LAUSR

Dynamic mechanical analysis (DMA) represents an important method for understanding the mechanical behavior of surface coatings. In this work, transparent composite films of nanofibrillated cellulose (NFC), derived from beech wood pulp, and 10 different commercial polymeric binders, representative binders for wood coatings, were prepared to study the viscoelastic properties of the composite films. DMA in tensile mode was used to determine the glass transition temperature (Tg), the storage and loss modulus and the cross-linking and entanglement density before and after accelerated aging. Additionally, Fourier transform infrared spectroscopy (FTIR) was applied to corroborate the findings of the dynamic mechanical analysis. Tg, moduli, cross-linking and entanglement density of prepared films depended on the initial properties of the neat polymers. The addition of 2.5 wt% NFC to the polymers had no significant influence on Tg and entanglement density, while the reinforcing effect of NFC influenced the moduli of all polymers, as well as the cross-linking density of the alkyds. Accelerated aging by UV radiation at 60 °C strongly affected the viscoelastic properties of neat alkyd polymer and its NFC composite films, while the aging effect was less pronounced for the acrylates. DMA and FTIR findings confirm that unmodified NFC did not adversely change the general aging behavior of the polymers.