共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
3.
4.
5.
6.
7.
提出了普通螺杆和屏障螺杆的计算机模拟方法,所用模型包括喟料区、固体输送区、熔融区和熔体输送区。在屏障螺杆中其固体熔融速率是按Tadmor模型计算出来的。而Tadmor模型的固体床速率是以固体床厚度和宽度的变化为基础。模拟的数据同实验数据相比较,可精确合理的预测出普通型和屏障型螺杆挤出特性。 相似文献
8.
鉴于聚合物组合的形态结构可使聚合物共混胶的性能测定达到准确无误的程度,为此,挤出机设计需要采用模型,以能计算熔体输送段中挤出机螺杆长度上的估算形态发展,由于观测到的最明显的形态变化出现于熔融段,本文就着重描述了挤出机这一段中的共混胶熔融过程中形态的形成和发展。文中对PP和PA6共混胶的熔融流变性、界面张力、熔融形态进行了描述,并对熔融过程中开始时的固体含量、固体温度平均熔体温度及熔体温度的发展熔融过程的模拟、熔融度、粘度比、单位挤出量恒定时的速度影响、挤出机规格影响、螺杆顶部的熔融度、挤出量恒定时螺杆速度的影响、恒速下挤出量的影响、粘度比的影响、微滴分散与聚结等作了较为详尽的计算与讨论,从而为研究熔融过程、形态发展以及为理论模型和形态发展对比提供了数据基础。 相似文献
9.
普通螺杆和屏障螺杆挤出机的计算机模拟 总被引:2,自引:0,他引:2
提出了普通螺杆和屏障螺杆的计算机模拟方法,所用模拟包括:喂料区、固体输送区、熔融区和熔体输送区。在屏障型螺杆中,其固体熔融速率是按Tadmor模型计算出来的,而Tadmor模型的固体床速率是以固体床厚度和宽度的变化为基础的。模拟的数据同试验数据相比,可精确合理以预测出普通型和屏障型螺杆的挤出特性。 相似文献
10.
在分析机筒衬套沟槽槽深、螺杆螺槽槽深和加工物料粒径关系的基础上,建立了沟槽机筒单螺杆挤出机3种常见的固体输送段产量粒径模型,该模型可用于研究机筒衬套沟槽槽深、螺杆螺槽槽深和颗粒物料粒径对固体输送机理的影响并定量计算沟槽机筒单螺杆挤出机固体输送段产量。此外,通过不同的机筒和螺杆组合及不同粒径的原料在自制的在线模拟试验机上对该模型进行了验证和试验分析。 相似文献
11.
George K. Ivanov 《Polymer Engineering and Science》2000,40(3):676-689
This study presents results, observations and new developments on the pulverization of low density polyethylene (LDPE) by a nontraditional technology. A twin screw conical counter‐rotating extruder, a mixer head with roller blades and a single screw extruder attached to a C.W. Brabender PL2000 Plasti‐Corder were utilized as pulverization apparatuses. The pulverization phenomenon was studied over a wide range of shear rates and at resin processing temperatures below and above the Vicat softening point, i.e., at solid and soft (visco‐elastic/rubbery‐like) state of the material. A hypothesis about the pulverization mechanism of LDPE at a temperature between melting/crystallization temperature and Vicat softening point is presented. 相似文献
12.
以过氧化二异丙苯(DCP)为引发剂,采用双螺杆熔融挤出技术将马来酸酐(MAH)接枝到氢化聚苯乙烯-聚丁二烯-聚苯乙烯三嵌段共聚物(SEBS)分子链上,通过傅里叶变换红外光谱(FTIR)确定了挤出过程中有SEBS-g-MAH生成,采用酸碱滴定法测定了SEBS-g-MAH的接枝率。通过单螺杆熔融挤出法制备了热塑性聚酯弹性体(TPEE)发泡片材,研究了SEBS-g-MAH对TPEE发泡片材性能的影响。结果表明,接枝物的加入对TPEE的熔体流动速率有显著的降低作用;SEBS-g-MAH对TPEE发泡制品力学性能和表观密度有明显的影响;发泡制品的压缩永久形变和断裂伸长率随着接枝物含量的增多而下降,当接枝物含量加到4份后,压缩永久形变和断裂伸长率都趋于稳定,发泡材料的泡孔大小均匀,分布均一。 相似文献
13.
介绍了锥形双螺杆的一个新概念,即混炼型锥形双螺杆。炼型锥形双螺杆保留了常规锥形双螺杆加料量大和正位移输送的特点,解决了常规锥形双螺杆混合效果及挤出压力波动等问题,使其不但能够加工PVC,而且也能够加工其它物料,拓宽了锥形双螺杆挤出机的加工应用范围。 相似文献
14.
利用EDEM软件对一种普通锥形和两种双锥型螺杆挤出机固体输送段进行模拟.分析了高密度聚乙烯(PE-HD)颗粒在锥形双螺杆挤出机内的运动状态和分布规律.对比分析了3种锥形螺杆挤出的质量流速率、填充率、平均速度、平均压力、平均剪切应力和力矩等参数,给出了普通型和双锥型螺杆挤出机固体输送机理以及主要影响因素.结果表明,相比于... 相似文献
15.
锥形双螺杆挤出机是塑料加工的一种重要机型。对SJSZ-55锥形双螺杆挤出机的螺杆进行了设计,研究结果可以指导同类螺杆的设计。 相似文献
16.
系统地介绍了锥形双螺杆挤出机螺杆的基本参数以及各功能段参数的设计依据,并针对SJSZ–35锥形双螺杆挤出机的螺杆进行了优化设计,对同类螺杆的设计具有一定的指导意义。 相似文献
17.
R. C. Donovan 《Polymer Engineering and Science》1971,11(3):247-257
A theoretical model for melting in plasticating extruders is described. Compared to previous models, this model introduces more accurate and less restrictive assumptions, adds a mass balance on the entire channel, and replaces certain approximate solutions by exact solutions. Flow of the solid bed is represented by a solid bed acceleration parameter, SBAP, which permits solid bed acceleration in a screw compression section. New experimental melting data for a variety of screw designs, polymers, and extruder sizes are presented and compared to the theoretical predictions. With the optimum SBAP, reasonably accurate model prediction of the melting profiles is observed for a wide variety of cases. 相似文献
18.
The effect of a vibration force field on the melting process of an extruder is studied. It is shown that the mechanism for melting differs from conventional theory. Experimental studies of melting of low‐density polyethylene (LDPE) pellets in a vibration‐induced single‐screw (VISS) extruder show that melting is initiated on the inside of the barrel and the surface of screw. Models were developed that explain the melting mechanism in those regions. The melting at the surface of the screw is mainly initiated by frictional work on the pellets by the vibration and rotation of the screw. The melting action at the barrel is induced by a barrel temperature higher than the melting point and propagated by viscous dissipation heating of the melt film produced. The theory is supplemented by a calculation sample, which shows good agreement with experimental data obtained on a transparent barrel VISS (T‐VISS) extruder and a half‐open barrel VISS (H‐VISS) extruder with LDPE. The results of the experiment and calculation sample indicate that the introduction of vibration‐induced field can improve the melting capacity of extruder to a great extent. The present model enables the prediction of processing parameters for VISS extruders, from which the optimum operating conditions can be obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2504–2514, 2007 相似文献
19.
This study investigates the effects of processing conditions (the screw speed, throughput, barrel temperature, and screw configuration) on the chemical conversion and morphology evolution of polyamide/polyolefin blends along a twin‐screw extruder. Polymer samples were collected rapidly at specific barrel locations with a special sampling device for subsequent chemical and morphological characterization. Increasing the screw speed or using more restrictive screw modules at the beginning of the melting zone promoted a faster reaction and better dispersion along the extruder. Increasing the throughput or decreasing the barrel temperature slowed the evolution of the morphology and chemical conversion along the extruder because of the lower melting rate. As soon as melting started, the chemical reaction took place. However, high chemical conversion rates required extensive melting, that is, significant interface generation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
20.
A series of small-angle X-ray scattering measurements were performed to study the polypropylene/nylon-6,6 polymer blends with or without the compatibilizer: maleated polypropylene. The blends were made at various temperatures using a venting conical twin-screw extruder with a constant extruding flow rate. The X-ray scattering results show that the dispersion of nylon-6,6 in polypropylene is improved for temperature above the melting point of nylon-6,6 (265°C) when the compatibilizer involved is not used. As the compatibilizer is incorporated, the dispersion is significantly improved, even at the temperature below 265°C. With the compatibilizer, the dispersed nylon-6,6 particle size and shape in the blends are independent of blending temperature, suggesting that the temperature effect is overwhelmed by the effect of the compatibilizer. © 1995 John Wiley & Sons, Inc. 相似文献