New approach to recycle office waste paper: Reinforcement for polyurethane with nano cellulose crystals extracted from waste paper.

New approach to recycle office waste paper was purposed in this paper, i.e., cellulose nanocrystal (CNC) was extracted from waste paper and then used CNC as the organic filler to reinforce polyurethane elastomer (PUE) in thermal properties. A series of CNC/PUE nanocomposites was prepared in situ using a two-step process in solvent N,N-dimethylformamide solution by changing the content of CNC from 0.5, 1, 2, 3, 4 to 5 wt%. The results showed that CNC was covalently bonded to PUE, and specifically concerned with the hard segments of PUE resulting from the strong hydrogen bonding. The interactions between CNC and PUE caused the increased thermal and thermo-mechanical properties, and decreased water absorption of nanocomposites. Importantly, the initial degradation temperature of PUE with 2 wt% content CNC (CNC/PUE2) increased by 21 °C. CNC/PUE2 had the better comprehensive properties with the worse water absorption, which made CNC/PUE2 appealing in load bearing and outdoor applications. Hence, this work not only provided a new recycling method of waste paper but also provided a thermolstable PUE with lower cost.