高抗冲聚苯乙烯(HIPS)的研究——Ⅲ两相流体的流变特性

以顺丁橡胶改性制备高抗冲聚苯乙烯(HIPS),其预聚体是一种多组份的两相流体,它的流变行为属非牛顿性,在混合、搅拌、传热等许多方面与一般的牛顿流体有很大的差别。本文着重研究不同橡胶分子量、搅拌转速、温度对HIPS预聚过程流变特性的影响,得出各种因素的内在关系。为HIPS预聚合反应器的设计和放大提供基础数据。     

抗冲聚苯乙烯预聚合动力学研究——Ⅱ 预聚体分子量和分子量分布

在分子量调节剂存在条件下,建立抗冲聚苯乙烯预聚体分子量和分子量分布数学模型。在80-130℃温度范围内,用引发剂引发和热引发所得的预聚体,用GPC测试其分子量分布.数学模型满意地拟合实验结果。     

MDI／聚醚二元醇预聚体的粘度—温度关系

本文制备了两个系列异氰酸根封端的MDI／聚醚二元醇预聚体，并结合结构分析考察了这些预聚体的粘度—温度关系。结果表明，粘流活化能Eη，随着预聚体中游离NCO含量的增加而变大；由分子量较大的聚醚制备的预聚体的Eη，相应地较低。本文结合分子结构特征合理地解释了Eη的变化规律。     

PUA共聚乳液及其胶囊的性能研究

采用甲苯二异氰酸酯(TDI)、聚乙二醇(PEG)。丙烯酸为原料,通过分子设计合成了带有双键的PU预聚体。用此预聚体与丙烯酸酯类单体进行共聚,通过测定乳液的粘度、粒径分布、胶膜的机械性能和热性能等方法,讨论了此预聚体用量对乳液和胶膜性能的影响。结果显示：随着预聚体用量的增加,共聚乳液的稳定性、粘度逐渐下降、乳液粒径有较大的变化;PUA共聚乳液胶膜的光泽度、附着力在预聚体用量为4％时最好,其胶膜的抗冲击强度及硬度均好于相应的PA乳液胶膜。     

MDI/PPG型预聚体的合成研究

以4,4’二苯基甲烷二异氰酸酯(MDI)和聚丙二醇(PPG)2000为原料,通过测定反应过程中的NCO含量来确定反应终点,并结合IR分析,探讨了催化剂、预聚时间、反应温度对合成MDI型聚醚聚氨酯预聚体的影响。结果表明在T12作为催化剂,温度为75℃,预聚反应为2 h的实验条件下,不同的投料比均可以获得与理论NCO值接近的预聚体。研究不同物料比对产物粘度和储存时间的影响,确定物料比为3∶1时得到的预聚体粘度与稳定性最佳。MDI/PPG型预聚体与传统的预聚体相比,成本降低,异氰酸酯挥发性低,绿色环保,透明度高,将来会在胶黏剂预聚体中得到广泛的应用。     

苯乙烯—低顺式聚丁二烯预聚体的流变特性

以苯乙烯-低顺式聚丁二烯橡胶接技共聚制备高抗冲聚苯乙烯。研究了胶样、橡胶含量,搅拌转速、温度对预聚体的流变行为的影响。发现随着起始橡胶浓度增加,相转变点推迟,当起始浓度达10％时,体系不发生相转变。     

高抗冲聚苯乙烯预聚体的流变特性

在研究不同橡胶分子量的高抗冲聚苯乙烯预聚体的流变行为时,发现除转相点外,在表观粘度-转化率曲线上约7%转化率处表观粘度又有个极小点;而且,预聚体的流变特性受搅拌速率的影响.此外还研究了温度对预聚体流变行为的影响,得到以下表观粘度-温度关系式η_α=B_2γ~(A_2)exp[(B_1·γ~(A_1)/T]     

聚脲一氨酯橡胶的制备

通过≥90％的多元醇(分子量1000—6000)和MDI或衍生物(NCO-OH比例≥3.2∶1)的反应以及将预聚体与剩余的多元醇和取代基≥1邻位的芳族二胺一起进行反应-注射模压而制备带有微孔的密封外层的聚脲—氨酯橡胶。预聚体(NCO含量12.4％,25℃下粘度为2.2Pa—s)由92公斤粗MDI(NCO含量32.5％)和446.8公斤聚丙烯甘醇(分子量2000)制备而成。以预聚体为100     

无溶剂型聚氨酯丙烯酸酯树脂的合成

采用本体法以MDI-50、不同的聚醚、聚酯多元醇及甲基丙烯酸羟乙酯为原料,合成了系列无溶剂型聚氨酯丙烯酸酯(PUA)预聚体,采用FT-IR红外光谱、热重分析、力学性能及涂膜性能测试表征了产物结构,研究了不同合成路线、异氰酸根指数R及聚二醇种类等对产物性能的影响。结果表明,产物预聚体的结构与理论一致,选用先封端再扩链路线得到的PUA预聚体粘度小,符合生产要求。当R为2.5~2.7、所用聚二醇为聚丙二醇PPG1000时,合成的聚氨酯丙烯酸酯树脂粘度较低,性能良好。     

聚氨酯预聚体流变性能的探究

本文采用预聚体法,用聚醚多元醇(PPG1000)、异佛尔酮二异氰酸酯(IPDI)、甲苯二异氰酸酯(TDI)、氢化苯甲基甲烷二异氰酸酯(HMDI)、二羟甲基丙酸(DMPA)、一缩二乙二醇(DEG)合成相应的预聚体,考察了初始氰羟比(NCO/OH)以及多异氰酸酯的种类对预聚体运动粘度的影响。结果表明,随着年n(-NCO)/n(-OH)的增大,聚氨酯预聚体的粘度逐渐降低;切变速率随剪切应力的增大而增大,这说明本实验合成的聚氨酯为非牛顿流体,且非牛顿指数n1,为假塑性流体。     

Studies on the rheological behavior of high-impact polystyrene prepolymerizing systems

The rheological behavior of high-impact polystyrene prepolymer and its two phases separated by ultracentrifugation was studied. The viscosities of prepolymer, polystyrene phase, and rubber phase were correlated with various parameters, and a quantitative relationship among these three viscosities was proposed.     

PP/PS-海泡石插层纳米复合材料的流变性能与形态结构

采用苯乙烯乳液聚合法对有机海泡石原位插层,将插层产物聚苯乙烯(PS)-海泡石与聚丙烯(PP)熔融共混制备PP/PS-海泡石插层纳米复合材料.流变测试结果表明:PP/PS-海泡石插层纳米复合材料为典型的假塑性流体,其偏离牛顿流体的程度随PS-海泡石含量增加而增大,表观黏度和零切黏度随着PS-海泡石含量的增加而减小,PS-...     

Rheological,mechanical and morphological properties of thermoplastic vulcanizates based on high impact polystyrene and styrene‐butadiene rubber

Thermoplastic vulcanizates (TPVs) based on high impact polystyrene (HIPS)/styrene‐butadiene rubber (SBR) blends were prepared by dynamic vulcanization technique. The rheological, mechanical and morphological properties of the dynamically vulcanized blends were investigated systematically. As determined by capillary rheometer, the apparent viscosity of the blends decreases as the shear rate increases, indicating obvious pseudoplastic behavior. At low shear rate, the apparent viscosity of these blends is considerably higher than that of neat HIPS and decreases with the increase of HIPS concentration. The increase of HIPS content in the dynamically vulcanized blends contributes to the increase of tensile strength and hardness properties, while elongation at break and tensile set at break reach a maximum at 30 and 50 wt % of the HIPS content, respectively. The etched surfaces of the HIPS/SBR TPVs were investigated using field‐emission scanning electron microscopy, the morphological study reveals continuous HIPS phase and finely dispersed SBR elastomeric phase in the TPVs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Coal—g—MAH／PMMA的制备及流变性能研究

采用预聚体的方法制备出煤接枝马来酸酐同甲基丙烯酸甲酯的复合物（Coal-g-MAH/PMMA），讲座了煤的用量，体系粘度及聚合温度对反应的影响，同时运用毛细管流变仪研究了共混体系和纯ＰＭＭＡ体系的流变性能，结果表明，两体系的流动都符合假塑性流体的流动规律，表观粘度随剪切速率的增大而下降。     

Melt rheology and morphology of physically compatibilized natural rubber–polystyrene blends by the addition of natural rubber-g-polystyrene

Blends of natural rubber (NR) and polystyrene (PS) were prepared by melt mixing in a Brabender plasticorder and by solution casting using chloroform as the casting solvent. Earlier studies have indicated that these blends are incompatible and immiscible, and their compatibility can be improved by the addition of a graft copolymer of NR and PS (NR-g-PS). The rheological behavior of these blends has been carried out in the presence and absence of the compatibilizer using a capillary rheometer and a melt flow indexer. The effects of blend ratio, processing techniques (melt mixing versus solution casting), shear stress, and temperature on the rheological behavior have been studied in detail. Both in the presence and absence of the copolymer, the blends showed a decrease in viscosity with an increase of shear stress, indicating pseudoplastic nature. Solution-cast blends showed a higher viscosity as compared to melt-mixed blends. The viscosity versus composition curve of both melt-mixed and solution-cast blends showed negative deviation from the additivity at a higher shear rate region. This is associated with the interlayer slip between the highly incompatible NR and PS phases. The effects of graft copolymer loading and temperature on solution-cast blends were studied, and it was found that as the copolymer loading increases, the shear viscosity increases. This is due to the high interfacial interaction between the two components in the presence of the copolymer. The copolymer, in fact, locates at the interface and makes the interface more broad. However, at higher loading of the copolymer, the viscosity of the blends decreases. This may be associated with the formation of micelles, which have a plasticizing action on the viscosity of the blends. Melt elasticity parameters like principal normal stress difference, recoverable elastic shear strain, and die swell were evaluated. Master curves have been generated using modified viscosity and shear rate functions that contain the melt flow index as a parameter. The extrudate morphology of the blends was studied using a scanning electron microscope. Addition of the copolymer reduces the domain size of the dispersed phase, followed by a leveling off at a higher concentration. The leveling off is an indication of interfacial saturation. The interparticle distance also decreased followed by a leveling off at a higher loading of the copolymer. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 69: 2673–2690, 1998     

Rheological behavior of low molecular weight polystyrene composites containing monodisperse crosslinked polystyrene beads

Steady shear viscosities and dynamic moduli of polymer composites, consisting of crosslinked polystyrene beads and low molecular weight polystyrene matrix, were measured in a cone-and-plate rheometer at different temperatures. Viscosities and dynamic moduli were found to be very sensitive to filler loading and measurement temperature. Steady shear viscosities of 30% and 40% loaded low molecular polystyrene composites showed a power-law behavior over the entire range of shear rates. Storage and loss moduli were initially linear with frequency on double logarithmic plots, with limiting slopes of 0.3 and 0.1. At high concentration of filler particles, they showed a flat plateau at low frequencies, indicating that these systems exhibit a yield behavior. A 20% PS composite loaded with beads of high crosslink densities resulted in poor dispersion of beads as a result of poor dispersion of particles. PS beads 1.16 μm in diameter showed a higher viscosity. It is due to the apparent increase in loading resulting from broken particles. At low measurement temperature, filler effects were suppressed by high viscosity matrix and showed a similar rheological behavior to high molecular weight by PS matrix. We suggest that rheological behavior reflects the state of dispersion of beads in the matrix.     

Rheological and mechanical properties of thermoplastic polyurethane elastomer derived from CO2 copolymer diol

CO₂ copolymer diol‐based thermal polyurethane elastomers (PPC‐TPU) were prepared by the reaction of CO₂ copolymer diol and methylene diphenyl diisocyanate and chain extender (ethylene glycol/1,4‐butanediol/1,6‐hexanediol) (EG/BDO/HG). The rheological and mechanical properties of PPC‐TPU were analyzed. The effects of shear rate, shear temperature, hard segment content, and variety of chain extender on the properties of PPC‐TPU were studied. The results showed that the apparent viscosity (η) of PPC‐TPU decreased with the increasing shear rate (τ), and the non‐Newtonian index (n) was less than 1. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. The degradation during the processing was obviously inhibited by adding plasticizer and antioxidant. It was also discovered that the apparent viscosity varied with the content of hard segment and chain extender. Under the same temperature (185 °C) and shear rate (50 s^?1), the apparent viscosity increased considerably with the raise of hard segment content, and the apparent viscosity and tensile strength of PPC‐TPU with EG as chain extender was the maximum. It can be seen that with the apparent shear rate increasing, the variation tendency of apparent shear stress levels off, and the nonlinear relationship of τ–γ curve tended to be obvious. PPC‐TPU exhibited a typical character of pseudoplastic non‐Newtonian rheological behavior. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45974.     

Shear and extensional rheology and flow‐induced orientation of carbon nanofiber/polystyrene melt composites

The rheological behavior and morphology of polystyrene/carbon nanofiber (PS/CNF) composites in their melt phase have been characterized through experimental measurements. Viscosity measurements of the PS/CNF composites in the linear viscoelastic regime show the ratio of the transient extensional viscosity to the transient shear viscosity to be greater than three, the Trouton ratio. This behavior is due to differences in the flow‐induced orientation of CNFs in shear and extensional flow. The orientation development of the CNFs in shear and extensional flow was analyzed through a method utilizing transmission electron microscopy and was used to explain observed rheological phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Blends of nylon/acrylonitrile butadiene rubber: Effects of blend ratio,dynamic vulcanization and reactive compatibilization on rheology and extrudate morphology

The melt flow behavior of thermoplastic elastomers from nylon and nitrile rubber (NBR) was studied as a function of blend ratio, dynamic crosslinking, compatibilization and temperature. The morphology of the extrudates, i.e., the size, shape and distribution of the domains, was analyzed. Uncompatibilized and compatibilized blends showed pseudoplastic behavior. The viscosity of the blends showed positive deviation from a linear rule of mixtures. Compatibilization using chlorinated polyethylene (CPE) increased the melt viscosity of the blends. The addition of the compatibilizer decreased the domain size of the dispersed phase, followed by an increase after a critical concentration of the compatibilizer, where the interface was saturated. The influence of dynamic vulcanization on the rheological behavior was also studied. The extrudate morphology depended on blend ratio, compatibilization and shear rate.