Abstract
Waterborne polyurethane-urea (WBPUU) dispersions, products having none or low contents of organic solvents, depending on the used synthesis process, can provide suitable environmentally-friendly strategies to prepare novel materials. Moreover, waterborne systems enable the incorporation of aqueous dispersible nanoentities and soluble additives, which provides a strategy to design versatile functional materials with tailored properties. Having demonstrated in previous work the bacteriostatic properties of a 3 wt% Salvia-based WBPUU against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, this work is focused in the preparation of Salvia-based WBPUU added with cellulose nanocrystals (CNC) tackling the preparation of functional green nanocomposite films with increased mechanical properties. Through this strategy, nanocomposites loaded with 1, 3 and 5 wt% of CNC were prepared, showing an effective CNC incorporation avoiding agglomerates. CNC addition is able to modulate soft and hard phase’s segregation, inducing enhanced mechanical stiffness, together with improved deformability, while retarding thermomechanical instability to higher temperatures.
Highlights
Waterborne systems, waterborne polyurethane-urea (WBPUU) dispersions, have drawn attention due to their versatility in terms of properties, which can be explored for different applications presenting advantages over the conventional solventborne systems [1]
Results showed that the incorporation of cellulose nanocrystals (CNC) was effective up 5 wt% load, leading to a suitable stress-transfer between the matrix and the reinforcement, translated by a progressive increase in E and σmax values [34], objective pursued in this work
The addition of CNC results in a stiffening effect of the film [35,36], evidenced by a decrease in strain at break values due to the high rigidity of cellulose [37]. This common effect was observed in the case of the composite with 1 wt% CNC (WBUU-1), where strain at break decreased in comparison with the Salvia-based Waterborne polyurethane-urea (WBPUU) matrix
Summary
Waterborne systems, waterborne polyurethane-urea (WBPUU) dispersions, have drawn attention due to their versatility in terms of properties, which can be explored for different applications presenting advantages over the conventional solventborne systems [1]. The isolation of the crystalline domains of cellulose by removing the amorphous domains, leads to the obtainment of high length/diameter (L/D) aspect ratio CNC providing high stiffness nanoreinforcements [12] In previous works, it has been corroborated the ability of CNC to tailor the properties of materials based on waterborne polyurethane dispersions, by analyzing CNCs incorporation route [13], or their effect in polyurethane microstructure [14], including the preparation of films. The selected Salviabased WBPUU comprised a load of 3 wt% of the respective aqueous extract, which was incorporated following an in-situ strategy, i.e. the incorporation was made during the dispersion formation step This se lection followed previous results that pointed out this formulation as the most promising based on its stability and bacteriostatic effects. In order to corroborate the successful addition of CNC and their properties modu lating effects, morphology studies of the nanocomposite films were conducted
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
