The quantification of anisotropy in graphene/natural rubber nanocomposites: Evaluation of the aspect ratio, concentration, and crosslinking

Abstract

In the processing of nanocomposites, high shear stresses at elevated temperatures orient two‐dimensional nanoparticles like graphene. This orientation leads to anisotropic mechanical, thermal or barrier properties of the nanocomposite. This anisotropy is addressed in this study by comparing graphene (few‐layer graphene, FLG) with a nanoscaled carbon black (nCB) at a filler content of 3 phr, by varying the vulcanization, and by comparing different FLG contents. Transmission electron microscopy gives insight into the qualitative orientation in the nanocomposite with FLG or nCB. The storage moduli parallel and normal to the orientation reveal the direction dependency of reinforcement through dynamic mechanical analysis (DMA). Dimensional swelling measurements show a restriction of the expansion parallel to the FLG orientation, and an increased expansion normal to the orientation. The vulcanization system and crosslinking determine the respective level of property values, and higher crosslinking densities increase the anisotropy in DMA resulting in values of up to 2.9 for the quantified anisotropy factor. With increasing FLG content, the anisotropy increases. A comparison of the results reveals swelling measurements as the most suitable method for the determination of anisotropy. Compared to recent literature, the presented processing induces higher anisotropy, leading to higher reinforcing effects in the direction of orientation.

Functional and Environmental Friendly Polyimine Elastomer Based on the Dynamic Covalent Network for a Flexible Strain Sensor

“…Besides, T g obtained from the differential scanning calorimetry (DSC) test also showed the same tendency (Figure S2). According to rubber elasticity theory, the cross-linking density (υ e ) of the elastomer is directly proportional to E ′ at the rubbery plateau ( T g + 40 K). , Therefore, υ e was calculated and is presented in Table . The υ e values of the PE0.5-0.2, PE0.5-0.5, and PE0.5-1.0 were 312, 392, and 619 mol m –3 , respectively, which was consistent with the tendency of the TFB ratio to increase.…”

Synergistic effects of graphite and carbon nanotube hybrid fillers on key properties of epoxidized natural rubber nanocomposites

“…These improvements are achieved by incorporating various nano llers. Carbon nanoparticles such as conductive carbon black [3], carbon nanotubes (CNTs) [4], graphene [5], graphene oxide [6], and graphite [7] have been employed to prepare NR nanocomposites. In NR-CNT nanocomposites, the formation of three-dimensional (3D) ller networks commonly occurs after reaching the percolation threshold concentration (PTC).…”