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首页> 外文学位 >Reverse temperature profile rheology and recycle study of polyhydroxybutyrate copolymer within an injection molding machine.
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Reverse temperature profile rheology and recycle study of polyhydroxybutyrate copolymer within an injection molding machine.

机译：注塑机内聚羟基丁酸酯共聚物的反向温度曲线流变学和循环研究。

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摘要

Polyhydroxyalkanoate (PHA) has gained significant attention as a substitute to conventional thermoplastics like Polypropylene (PP) and Polyethylene (PE) due to its biodegradability, biocompatibility, and renewability. PHA's have a great potential for durable applications as they possess properties comparable to those of Polyolefins'. Polyhydroxybutyrate (PHB), the most commonly available type of PHA, for example has high crystallinity and mechanical properties. The use of these polymers is limited due to their brittleness and narrow processing window. Various attempts have been made to overcome these drawbacks and improve the processing of PHB.;This research focuses on the reverse temperature profile rheology study of PHB copolymer within the injection molding machine, and also the stability of the material when used as regrind material. A modified nozzle with pressure and temperature measurement ports was installed on an injection molding machine. Capillary dies were installed within the modified nozzle and viscosity measurements at various shear rates and temperatures were conducted. An inline measurement method was used to quantify the effect of residence time, screw shear rate, and reverse temperature profile. This rheology data was compared to capillary rheology data. The inline rheology data was then curve fit with the Cross-WLF viscosity model used by Moldflow and obtained constants were then used for simulation studies. Simulated results were compared to actual cavity pressure results obtained from an instrumented tool. Simulation over predicted the pressures but predicted the trend with good replication to real time pressure data. These results were then used to develop the processing window for the material.;The material was also studied for its stability with the addition of regrind material. The ability of PHB copolymer to be processed a number of times and the use of different virgin to regrind ratios was investigated to understand the effect of regrind levels and heat history on material properties. The material was recycled for 10 regrind generations and also was studied for 7 regrind ratios with virgin material. A 79% reduction in viscosity and 10% reduction in ultimate tensile strength were observed after 10 regrind generations. Also a drop of 5% was observed in the viscosity and ultimate tensile strength with a 50:50 virgin to regrind ratio at generation two.
机译：聚羟基链烷酸酯（PHA）具有可生物降解性，生物相容性和可再生性，因此已成为聚丙烯（PP）和聚乙烯（PE）等常规热塑性塑料的替代品，引起了广泛关注。 PHA具有与聚烯烃相当的性能，因此具有持久应用的巨大潜力。聚羟基丁酸酯（PHB）是最常见的PHA类型，例如具有高结晶度和机械性能。这些聚合物的脆性和狭窄的加工范围限制了它们的使用。为了克服这些缺点并改善PHB的加工方法，已经进行了各种尝试。本研究的重点是注塑机内PHB共聚物的反向温度分布流变学研究，以及用作再研磨材料时材料的稳定性。具有压力和温度测量端口的改进喷嘴安装在注塑机上。将毛细管模安装在改进的喷嘴内，并在各种剪切速率和温度下进行粘度测量。在线测量方法用于量化停留时间，螺杆剪切速率和反向温度曲线的影响。将该流变数据与毛细管流变数据进行比较。然后将在线流变数据与Moldflow使用的Cross-WLF粘度模型进行曲线拟合，然后将获得的常数用于仿真研究。将模拟结果与从仪器上获得的实际空腔压力结果进行比较。仿真可以预测压力，但是可以很好地复制到实时压力数据中来预测趋势。然后将这些结果用于开发材料的加工窗口。;还研究了材料的稳定性，并添加了再研磨材料。研究了PHB共聚物多次加工的能力以及使用不同的原始料与再磨料的比例，以了解再磨料水平和热历史对材料性能的影响。该材料被回收了10次再研磨，还用原始材料研究了7种再研磨比率。经过十次再研磨后，发现粘度降低了79％，极限抗拉强度降低了10％。还观察到在第二代时粘度和极限拉伸强度下降了5％，其中原始料比与再生料比为50:50。

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  • 作者

    Shah, Bhavin Jitendra.;

  • 作者单位

    University of Massachusetts Lowell.;

  • 授予单位 University of Massachusetts Lowell.;
  • 学科 Plastics Technology.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 111 p.
  • 总页数 111
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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