聚丙烯/纳米羟基磷灰石复合材料流变性能研究

采用毛细管流变仪对聚丙烯/纳米羟基磷灰石(PP/n HA)复合材料的流变性能进行了研究,并讨论了复合材料的表观黏度、非牛顿指数、黏流活化能与温度、剪切速率、n HA用量之间的关系。结果表明:PP/n HA熔体为假塑性流体,其表观黏度随着n HA用量的增加总体呈上升趋势,但在其用量为1%时达到极小值;非牛顿指数随着温度的提高而增大,随着n HA用量的增加而逐渐减小;黏流活化能则随着剪切速率的增加逐渐降低,随着n HA用量的增加呈上升趋势。     

LLDPE/纳米ZnO复合材料熔体流变性的研究

将纳米ZnO(或改性纳米ZnO)与LLDPE经Brabender挤出机熔融共混制备了LLDPE/纳米ZnO复合材料,采用毛细管流变仪和HAAKE转矩流变仪研究了该复合材料的熔体流变性能,讨论了纳米ZnO、改性纳米ZnO及KH550偶联剂含量对LLDPE熔体流变性能的影响。结果表明:少量纳米ZnO的加入略提高了LLDPE的表观黏度、黏流活化能和熔体的平衡转矩,改性纳米ZnO复合材料的表观黏度比未改性纳米ZnO复合材料的略低。     

Melt Rheological Properties of PBT/ABAS/Mica Composites

Melt rheological properties of poly (butylene terephthlate) (PBT)/poly (acrylonitrile–butyl acrylate-styrene) terpolymer (ABAS)/mica composites were studied at 0.02 to 0.14 vol fraction (Φ_f) of mica at 518 K. The shear stress vs. shear rate plots was linear and the melts obeyed power law relation. The composites melts were shear thinning. Apparent melt viscosity decreased initially up to Φ_f = 0.07 the parameter increased with further increase in Φ_f. Melt elasticity viz. extrudate swell ratio also decreased up to Φ_f = 0.07 whereas the data increased at Φ_f > 0.07. Surface treatment of mica particles by zirconate coupling agent, NZ-97, brought about further modification of the rheological properties through enhanced interaction between the matrix and the dispersed phase.     

回收料制备人造草丝熔体的流变性能研究

采用聚合物动态流变测试仪研究了含回收料的人造草丝熔体的流变性能,探讨了回收料用量、温度、口模长径比对熔体表观黏度和挤出胀大比的影响。结果表明,人造草丝熔体属于假塑性熔体,其表观黏度随剪切速率和回收料用量的增加而降低。在剪切速率500s-1时,回收料用量越低,熔体的表观黏度降低越明显;剪切速率1800s-1时,熔体的表观黏度变化平缓且较为接近。对于100%回收料草丝熔体,其表观黏度随温度的升高和口模长径比的减小而降低;挤出胀大比则随温度的升高和口模长径比的增大而降低。     

高刚性无卤阻燃聚丙烯的制备及性能

在合理选择型无卤复配氮磷阻燃体系的基础上,采用复合增强方法,制备出高刚性无卤阻燃聚丙烯材料。     

无机刚性粒子改性聚丙烯复合材料的结构和性能研究

通过熔融共混的方法,制备了两种不同种类、不同含量的无机刚性粒子改性聚丙烯复合材料,并详细研究了无机刚性粒子对复合材料的拉伸强度、冲击强度及负荷热变形温度的影响。结果表明：纳米硫酸钡改性复合材料的拉伸强度略有下降,冲击强度提高了21.1%。滑石粉改性复合材料的拉伸强度略有提高,但冲击强度随着滑石粉含量的增加下降了77.5%。两种无机刚性粒子均可使复合材料的负荷热变形温度显著提高。低含量下,纳米硫酸钡对提高聚丙烯的负荷热变形温度作用更显著。     

聚丙烯/膨胀石墨/碳纳米管复合材料电性能、微观结构及其流变学研究

研究了以膨胀石墨(EG)和多壁碳纳米管(MWNT)共同填充聚丙烯(PP)体系的电性能、微观结构及其流变行为。结果表明,EG和MWNT的协同导电作用显著降低了复合材料的体积电阻率和逾渗阀值,当MWNT用量为5 phr、EG为10 phr时,与PP/EG(15 phr)材料相比,复合材料的体积电阻率降低了1 600倍,通过其低频区流变行为的研究,表明EG同MWNT协同形成了更完善的三维网络结构,扫描电镜(SEM)分析表明,MWNT在复合体系中起到桥连作用,连接基体与EG,以及EG片层与片层,因此获得了更好的导电特性。     

熔融插层法制备聚丙烯／粘土复合材料及性能研究-I增容剂对聚丙烯／粘土复合材料力学性能的影响

通过添加不同含量的粘土制备了三个不同类型（PP／DK1,PP／PPMA／DK1,PP／PPMA＋DK1）纳米粘七／聚丙烯复合材料。使用力学性能测试对实验样品进行力学性能分析,结果表明：相对于纯聚丙烯,复合材料的拉伸强度、断裂伸长率随着粘土含量的增加呈先增加后下降趋势;而随着PPMA量的增加,基体的总体性能都呈现下降的趋势。     

Melt Rheological Behavior and Thermal Properties of Low-Density Polyethylene/Palm Kernel Shell Composites: Effect of Polyethylene Acrylic Acid

The melt flow behavior and thermal properties of low-density polyethylene (LDPE)/palm kernel shell (PKS) composites were studied. Polyethylene acrylic acid (PEAA) was used as a compatibilizer in the composites. The results showed that the increasing of PKS loading had decreased MFI values of LDPE/PKS composites. The presence of PEAA increased the MFI values of the LDPE/PKS composites. The apparent viscosity of the composites was found to exhibit a linear relationship with the reciprocal of the temperature. Thermal properties showed that higher filler loading tended to reduce the onset temperature as the PKS possessed lower degradation temperature compared to the LDPE. The presence of the PKS in the LDPE polymeric matrix improved the thermal stability of the composites. The addition of PEAA into the composites provided better interfacial bonding between the LDPE matrix and PKS filler, while higher onset temperature and lower total weight loss were observed of LDPE/PKS composites. The activation energy of the LDPE/PKS composites was increased with increasing filler loading. At similar filler loading, the presence of PEAA increased the activation energy of the LDPE/PKS composites.     

阻燃处理对竹粉增强聚乳酸复合材料阻燃抑烟性能影响

分别采用氢氧化铝(ATH)、聚磷酸铵(APP)及ATH+ APP复合阻燃剂对竹粉增强聚乳酸复合材料进行阻燃抑烟处理,并对处理后的复合材料性能进行测试与表征.结果表明,两种阻燃剂均显著增加了复合材料的成炭率,ATH+ APP产生了协同作用,使复合材料成炭率提高了近4倍,达到了45.3％;复合材料经阻燃处理后其阻燃性能均得到了不同程度的提升.其中,APP对复合材料燃烧过程中热量释放的抑制作用最明显,ATH对复合材料表现出了较强的抑烟效果,而ATH +APP复合阻燃剂产生的协同作用使复合材料具有阻燃和抑烟的双重特性.     

Rheological Properties of Hot Melt Pressure Sensitive Adhesives (HMPSAs) Based on Styrene-Isoprene Copolymers, Part 3: Rheological Behavior of Different Block Copolymers With High Diblock Content

The processing and application properties of hot-melt pressure-sensitive adhesives (HMPSA) are governed, to a large extent, by their rheological properties. Coating of the HMPSA is performed at high temperatures in the molten state. At room temperature, the adhesive satisfies the Dahlquist criterion and, consequently, has permanent tack. We have particularly studied the full formulations based on triblock and diblock copolymers, and also those based on newly designed molecules, such as tetrablock or radial copolymers. We have demonstrated in the previous articles of this series that, for these systems, the volume fraction of the free polyisoprene is the most important parameter that drives the tack performances by controlling the level of the secondary elastic plateau modulus observed in the low-frequency range. To improve the end-user properties, we have increased the diblock content in the blends. We describe here the dynamic mechanical properties, at room temperature, of the pure copolymer blends (i.e., without addition of a tackifying resin) and the full HMPSA formulations. We focus particularly in this article on blends that contain a high diblock content. The effect of the morphology of the diblock copolymer on the rheological behavior of the adhesive is discussed in detail. Finally, we propose a model, based on molecular dynamics concepts, which describes the rheological behavior in a very wide range of frequencies for all copolymers and full formulations of the study.