Fedorenko Elena, Luinstra Gerrit A
Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany.
Polymers (Basel). 2025 Jan 1;17(1):90. doi: 10.3390/polym17010090.
Carbon-fiber-reinforced composites of ultra-high-molecular-weight polyethylene (UHMWPE) are not easily prepared because of their high viscosity, although they can be advantageous in advanced engineering applications due to their superior mechanical properties in combination with their low specific weight and versatility. Short polyacrylonitrile-based carbon-fiber-reinforced UHMWPE composites with fiber contents of 5, 10, and 15 wt.% could easily be prepared using in situ ethylene polymerization. Therefore, MgCl was generated at the Brønsted acidic groups of the fiber surface by employing a reaction between the co-catalysts Mg(CH) and AlEtCl. Titanation with TiCl resulted in a catalyst directly on the fiber surface. The catalyst polymerized ethylene (2 bar pressure at 50 °C), forming a UHMWPE matrix near the surface; its fragmentation led to polymer particles associated with the fiber. The catalyst activity on the fiber surface of untreated (CF-Pr, 3.48 ± 0.24 wt.%) and oxidized fibers (CF-Ox, 7.41 ± 0.03 wt.%) was 20% lower. CF-Pr compression-molded samples showed tensile strengths of up to 50.4 ± 1.3 MPa, while CF-Ox samples reached 39.1 ± 0.6 MPa, surpassing the performance of composites prepared by melt compounding. The stiffness of 1.58 ± 0.17 GPa for a melt-compounded material was lower than the 3.24 ± 0.10 GPa for CF-Pr and 2.19 ± 0.07 GPa for CF-Ox composites. A fracture examination showed fiber pull-outs, matrix residues on the fibers, and the formation of some extensional polymer fibrils. The latter explains the higher stress at yield and the breakage of the CF-Pr based composites in particular. The potential of in situ polymerized UHMWPE composites for the utilization in high-performance structural applications is thus demonstrated.
超高分子量聚乙烯（UHMWPE）的碳纤维增强复合材料由于其高粘度而不易制备，尽管由于其优异的机械性能、低比重和多功能性，它们在先进工程应用中可能具有优势。使用原位乙烯聚合可以轻松制备纤维含量为5%、10%和15%（重量）的短聚丙烯腈基碳纤维增强UHMWPE复合材料。因此，通过助催化剂Mg(CH)和AlEtCl之间的反应，在纤维表面的布朗斯台德酸性基团处生成了MgCl。用TiCl进行钛化处理，直接在纤维表面形成了催化剂。该催化剂使乙烯聚合（50℃、2巴压力），在表面附近形成UHMWPE基体；其破碎导致与纤维相关的聚合物颗粒。未处理纤维（CF-Pr，3.48±0.24%（重量））和氧化纤维（CF-Ox，7.41±0.03%（重量））表面的催化剂活性低20%。CF-Pr压缩模塑样品的拉伸强度高达50.4±1.3MPa，而CF-Ox样品达到39.1±0.6MPa，超过了通过熔融共混制备的复合材料的性能。熔融共混材料的刚度为1.58±0.17GPa，低于CF-Pr复合材料的3.24±0.10GPa和CF-Ox复合材料的2.19±0.07GPa。断裂检查显示有纤维拔出、纤维上的基体残留物以及一些拉伸聚合物原纤维的形成。后者解释了特别是基于CF-Pr的复合材料在屈服时的较高应力和断裂。因此，证明了原位聚合的UHMWPE复合材料在高性能结构应用中的利用潜力。
