Silva Sofia, Barbosa José M, Sousa João D, Paiva Maria C, Teixeira Paulo F
CeNTI-Centre for Nanotechnology and Smart Materials, R. Fernando Mesquita 2785, 4760-034 Vila Nova de Famalicão, Portugal.
Department of Polymer Engineering, Institute for Polymers and Composites, University of Minho, 4800-058 Guimarães, Portugal.
Polymers (Basel). 2024 Feb 21;16(5):583. doi: 10.3390/polym16050583.
High-performance engineering thermoplastics offer lightweight and excellent mechanical performance in a wide temperature range. Their composites with carbon nanotubes are expected to enhance mechanical performance, while providing thermal and electrical conductivity. These are interesting attributes that may endow additional functionalities to the nanocomposites. The present work investigates the optimal conditions to prepare polyether ether ketone (PEEK)/multi-walled carbon nanotube (MWCNT) nanocomposites, minimizing the MWCNT agglomerate size while maximizing the nanocomposite electrical conductivity. The aim is to achieve PEEK/MWCNT nanocomposites that are suitable for melt-spinning of electrically conductive multifilament's. Nanocomposites were prepared with compositions ranging from 0.5 to 7 wt.% MWCNT, showing an electrical percolation threshold between 1 and 2 wt.% MWCNT (10-10 S/cm) and a rheological percolation in the same range (1 to 2 wt.% MWCNT), confirming the formation of an MWCNT network in the nanocomposite. Considering the large drop in electrical conductivity typically observed during melt-spinning and the drawing of filaments, the composition PEEK/5 wt.% MWCNT was selected for further investigation. The effect of the melt extrusion parameters, namely screw speed, temperature, and throughput, was studied by evaluating the morphology of MWCNT agglomerates, the nanocomposite rheology, and electrical properties. It was observed that the combination of the higher values of screw speed and temperature profile leads to the smaller number of MWCNT agglomerates with smaller size, albeit at a slightly lower electrical conductivity. Generally, all processing conditions tested yielded nanocomposites with electrical conductivity in the range of 0.50-0.85 S/cm. The nanocomposite processed at higher temperature and screw speed presented the lowest value of elastic modulus, perhaps owing to higher matrix degradation and lower connectivity between the agglomerates. From all the process parameters studied, the screw speed was identified to have the higher impact on nanocomposite properties.
高性能工程热塑性塑料在很宽的温度范围内具有轻质且优异的机械性能。它们与碳纳米管的复合材料有望提高机械性能，同时具备热导率和电导率。这些都是有趣的特性，可能赋予纳米复合材料额外的功能。本工作研究了制备聚醚醚酮（PEEK）/多壁碳纳米管（MWCNT）纳米复合材料的最佳条件，在使MWCNT团聚体尺寸最小化的同时使纳米复合材料的电导率最大化。目标是获得适用于熔体纺丝制备导电复丝的PEEK/MWCNT纳米复合材料。制备了MWCNT含量在0.5至7 wt.%范围内的纳米复合材料，其电渗流阈值在1至2 wt.% MWCNT（10-10 S/cm）之间，流变渗流也在相同范围内（1至2 wt.% MWCNT），这证实了纳米复合材料中形成了MWCNT网络。考虑到在熔体纺丝和长丝拉伸过程中通常会观察到电导率大幅下降，选择了PEEK/5 wt.% MWCNT的组合物进行进一步研究。通过评估MWCNT团聚体的形态、纳米复合材料的流变学和电学性能，研究了熔体挤出参数（即螺杆转速、温度和产量）的影响。观察到较高的螺杆转速和温度曲线的组合会导致MWCNT团聚体数量减少且尺寸更小，尽管电导率略低。一般来说，所有测试的加工条件都能得到电导率在0.50 - 0.85 S/cm范围内的纳米复合材料。在较高温度和螺杆转速下加工的纳米复合材料呈现出最低的弹性模量值，这可能是由于基体降解程度更高以及团聚体之间的连通性更低。在所有研究的工艺参数中，螺杆转速对纳米复合材料性能的影响最大。
