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首页> 外文学位 >Influence of temperature and polymer/mold surface interactions on micro-feature replication at ambient pressure in micro injection molding .
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Influence of temperature and polymer/mold surface interactions on micro-feature replication at ambient pressure in micro injection molding .

机译：温度和聚合物/模具表面相互作用对微注射成型中环境压力​​下微特征复制的影响。

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摘要

Microinjection molding is based on the concept of vario-thermal processing in which the injection unit heats the polymer and presses it into a micro featured mold. After the unit cools, the featured part is de-molded. An inherent problem with microinjection molding is poor feature replication. The polymer in the micro-cavity instantaneously freezes when it comes in contact with the mold wall thus, limiting the achievable aspect ratio of the features in the part.; This study assesses micro-feature replication at elevated mold temperature and ambient pressure using a variety of polymers and commonly used mold surfaces. In order to more fully explore the micro injection molding processing window, a better understanding of the interaction of polymer melt with the mold surface is needed. These interactions can be partially determined by measuring the contact angle of polymer melt directly onto the mold surface which can subsequently be correlated to the wetting and surface tension. Viscosity measurements provided a comparison of the behavior of different polymers to varying shear rates. Molding trials were performed on micro and nano featured mold surfaces at elevated mold temperatures and ambient pressure. Feature replication was analyzed quantitatively using an atomic force microscope, comparing the attained depth of the polymers for different aspect ratio features. A qualitative and dimensional analysis was also performed by field-emission scanning electron microscope. Crystallinity of the polymers in the molded parts was attained by X-ray diffractometer. While feature detail was well replicated for all the polymers, the moldings exhibited poor dimensional accuracy due to high shrinkage in the parts. In general, polymers with low viscosity and crystallinity and a surface tension comparable to that of the mold material showed the best feature replication.
机译：微注射成型基于可变热处理的概念，其中注射单元将聚合物加热并将其压入微细模具中。装置冷却后，将特征零件脱模。显微注射成型的固有问题是不良的特征复制。当与型腔壁接触时，微型腔中的聚合物会立即冻结，从而限制了零件中可达到的长宽比。这项研究使用各种聚合物和常用的模具表面评估了在升高的模具温度和环境压力下的微观特征复制。为了更充分地探索微注射成型加工窗口，需要更好地了解聚合物熔体与模具表面的相互作用。这些相互作用可以通过测量聚合物熔体直接在模具表面上的接触角来部分确定，该接触角随后可以与润湿和表面张力相关。粘度测量提供了不同聚合物对不同剪切速率的行为的比较。在升高的模具温度和环境压力下，对具有微米和纳米特征的模具表面进行了成型试验。使用原子力显微镜对特征复制进行了定量分析，比较了不同纵横比特征下聚合物达到的深度。还通过场发射扫描电子显微镜进行了定性和尺寸分析。通过X射线衍射仪获得成型部件中聚合物的结晶度。尽管所有聚合物都很好地复制了特征细节，但由于零件的高收缩率，模制品的尺寸精度差。通常，具有低粘度和结晶度以及与模具材料相当的表面张力的聚合物显示出最佳的特征复制。

著录项

  • 作者

    Thakur, Varun.;

  • 作者单位

    Clemson University.;

  • 授予单位 Clemson University.;
  • 学科 Engineering Mechanical.; Engineering Materials Science.
  • 学位 M.S.
  • 年度 2006
  • 页码 110 p.
  • 总页数 110
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;工程材料学;
  • 关键词

  • 入库时间 2022-08-17 11:39:30

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