High density polyethylene/cenosphere composites reinforced with multi-walled carbon nanotubes: Mechanical, thermal and fire retardancy studies

• HDPE/fly ash cenospheres/MWCNT nanocomposites were developed.
• Cenospheres and MWCNT together exhibits synergistic effect with enhances fire retardancy.
• The modulus and strength values improved by adding cenospheres and MWCNT.
• The thermal stability also improved due to the addition of cenospheres.

Nanocomposites of high density polyethylene (HDPE) along with lightweight hollow fly ash cenospheres and acid functionalized multi-walled carbon nanotubes (MWCNT) have been developed. In order to enhance the interfacial adhesion, an epoxy functionalized HDPE has been added to the composites while the cenospheres have been surface modified using aminosilane coupling agent. Improvement in mechanical properties for the nanocomposites using both cenospheres and MWCNT was seen and were further analysed using micromechanical models. The addition of both cenospheres and MWCNT together exhibited synergism which led to lowering of peak heat release rates as observed by cone calorimetry. A uniform char layer was formed by using both the fillers together. The nanocomposites showed enhanced thermal stability. Differential scanning calorimetric analysis indicated lowered crystallinity percentage values of the HDPE phase due to improved interfacial interactions.