挤出机各段温度对开孔型橡塑共混材料性能的影响

研究开孔型橡塑共混材料在不同挤出加工工艺中结构形态及力学性能的变化规律。结果表明，挤出机的机头温度应稍高于发泡剂的分解温度，均化段温度要设在发泡剂分解温度区的低温段，在挤出加工工艺中，要特别注意挤出机均化段温度及机头温度的设定，温度设定不好会使发泡剂无法发挥作用。     

挤出温度对开孔型橡塑多孔材料性能的影响

研究了挤出温度对开孔型橡塑多孔材料性能的影响。结果显示：挤出机均化段温度和机头温度是影响多孔材料性能的关键因素；多孔材料的拉仲强度及断裂仲长率随挤出机均化段温度的变化曲线均显现出极小值；多孔材料的拉仲强度和断裂伸长率随挤出机机头温度的升高呈现降低趋势；而其弹性模量随挤出机机头温度变化曲线存在极大值。     

聚氯乙烯硬管挤出成型故障的排查

●表面焦粒 故障分析及排除方法： （1）挤出温度太高。应适当降低。 （2）机头分流梭处熔料分解或机头内未清理干净。应改进机头结构，清除滞料死角，检查机头镀铬层有否脱落，彻底清理机头。     

挤出胎面气孔的形成机理及解决措施

分析挤出胎面气孔的形成机理并结合生产实践提出相应的解决措施。机头温度过高、挤出速度过快、原材料中水分和挥发分含量较大、热炼时混入空气、供胶不足及机头内部压力不足等是胎面气孔产生的主要原因,分析时既要考虑内在因素(如胶料配方),也要考虑外在因素(如挤出机温度、挤出速度等),选择内、外因素的最佳结合点才是提高胎面挤出质量的关键。添加加工助剂GE3082可以有效降低胶料的挤出温度,增大挤出速度,减小主机电流,降低能耗。     

销钉机筒挤出机挤出质量影响因素的回归模型

对销钉机筒挤出机生产过程中的挤出温度、单位体积能耗、胶料粘度及机头压力等工艺参数进行回归分析，得到工艺参数的回归方程。显著性检验表明回归得到的因数和方程是高度显著的。回归分析结果表明，对挤出温度的相关程度由大到小依次为挤出段加热温度、机头段加热温度、螺杆加热温度、塑化段加热温度、螺杆转速和口型大小。回归方程除可用于确定挤出工艺参数外，还可预测单位体积能耗和挤出胶料温度。     

工艺参数对PP挤出发泡泡孔结构的影响

研究了螺杆转速、机头口模形状以及机头温度对挤出发泡聚丙烯(PP)泡孔结构的影响。结果表明：在挤出发泡过程中，一定配方、机头形状和温度下，螺杆转速存在最佳值；机头形状越有利于建立高压，制得的泡沫的泡孔越细密均匀且发泡倍率越高；机头口模温度在保证顺利挤出情况下．越低越有利于制得高发泡倍率的泡沫。     

Купаг(聚偏氟乙烯)的品种、性能及加工应用(二)

Kynar 树脂的加工指导Eynar Flex 2800作电缆护套的加工1.挤出工艺(1)挤出温度分布如下加料段 204～232℃,过渡段 232～246℃,计量段 246～260℃,机头 300～327℃,熔融温度 300～330℃,十字机头处的压力 6,000～9,000psi。(2)挤出设备挤出机应在它最大挤出量的70～85%处操作,这也是选择何种大小之挤出机的标准。机筒:长径比24:1,机筒内衬 Xaloy306、101、800或同类合金钢,至少要有三段     

板材挤出成型故障的产生原因及排除方法：单层板材挤出成型故障的排查

故障分析及排除方法：(1)挤出温度偏低，熔料塑化不良。应适当提高机身及机头温度。通常，挤出机机身温度应根据成型原料的种类而定，机头温度一般比机身温度高5～10℃左右，机头温度的分布按中间低、两边高的原则来控制。几种热塑性塑料板材挤出加工温度条件如表所示。     

聚丙烯挤出发泡中的关键技术——加工设备和成型工艺研究

从聚丙烯挤出发泡的加工设备包括挤出机的类型、发泡机头的设计、发泡剂的注入和计量控制以及聚丙烯挤出发泡的成型工艺包括螺杆转速、压力降和压力降速率、成核剂的分散、发泡机头的温度等系统介绍了聚丙烯挤出发泡中的一些关键技术。目前的研究表明：采用双螺杆挤出机进行挤出发泡时需要考虑发泡剂逃逸和压力的升高与稳定；可以通过改变机头的形状和尺寸获得不同的压力降和压力降速率，从而控制挤出发泡的成核速率。提高螺杆转速、增加压力降和压力降速率有利于优质发泡材料的获得；优选适宜的发泡机头温度可以抑制气体逃逸，提高发泡倍率，获得更低密度的聚丙烯发泡材料。     

塑料异型材的挤出成型

概述塑料异型材的优点及应用实例，从原料选择与配方设计、挤出设备、制品断面设计及机头模具、挤出成型工艺等方面阐述了塑料异型材的挤出成型技术，介绍了低发泡、复合共挤出等其它异型材的成型技术，并展望了塑料异型材的发展趋势。     

RPVC低密度自由发泡挤出板材生产工艺探讨

重点研究了RPVC低密度自由发泡板材配方中主要组成对挤出过程物料流变行为和发泡性能的影响,以500kg/m^3的发泡板材为例,设定、筛选出其生产配方：PVC树脂（聚合度800）100份;ADC发泡剂0.5份;Pb类稳定剂2.5－4.0份;高分子改性剂6-10份;润滑剂1－2份;消黄剂少许。简述了生产工艺流程和对加工湿度、机头压力、螺杆转速等工艺条件的控制。     

改性PVC基树脂铅芯的制备与性能

聚氯乙烯(PVC)基树脂铅芯主要以PVC树脂为黏结剂,以石墨、其他有机或无机颜料为着色剂制作而成的铅芯,PVC基树脂铅芯的配方决定着其加工的工艺性与铅芯质量。通过对现有PVC基树脂铅芯的配方产量低、易分解的问题基础上进行分析,提出添加钙锌稳定剂或硬脂酸钙作PVC热稳定剂、环氧大豆油作助稳定剂的改进方案,并进行挤出实验分析和性能测试。结果表明,当加入10份硬脂酸钙、5份环氧大豆油时能获得较稳定的挤出机扭矩、熔体压力和挤出量,可作为生产测试新配方,采用新工艺、新材料成功实现了使用单螺杆挤出机连续挤出改性PVC基树脂铅芯的目标。     

Solid state extrusion of vinylidene fluoride (VF2)/vinylidene trifluoride (VF3) copolymers. I: Dynamics of solid state extrusion

Solid state extrusion dynamics of poly(vinylidene fluoride) and its copolymers have been studied using an Instron capillary rheometer with specially designed die set. At and above the Curie transition temperatures, the copolymers rapidly soften while preserving the semicrystalline structure. This allows them to be solid state extruded between this temperature and melting temperature. The processing windows within which high quality extrudates can be obtained were established for two copolymer compositions and they were found to be much wider than those typically observed in semicrystalline homopolymers such as polyethylene and polypropylene. Extrudate swell under all solid state extrusion condition remains constant and is always less than 1 and it was found to increase above this value as the extrusion temperature increased through the melting region which is typical of melt extrusion of these polymers.     

Verfahrenstechnische und wirtschaftliche Vorteile der Kochextrusion im Vergleich zu herkömmlichen Verfahren der Lebensmittel-Industrie

Economic and process engineering advantages of extrusion cooking in comparison with conventional processes in the food industry . Extrusion cooking is introduced as a modern high-temperature short-time process. Possible process steps in extruder machine systems, such as continuous conveying, mixing, homogenizing and reactions, mechanical and thermal energy dissipation for plasticizing and modifying biopolymers, are explained. This process creates new products with completely new textures, for example in the snack and breakfast cereal sector, while on the other hand the extrusion process competes with long-standing conventional processes. The latter work slowly with low pressures, low temperatures and energy dissipation with high water contents in large batch-operated machines. The quality of extruder-cooked products depends on the extrusion system. The self-cleaning corotating twin-screw extruder with its narrow residence time spectrum is the optimum system. However, the counter-rotating intermeshing machine has certain advantages for products of low viscosity. The cooking time at high temperature is a matter of seconds, which serves to maintain the properties of the ingredients and active substances, while ensuring fast destruction of microorganisms. The end-products have a long shelf-life on account of their low process moisture content. Continuous extrusion cooking has economic advantages mainly because it replaces many batch processes and because extrusion is carried out entirely or almost entirely with the final moisture content, thus avoiding the necessity to evaporate huge quantities of water.     

Silicon doped diamond like carbon as substitute for lubrication in spin-extrusion

To protect tools and to fulfil the request of good surface quality of the workpiece, it is normally necessary to use solid lubricants like molybdenum disulfide (MoS₂) or graphite in warm bulk metal forming. Caused by economical and ecological aspects, it is desirable to avoid lubrication and to substitute it by systems like coatings without the necessity to renew the protecting and lubricating film after every forming process.So called low wear friction coatings like Diamond like Carbon (DLC) are candidates for substituting lubricants or combinations of lubricants and hard coatings like TiN. The advantages of DLC are its high hardness, high Young's modulus and low coefficient of friction. Another important aspect is the property of DLC to graphitise the surface at high pressures, so the coating becomes a kind of self-lubricating. In massive forming at low temperatures like cold extrusion, DLC is applied today.The aim of the work is to show the suitability of DLC as a protective low wear friction coating for warm massive forming, especially for a technique called spin-extrusion. The greatest tribological problems of this forming process are a low sliding velocity and high temperatures in the working zone between tool and workpiece, which can reach a maximum temperature of about 800 °C. Normally, the maximum working temperatures of DLC should be lower than 400 °C when working in air atmosphere. So, the DLC was doped with silicon to raise the maximum working temperature of the coating. Also, the time a-C:H:Si is subjected to this temperature is short, and the air content in the working zone is reduced during the process. The behaviour of a-C:H:Si coated tools during spin-extrusion without additional lubrication of the tool is compared with the forming behaviour of uncoated, but lubricated tools.     

新型高速挤出机计量段冷却方法研究

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却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。     

Numerical investigation of the effect of screw geometry on the mixing of a viscous polymer melt

In polymer extrusion processing, mixing enhancement is an important consideration when an extruder screw is being designed. There are a variety of mixing elements used in the extrusion industry, with little consensus about what differentiates a good mixing section from a poor one. However, good mixing is important for homogenizing the material structure and temperature profile in the flow channel. This article presents a numerical analysis of the role of screw geometry in mixing in a cooling extruder. Four geometries, typical of those used by the extrusion industry, are assessed by the study of the polymer melt flow and heat transfer in the screw channels. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of polymerization catalyst technology on the melt processing stability of polyethylenes,Part 3: Additives blends performance

This article considers the interaction between additives that occur during the stabilization process. The simultaneous effects of the additives and associated interactions on melt processing stability and processing discoloration were of particular interest. Melt stability is an important factor to consider because physical changes in the processed polymer can occur during the compounding and fabrication steps. Furthermore, discoloration is one of the most important problems affecting commercial polymers. Most discoloration manifests itself as yellowing, especially in the case of polyolefins. Although yellowing can often be associated with degradation processes caused by various agents, such as light or heat, this is not always the case; yellowing can also be due to the interaction of additives in the stabilizer packages. Blends of primary antioxidants (AOs), secondary AOs, and hindered amine light stabilizers have been studied with the intention of further improving stabilization performance together with cost reduction of the stabilized polymer. Although synergism between AOs and a stabilizer is fairly common, antagonism was also observed in terms of melt flow protection and in color stability in some of the AOs tested. The effects of a range of thermal and light stabilizers on the melt stability (investigated via multiple pass extrusion) and color stability of three different polyethylenes (PEs) were examined. The PEs varied in terms of the catalyst system used to synthesize the polymers and included a high‐density polyethylene (HDPE) produced by using a chromium‐based Phillips catalyst and two linear low‐density polyethylenes (LLDPEs) produced via chromium‐based metallocene and titanium‐based Ziegler‐Natta catalysts. The apparent lack of influence of polymerization catalyst system on the mode of stabilizer interaction should lead to the reassessment of stabilizer formulation strategies in relation to PE type/catalyst system and associated commercial/economic considerations. J. VINYL ADDIT. TECHNOL., 22:117–127, 2016. © 2014 Society of Plastics Engineers     

Fabrication and characterization of millimeter-sized glass shells for inertial confinement fusion targets

To fabricate target quality millimeter-sized glass shells for inertial confinement fusion (ICF) fuel micro-containers by sol–gel technology, the effects of gel particle properties and processing parameters on the diameter, quality and yield of resulting glass shells were investigated by simulation and experiments. The results show that the initial compositions and sizes of the gel particles, the blowing agents, the pressures and compositions of furnace atmosphere, the refining temperatures and the lengths of refining zone are the key parameters to obtain target quality millimeter-sized glass shells. Increasing the gel particle sizes and/or lowering the furnace atmosphere pressures, the resulting glass shell diameters increase rapidly but the sphericity, wall uniformity and surface finish decrease notably. Displacing argon gas with helium gas in the furnace atmosphere can significantly improve the glass shell diameters, quality and yields; however, keeping appropriate fraction of argon gas in the furnace atmosphere can reduce the fragmentation of the gel particles and the ripples and collapse on the shell walls. The quality and yields of the resulting glass shells can also be improved by increasing the temperatures and lengths of the refining zone.