Blends of Castor Oil and Polycaprolactone Waterborne Polyurethanes

MUCCI, V.; MACCHI, C.; ANBINDER, S.P.; PÉREZ, C.J.; SOMOZA, A.; ARANGUREN, M. I.

Buenos Aires

Congreso; WCCE11-11th World Congresses of Chemical Engineering; 2023

AAIQ

The increasing public involvement in environmental issues has fueled the research and development of water-based formulations of films and coatings. The known versatility of polyurethanes has also boosted the development of waterborne polyurethanes (WBPU), thus reducing the release of organic compounds during coating applications. Besides, there is increasing interest in the development of bio-based polyurethanes (usually derived from bio-based polyols), which also contribute to the reduction of the fossil carbon content in the resulting polymers [1]. In the present work, anionic bio-based waterborne polyurethanes synthesized from isophorone diisocyanate and specifically based on castor oil (CO) as the polyol and tartaric acid (TA), byproduct from the grape wine industry, as the internal emulsifier, were investigated. The CO-TA suspensions were used to prepare yellowish but highly transparent films. However, these films were also fragile; therefore, to increase their flexibility a simple blending method was used. For the present work, two WBPU blends were prepared from bio-degradable polycaprolactone (PCL) using a synthetic emulsifier, dimetilolpropionic acid, or the bio-compound, TA. Blends were obtained by a simple mixing of one of the last WBPU with CO-TA at different weight ratios [2]. The addition of one of the PCL-containing WBPU gives a higher flexibility to the films due to the long PCL chain when compared with the triglyceride molecule (CO). Results of dynamic mechanical analysis (DMA) of the samples show that the partial crystallinity of the PCL segments increase the low temperature modulus, while the crosslinking structure of the CO-TA improve the cohesion of the material and the mechanical properties at high temperature. It was observed that the % of crystallinity and the kinetics of the crystallization of the samples are affected by the presence of the amorphous CO-TA, a feature that was investigated by DSC and XRD. Additionally, the nuclear technique positron annihilation lifetime spectroscopy (PALS) was used to quantitatively compare the mobility of the chains in the different environments; the results obtained are correlated with the dynamic properties of the materials. The simple strategy of mixing the WBPU suspensions made it possible to obtain materials with different properties that could be applied to accomplish with different requirements.