Full elastic constitutive relation of non-isotropic aligned-CNT/PDMS flexible nanocomposites

Abstract

The elastic response of vertically aligned-carbon nanotube/polydimethylsiloxane (A-CNT/PDMS) nanocomposites is presented in this study and related to the underlying aligned-CNT morphology. Multiwalled carbon nanotubes (MWCNTs) at 1% Vf are embedded in a flexible substrate of PDMS to create a flexible polymer nanocomposite (PNC). The PNC properties are evaluated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile mechanical tests, and the full linearly elastic constitutive relation is established for such a PNC. The results suggest that the CNTs retain the alignment after wetting and curing of PDMS. PDMS is significantly modified by the reinforcing aligned-CNT fibers, demonstrating non-isotropic (as opposed to the isotropic neat PDMS) elastic properties all different from PDMS (Young's modulus of 0.8 MPa), including an anisotropy ratio of 4.8 and increases in the modulus of A-CNT/PDMS over PDMS by more than 900% and 100%, in the CNT longitudinal and transverse directions, respectively. This study reports the first full constitutive relation that may be useful in modeling PNCs as composites or as elements of hierarchical nanoengineered composites, particularly PDMS-CNT PNCs are envisioned as elements in biomedical devices such as pressure transducers and energy harvesters.

Temperature dependent compressive behavior of graphene mediated three-dimensional cellular assembly

“…In the glassy state, an addition of 5% CNT enhances the storage modulus by 49% for aligned composite and 10% for randomly aligned [24]. CNT based composites with the polydimethyl siloxane polymer (PDMS) were also found to reveal the frequency dependence over a wide range of 1-80 Hz [25] where the storage modulus was enhanced by 26.3% at 1 Hz and 28% at 80 Hz as compared to pure PDMS. Xu et [26].…”

Three-dimensional elastic constitutive relations of aligned carbon nanotube architectures

“…To map the evolution of strain in the tensile tests with a high degree of accuracy, DIC was performed using the Vic 2D software from Correlated Solutions, Inc. This method is well known for its high resolution, 37 and was recently used to determine the moduli (elastic and shear), 38 and Poisson ratios, 38,39 of low V f ( 1 vol. % CNTs) polymer composites.…”

Morphology and processing of aligned carbon nanotube carbon matrix nanocomposites

“…These materials can be produced through the heat treatment (pyrolysis) of aligned nanofiber polymer matrix nanocomposite (A-PNC) precursors, which are analogous to the APNCs reported elsewhere [15][16][17][18][19][20][21][22][23][24] . Such processing follows the typical synthesis routes of polymer derived ceramics [25][26][27][28] , but relies on capillary [15][16][17][18][19][20][21] or vacuum [21][22][23][24] assisted wetting of the aligned nanofibers rather than surfactant or functionalization assisted mixing. In order to manufacture aligned nanofiber carbon matrix nanocomposites (A-CMNCs) with tailored properties, the porosity of the matrix, which strongly influences its material properties, must be controlled.…”