Preparation of TPU@DHPL-SiO2NPs composite films and their mechanical degradation behavior under tensile, UV or thermal conditions

To address the oxidative degradation of thermoplastic polyurethane (TPU) under UV or thermal exposure, silica nanoparticles surface-modified with the antioxidant 2,6-di-tert-butyl-4-hydroxymethylphenol (DHPL-SiO 2 NPs) were incorporated into TPU to prepare TPU@DHPL-SiO 2 NPs composite films. DHPL-SiO 2 NPs effects on the mechanical degradation behavior of TPU films after bearing mechanical tensile, UV exposure, or thermal exposure were investigated. The results indicate that among the prepared films, the TPU film containing 3 wt% DHPL-SiO 2 NPs (TPU-3) presents desirable mechanical degradation behaviors under different conditions. When the strain amplitude is 700% during cyclic loading-unloading tensile measurements, TPU-3 shows lower internal heat accumulated with a hysteresis energy dissipation of 52.1 ± 2.55 MJ m −3 and superior flexibility with a secant modulus of 6.3 ± 0.11 MPa. After 8 days of UV exposure, TPU-3 indicates tensile strength and elongation loss rates of 5.1 ± 0.21% and 13.3 ± 0.62% (8.1 ± 0.32% and 12.7 ± 0.53% for TPU-0), respectively. While after 8 days of thermal exposure, TPU-3 presents only tensile strength and elongation loss rates of 3.3 ± 0.11% and 3.0 ± 0.25% (13.3 ± 0.33% and 10.5 ± 0.57% for TPU-0), respectively. Furthermore, when bearing 8 days of thermal exposure and then subjected to cyclic tensile tests with a fixed strain of 200%, TPU-3 still maintains a low tensile strength loss rate of 17.8 ± 0.33% and a high hysteresis ratio of 20.2 ± 0.21% (22.8 ± 0.38% and 18.5 ± 0.22% for TPU-0). Compared with neat TPU films, TPU composites filled with 3 wt% DHPL-SiO 2 NPs exhibit retarded mechanical degradation behavior.