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Cellulose nanofibers and the film-formation dilemma: Drying temperature and tunable optical, mechanical and wetting properties of nanocomposite films composed of waterborne sulfopolyesters
Ist Teil von
Journal of colloid and interface science, 2021-09, Vol.598, p.369-378
Ort / Verlag
United States: Elsevier Inc
Erscheinungsjahr
2021
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
[Display omitted]
Waterborne sulfopolyesters have gained considerable interest as coating materials due to their excellent film-forming and optical properties. Their commercial use has been limited, however, due to their fragile nature. Incorporating cellulose nanofiber (CNF), a sustainable biopolymer, into the polymer matrix is expected to enhance the mechanical integrity of the nanocomposite as these two components synergistically interact.
In this study, we have investigated the suspension and film characteristics of three sulfopolyesters varying in charge density, glass transition temperature and molecular weight, as well as their mixtures with CNF. We have performed steady-shear rheology on mixtures with different CNF loading levels, and resulting films have been subjected to quasistatic uniaxial tensile and water contact-angle tests to elucidate the effects of CNF on mechanical and surface properties.
Addition of CNF to waterborne polyester promotes shear-thinning behavior that remains unaffected by the CNF content. Solid films cast from these suspensions possess enhanced mechanical properties, as well as tailorable surface hydrophilicity, depending on composition and film-drying temperature. Tensile tests reveal that films containing 10 wt% CNF display the greatest mechanical improvements, suggesting the existence of a previously unidentified Goldilocks composition window.