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Paste extrusion of polytetrafluoroethylene (PTFE) fine powder resin: The effects of processing aid physical properties.

机译：聚四氟乙烯（PTFE）细粉树脂的糊料挤出：加工助剂物理性能的影响。

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摘要

The rheological properties of a number of polytetrafluoroethylene (PTFE) pastes were studied relevant to paste extrusion process. The effects of the physical properties of lubricants and the geometrical characteristics of the extrusion die on the preforming, extrusion pressure and mechanical properties of the final extrudates were studied. A number of lubricants were identified as suitable for the paste extrusion of polytetrafluoroethylene (PTFE). They were characterized in terms of both flow and surface properties. It was found that it is possible to alter the flow and surface properties of these lubricants independently and thus it became possible to study their relative effects on preforming and extrusion of PTFE paste. Based on this study, it was concluded that preforming quality increases with increase of lubricant viscosity and with improvement in the wetting characteristics of the lubricant with PTFE. The effects of the lubricant physical properties on the processing of polytetrafluoroethylene (PTFE) fine powder resins were also studied by using dies of various geometrical characteristics and resins having a variety of molecular architecture. It was found that the wettability (surface tension) of the lubricant strongly affects the pressure needed to extrude the PTFE pastes. The viscosity of the lubricant was also found to play a significant role in the process since a lubricant with a low viscosity causes the paste to be extruded at a lower pressure. These effects significantly influence the mechanical properties of the final extrudates. The latter are functions of the degree of fibrillation which is significantly influenced by the wettability and viscosity of lubricants. The effects of die geometry on extrusion pressure and mechanical properties of extrudates were assessed in order to determine the geometrical characteristics and operation conditions for the optimization of the process. A rheological equation was developed and proposed for flow simulations of the paste extrusion of PTFE pastes, aiming at optimizing this process. Finally, various additives were tested in order to determine possible processing aids for the paste extrusion of PTFE. It was found that moderate amount of boron nitride and organically modified clays can have beneficial effects on mechanical properties of the final extrudates.
机译：研究了许多与糊料挤出工艺有关的聚四氟乙烯（PTFE）糊料的流变性能。研究了润滑剂的物理性能和挤出模头的几何特性对最终挤出物的预成型，挤出压力和机械性能的影响。已确定许多润滑剂适合于聚四氟乙烯（PTFE）的糊料挤出。根据流动性和表面性质对它们进行了表征。发现可以独立地改变这些润滑剂的流动性和表面性质，因此有可能研究它们对PTFE糊料的预成型和挤出的相对影响。根据这项研究，可以得出结论，预成型质量随着润滑剂粘度的增加和PTFE润滑剂润湿特性的改善而提高。还通过使用各种几何特性的模具和具有多种分子结构的树脂，研究了润滑剂物理性能对聚四氟乙烯（PTFE）细粉树脂加工的影响。已经发现润滑剂的润湿性（表面张力）强烈影响挤出PTFE糊剂所需的压力。还发现润滑剂的粘度在该过程中起重要作用，因为低粘度的润滑剂使糊料在较低的压力下挤出。这些影响显着影响最终挤出物的机械性能。后者是原纤化程度的函数，原纤化程度受润滑剂的润湿性和粘度的影响很大。评估模具几何形状对挤出压力和挤出物机械性能的影响，以确定几何特征和操作条件以优化工艺。为了优化该工艺，开发了流变方程并提出了用于PTFE糊料挤出的流动模拟的流变方程。最后，测试了各种添加剂，以确定用于PTFE糊料挤出的可能加工助剂。已经发现适量的氮化硼和有机改性的粘土可以对最终挤出物的机械性能具有有益的影响。

著录项

  • 作者

    Ochoa, Isaias.;

  • 作者单位

    The University of British Columbia (Canada).;

  • 授予单位 The University of British Columbia (Canada).;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 182 p.
  • 总页数 182
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化工过程（物理过程及物理化学过程）;
  • 关键词

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