Khalil Yas, Hopkinson Neil, Kowalski Adam J, Fairclough John Patrick A
Department of Mechanical Engineering, University of Sheffield, Sheffield S3 7HQ, UK.
Stratasys Ltd., 5-6 William Lee Buildings, Science Park, Nottingham NG7 2RQ, UK.
Polymers (Basel). 2022 Aug 15;14(16):3320. doi: 10.3390/polym14163320.
Activated Carbon (AC) is widely available at a relatively low cost, has a high porosity and is commonly used as a filter material for a range of applications. However, it is a brittle and friable material. Ultra-High Molecular Weight Polyethylene (UHMWPE) polymer is a tough engineering plastic that has been used as a binder. The traditional method used in manufacturing AC/UHMWPE filters involves compressing AC/UHMWPE composite powder during heating in a mould. This process compresses the particles together and the materials undergo sintering. This process results in a low pore interconnectivity, which has a considerable impact on the filter's efficiency. Selective Laser Sintering is a laser powder bed fusion additive manufacturing technique for polymers. This has a number of advantages compared to the conventional technique and produces a porous structure with improved filtration efficiency. We propose that this is due to the greater pore interconnectivity. In this work, AC/UHMWPE powdered composites were prepared with different AC and UHMWPE ratios. The structure and properties of the AC/UHMWPE composite were investigated and characterised to assess their suitability for selective laser sintering. Particle size and morphology analysis were conducted, as well as density measurements, powder flow, thermal analysis, and crystallinity measurements. The results reveal that the addition of AC improves the UHMWPE flow. The thermal analysis results show that the intrinsic thermal properties of UHMWPE powder are not significantly affected by the introduction of activated carbon. However, thermal gravimetric analysis revealed that the onset of mass loss is considerably shifted (20 °C) to higher temperatures for the AC/UHMWPE composites, which is favourable for laser sintering. Additionally, the change in the composition ratio of untreated composite does not have a significant effect on the degree of crystallinity. Laser-sintered AC/UHMWPE parts were successfully manufactured using a commercial laser-sintering machine.
活性炭（AC）成本相对较低，易于获取，具有高孔隙率，常用于一系列应用的过滤材料。然而，它是一种脆性易碎材料。超高分子量聚乙烯（UHMWPE）聚合物是一种坚韧的工程塑料，已被用作粘结剂。制造AC/UHMWPE过滤器的传统方法是在模具中加热时压缩AC/UHMWPE复合粉末。这个过程将颗粒压缩在一起，材料发生烧结。这个过程导致孔隙连通性低，对过滤器的效率有相当大的影响。选择性激光烧结是一种用于聚合物的激光粉末床熔融增材制造技术。与传统技术相比，它有许多优点，并能产生具有更高过滤效率的多孔结构。我们认为这是由于更大的孔隙连通性。在这项工作中，制备了不同AC与UHMWPE比例的AC/UHMWPE粉末复合材料。对AC/UHMWPE复合材料的结构和性能进行了研究和表征，以评估它们对选择性激光烧结的适用性。进行了粒度和形态分析，以及密度测量、粉末流动性、热分析和结晶度测量。结果表明，AC的加入改善了UHMWPE的流动性。热分析结果表明，活性炭的引入对UHMWPE粉末的固有热性能没有显著影响。然而，热重分析表明，AC/UHMWPE复合材料的质量损失起始温度显著升高（20℃），这有利于激光烧结。此外，未处理复合材料的组成比例变化对结晶度没有显著影响。使用商用激光烧结机成功制造了激光烧结的AC/UHMWPE零件。
