Tensile and tear properties of high density polyethylene/organo-fluoromica nanocomposites

Abstract

Polymer nanocomposite can be produced through combination of organic polymer matrix with dispersed inorganic nanofillers. In this study, fluoromica was employed as inorganic nano filler to reinforce high density polyethylene (HDPE) matrix. Optimum nano filler loading to improve mechanical properties of the HDPE nanocomposite was investigated. The fluoromica was first surface modified through ion exchange method using dimethyldioctadecylammonium chloride (DODMAC) to obtain organically modified fluoromica (organo-fluoromica) with hydrophobic surface characteristic. The organo-fluoromica was incorporated into HDPE matrix in 0, 1, 2 and 4 wt%, melt mixed using twin screw extruder and compressed into sheets. The resultant HDPE/organo-fluoromica nanocomposites were subjected to the mechanical tests (tensile and tear tests). Results indicate that the HDPE nanocomposites with 2wt% of organo-fluoromica (HDPEOF2) possesses the highest tensile strength which is 23.72 MPa. The value is ∼15% higher than the neat HDPE. This was due to the good interactions between the organo-fluoromica nanofiller with the HDPE matrix. The surface modification produced hydrophobic nano filler for improving its compatibility with the hydrophobic HDPE matrix. Accordingly, elongation at break of the nanocomposite reduced while the Young’s modulus increased. This was caused by the restricted molecular motion of the HDPE chains as a result of nanofiller-matrix interactions. Findings also indicate that the use of nanofiller greater than 2wt% decreases the mechanical properties of the HDPE due to filler-filler interaction and therefore reducing the contact surface between the clay and the polymer matrix. Furthermore, the stiffness of the HDPE nanocomposite increased as concentration of nanofiller increased. The result of tear test follows the trend of tensile test, where the HDPE nanocomposite with 2wt% organo-fluoromica shows the best tear property. The tear strength of HDPEOF2 nanocomposites is found to be increased by 8.14% when benchmarked with the neat HDPE. This may be due to nanometric dispersion of the silicate layers and enhancement in nanofiller-matrix interactions that can improve the tearing resistance of the HDPE. The findings of this study revealed the potential of organo-fluoromica as reinforcing filler in the HDPE nanocomposite system, thus demand further research and development in this particular area.