Disentangled UHMWPE composites for warp-free SLS parts

该项目的目标是在SLS中制备和使用定制的聚合物复合颗粒，从而产生具有扩展性能的SLS部件，特别是为了克服目前有限的层间粘附。将原位聚合技术用于功能粉末的生产和模拟支持的SLS零件工艺优化相结合，是提高零件机械稳定性和尺寸稳定性的方法。在第一种方法中，将制备和烧结具有解缠超高分子量聚乙烯的单壁碳纳米管纳米复合材料粉末。这将导致基于超高分子量聚乙烯的部件；由于其优异的机械和化学稳定性，选择后者作为零件的材料。预计在烧结过程中缠结的形成将导致颗粒之间更高的附着力，这也是由起始复合材料的较低粘度所决定的。将建立一个数值模拟，验证并采用热像仪记录的数据。然后，通过模拟评估的温度分布将与材料特定的结晶行为相关联。在此基础上，通过调温可以避免结晶不均匀和翘曲。随后，SLS部件的材料性能将被确定，并与常规模制超高分子量聚乙烯纳米复合材料等参考材料进行比较。这样就建立了一个关于材料性能和工艺参数的反馈和优化循环。

The proposed project targets the preparation and use of tailor-made polymer composite particles in SLS, allowing to generate SLS parts with extended properties, in particular with the aim to overcome the current limited interlayer adhesion. The combination of in-situ polymerization techniques for the production of functional powders and simulation supported process optimization for generating SLS parts is the approach to reach improved mechanical and dimensional stability of the resulting parts. In a first approach, single-walled CNT nanocomposites powders with disentangled UHMWPE will be prepared and sintered. This would lead to parts based on UHMWPE; latter was chosen as material for the parts on account of the outstanding mechanical and chemical stability. It is expected that the formation of entanglement in the sintering process will lead to a much higher adhesion between the particles, also given by the lower viscosity of the starting composite.A numerical simulation will be established validated and adapted by data recorded from a thermal camera. Then the temperature distribution assessed by the simulation will be correlated to the material-specific crystallization behavior. Based on this correlation inhomogeneous crystallization and thus warpage will be avoided by means of post-build temperature adjustments.Subsequently, the material properties of SLS parts will be determined, compared against reference materials like commonly molded UHMWPE nanocomposites. A feedback and optimization loop will be thus established regarding material properties and process parameter.