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采用经验特性粘度方程表征聚苯乙烯(PS)的热降解可以大大简化试验过程。该方法只需测定一个溶液浓度下的增比粘度(ηsp)、相对粘度(ηr)值就可以计算PS溶液的特性粘度[η],再用[η]求出其分子量,从而得出PS在热降解过程中分子量与温度、时间的关系。研究结果表明,PS的分子量随温度的升高、时间的加长呈线性关系降低;降解速度随温度的升高呈对数关系增大;当温度高于300℃时,热降解显著加快。这一结果与TG分析等方法的结论一致,说明用经验特性粘度方程来研究PS的热降解过程方法简便可行。 相似文献
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超级分散氧化镁对SMC/BMC树脂糊粘度的影响 总被引:1,自引:1,他引:0
本文重点研究了在SMC/BMC树脂糊制做过程中超级分散的氧化镁对树脂糊增稠特性的影响。本研究对改进SMC/BMC的成型压力,片材流动,制品质量模塑料的贮存使用期有一定的指导意义。 相似文献
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溶剂对壳聚糖粘度及Mark-Houwink方程参数的影响 总被引:2,自引:0,他引:2
采用粘度法分析了不同溶剂对壳聚糖粘度的影响 ,用光散射法测定了超声波分级的壳聚糖的相对分子质量。实验结果表明 :四种溶剂体系分别溶解壳聚糖 ,其粘度行为不同 ,溶剂的离子强度越大 ,壳聚糖的比浓粘度越小。在 0 .3mol/ L乙酸 + 0 .3mol/ L乙酸钠溶剂的条件下 ,应用 Mark-Houwink方程测得 K=0 .1 81 cm3 / g、α=0 .62 ,说明离子强度越大 ,壳聚糖分子的聚集态越大 ,α越小。为了获得准确的 K、α值和壳聚糖的相对分子质量 ,必须选择合适的溶剂体系来消除这种聚集态的影响。 相似文献
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主要讨论了有关粘土胶防老剂的选用、配用和筛选。通过采用天然橡胶塑性保持率的测定方法、橡胶热空气老化试验方法、热分析技术、扫描电镜分析等,对有关防老剂及其配方的性能进行了比较,优选出防老剂C- 4 # ———酚类与硫化物复配物等一系列对粘土胶有优异的耐热氧老化效果的防老剂及其配方。 相似文献
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二元体系液体混合物粘度的工程应用预测模型 总被引:1,自引:0,他引:1
从普遍适用的热力学关系出发 ,对Eyring模型进行修正 ,得到一个新的修正Eyring粘度模型。与Grunberg -Nissan和McAllister模型比较结果表明 ,该模型关联结果最优 ,特别是对于含水系统 ,超过了McAllister方程 ,因此其修正更为合理 ,更具工程应用前景 相似文献
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Accurately measuring the viscosity of a solids suspension requires uniform suspension of the solids in the viscometer cup. In a cup‐and‐impeller viscometer system, solids may settle when the impeller speed is too low, causing viscosity measurements to appear lower than that of a well‐suspended slurry. Pre‐mixing of a solids suspension is typically performed to achieve steady state prior to measurements. Data here shows that the measured viscosity values differ depending on the pre‐mixing speed, indicating that the solids are not properly suspended at all speeds. A commonly used cup‐and‐vane impeller system can be thought of as a mixing tank that should operate above the uniform‐suspension speed (USS), although determining the USS experimentally is rather subjective. Computational fluid dynamics (CFD) is employed here to determine the USS of a pretreated corn stover (PCS) solids suspension and to confirm the experimentally measured USS. 相似文献
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An Empirical Equation for Estimation of Kinematic Viscosity of Fatty Acid Methyl Esters and Biodiesel 下载免费PDF全文
Suriya Phankosol Kaokanya Sudaprasert Supathra Lilitchan Kornkanok Aryusuk Kanit Krisnangkura 《Journal of the American Oil Chemists' Society》2015,92(7):1051-1061
Kinematic viscosity (µ) is an important physical property of fatty acid methyl esters (FAME) and biodiesel. In this work, the Martin's rule of free energy additivity is extended to cover the kinematic viscosity of saturated and unsaturated FAME commonly found in nature. The proposed model can also be extended to estimate kinematic viscosity of biodiesel. The kinematic viscosity of a FAME or a biodiesel can be easily estimated from its carbon number (z), number of double bonds (nd) at different temperatures (T) without a prior knowledge of the viscosity of individual FAME. Both zave and nd(ave) can be derived from its fatty acid composition. Thus, kinematic viscosity of biodiesel at temperatures between 20 and 100 °C and at atmospheric pressure can be estimated. The average absolute deviation (AAD) estimated at 20–100 °C for saturated, unsaturated FAME, biodiesels and biodiesel blends are 4.15, 3.25, 6.95 and 2.79 %, respectively. The biodiesels collected in this study (191 data points) have the zave and nd(ave) between 14.10 and 17.96 and 0.21–1.54, respectively. The standard deviation was 0.249. The proposed model would be good for estimation of viscosity of biodiesel containing normal fatty acids, generally found in biodiesel feed stocks. 相似文献
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J.D. Sherwood 《Chemical engineering science》2006,61(20):6727-6731
Cell models for the viscosity μ of a suspension of spherical particles in Newtonian fluid of viscosity μ0 are discussed. Various boundary conditions on the outer boundary of the spherical cell lead to different results: the viscosity predicted for a zero velocity perturbation boundary condition is higher than those predicted with zero tangential stress perturbation. However, in all cases Einstein's prediction μ/μ0=1+2.5φ+? holds in the limit of small solid volume fraction φ?1. 相似文献
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反相悬浮聚合法合成高吸水性树脂的研究 总被引:4,自引:0,他引:4
以环己烷为分散介质,聚乙烯醇为主分散剂,十二烷基磺酸钠为助分解剂,N,N-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,采用反相悬浮聚合法合成了丙烯酸-丙烯酸-丙烯酰胺三元共聚交联型高吸水性树脂,产物呈软珠粒状。吸自来水达650倍,0.9%的生理盐水达75倍。 相似文献
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本文研究了影响AIN流延浆料粘度的主要因素,结果表明,环境温度或溶剂比例的增加,浆料的粘度值下降,而较细的粒度和增塑剂的减少则使粘度上升。本文还指出了严格控制各影响因素以实现稳定流延工艺的必要性。 相似文献
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