Volumetric composition of nanocomposites

Detailed characterisation of the properties of composite materials with nanoscale fibres is central for the further progress in optimization of their manufacturing and properties. In the present study, a methodology for the determination and analysis of the volumetric composition of nanocomposites is presented, using cellulose/epoxy and aluminosilicate/polylactate nanocomposites as case materials.

The buoyancy method is used for the accurate measurements of materials density. The accuracy of the method is determined to be high, allowing the measured nanocomposite densities to be reported with 5 significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials.

The known gravimetric composition of the nanocomposites is converted into a volumetric composition. An analytical model, previously established for conventional fibre composites, is used for the analysis of the volumetric composition. For the aluminosilicate/polylactate nanocomposites, based on the established linear relationship between the porosity content and the fibre volume content, the fibre correlated porosity factor is determined to be 0.18.

Geometrical considerations of the packing of parallel nanofibres in a square array are used to make the assumption that the maximum obtainable fibre volume content in the nanocomposites will not exceed 6 % due to the small fibre spacing that restricts full matrix impregnation. The predicted volumetric composition and density of the aluminosilicate/polylactate nanocomposites is in good agreement with the experimental data.

It is demonstrated that the model provides a valuable tool for the prediction and analysis of the volumetric composition of composites with nanoscale fibres.