PP-R管材料熔融挤出过程MFR控制研究

分析了PP-R（无规共聚聚丙烯）管材料MFR（熔体流动速率）的变化对力学性能的影响，着重通过双螺杆挤出机研究了PP—R管材料熔融挤出过程中影响MFR变化的因素。结果表明，合适的加工工艺控制和优良的抗氧体系是保证PP-R管材料加工过程中MFR稳定的前提。     

原位成纤复合法改善PP-R的挤出螺纹畸变

研究了聚丙烯熔体挤出螺纹畸变产生的机理,采用原位成纤复合法制备无规共聚聚丙烯(PP-R)/聚对苯二甲酸乙二醇酯(PET)复合材料来改善PP-R的挤出性能。结果表明:口模入口区的环向次级流动是PP-R熔体产生螺纹畸变的主要原因;采用"挤出-热拉伸-淬冷"工艺制得的复合样品中PET以微纤状分散于PP-R基体中,有效地推迟了PP-R熔体挤出螺纹畸变的发生。     

PP-R双螺杆挤出熔体输送和降解行为的研究

对无规共聚聚丙烯(PP-R)在ZSK-300型双螺杆挤出机中熔体输送特性和热降解行为进行了研究,计算了ZSK-300的最大挤出量．分析了熔体输送流场;并对加料量、熔体流动指数、助剂量、熔体温度等工艺操作条件对熔体输送和降解行为的影响进行了讨论。结果表明,加料量的改变需要适当调整加热温度：粉料熔体流动指数的微小波动,对挤出物的质量和挤出过程的稳定性没有影响;降低熔体挤出温度,可明显降低PP-R的热氧降解。     

青岛山塑研制成功PP-R玻纤管材挤出设备

<正>一种可生产PP-R玻纤稳态增强管材的塑料机械挤出设备,日前在青岛山塑挤出设备有限公司研制成功并发往用户。用该设备生产的PP-R玻纤稳态增强管材在同等壁厚的情况下,比普通的PP-R管材耐压强度高,高温下不     

基于Polyflow的一出二挤管机头模拟分析

介绍了Polyflow软件的特点及基本分析流程。以无规共聚聚丙烯（PP-R）圆管挤出为例,详细介绍了如何应用Polyflow进行挤管机头内流动场分析和口模逆向设计。结果表明,通过Polyflow能够预测熔体在机头内复杂的流动,并且利用其逆向挤出功能可以提高口模设计的一次成功率。     

聚丙烯管材专用料的熔体降解及其对力学性能的影响

在双螺杆挤出机中，对无规共聚聚丙烯（PP-R）和嵌段共聚聚丙烯（PP-B）管道专用料的熔体降解行为及其对力学性能的影响进行了研究：对助剂量、熔体温度等工艺条件对降解行为的影响进行了讨论。结果表明：降低熔体温度，可明显降低PP-R和PP-B的热降解速率：降解优先发生在长链分子，导致摩尔质量减小．摩尔质量分布变窄，力学性能下降。     

高强无规PP管材级新牌号

据“British Plastics ＆ Rubber”，2004，（Nov）：24报道，Borealis（北欧化工）公司推出冷水管和热水管用无规PP共聚物（PP-R）新牌号Beta-PPR RA 7050 PP-R用于冷水管和热水管输送系统已20多年，但这么多年PP-R的性能并没有明显的改进，到目前为止，PP-R的弹度仍无变化，而材料强度是计算管材壁厚的基础，决定单位长度管材的材料用量和安装后水管系统的耐压性。     

抗冲击改性无规共聚聚丙烯管材

介绍了一种抗冲击改性无规共聚聚丙烯管材的制备方法,通过热塑性弹性体和纳米碳酸钙与PP-R原料的三元共混体系。首先,经过高速混合机混合后,然后由双螺杆挤出设备进行造粒,最后通过管材挤出设备制备出经改性的无规共聚聚丙烯(PP-R)管材。经增韧增强后PP-R管材的抗冲击性能有很大提高,可以应用于我国北方严寒地区。     

用PET改善PP-R的挤出流变性能

研究了聚对苯二甲酸乙二酯(PET)对无规共聚聚丙烯(PP-R)挤出畸变行为的改善作用。结果表明:加入少量PET即有较好的改善效果,m(PP-R)/m(PET)为94:6的试样在高速挤出时表观质量较好。挤出拉伸造粒过程中形成的PET短纤维在毛细管入口区拉伸流场中沿流动方向取向,流动应力集中效应减轻,拉伸流动趋稳,挤出畸变减轻或消除。     

青岛山塑新推PP-R玻纤稳态管材生产线

<正>一种可生产PP-R玻纤稳态增强管材的塑料机械挤出设备,日前在青岛山塑挤出设备有限公司研制成功并发往用户。该公司推出的PP-R玻纤稳态增强管材生产线,采用PLC控制系统,单螺杆挤出机、三层复合共挤模具,使管     

Frictional properties of polyolefins treated with fluoroelastomer processing aids

A friction measurement system was designed that made possible the measurement of the friction coefficient between a polymer melt and a metal die wall. The shear stresses developed in the capillary rheometer and the friction coefficient measured in the friction measurement system were compared in an attempt to understand the mechanism of fluoroelastomer processing aids (FPA) in the extrusions of polypropylene (PP) and linear low-density polyethylene (LLDPE). The apparent viscosity drops of LLDPE treated with FPA were larger than those of PP treated with FPA. The friction coefficient drops of LLDPE treated with FPA were also larger than those of PP treated with FPA. High viscosity FPA showed a moderate friction coefficient drop in the actual extrusion of PP even though it showed only a poor effect in the capillary rheometer. The frictional forces were calculated from the friction coefficient measurement made during extrusions of FPA-treated and untreated samples. © 1995 John Wiley & Sons, Inc.     

高填充性聚丙烯基纳米复合材料挤出胀大行为研究

使用毛细管流变仪考察了3种高填充聚丙烯（PP）纳米复合材料的挤出胀大行为,研究了口模温度、剪切速率、熔体压力、纳米粒子填充比例和纳米粒子形貌对PP纳米复合材料熔体挤出胀大比的影响。结果表明,3种PP纳米复合体系熔体的挤出胀大比均随口模温度的增加而减小,且大致呈线性关系;随着剪切速率的增大而增加,且随着填料填充比例的增加有减小的趋势;随着熔体压力的增大而增加,并且随着熔体压力的增加,其挤出胀大比随填料填充比例的增加而减小的幅度下降;3种颗粒形貌纳米粒子填充体系中,在相同的体积分数和温度下,片状结晶纳米氢氧化镁［Mg（OH）2］填充体系熔体挤出胀大比最小,球状纳米碳酸钙（CaCO3）填充体系熔体挤出胀大比最大,棒状粒子埃洛石纳米管（HNTs）填充体系熔体挤出胀大比介于两者之间。     

Study on the viscosity of polypropylene composites filled with different size and size distribution CaCO3

Two kinds of different size calcium carbonates are blended and filled into polypropylene in 30 wt%. The melting viscosity of PP composites samples is measured by capillary extrusion rheometer at 230°C. The results show that the melt viscosity of PP composites evidently decreased when that was filled with the blending 325 and 1,500 mesh CaCO₃ and the 1,500 mesh proportion in fillers was from 20 to 60 wt%. The viscosity in the low shear velocity decreased more than that in the high shear velocity. The shear viscosity of single filler and filler samples with the size distribution at the different temperature was studied by capillary extrusion rheometer. The results show that the flow activation energy and the flow activation entropy of composites filled with the size distribution filler increased. The change of the flow activation entropy and the model of the efficient arrangement of the structure are used to explain the phenomenon in melting viscosity decrease of PP filled with the size distribution fillers. A structural model of composites that filled with the size distribution fillers was set up. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

A die rotating system for moderations of extrusion load and pressure drop profiles for molten PP and wood/polypropylene composites in extrusion processes

A die‐rotating system was proposed in this work for moderations of extrusion forces and entrance pressure drop for molten polypropylene (PP) and wood/polypropylene (WPP) composites in a capillary rheometer and a single screw extruder. The effects of processing conditions and wood loading in PP were of our interests. The extrusion force and entrance pressure drop with and without the die rotating system were monitored in real‐time. This was the first time that the die‐rotating system was used for processing of highly viscous wood/polymer composite materials. It was found that the flow properties of the molten PP and WPP composites obeyed pseudoplastic non‐Newtonian behavior. The behavior was more obvious at wood contents of above 6 wt % and in the capillary rheometer. The rotation of the die could moderate the extrusion load by 60% and entrance pressure drop by 20% in the capillary rheometer, and the entrance pressure drop by 30% in the single screw extruder, especially at the conditions where the viscosities of the WPP and the extrusion rate were high. Greater fluctuations in entrance pressure drop caused by die rotation were observed in the single screw extruder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120:1006–1016, 2011     

中熔均聚聚丙烯1100N流变性能研究

借助旋转流变仪、毛细管流变仪等研究了中熔均聚聚丙烯(PP1100N)及PP1120,PPV30G的熔体流变性能。结果表明,PP1100N与对比试样的流变性能略有差异,3种试样均具有良好的加工流动性。PP1100N相对分子量最大;PPV30G居中;PP1120相对分子量最小。PP1100N和PPV30G的挤出胀大直径变化相差不大,PP1120的挤出胀大直径变化相对较小,3种试样在挤出胀大实验中均未出现试样熔体破裂现象。     

聚丙烯发泡塑料挤出胀大行为的实验研究

使用HAAKE挤出流变仪研究了聚丙烯发泡塑料挤出胀大行为，考察了毛细管数、螺杆转速和温度等参数与PP发泡塑料挤出胀大的关系，同时指出气泡的存在对发泡制品挤出胀大有较大影响，分析了气泡体积的大小等对PP发泡塑料的挤出胀大的影响。     

Preparation and properties of self-reinforced polypropylene/liquid crystalline polymer blends

The mechanical properties of self-reinforced liquid crystalline polymer/polypropylene (LCP/PP) blends strongly depend on the viscosity ratio of the blend components in the melt. This ratio was determined for PP blends with different commercial LCPs (Vectra A950 and Vectra B950), by means of capillary rheometry, under conditions representative for the blending process during extrusion. It was found that optimal mechanical properties were achieved when the LCP/PP viscosity ratio at 285°C ranges between 2 and 4 at a shear rate of 800–1000s⁻¹. The LCP/PP viscosity ratio appears to be shear stress dependent. This creates the option of fine tuning the LCP droplet deformation process by means of the extrusion rate. This shear stress dependence is more pronounced for PP blends with Vectra B950 than for blends with Vectra A950.     

加工参数及配方对PP/LLDPE共混物泡孔形态的影响

采用高压毛细管流变仪对不同含量碳酸钙(CaCO3)的聚丙烯/线型低密度聚乙烯(PP/LLDPE)共混物的流变性能进行了表征;并利用自制的实验装置,在不同发泡温度和饱和压力下,对共混物进行了超临界CO2模拟挤出发泡实验研究。结果表明:使用高熔体强度聚丙(烯HMSPP)发泡可以获得较好的泡孔形态;添加成核剂CaCO3可以使发泡试样的泡孔结构更加规则,泡孔分布更加均匀;随着CaCO3含量的增加,共混物的稠度上升,非牛顿指数降低,当CaCO3含量为3%时,共混物的发泡效果较好;130℃为最佳发泡温度,此时发泡试样的结构完整尺,寸均匀;随着饱和压力的增加发,泡试样的泡孔密度也有所提高。     

振动力场作用下聚合物填充体系挤出混合特性

本文利用一种新型毛细管动态流变仪,对碳酸钙填充聚丙烯体系进行了实验性研究。发现质量百分比为８５／１５的ＰＰ／ＣａＣＯ３填充体系,在一较佳振动条件下动态挤出时,振动场的存在对ＣａＣＯ３在ＰＰ熔体中的分散有促进作用,大大改善了混合料的混合程度。     

PP2400的流变性能对BOPP成膜性能的影响

本文研究了ＰＰ２４００的流变性能对其ＢＯＰＰ成膜性能的影响。通过与进口ＰＰ进行对比试验，发现ＰＰ２４００的分子量高、粘度大、熔体强度较大。正是由于分子量较高，导致粘度较高，ＰＰ２４００料的塑化度减小，影响了塑化的均匀性，从而造成挤出性能的恶化。指出问题的关键在于如何处理好粘度与熔体强度之间的平衡关系。掺混进口ＢＯＰＰ料，可降低体系的挤出粘度，提高塑化的均匀性，使厚片的厚度与宽度控制精确，并使厚片内应力均匀，对后续成膜工艺相当重要。加大口模长度，延长ＰＰ分子链的松弛时间对改善厚片质量进而提高成膜性能有所裨益。适当提高挤出厚片时的挤出温度，将能改善体系的流动性能，提高塑化的均匀性，减小出口膨胀率