Toughening Effect of Oxirane-Tetrahydrofuran Polyether (PEOT) on Blended and Cross-Linked Nitrocellulose

A series of cross-linked and physical blends of nitrocellulose (NC) with oxirane-tetrahydrofuran copolyether (PEOT) in different proportions were prepared using toluene-2,4-diisocyanate (TDI) as a crosslinking agent. The critical mechanical properties were evaluated by a universal material tensile testing machine and the dynamic mechanical thermal analyses (DMA). The reaction mechanism of the crosslinking process as well as the interaction between NC and PEOT were studied through Fourier transform infrared spectroscopy (FT-IR). It was shown that as the mass fraction of PEOT increases, the T_g of the polymer blends gradually decreases, which can reach as low as −22.3 °C. It was further indicated that the low-temperature mechanical properties of NC were significantly improved after blending. In comparison to the physical blending polymers, the miscibility between NC and PEOT was improved after cross-linking reaction with TDI. When the mass fraction of NC was 50 %, the tensile strength of NC/PEOT physical blend and NC/PEOT/TDI cross-linked blend reaches 20.82 MPa and 24.93 MPa, respectively. The corresponding elongation at break of these two systems was 96.58 % and 102.7 %, which means the toughening effect of PEOT on NC could be enhanced by crosslinking.