Expanded Polystyrene Using Water as Blowing Agent Stabilized by Cellulose Nanocrystals

Herein, we report a new generation of water expandable polystyrene (WEPS) beads, synthesized through Pickering emulsion polymerization in which cellulose nanocrystals (CNCs) was used as water droplet stabilizer. Synthesized beads with different CNC content could encapsulate 1-5 wt.% of the water droplets of 3−4 μm in diameter. Thermogravimetric analysis showed that the entrapped water is mainly bound water with a strong adsorption to the cellulose nanoparticles. The expansion behavior of the beads was investigated in hot oil at 135 °C. The expansion ratio of ∼9 for as-synthesized were obtained for the sample containing 0.0125 wt.% of CNC and 3.8 wt.% of water in the form of uniformly distributed microdroplets. Finally, the morphological investigation of the expanded beads revealed that the CNCs not only stabilize the water microdroplets in the beads but also reinforce the foam during expansion and inhibit cell wall rupture.

Keywords:

Water Expandable Polystyrene , Pickering emulsion polymerization , cellulose nanocrystals