We synthesized polyols with high hydroxyl functionalities (F OH s), between 9.0 and 12.6, and characterized them with differential scanning calorimetry, thermogravimetric analysis, and size exclusion chromatography after we parametrically studied the ringopening reaction of epoxidized soybean oil with lactic acid (LA) as a function of the reaction temperature and lactic acid equivalent fraction (f LA ). An increase of only 20 C in the reaction temperature (from 80 to 100 C) caused changes in the hydroxyl number (+17.8%), F OH (-25%), viscosity (-14.0%), and oligomeric content (-24.1%). f LA mostly affected the ring-opening yield, and only for f LA values above 0.4 was possible to achieve values higher than 80%. Rigid polyurethane foams (rPUFs) were synthesized and characterized with scanning electron microscopy, dynamic mechanical analysis (DMA), and compressive mechanical tests. rPUFs with a very high specific compressive strength (7.8 kPa kg -1 m 3 ) were synthesized solely with biobased soybean oil. DMA revealed a compromised relationship between the specific compressive strength and its temperature dependence. To increase the first one, the most relevant method was to increase F OH . Instead, to increase the latter one, the OH number had to be maximized.
The fabrication of electrospun fibers made from aqueous dispersions of polyurethane obtained from renewable sources is an eco-friendly method to produce porous membranes for different applications. Polyethylene oxide (PEO) has been already employed in formulations for allowing fiber formation, but its role was not yet completely understood. In this work the fabrication of electrospun fibers made from biobased polyurethane aqueous dispersion with PEO in order to obtain regular fibers is performed. The role of PEO was studied by thermal analysis, infrared and Raman spectroscopy, rheology, and fiber morphology. Polyurethane fibers were obtained only when PEO was added, otherwise the dispersion is electrosprayed and particles are formed. It was observed that PEO modifies the rheology of dispersion and assists coalescence of polyurethane particles. On the other hand, polyurethane fibers conserved their diameter and their homogeneous structure after removal of PEO by immersion in water, which indicates that the distribution of both polymers was even within the fibers. This work provides both an insight on the role of PEO and a route for the fabrication of eco-friendly biobased polyurethane microfibers from aqueous dispersions.
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