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单螺杆挤出机挤出理论研究进展 总被引:2,自引:0,他引:2
潘龙;张玉霞;金志明;薛平 《中国塑料》2009,23(5):12-19
论文回顾了单螺杆挤出机挤出理论发展史,并从固体输送、熔融、熔体输送和混合四个方面详细介绍了近十年来挤出理论的最新研究进展。在指出现有不足的同时,提出了单螺杆挤出机未来的研究方向。 相似文献
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聚合物熔体在圆锥短口模的挤出胀大方程 总被引:3,自引:1,他引:3
深入讨论了聚合物熔体在不同长径比、不同角度圆锥短口模的挤出胀大现象及机理,利用生产用挤出机进行不同角度的圆锥短口模实验。结果表明,圆锥短口模挤出过程中,熔体在收敛流道受到拉伸流变,导致强烈的入口弹性效应,表现为熔体在短口模挤出时显著的挤出胀大。理论和实验研究结果进一步表明不同圆锥口模入口角对实验材料表现出有不同的挤出胀大值。 相似文献
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在螺杆转速高于300r/min的新型高速挤出机中,为了保证挤出制品质量,除了改进挤出机械的结构,计量段的冷却变得尤为重要。在对高速挤出过程中的计量段进行传热分析的基础上,对不同操作条件下冷卸装置的换热效果进行分析比较,为设定高速挤出过程中的计量段冷却方案找到理论依据,进而更好地控制机筒的表面温度,提高机筒内的熔体混合效果,使物料均匀挤出。 相似文献
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使用两台螺杆头部结构有差异的反应挤出机,在配方和工艺完全相同的条件下研究了聚对苯二甲酸乙二酯(PET)瓶片在挤出过程中熔体压力波动和扩链反应情况。结果表明:使用头部设计有改进型直槽混炼件的35型反应螺杆,无论是直接挤出还是混合有扩链剂均苯四甲酸二酐的挤出,挤出过程中的压力波动均比头部为普通螺纹的30型反应螺杆显著降低,而且熔体压力平均值也高;使用35型反应螺杆挤出产物的特性黏数([η])略高于30型反应螺杆挤出的;提高螺杆转速既有利于提高挤出产物的[η],又有利于提高机头处的熔体压力平均值,相当于提高了挤出机产量。使用头部设计有改进型直槽混炼件的反应螺杆非常有利于稳定挤出PET瓶片,成型制品。 相似文献
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每期文摘的题目均按汉语拼音顺序排列,英文按其字母顺序排列在汉字之前,数字开头的排在最前面。 HDPE/PA6共混物层状挤出过程的数值分析/李萍(江苏石油化工学院)/中国塑料,1999,13 (5):44~ 47。对HDPE/PA6在挤出机中共混并层状挤出的机理进行了数值分析。提出的HDPE/PA6/HDPE三层混合模型能处理熔体粘度随剪切速率和温度变化的二元共混物的层流混合,预测熔体的形变。数值计算的结果对合理选择工艺条件、得到合格的层状阻隔制品具有一定的指导意义。HDPE熔体连续挤出自增强的研究(Ⅰ)、机头… 相似文献
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The melt flows of linear low-density polyethylene (LLDPE) and branched low-density polyethylene (LDPE) have been compared in a fully intermeshing co-rotating twin-screw extruder. The polyethylene melts were selected in order to investigate the effects of the melt rheology on the mixing. Their shear vicosity curves are quite similar, but the LDPE has a markedly higher apparent extensional viscosity over a wide range of stretch rates. The stagger of the paddles in the mixing zone of the extruder creates axial pressure-driven axial flow can have significant extensional strain components. Residence time distributions obtained in the melt zones of the extruder with tracer dye reveal that the LDPE has a narrower residence time distribution than the LLDPE over a wide range of operating conditions. The axial dispersion for the LDPE is significantly lower than the axial dispersion for the LLDPE. This is attributed to the greater extensional viscosity of the LDPE. During the reactive extrusion process, solid maleic anhydride and polyethylene were added at the feed port but the peroxide provides better control of the crosslinking reaction. Residence time distributions measured for the chemically more reactive LLDPE melt indicate reduced levels of axial mixing with reaction. The reduction in mixing is due to a crosslinking reaction that occurs in parallel to the grafting reaction. This change in mixing is smaller than the difference in mixing between LDPE and LLDPE. 相似文献
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介绍了一种国外开发的用于改善单螺杆挤出机混合性能的新型带孔(或带槽)销钉混合段,与常规销钉混合段相比,其混合能力强,熔体温度 低,当销钉间的轴向距离在11-14mm之间时,有效地加强了熔体的周向汉动,极大地改善了单螺杆挤出机的分布混合性能。 相似文献
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基于熔融共混法,分别采用双转子连续混炼挤出机和同向啮合双螺杆挤出机制备了20 %玻璃纤维增强聚丙烯(GFRPP)复合材料,并对制备出的GFRPP复合材料中玻璃纤维残存长度及其力学性能进行了相应表征,在此基础上探讨了具有不同混炼特性的混炼设备结构对GFRPP复合材料中玻璃纤维残存长度及其力学性能的影响。结果表明,GFRPP复合材料的力学性能随玻璃纤维残存长度的增加而明显提高;双转子连续混炼挤出机相对于同向啮合双螺杆挤出机更有利于保留长玻璃纤维,同时适当减弱双转子连续混炼挤出机的转子的分散混合能力,降低转子转速,有利于提高玻璃纤维的残存长度,制备出更高性能的GFRPP复合材料。 相似文献
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The flow of polyethylene melt in new tri-screw extruder was simulated using the finite element method (FEM). A special study of flow in central region was performed by analysis of the velocity, pressure, and resident time distribution (RTD). The extrusion characteristics of tri-screw extruder, namely the abilities of material conveying, mixing, and power consumption, were compared with those of twin screw extruder. The results showed that there was circumfluence in central region but no stagnation in it. Tri-screw extruder had better operative abilities and high productivity ratio than twin screw extruder in the aspect of material conveying and mixing. 相似文献
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介绍了基于动态成型过程强化分散混炼的方法以及实现这些方法的动态混炼挤出机的结构及工作原理。这种低能耗强混炼技术包括在单螺杆上增设差动混炼单元、增加物料沿程反馈螺杆以及采用三螺杆劫态混炼挤出机等。 相似文献
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Milan Kracalik Stephan Laske Michael Gschweitl Walter Friesenbichler Günter Rüdiger Langecker 《应用聚合物科学杂志》2009,113(3):1422-1428
A melt pump was assembled into the compounding line to ensure both sufficient time for diffusion process of polymer chains into the silicate gallery and sufficient mechanical shear energy for exfoliation of clay layers. The melt pump in front of the open co‐rotating twin‐screw extruder controls the throughput rate and the residence time, whereas the screw speed and screw geometry in the extruder determine the mechanical shear energy applied on the compound. Due to melt pump employment, the melt in metering zone can be accumulated, which results in higher mixing efficiency. It was found that using the melt pump leads to up to two times higher residence time and, consequently, higher level of material reinforcement as investigated by extensional rheology. Different melt pump adjustments, screw geometries, and screw speeds were tested and their effect on processing characteristics and material reinforcement was investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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在传统的三螺杆挤出机的基础上,设计了一种新型偏心三螺杆挤出机。该三螺杆挤出机中具有螺杆几何结构偏心、螺槽构型呈梯度变化特殊以及较高的面积利用系数等特征。利用有限元法对聚丙烯(PP)熔体在新型偏心三螺杆挤出机中流动和混合规律进行三维数值模拟,给出偏心三螺杆挤出机中压力和速度分布规律,计算了3种偏心螺杆挤出流场的停留时间分布、分布指数、分离尺度、最大剪切应力等混合表征参数。结果表明,螺杆偏心距不仅决定了螺杆端面形状,也改变了螺槽梯度的变化程度。随着螺槽梯度的逐渐减小,挤出机内粒子团聚效应逐渐降低、物料剪切作用逐渐增强。在3种新型偏心三螺杆挤出机中,偏心距e=3 mm的新型偏心螺杆挤出机的混合性能相对较好。 相似文献
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W. G. Yao K. Takahashi K. Koyama Y. Yamashita 《Polymer Engineering and Science》1998,38(10):1623-1632
The effect of a holed-pin mixing section on the performance of a single screw extruder was investigated and compared with a free flight and a normal pin mixing section, using a practical single-screw extruder. The effect of axial distance between two pins in a holed-pin mixing section on performance was also studied. Mixing ability was quantified using the statistical approach of carbon black concentration distribution in the extruded film mixed with a carbon black masterbatch. The results indicate that a free flight gives the lowest melt temperature rise, pressure drop, and driver power, but the worst mixing; a holed-pin mixing section has better mixing ability, lower melt temperature rise, and lower driver power than a normal pin mixing section does; the value of the pressure drop of the two types of pin mixing sections is approximately identical. A longer axial distance between the two pins in a holed-pin mixing section gives better mixing and lower melt temperature rise than a shorter one; however, when the distance is longer than a critical value, the improvement of mixing is not so outstanding; for different axial distances between two pins, no great change in pressure drop was found and the extrusion throughput has almost no great relation to the axial distance. 相似文献