硅藻土含量及粒径对聚丙烯复合材料流动特性的影响

应用熔体流动速率仪测量了3种硅藻土填充聚丙烯复合材料的熔体体积流动速率(MVR),以考察填料含量和粒径对复合体系流动特性的影响。结果表明:复合材料的MVR随着温度的提高和载荷的增加而呈非线性函数形式增大;而随着填料体积分数和粒径的增加而下降。     

挤出条件对PP/硅藻土口模膨胀行为影响

应用熔体流动速率仪测定了3种粒径硅藻土(体积分数为10%)填充聚丙烯(PP)复合材料的口模膨胀比(B),考察口模直径和挤出工艺条件对复合体系口模膨胀行为的影响.结果表明.复合体系的B随着剪切应力和剪切速率的增加而非线性增大,且随着温度的上升而线性下降;当载荷及温度一定时,B随着口模直径增加呈非线性提高,随着口模长径比增加呈非线性减小.     

硅藻土含量和粒径对聚丙烯/硅藻土复合材料口模膨胀行为的影响

应用熔体流动速率仪测定了3种粒径硅藻土填充聚丙烯复合材料的口模膨胀比,考察了硅藻土含量和粒径对复合材料口模膨胀行为的影响。结果表明:当载荷和温度一定时,复合材料的口模膨胀比随着硅藻土体积分数的增加而非线性减小,随着硅藻土粒径的增加而非线性提高,两者之间成二次函数关系。     

硅藻土含量和粒径对聚丙烯／硅藻土复合材料挤出膨胀行为的影响

应用熔体流动速率仪测定了3种粒径硅藻土填充聚丙烯复合材料的口模膨胀比，考察了硅藻土含量和粒径对复合材料口模膨胀行为的影响。结果表明：当载荷和温度一定时，复合材料的口模膨胀比随着硅藻土体积分数的增加而非线性减小，随着硅藻土垃径的增加而非线性提高，两者之间成二次函数关系。     

PP/Al(OH)_3/Mg(OH)_2阻燃复合材料的流动性能

制备了PP/Al(OH)_3/Mg(OH)_2阻燃复合材料,利用熔体流动速率仪测定了复合材料的熔体体积流动速率(MVR),并计算出其密度。结果表明:MVR随着阻燃剂质量分数的增加而减小,随着阻燃剂粒径的增加先降后升;复合材料密度随阻燃剂用量的增加呈近似线性增加,随阻燃剂粒径的增加呈近似线性降低,随着载荷的增加而提高。     

外消旋聚乳酸/纳米碳酸钙复合材料的熔体流动性能

采用双螺杆挤出机挤出造粒得到外消旋聚乳酸(PDLLA)/纳米碳酸钙(nano-CaCO3)复合材料.复合材料的熔体体积流动速率(MVR)随着温度、载荷的增加而升高,但随着w(nano-CaCO3)的增加而降低;在相同载荷或温度下,PDLLA/nano-CaCO3复合体系[w(nano-CaCO3)为4%]的MVR较PD...     

HDPE/云母复合材料的流动性能

制备了云母填充高密度聚乙烯(HDPE)复合材料(云母质量分数分别为5%,10%,15%)。在温度为463~493K和载荷为10.0~17.5kg的条件下,测定了HDPE/云母复合材料的熔体体积流动速率(MVR)和密度。结果发现,MVR随着云母质量分数的增加而呈线性减小;MVR对温度的依赖性符合Arrhenius方程;MVR随着载荷的增加而提高,两者之间关系服从幂律;熔体密度与云母质量分数呈近似线性函数关系,且随着温度的升高而减小,随着载荷的增加而提高。     

FEP/PP共混物熔体挤出胀大行为研究

应用熔体流动速率仪考察了聚丙烯(PP)含量、温度、载荷及口模直径对FEP(聚全氟乙丙烯)/PP共混物熔体的挤出胀大行为的影响.结果表明,在试验条件下,FEP/PP共混物熔体的挤出胀大比(B)基本上随着温度的升高而线性增大,随着载荷的增加而非线性提高,随着PP含量的增加B略为下降;当口模直径小于1.500 mm时,B随着口模直径的增加急速减少,然后,B随着口模直径的增加显著增加.     

PP/HGB复合材料流动性能的研究

应用熔体流动速率测定仪,于190℃-230℃下考察了中空玻璃微珠填充聚丙烯(PP/HGB)复合材料的流动性能。结果表明:熔体的剪切流动基本上服从幂定律;剪切粘度(ηa)对温度的依赖性符合Arrhenius关系;在较低HGB体积分数下,复合体系的流动性优于纯PP树脂;在一定温度下,ηa随着γa的增加而下降;当φf一定时,复合体系的ηa随着HGB直径的减小而上升。     

FEP/PP共混物流动性能的研究

应用熔体流动速率仪考察了口模直径、聚丙烯(PP)含量、剪切速率及温度对聚全氟乙丙烯(FEP)/PP共混物熔体的流动性能的影响.结果表明,在试验条件下,熔体的剪切流动服从幂律定律;熔体的表观温度对温度的依赖性符合Arrhenius方程;当PP的质量分数(w)小于10%时,熔体的表观粘度随着w的增加急剧下降,w大于10%时,趋于平缓;熔体的表观粘度随着口模直径的增加而非线性的增加.     

ABS/镁盐晶须复合材料的研究

以（乙烯／乙酸乙烯酯／苯乙烯）三元共聚物（BS树脂）为增容荆，采用双螺杆挤出机制备了（丙烯腈／丁二烯／苯乙烯）共聚物（ABs）／镁盐晶须复合材料，研究了BS树脂、镁盐晶须用量对复合材料力学性能、流动性能的影响、结果表明，加入BS树脂有利于提高复合材料的拉伸强度和冲击强度，复合材料的熔体流动速率（MFR）随BS树脂用量增加而增大，且其MFR对温度或负荷呈非线性函数关系，比ABS对负荷更为敏感．     

Melt Flow Properties and Melt Density of POM/EVA/HDPE Nanocomposites

The nanometer calcium carbonate filled Polyformaldehyde/ethylene-vinyl acetate copolymer/high-density polyethylene (HDPE) composites were prepared using a twin-screw extruder. The effects of load and temperature on the melt volume flow rate (MVR) and melt density (ρ _m ) of the composites were investigated by using a melt flow rate instrument under experimental conditions with temperatures range from 170 to 220°C and loads varying from 1.2 to 12.5 kg. The results showed that the MVR of the composites increased with an increase of temperature and load, while reduced with an increase of the weight fraction (φ) of the HDPE, and the relationship between the MVR and φ was almost consistent with a linear law function. The melt density of the composites increased nonlinearly with an increase of load, while decreased with a rise of temperature. Moreover, the ρ _m of the composites decreased with increases in φ.     

溴化环氧树脂协同三氧化二锑阻燃PBT的性能研究

采用溴化环氧树脂协同不同粒径的三氧化二锑(Sb2O3)复配制备了阻燃聚对苯二甲酸丁二醇酯(PBT),研究了阻燃PBT的物理力学性能、垂直燃烧性能、阻燃性能和烟气释放情况。结果表明:溴化环氧树脂协同Sb2O3阻燃体系的加入,使得阻燃PBT的熔体流动速率、邵D硬度、弯曲强度和弯曲模量提高,注塑成型收缩率略有增加,维卡软化点略有下降,缺口冲击强度和断裂伸长率明显下降。锥形量热仪的测试结果表明:溴化环氧树脂协同Sb2O3阻燃PBT的燃烧性能显著减低,阻燃级别均可以由UL94HB级提高到UL94V—0级;且Sb2O3粒径越小,阻燃效果越好,当Sb2O3的粒径为0.4μm时,阻燃PBT的综合性能最佳;溴化环氧树脂协同Sb2O3体系在PBT中的阻燃作用明显,但不能抑制烟毒的产生。     

等径异长毛细管口模的聚丙烯流变性能研究

采用组合式转矩流变仪研究了聚丙烯(PP)熔体在等径异长毛细管流道(长径比L/D为20,30,40)的流变行为。结果表明,非牛顿指数随着长径比的增加而减小,即熔体的非牛顿性增强,剪切速率对黏度敏感性增加;熔体黏流活化能随剪切速率的增大而减小,表现为低剪切速率范围黏度对温度较敏感,其中又以L/D=30情况下的敏感性最高。     

木粉粒径对木塑复合材料性能的影响

采用不同粒径的木粉填充高密度聚乙烯制备木塑复合材料，研究了木粉粒径对木塑复合材料力学性能和加工流动性的影响。结果表明：木粉粒径对复合材料性能的影响十分明显，较大粒径的木粉有利于复合材料弯曲性能和冲击强度的提高。木粉粒径从100μm增加到850μm，复合材料弯曲强度增加10．4％，弯曲模量增加56．3％，冲击强度增加14．6％。随木粉粒径的增大，拉伸强度呈现先上升后下降的趋势，在200μm时出现最大值。木粉粒径对熔体流动速率（MFR）和密度的影响十分明显，大粒径的木粉使复合材料具有较高的MFR和较低的密度。     

A coupled DEM/CFD analysis of the effect of air on powder flow during die filling

Die filling from a stationary shoe in a vacuum and in the presence of air was numerically analyzed using an Eulerian‐Lagrangian model, which employs a discrete element method (DEM) for the particles and computational fluid dynamics (CFD) for the air with a two‐way air‐particle interaction coupling term. Monodisperse and polydisperse powder systems have been simulated to explore the effect of the presence of air on the die filling process. For die filling with monodisperse powders, the influences of particle size and density on the flow behavior were explored. The numerical simulations revealed that the presence of air has a significant impact on the powder flow behavior, especially for systems with smaller and/or lighter particles. Flow has been characterized in terms of a dimensionless mass flow rate, and it has been shown that for die filling in a vacuum this is constant. The flow characteristics for die filling in air can be classified into two regimes. There is an air‐inert regime in which the particle size and density are sufficiently large that the effect of air flow becomes negligible, and the dimensionless mass flow rate is essentially identical to that obtained for die filling in a vacuum. There is also an air‐sensitive regime, for smaller particle sizes and lower particle densities, in which the dimensionless mass flow rate increases as the particle size and density increase. The effects of particle‐size distribution and adhesion on the flow behavior have also been investigated. It was found that, in a vacuum, the dimensionless mass flow rate for polydisperse systems is nearly identical to that for monodisperse systems. In the presence of air, a lower dimensionless mass flow rate is obtained for polydisperse systems compared to monodisperse systems, demonstrating that air effects become more significant. Furthermore, it has been shown that, as expected, the dimensionless mass flow rate decreases as the surface energy increases (i.e., for more cohesive powders). © 2008 American Institute of Chemical Engineers AIChE J, 2009