Validation of experimental results for polyhedral oligomeric silsesquioxane, carbon nanotube and functionalized carbon nanotube/polymer nanocomposites through density functional theory study

The mechanical and thermal properties of polymer nanocomposites could be influenced by different parameters. Interfacial interaction between nanomaterial and polymer composite can effectively influence the properties of nanocomposite. In this paper, the interaction between carbon nanotube (CNT), functionalized carbon nanotube with Amin (CNT-Amin), and Polyhedral Oligomeric Silsesquioxane (POSS), absorbing on PA/EVA composite surface theoretically were investigated based on the density functional theory (DFT) calculations. The interaction energy of -36.64 kJ/mol between PA and CNT-Amin and -22.31 kJ/mol between EVA and CNT-Amin means that the absorption of CNT-Amin on PA and EVA monomer are stronger than CNT and POSS which could affect the mechanical and thermal properties of the nanocomposites. However, the interaction between the polymer composite and the nanomaterials was physisorption. Additionally, thermal and mechanical tests were conducted on nanocomposite samples. Thermal and mechanical results show that the DFT calculations are in good agreement with the experiment. DSC analysis shows that the melting temperature for PA in PA/EVA/CNT-Amin changed from 221.6 to 225.2 degrees C and crystallization temperature from 188.8 to 191.9 degrees C which illustrates that the CNT-Amin nanomaterial adsorbed to PA in PA/EVA composite. Finally, mechanical properties show that the modulus of PA/EVA/CNT-Amin nanocomposite changed from 307.4 to 327.2 MPa compared to neat PA/EVA composite emphasizing that the interaction between CNT-Amin nanomaterial and PA improves the strength of the nanocomposite and in addition, EVA adsorbs the CNT which affected the strain of the nanocomposite at break by 16 % which corresponds to the calculation result prediction.