Diekmann Astrid, Omelan Marvin C V, Giese Ulrich
Deutsches Institut für Kautschuktechnologie e. V., Eupener Straße 33, 30519 Hannover, Germany.
Polymers (Basel). 2021 Apr 21;13(9):1355. doi: 10.3390/polym13091355.
Incorporating nanofillers into elastomers leads to composites with an enormous potential regarding their properties. Unfortunately, nanofillers tend to form agglomerates inhibiting adequate filler dispersion. Therefore, different carbon nanotube (CNT) pretreatment methods were analyzed in this study to enhance the filler dispersion in polydimethylsiloxane (PDMS)/CNT-composites. By pre-dispersing CNTs in solvents an increase in electrical conductivity could be observed within the sequence of tetrahydrofuran (THF) > acetone > chloroform. Optimization of the pre-dispersion step results in an AC conductivity of 3.2 × 10 S/cm at 1 Hz and 0.5 wt.% of CNTs and the electrical percolation threshold is decreased to 0.1 wt.% of CNTs. Optimum parameters imply the use of an ultrasonic finger for 60 min in THF. However, solvent residues cause a softening effect deteriorating the mechanical performance of these composites. Concerning the pretreatment of CNTs by physical functionalization, the use of surfactants (sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylene lauryl ether ("Brij35")) leads to no improvement, neither in electrical conductivity nor in mechanical properties. Chemical functionalization enhances the compatibility of PDMS and CNT but damages the carbon nanotubes due to the oxidation process so that the improvement in conductivity and reinforcement is superimposed by the CNT damage even for mild oxidation conditions.
将纳米填料加入到弹性体中可得到具有巨大性能潜力的复合材料。不幸的是，纳米填料往往会形成团聚物，抑制填料的充分分散。因此，本研究分析了不同的碳纳米管（CNT）预处理方法，以提高聚二甲基硅氧烷（PDMS）/CNT复合材料中填料的分散性。通过将碳纳米管预分散在溶剂中，在四氢呋喃（THF）>丙酮>氯仿的顺序中可观察到电导率增加。预分散步骤的优化导致在1 Hz和0.5 wt.%的碳纳米管含量下，交流电导率为3.2×10 S/cm，并且渗流阈值降低到0.1 wt.%的碳纳米管含量。最佳参数意味着在THF中使用超声探头60分钟。然而，溶剂残留会产生软化效应，使这些复合材料的机械性能恶化。关于通过物理功能化对碳纳米管进行预处理，使用表面活性剂（十二烷基苯磺酸钠（SDBS）和聚氧乙烯月桂醚（“Brij35”））在电导率和机械性能方面均未带来改善。化学功能化增强了PDMS与CNT的相容性，但由于氧化过程会损害碳纳米管，因此即使在温和的氧化条件下，碳纳米管的损伤也会叠加在电导率和增强效果的改善之上。
