Thermal, Mechanical, and Morphological Characterisations of Graphene Nanoplatelet/Graphene Oxide/High-Hard-Segment Polyurethane Nanocomposite: A Comparative Study

Polymers (Basel). 2022 Oct 9;14(19):4224. doi: 10.3390/polym14194224.

Abstract

The current work investigates the effect of the addition of graphene nanoplatelets (GNPs) and graphene oxide (GO) to high hard-segment polyurethane (75% HS) on its thermal, morphological, and mechanical properties. Polyurethane (PU) and its nanocomposites were prepared with different ratios of GNP and GO (0.25, 0.5, and 0.75 wt.%). A thermal stability analysis demonstrated an enhancement in the thermal stability of PU with GNP and GO incorporated compared to pure PU. Differential Scanning Calorimetry (DSC) showed that both GNP and GO act as heterogeneous nucleation agents within a PU matrix, leading to an increase in the crystallinity of PU. The uniform dispersion and distribution of GNP and GO flakes in the PU matrix were confirmed by SEM and TEM. In terms of the mechanical properties of the PU nanocomposites, it was found that the interaction between PU and GO was better than that of GNP due to the functional groups on the GO's surface. This leads to a significant increase in tensile strength for 0.5 wt.% GNP and GO compared with pure PU. This can be attributed to interfacial interaction between the GO and PU chains, resulting in an improvement in stress transferring from the matrix to the filler and vice versa. This work sheds light on the understanding of the interactions between graphene-based fillers and their influence on the mechanical properties of PU nanocomposites.

Keywords: graphene nanoplatelets; graphene oxide; high hard-segment polyurethane; mechanical properties; nanocomposites; thermal stability.

Grants and funding

The financial support for this project was given by the Ministry of Higher Education and Scientific Research of Iraq (Grant No. 1033). The authors are also grateful to Diamond Light Source (Didcot, UK) for providing beam times (SM15246 and SM15478). J.K.W. gratefully acknowledges the Northwest Nanoscience Doctoral Training Centre (NOWNANO DTC grant no.: EP/G03737X/1. A.S. gratefully acknowledges funding from the EPSRC (Fellowship grant no.: EP/K016210/1).