Eco-friendly waterborne polyurethane reinforced with cellulose nanocrystal from office waste paper by two different methods.

Focusing on eco-friendly materials, cellulose nanocrystal (CNC) extracted from office waste paper was used to reinforce waterborne polyurethane (WPU) with varying content by two incorporation routes including blending method by sonication after WPU synthesis (BCNC/WPU) and the alternative in-situ during the WPU synthesis process (CNC/WPU). The results showed that new interaction between CNC and WPU through hydrogen bonds in the interfacial area was formed and CNC reinforced hard segments effectively. However, the interaction in BCNC/WPU was not as stronger as that in CNC/WPU. Besides, CNC improved thermal stability of WPU remarkably, especially BCNC/WPU. The addition of CNC caused a delay around 50 °C in the start of the degradation process, and a delay of 5-18 °C and 2-20 °C in the temperatures at 10 and 50 wt% weight loss, respectively. These eco-friendly and biodegradable novel materials have potential applications in medical and biologic fields.