Films From Vegetable Oil-Based Waterborne Polyurethane Blends: Crosslinking and Crystallinity

MUCCI V; MACCHI, C.; PEREZ, J.; SOMOZA, A.; ARANGUREN, M. I.

Conferencia; International Conference on Renewable Materials-ICRM2023; 2023

Polyurethanes are among the most widely used polymers due to their versatility to adapt to very diverse requirements. As coating layers, traditional polyurethanes are delivered in the form of organic solutions with the consequent harmful effect on the environment. Instead, waterborne polyurethanes (WBPU) are formulated as aqueous dispersions, so that water is the only solvent evaporated during drying of the coating. Additionally, more eco-friendly formulations can be prepared using biobased chemicals (most usually the polyol part of the formulation).Three different formulations of anionic WBPU were considered, which were used in the preparation of blends, to vary the final properties of the coatings/films. The raw materials included castor oil (CO), polycaprolactone diol (PCL) and tartaric acid (TA) among the biobased and/or biodegradable components.The crystallinity of the PCL segments and crosslinking due to the ability of CO and TA to react with the isocyanate were the main variables affecting the film properties. Crystallinity of PCL contributed to the rigidity at temperatures below the melting of the crystals and crosslinking contributed to the cohesion of the material, allowing the usability of the films up to higher temperatures. The kinetics of crystallization was also affected according to DSC studies.Positron annihilation lifetime spectroscopy (PALS), was used to quantitatively compare the mobility of the chains in the different environments once the final state was reached. The results obtained are well correlated with the dynamic mechanical properties of the materials.