Electrical behavior of polyurethane derived from polyols synthesized with glycerol, phthalic anhydride, and oleic acid

Abstract

The direct current (DC) and alternating current (AC) conductivity of polyurethane (PUR) derived from polyols synthesized with glycerol, phthalic anhydride, and oleic acid were investigated in this article. The PUR was prepared by varying the oleic acid content in polyol (28, 40, and 65%) and the NCO/OH ratio of the PUR was varied to 1.2, 1.4, and 1.6. The electrical conduction studied by measuring the dependence of current on the applied field and temperature. Electrical conductivity in PUR was expressed by Arrhenius relations and the activation energies were calculated. Moreover, hyperbolic sine function was used to determine the conduction mechanism in PUR. It's presumed that the conduction mechanism was assisted by ions for the PUR which were contributed by oleic acid due to dissociation of protons and highly polar urethane groups in PUR. Furthermore, the dielectric behaviors of the material have been measured at room temperature in the frequency range of 100 Hz to 40 MHz. The frequency-dependent conductivity of PUR materials has been analyzed using a Jonscher's power law expression and the plot exhibits the typical behavior of ionic materials, i.e., the DC plateau and the frequency dependent region.

Synthesis, Properties, and Applications of Ion‐Containing Polyurethane Segmented Copolymers

“…Figure illustrates the structural resemblance between glycerol and castor oil. Velayutham et al applied a similar design to obtain an oleic acid‐containing polyol, reacting glycerol, phthalic anhydride, and oleic acid in a two‐step procedure. Linear step‐growth polymerization requires perfectly difunctional monomers and near 100% conversion to obtain high‐molecular‐weight polymers .…”

“…The introduction of multifunctional monomers ( f >2), such as A 2 B or B 3 monomers, where A and B represent different functional groups, lead to branched, hyperbranched, or crosslinked polymers . The polyols derived from oleic acid, soybean oil, and castor oil all possess f ≫ 2, thus the one‐shot method afforded crosslinked polyurethanes upon curing …”

“…The oleic acid‐containing oligomer represents the only polyol in the earlier literature with inherent ionic content due to the presence of unreacted pendant carboxylic acid groups, where conductivity measurements confirmed ionization . Epoxidized soybean oil (ESBO) and castor oil both contain reactive functional groups, epoxides and hydroxyl groups, respectively, which facilitate chemical modifications .…”

“…The use of naturally occurring compounds as starting materials adheres to the principles of green chemistry . Oleic acid, castor oil, soybean oil, and natural rubber were all converted to functionalized polyols and subsequently used in the synthesis of ion‐containing polyurethanes for various applications . The chemical structures of castor oil and soybean oil contain a glycerol core with functional groups along primarily hydrocarbon chains .…”