High performance polyurethane nanocomposite films prepared from a masterbatch of graphene oxide in polyether polyol

• A masterbatch of GO in polyol was prepared and used for the preparation of PU composites.
• Grafted PU chain on the surface of GO was facilitated the stress transfer benefit between matrix and filler.
• The effect of GO on the strain hardening of PU was investigated.
• The improvement of tensile strength without sacrificing the elongation of PU composites was most significant ever reported.

A masterbatch of graphene oxide (GO) in polyol was prepared and used for the preparation of polyurethane (PU)/GO nanocomposites by bulk in-situ polymerization. The prepared nanocomposites were characterized in terms of their thermal, mechanical, and morphological properties as a function of GO loading. Here, grafted PU chains on the surface of GO facilitated the beneficial stress transfer from the PU matrix to GO. This stress transfer occurs due to the reaction of the hydroxyl and carboxyl groups of GO with the isocyanate groups of 4,4′-methylene diphenyl diisocyanate (MDI) and the PU pre-polymer. The Young’s modulus of the PU was improved by 280.5% through the incorporation of 3 wt% GO. Additionally, an improvement of 40.5% in the tensile strength and 19% in the elasticity was achieved at 1 wt% GO. Strain hardening of PU was improved with GO loadings up to 1 wt% due to the synergetic orientation of the soft segment and the PU-grafted GO in the strain direction. However, the large increase in cross-link density that occurred at 2 wt% GO prevented strain hardening, and the ultimate tensile strength decreased. The Halpin–Tsai model was used to predict the orientation of GO in PU nanocomposites. The randomly oriented 3D arrangement of GO in PU showed better agreement between the theoretically calculated and experimentally determined moduli compared to the 2D alignment. These results demonstrate that the preparation of PU nanocomposites using masterbatch dilution is an excellent method to attain well-dispersed GO. This technique can also be used to overcome the environmental problems associated with volatile organic compound (VOC) emission, as well as addressing some of the difficulties found in the plastics processing industry.

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