High mechanical strength and low ablation rate of phenolic resin composites incorporated with polyhedral oligomeric silsesquioxane‐modified graphene oxide

Abstract

Hybrid composites of phenolic resin are prepared by incorporating graphene oxide (GO) functionalized with aminophenyl silsesquioxane (NH2‐OPS) for different functionalities. The covalent grafting of NH2‐POSS to GO is favorable for its homogeneous dispersion in the polymer matrix. For this purpose, GO is modified with NH2‐OPS to obtain GO‐3NH2‐OPS (GP‐3), GO‐5NH2‐OPS (GP‐5), GO‐8NH2‐OPS (GP‐8), according to the functionality of NH2‐OPS, respectively. The GP samples are then incorporated into phenolic resin (PR) to obtain PR/GP composites. The successful modification for GO with NH2‐OPS is confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy and specific surface and pore size analysis. The thermogravimetric analysis results show that the thermal stabilities of GP‐3, GP‐5 and GP‐8 are significantly increased compared with pure GO. Furthermore, the mechanical and ablative properties of the PR/GP composites are effectively enhanced. In particular, with the addition of 0.5 wt% GP‐5, the linear ablation rate of the PR/GP‐5 composite is reduced by 55.5% from 0.128 to 0.057 mm/s and the flexural strength is increased by 80.6% from 47.74 to 86.23 MPa, compared with pure PR.