Azubuike Lilian, Sundararaj Uttandaraman
Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
Materials (Basel). 2021 Aug 25;14(17):4813. doi: 10.3390/ma14174813.
The process of strengthening interfaces in polymer blend nanocomposites (PBNs) has been studied extensively, however a corresponding significant enhancement in the electrical and rheological properties is not always achieved. In this work, we exploit the chemical reaction between polystyrene maleic anhydride and the amine group in nylon (polyamide) to achieve an in-situ compatibilization during melt processing. Herein, nanocomposites were made by systematically adding polystyrene maleic anhydride (PSMA) at different compositions (1-10 vol%) in a two-step mixing sequence to a Polystyrene (PS)/Polyamide (aPA) blend with constant composition ratio of 25:75 (PS + PSMA:aPA) and 1.5 vol% carbon nanotube (CNT) loading. The order of addition of the individual components was varied in two-step mixing procedure to investigate the effect of mixing order on morphology and consequently, on the final properties. The electrical and rheological properties of these multiphase nanocomposite materials were investigated. The optical microscope images show that for PS/aPA systems, CNTs preferred the matrix phase aPA, which is the thermodynamically favorable phase according to the wettability parameter calculated using Young's equation. However, aPA's great affinity for CNT adversely influenced the electrical properties of our blend. Adding PSMA to PS/aPA changed the structure of the droplet phase significantly. At 1.5 vol% CNT, a more regular and even distribution of the droplet domains was observed, and this produced a better framework to create more CNT networks in the matrix, resulting in a higher conductivity. For example, with only 1.5 vol% CNT in the PBN, at 3 vol% PSMA, the conductivity was 7.4 × 10 S/m, which was three and a half orders of magnitude higher than that seen for non-reactive PS/aPA/CNT PBN. The mechanism for the enhanced conductive network formation is delineated and the improved rheological properties due to the interfacial reaction is presented.
聚合物共混纳米复合材料（PBNs）中增强界面的过程已得到广泛研究，然而，电性能和流变性能并非总能相应地显著提高。在这项工作中，我们利用聚苯乙烯马来酸酐与尼龙（聚酰胺）中的胺基之间的化学反应，在熔融加工过程中实现原位增容。在此，通过在两步混合过程中以不同组成（1 - 10体积%）系统地添加聚苯乙烯马来酸酐（PSMA）到具有25:75恒定组成比（PS + PSMA:aPA）且碳纳米管（CNT）负载量为1.5体积%的聚苯乙烯（PS）/聚酰胺（aPA）共混物中，制备了纳米复合材料。在两步混合过程中改变各组分的添加顺序，以研究混合顺序对形态的影响，进而对最终性能的影响。研究了这些多相纳米复合材料的电性能和流变性能。光学显微镜图像显示，对于PS/aPA体系，CNTs更倾向于基体相aPA，根据使用杨氏方程计算的润湿性参数，这是热力学上有利的相。然而，aPA对CNT的强亲和力对我们共混物的电性能产生了不利影响。向PS/aPA中添加PSMA显著改变了液滴相的结构。在1.5体积% CNT时，观察到液滴域分布更规则、更均匀，这产生了一个更好的框架，以便在基体中形成更多的CNT网络，从而导致更高的电导率。例如，在PBN中仅含有1.5体积% CNT时，在3体积% PSMA时，电导率为7.4×10 S/m，比非反应性PS/aPA/CNT PBN高三个半数量级。阐述了增强导电网络形成的机制，并介绍了由于界面反应导致的流变性能改善。
