Extrusion screw designs and validation are presented for three multiple channel, fractal screws for comparison with common general purpose, and barrier screws using an instrumented single screw extruder with high impact polystyrene (HIPS) and low density polyethylene (LDPE) at varying screw speeds. The fractal screws are designed with multiple channels and pressure–volume–temperature relations to control shear heating with cooling by adiabatic decompression. The general‐purpose design had the highest throughput but did not provide sufficient mixing and so resulted in excessive variation in the melt temperature and pressure at screw speeds above 40 RPM. The barrier screw was a capable design with good performance for LDPE and HIPS with screw speeds from 20 to 60 RPM. However, it tended to provide excessive shear heating at higher screw speeds due to the large surface area of the barrier and mixing sections. The first fractal screw design was a multichannel variant of the general‐purpose design and exhibited good consistency but excessive heating due to the large bearing area between the flights and barrel. The second fractal screw design provided decompression in the feed zone and metering zone to improve throughput but was limited by a poor transition section design. The third fractal screw design remedied these deficiencies with an improved transition section and intermittent clearances for dispersive mixing. Its performance rivaled that of the barrier screw with respect to volumetric output and energy efficiency but provided better melt pressure consistency. Cold screw freezing experiments were performed for all five screws with 5% black, blue, and violet colorants serially added to neat HIPS. The cold screw pulls showed that the general purpose and barrier screws exhibited significant racing of the materials within their screw channels and, thus, broad residence time distributions. Examination of the material cross sections indicated persistent coiled sheet morphologies, which were best dispersed with the third fractal screw. POLYM. ENG. SCI., 60:752–764, 2020. © 2020 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.

中文翻译：

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通用，屏障和多通道塑化挤出螺杆的设计和评估

介绍了三种多通道挤出螺杆的设计和验证，与普通通用目的比较的分形螺杆和使用仪器单螺杆挤出机的屏障螺杆，该螺杆具有高抗冲聚苯乙烯（HIPS）和低密度聚乙烯（LDPE），并且螺杆速度不同。分形螺杆设计有多个通道，并具有压力-体积-温度关系，可通过绝热减压控制切变加热和冷却。通用设计具有最高的通过量，但不能提供足够的混合，因此，在螺杆转速高于40 RPM时，熔体温度和压力会发生过度变化。防护螺杆是一种性能优良的设计，对于LDPE和HIPS而言，螺杆速度为20至60 RPM，性能良好。然而，由于阻挡层和混合部分的表面积大，它倾向于在较高的螺杆速度下提供过多的剪切加热。第一种分形螺杆设计是通用设计的多通道变体，由于螺纹和机筒之间的轴承面积较大，因此具有良好的一致性，但会产生过多的热量。第二种分形螺杆设计在进料区和计量区提供减压，以提高生产量，但由于过渡段设计不佳而受到限制。第三种分形螺杆设计通过改善过渡段和分散混合的间歇间隙来弥补这些缺陷。在体积输出和能效方面，它的性能可与隔离螺杆媲美，但提供了更好的熔体压力一致性。对所有五个螺丝进行了冷螺丝冷冻实验，在纯HIPS中依次添加了5％的黑色，蓝色和紫色着色剂。冷螺钉拉力显示，通用螺钉和防护螺钉在其螺钉通道内显示出明显的材料飞散现象，因此，停留时间分布较宽。对材料横截面的检查表明存在持续的卷曲板状形态，最好用第三个分形螺杆分散。POLYM。ENG。SCI。，60：752–764，2020.©2020作者。对材料横截面的检查表明存在持续的卷曲板状形态，最好用第三个分形螺杆分散。POLYM。ENG。SCI。，60：752–764，2020.©2020作者。对材料横截面的检查表明存在持续的卷曲板状形态，最好用第三个分形螺杆分散。POLYM。ENG。SCI。，60：752–764，2020.©2020作者。Wiley Periodicals，Inc.代表塑料工程师协会出版的《聚合物工程与科学》。