Mohoppu Madara, Ayan Utsab, Schwartz Jacob, Al-Ostaz Ahmed, Ucak-Astarlioglu Mine G, Villacorta Byron S
Department of Chemical Engineering, University of Mississippi School of Engineering, University, Mississippi 38677, United States.
Center for Graphene Research and Innovation, University of Mississippi School of Engineering, University, Mississippi 38677, United States.
ACS Omega. 2024 Nov 25;9(49):48546-48562. doi: 10.1021/acsomega.4c07372. eCollection 2024 Dec 10.
A cutting-edge method that uses electromagnetic (EM) energy for the melt processing of thermoplastic polymer nanocomposites (TPNCs) is reported. The properties and microstructures of TPNCs produced via the proposed EM-processing method and TPNCs via conventional heat processing are contrasted. The EM-processed TPNCs prepared with EM-susceptible carbon nanotubes (CNTs) exhibited a significant enhancement in transport and mechanical properties, outperforming the conventionally processed TPNCs. Thus, the EM-processed TPNCs demonstrated an ultralow electrical percolation threshold (∼0.09 vol %) and a remarkable increase in volume electrical conductivity of 8 orders of magnitude (i.e., 1.1 × 10 S/m) at only 1.0 wt % CNT loading, compared to their hot-pressed counterparts. This highlights the superior network formation, level of segregation, and structuring enabled by EM processing. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) revealed that EM-processed TPNCs exhibited higher crystallinity (∼9% higher) and a predominantly α crystal phase compared to the hot-pressed TPNCs. Microstructural inspection by electron microscopy disclosed that EM processing led to segregated but interconnected multiscale networks of a thin and well-defined CNT interphase that encompassed from the nanoscale of the CNTs to the macroscopic scale of TPNCs. In contrast, conventional processing developed a more diffused CNT interphase with less interconnectivity. The EM-processed TPNCs developed a statistically higher stiffness (+20%) and in certain cases, even better strength (+10%) than the hot-pressed TPNCs. However, the EM-processed TPNCs displayed significantly lower ductility, owing to their higher crystallinity, more brittle crystal α phase, and the potential formation of microvoids in the bulk of the TPNCs inherent to the unoptimized EM processing. This work provides an understanding of an alternative and unconventional processing method capable of achieving higher structuring in nanocomposites with advanced multifunctional properties.
报道了一种利用电磁（EM）能量对热塑性聚合物纳米复合材料（TPNCs）进行熔体加工的前沿方法。对比了通过所提出的电磁加工方法生产的TPNCs和通过传统热加工生产的TPNCs的性能和微观结构。用对电磁敏感的碳纳米管（CNTs）制备的电磁加工TPNCs在传输和机械性能方面有显著提高，优于传统加工的TPNCs。因此，电磁加工的TPNCs表现出超低的电渗流阈值（约0.09体积%），并且在仅1.0重量%的CNT负载量下，与热压对应物相比，体积电导率显著增加了8个数量级（即1.1×10 S/m）。这突出了电磁加工所实现的优异网络形成、相分离水平和结构。差示扫描量热法（DSC）和X射线衍射（XRD）表明，与热压TPNCs相比，电磁加工的TPNCs表现出更高的结晶度（约高9%）和主要为α晶相。通过电子显微镜进行的微观结构检查表明，电磁加工导致了由薄且定义明确的CNT界面组成的分离但相互连接的多尺度网络，该网络从CNT的纳米尺度延伸到TPNCs的宏观尺度。相比之下，传统加工形成的CNT界面更弥散，相互连接性更低。电磁加工的TPNCs在统计上表现出更高的刚度（+20%），在某些情况下，甚至比热压TPNCs具有更好的强度（+10%）。然而，由于其更高的结晶度、更脆的α晶相以及未优化的电磁加工导致TPNCs本体中潜在形成的微孔，电磁加工的TPNCs表现出显著更低的延展性。这项工作有助于理解一种能够在具有先进多功能特性的纳米复合材料中实现更高结构的替代且非常规的加工方法。
