فهرست نشریات علمی دسترسی آزاد ایران

The surface wettability, moisture permeability, mechanical durability, and thermal stability of polyurethane (PU) and PU@TiO2 nanocomposite films at different weight contents of TiO2 nanoparticles (NPs) were studied experimentally. An increase in the NPs wt. % led to an increase in the hydrophobic property, thermal stability and mechanical durability of the films. The water contact angle (WCA) increased from 94.7o to 98.9o with the films' surface roughness due to NP agglomeration. The curing temperature (Tc) influenced the films wettability at Tc ≤ 140 °C, while film surface segregation was observed at Tc > 160 °C. The WCA of pure PU increased from 93.4o to 107.1o with an increase in Tc from 60 to 200 oC, respectively. Moisture permeability improved with the incorporation of 5 wt. % NPs. Due to the more porous structure of the 7 wt.% sample, its water absorption rate was slightly higher than that of the 5 wt.% sample. The glass transition temperature and melting temperature of the 7 wt.% sample were 88.2 and 185.5 oC, respectively, while the enthalpy of fusion was determined to be 22.82 J/g. The tensile strength and elongation at the break of the films slightly decreased with an increase in the NPs wt. %. The kinetic model of water absorption indicated that the effective diffusion coefficient (Deff) is highly influenced by the porous structure of the film. Deff decreased from 2.4×10-8 to 1.4×10-10 cm2.s-1 as the NP weight content increased from 3 to 7 wt.%, while the permeability coefficient (Peff) exhibited an increase from 3.2×10-11 to 8.0×10-11 mg.cm(Pa.s)-1. Additionally, relative humidity showed a greater effect on Deff than NP weight content, while the opposite was observed for Peff.