One-Step Toughening of Soy Protein Based Green Resin Using Electrospun Epoxidized Natural Rubber Fibers

Abstract

Epoxidized natural rubber (ENR) fibers (ENRFs) were electrospun to obtain diameters ranging from a few hundred nanometers to a few micrometers by changing the ENR solution concentration. ENRFs were used to toughen soy protein isolate (SPI) based resin. A facile 1-step process was developed for wet electrospinning and blending the ENRFs directly into SPI resin. As the ENR concentration increased from 0.1% to 5%, the surface topography of ENRFs changed from irregular to somewhat bumpy. The average diameter of ENRFs also increased from 250 nm to 17 μm. Increased ENRF (electrospun from 3% concentration) loading from 0 to 20% in SPI resin increased the fracture strain significantly from 1.7 to 18.8% and increased the toughness by a factor of 10. Interestingly, tensile strength and Young’s modulus decreased only slightly compared to the increase in the toughness. Cross-linking between the epoxy groups in ENR and amine and/or carboxylic groups in SPI as well as the high aspect ratio of the ENRFs contributed to i...