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Cross linked sheets for highly stressed thermoforming applications

适用于高应力热成型应用的交联片材

基本信息

批准号：
283899356
负责人：
Professor Dr.-Ing. Dietmar Drummer
金额：
--
依托单位：
Lehrstuhl für Kunststofftechnik (LKT)
依托单位国家：
德国
项目类别：
Research Grants (Transfer Project)
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/283899356?language=en
关键词：
Cross linked sheets highly stressed

项目摘要

Basic knowledge about the effects of a partial cross linking of macromolecules on the thermoformability of semi-crystalline thermoplastics was gathered in the preceding project using the example of polyamide 12 (PA12). Semi-crystalline thermoplastics are generally less suitable for thermoforming compared to amorphous thermoplastics due to their sharp drop in stiffness with crystalline melting and the melts insufficient elongational rheological properties. Thus the availability of semi-crystalline technical thermoplastics, which meet the requirements of the thermoforming process, is highly limited up to now. This hinders the development of technical thermoforming parts. It could be shown that partial cross linking of the macromolecules by high energy irradiation changes melt stiffness and elongational rheological properties of PA12, which has significant impact on the thermoforming process. The increased melt stiffness prevents excessive sagging of the sheet during heating, while the mainly elastic behavior of the melt reduces the chance of webbing. As a result the processing temperature window is greatly increased.Furthermore cross linking leads to strain hardening material behavior and thus to more homogenous wall thicknesses, especially for geometries with high draw ratios. It is the aim of the transfer project to enhance the knowledge from the preceding project and to transfer it into application by means of a demonstrator, which is a reusable tray for electric drive components. Large-area trays are generally suitable geometries for thermoforming. However available amorphous thermoforming materials do not meet all requirements of technical trays, e.g. they need a high heat resistance when taking up parts from an injection molding process.Furthermore a good wear resistance is needed to ensure reusability. Trays for metal parts often need additional chemical resistance against oils and greases. These requirements shall be met by using cross linked semi-crystalline thermoplastics. Besides verifying the results for the industrial production scale, additional fundamental questions arise. First of all it has to be investigated whether the results from PA12 are also valid for other materials like different polyamides, polyolefines or polyesters. Moreover possible interactions of additives like cross linking aids, stabilizers or pigments and high energy irradiation influencing the sheet properties as well as their processability and resulting part properties have to be investigated. Furthermore effects of sheet processing on thermoformability as well as effects of thermoforming conditions on part properties have to be measured. Here the range of investigated properties shall be expanded to include some of the relevant advantages of semi-crystalline thermoplastics for applications, like wear behavior or chemical resistance.

在之前的项目中，以聚酰胺 12 (PA12) 为例，收集了有关大分子部分交联对半结晶热塑性塑料热成型性影响的基本知识。与无定形热塑性塑料相比，半结晶热塑性塑料通常不太适合热成型，因为它们的刚度随着晶体熔化而急剧下降，并且熔体的拉伸流变性能不足。因此，迄今为止，满足热成型工艺要求的半结晶技术热塑性塑料的可用性非常有限。这阻碍了热成型零件技术的发展。结果表明，高能辐照引起的大分子部分交联改变了PA12的熔体刚度和拉伸流变性能，这对热成型过程具有显着影响。熔体刚度的增加可防止片材在加热过程中过度下垂，而熔体的主要弹性行为则减少了织带的可能性。因此，加工温度范围大大增加。此外，交联会导致材料应变硬化，从而获得更均匀的壁厚，特别是对于具有高拉伸比的几何形状。该转移项目的目的是增强先前项目的知识，并通过演示器将其转化为应用，该演示器是用于电力驱动部件的可重复使用的托盘。大面积托盘通常具有适合热成型的几何形状。然而，可用的非晶态热成型材料不能满足技术托盘的所有要求，例如当从注塑工艺中取出零件时，它们需要高耐热性。此外，还需要良好的耐磨性以确保可重复使用性。金属部件托盘通常需要额外的耐油和耐油脂化学性能。这些要求应通过使用交联半结晶热塑性塑料来满足。除了验证工业生产规模的结果之外，还出现了其他基本问题。首先，必须研究 PA12 的结果是否也适用于其他材料，如不同的聚酰胺、聚烯烃或聚酯。此外，还必须研究交联助剂、稳定剂或颜料等添加剂与高能辐射之间可能的相互作用，这些相互作用会影响板材的性能及其可加工性和所得部件的性能。此外，还必须测量板材加工对热成型性的影响以及热成型条件对零件性能的影响。这里研究的性能范围应扩大到包括半结晶热塑性塑料在应用中的一些相关优势，例如磨损行为或耐化学性。