Thermally activated energy dissipation in semi-crystalline polymer nanocomposites

Abstract

In this manuscript, we demonstrate the concept of active damping in semi-crystalline thermoplastics which are reinforced with a percolated network of CNTs, where the damping of the composite was augmented considerably, controllably and reversibly via Joule heating. The Joule heating triggered relaxation mechanisms in the amorphous phase of the matrix. To this end, semi-crystalline poly ether ether ketone (PEEK) polymer and PEEK/carbon nanotube (CNT) composites were fabricated and their viscoelastic properties studied. The damping capability was experimentally tested by dynamic mechanical analysis. The polymer relaxation resulting from an increase in temperature, triggered by the Joule heating of the nanoparticles, demonstrated the potential for damping enhancement in the composite. A considerable enhancement in damping (by as much as 400%) was achieved at a significantly lower relative loss in storage modulus (40%), both caused by relaxation mechanisms in Joule heated samples. This enhancement in damping corresponds to a 150% improvement in the figure of merit for damping materials. The non-uniform temperature distribution in the sample was measured experimentally at the macroscale and estimated via continuum models at the microscale. It was concluded that non-uniform temperature distribution in the composite, especially at the microscale, had a large effect on the overall damping enhancement. Based on the microscale models, potential mechanisms by which the active damping can be enhanced are discussed.

Non-Isothermal Crystallization Kinetics of Polyether-Ether-Ketone Nanocomposites and Analysis of the Mechanical and Electrical Conductivity Performance

“…To fully leverage the superior properties of the PEEK matrix, the functionalities can be further tailored by incorporating with high-performance fibers. So far, a number of reinforcement fibers have been utilized to increase the intrinsic strength of the PEEK matrix, including carbon fiber (CF) [ 2 , 3 ], carbon black (CB) [ 4 ], boron nitride (BN) [ 5 , 6 ], carbon nanotubes (CNTs) [ 7 , 8 ], etc. Of all the fillers under consideration, CNTs have attracted significant attention due to their low density, high tensile strength and elastic modulus.…”