Mechanical characterization and induced crystallization in nanocomposites of thermoplastics and carbon nanotubes

Abstract

Nanocomposites built from polymers and carbon nanotubes (CNTs) are a promising class of materials. Computer modeling can provide nanoscale views of the polymer–CNT interface, which are much needed to foster the manufacturing and development of such materials. However, setting up periodic nanocomposite models is a challenging task. Here we propose a computational workflow based on Molecular Dynamics simulations. We demonstrate its capabilities and showcase its applications, focusing on two existing nanocomposite materials: polystyrene (PS) with CNT and polyether ether ketone with CNT. The models provide insights into the polymer crystallization inside CNTs. Furthermore, the PS+CNT nanocomposite models are mechanically tested and able to predict an enhancement in Young’s modulus due to the addition of highly dispersed CNTs. We accompany those results with experimental tests and provide a prediction model based on Dynamic Quantized Fracture Mechanics theory. Our study proposes representative simulations of polymer–CNT nanocomposites as promising tools to guide the rational design of this class of materials.

Computational Design for the Damping Characteristics of Poly(ether ether ketone)

“…With respect to the content of functional groups, the densities of PEEK derivatives modified with different functional groups is provided in Figure b. The density of pristine PEEK is 1214 kg/m 3 , which agrees with the experimental findings in the literature and the MD computational results in the literature . As the content of some functional groups (−OH, −NH 2 , −F, −COOH, and −SO 3 H) increases, the densities of the modified PEEK derivatives increases linearly.…”

“…Successive NVT ensemble and NPT ensemble relaxation simulations are performed twice for 400 ps, 42 (Figure 1a). The dimensions and density of the equilibrated model are 6.2 nm × 6.2 nm × 6.2 nm and 1.23 g/cm 3 , respectively, which is consistent with the experimental result of 1.26 g/cm 3 .…”

“…The density of pristine PEEK is 1214 kg/m 3 , which agrees with the experimental findings in the literature 47 and the MD computational results in the literature. 3 As the content of some functional groups (−OH, −NH 2 , −F, −COOH, and −SO 3 H) increases, the densities of the modified PEEK derivatives increases linearly. In contrast, as the content of other functional groups (−CH 3 and −C 6 H 5 ) increases, the densities of the modified PEEK derivatives decreases linearly.…”

“…Because of the outstanding mechanical properties − and low manufacturing cost, , thermoplastic polymers have been extensively investigated as damping materials in passive vibration elements for advanced equipment . Poly­(ether ether ketone) (PEEK) has gained a great deal of attention due to its mechanical stability, − dynamic fatigue, and impact resistance under high working temperatures.…”

Multiscale Friction Simulation of Dry Polymer Contacts: Reaching Experimental Length Scales by Coupling Molecular Dynamics and Contact Mechanics

“…Here, we consider Poly-Ether-Ether-Ketone (PEEK), a semicrystalline thermoplastic with outstanding mechanical properties, thermal stability, and chemical resistance, thus constituting an excellent material for bearing and sealing applications. Few MD studies exist for this material, mostly focused on its structural [21,22] and mechanical properties [23,24], but not on its tribological performance. In this open field, we will investigate what insights MD can provide into friction at the molecular scale, and especially on the shear strength of adhesive junctions.…”