端聚二甲基硅氧烷的数均摩尔质量（Ｍｎ），研究了其特性粘数（［η］）与Ｍｎ之间的关系。     

环氧基封端聚二甲基硅氧烷的特性粘数与摩尔质量的关系

采用端基分析法测定了环氧基封端聚二甲基硅氧烷的数均摩尔质量（Ｍｎ），研究了其特性粘数（η）与Ｍｎ之间的关系。     

修正的Mark—Houwink方程及其应用

Ｍａｒｋ—Ｈｏｕｗｉｎｋ方程是高分子物理中最常用的方程之一，但由于该方程尚有不足之处，近年来国外学者对其加以修正，本文就此进行较详细的介绍。修正方程把特性粘数［η］与多分散聚合物的Ｍｎ、Ｍｗ和Ｍｚ相联系。该方程的有效性不仅经过大量具有连续性的和不连续性的分子量分布的聚合物实例的检验，并且通过具体实验指出由该方程确定三种平均分于量以及Ｍａｒｋ—Ｈｏｕｗｉｎｋ方程中Ｋ、ａ常数时的成功与不足之处。     

含铂聚二甲基硅氧烷材料的阻燃机理

利用分析裂解技术和碱水解气相色谱研究了在硅橡胶中添加百万分之几数量级的铂化合物．进行阻燃的机理。由阻燃硅橡胶(FR-SR)试样的热降解测定表明，与对比试样SR相比．FR-SR试样在400℃～800℃温度范围内产生了大量的甲烷，从而大大抑制了环状硅氧烷的生成。另一方面，由FR-SR经过400℃以上热处理后．其残留试样水解产物的气相色谱图得知，在聚合物链中反映交联结构的大量特征性生成物是通过亚甲基键和三官能硅氧烷结构连接的。这些结构说明，在燃烧过程中由于铂化合物引发生成的交联结构大大抑制了FR-SR材料的热降解，起到阻燃作用。     

含聚二甲基硅氧烷的嵌段共聚物的制备技术

按聚合机理划分方法综述了含聚二甲基硅氧烷的嵌段共聚物的相关制备技术.包括阴离子聚合法、缩聚法、氧氮自由基聚合法、原子转移自由基聚合法、可逆加成-断裂链转移聚合法.     

聚甲基丙烯酸氨基乙酯的合成及染色性能

以白油为分散介质,偶氮二异丁腈为引发剂,甲基丙烯酸氨基乙酯为单体,采用反相悬浮聚合法合成聚甲基丙烯酸氨基乙酯(PTAM),研究了引发剂用量、反应温度、反应时间、单体浓度对PTAM特性粘数的影响。将PTAM与聚丙烯腈(PAN)共混纺丝制得共混纤维,用酸性染料染色,考察其上染率。结果表明:合成PTAM的最佳工艺条件为引发剂质量分数0.05%,单体质量分数60%,反应温度65℃,反应时间2h,所得PTAM的特性粘数为690mL/g。染色实验结果表明,PTAM质量分数为7%时,PAN共混纤维的上染率达88%。     

水质阻垢剂聚天冬氨酸分子量的测定

聚天冬氨酸(KASP)因其良好的生物降解性,广泛应用于各个方面,如工业水处理、农业肥料增效等。目前关于快捷、简便的测定KASP分子量的方法鲜有报道,本文通过对59个聚天冬氨酸样品的分子量M与极限黏数[η]进行测定,结合Mark-Houwink公式,进行了线性回归分析,得出了用KASP极限粘数计算其分子量的计算式:,从而建立了一个操作简便、仪器条件要求较低、准确性良好的分析聚天冬氨酸分子量的方法。     

胆甾液晶齐聚物/聚二甲基硅氧烷橡胶复合膜的制备及血液相容性研究

将2种胆甾液晶单体接枝到含氢聚硅氧烷上制备了胆甾液晶齐聚物,并将此齐聚物与聚二甲基硅氧烷复合制备了一系列复合膜.以偏光显微镜观察了不同液晶含量对复合膜的表面结构形态的影响.通过溶血实验和动态凝血实验研究了其血液相容性,结果表明改性的复合膜具有很好的血液相容性.表面接触角的测定表明复合膜的亲水性由于聚二甲基硅氧烷表面胆甾液晶相的存在得到明显改善.     

一种部分水解聚丙烯酰胺的合成及性能评价

分别选用丙烯酰胺、丙烯酸、DMMAC作为主链单体、亲水单体及疏水单体,合成了一种三元共聚高相对分子质量部分水解聚丙烯酰胺,其具有较大的分子量,较好的化学稳定性和热稳定性。同时,该聚合物产品的固含量较高,可达51.35%。此聚合物溶液在0.0008416 g/mL的浓度下就具有较高的黏度,高达1.4614,是一种不错的增稠剂。本次研究所合成的聚合物材料的粘均分子量约为166万,分子量较大,具有优良的溶胀特性,在聚合物驱中应用前景广阔。     

聚天冬氨酸的合成制备研究

以马来酸酐为原料合成聚天冬氨酸,研究了合成聚天冬氨酸时铵盐的种类、马来酸酐与碳酸铵的比例、合成时间以及合成温度对目的产物聚天冬氨酸产率和分子量的影响。得出产率最高的合成工艺条件为:n(马来酸酐)∶n(碳酸氨)=1∶1.2,聚合温度为180℃,聚合时间为1.0 h。制备的聚天冬氨酸纯度高达90%以上,产率也在94%以上。所制备的聚天冬氨酸具有一定的缓蚀阻垢作用,可广泛应用于工业循环冷却水处理、油田水处理等领域。     

Comments on the accuracy of zero shear intrinsic viscosity of high molecular weight polyacrylamide

The intrinsic viscosity of a polymer is traditionally measured with a capillary tube viscometer where the shear rate range is moderately high. Such method is valid when the polymers are non-ionic and have low to moderate molecular weight. The viscosity-shear rate curves obtained for dilute aqueous solutions of two high molecular weight polyacrylamides using two rotational viscometers indicate a strong shear-dependent viscosity in the medium to high shear rate regions. The zero shear intrinsic viscosity of the polymers determined by extrapolation from the high shear rate region to the zero shear condition may result in large errors. Its implication in predicting the molecular weight of polymers using the Mark-Houwink-Sakurada equation is discussed. A rheological equation for intrinsic viscosity as a function of shear rate is proposed.     

Polybenzimidazole (PBI) molecular weight and Mark‐Houwink equation

The molecular weight, and intrinsic viscosity of polybenzimidazole (PBI) and its phosphonylated derivatives are reported. The relationship between intrinsic viscosity [η] and weight average molecular weight (M_w) for PBI has been established in H₂SO₄ and DMF‐LiCl. The Mark Houwink constants K_w of 5.2 × 10^?3 mL/g, α of 0.92 for H₂SO₄ solvent systems and, K_w of 3.2 × 10^?2 mL/g, α of 0.754 for DMF‐LiCl solvent system have been determined at M_w < 65,000. The intrinsic viscosity of PBI determined by the Huggins–Kraemer method was compared with a single point method, and found that both methods fit well for PBI in relatively low concentration solvent system, giving ～ 99% accuracy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Practical relationship between apparent viscosity and molecular weight of urea-formaldehyde resin adhesives

The proper viscosity of urea-formaldehyde (UF) resin adhesive for optimum adhesion depends on the type of a raw wood material for wood-based composite panels. This study investigated the practical relationship between apparent viscosity and molecular weight (MW) of UF resin adhesives during the control of their synthesis. The UF resins were synthesized at various formaldehyde/urea (F/U) mole ratios ranging from 0.8 to 1.5 with different apparent viscosities. In addition, low- and high-viscosity UF resins with 1.0 and 1.2 F/U mole ratios, respectively, were mixed at five different blending ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 to obtain different viscosities. The MW of each resin was measured by gel permeation chromatography, and the relationship between apparent viscosity and MW was derived using the Mark-Houwink (M-H) equation. The results showed a good relationship between the two parameters, allowing the prediction of the MW of UF resins based on their apparent viscosity after synthesis. The weight average molecular weight (Mw) values fit well with the M-H equation, while the number average molecular weight (Mn) values did not. For the first time, this paper has reported that k and α, constants of the M-H equation based on Mw of the UF resin, ranged from 0.015 to 0.017 and 1.172 to 1.276, respectively. These suggest that the relationship between apparent viscosity and Mw should be considered for the synthesis of UF resin adhesives.     

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。     

Unperturbed dimensions and intrinsic viscosity-molecular weight relationship of copolyesters poly(ethylene terephthalate-co-ethylene isophthalate)

The relationship [η] = KM^a and unperturbed dimensions of the copolyesters poly(ethylene terephthalate-co-ethylene isophthalate) with 7.5% and 25% isophthalic structures in the main chain were determined. The experimental data proved the influence of the amount of isophthalic structures upon the values of K and a from the relation between intrinsic viscosity and molecular weight and on the values for unperturbed dimensions.     

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%。     

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     

Intrinsic viscosity–number average molecular weight relationship for poly(1,4‐butylene adipate) diol

The relationship between number average molecular weight (M_n) and intrinsic viscosity ([η]) was studied for poly(1,4‐butylene adipate) diol (PBAD) in tetrahydrofuran, toluene, and ethyl acetate at 25°C. Thus, a series of PBAD samples were prepared by polymerization between 1,6‐adipic acid and 1,4‐butanediol. The values of M_n for the samples were determined by end‐group analysis as well as by ebulliometry, and the average difference of M_n between the two analysis ways was about 2.69%. The Mark–Houwink–Sakurada equations for PBAD were obtained to relate [η] with M_n in the range of 1900–10,000. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚丙烯熔体流动指数与分子量及其分布的关系

研究了聚丙烯(PP)的熔体流动指数(MI)与聚合物不同分子量之间的关联性,对于分子量分布较窄的PP,数均分子量(Mn)、重均分子量(Mw)和粘均分子量(Mv)均能较好的关联;反之,MI与Mn关联性下降,而MI与Mn和Mv的关联性仍很好,尤其是MI与Mv的关联性受分子量分布的影响很小;MI与Z均分子量的关联性很差。同时．确定了MI与各种分子量之间的关联式,该式用于本体PP工艺反应器内氢气浓度的计算和MI的预测,与实验测量结果吻合良好。     

Intrinsic viscosity–molecular weight relationship and hydrodynamic volume for pullulan

A numerical method for determination of Mark–Houwink–Sakurada (MHS) equation constants, a and K, was tested with success for two series of pullulan standard samples having narrow and broad molecular weight distributions (MWD) and taken into account their polydispersity. Different solvents, which were used to determine the intrinsic viscosities and the viscometric constants, a and K (published in the literature for pullulan), were compared. The various parameters affecting the constants are discussed. The procedure to determine the correct value of the hydrodynamic volume for pullulan was also described. This study resulted in the following MHS equations for narrow and broad MWD series of pullulan samples with M_w in the range of 5–1000 kDa: where q_MHS is the polydispersity correction factor and [η] is the intrinsic viscosity in dL g^?1. The plot of log K versus exponent a was linear and inversely related. This curve was used to estimate the constant K for pullulan with a known exponent a. Among various reported solvents, the diluted aqueous salt solutions have more advantages than other solvents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4325–4332, 2006