A soy flour based thermoset resin without the use of any external crosslinker

Abstract

In the current research a novel water based reaction scheme was developed to crosslink the protein from soy flour (SF) without using any external crosslinker. Soy flour, which contains about 55% protein and 32% carbohydrate and is the least expensive commercially available soy protein variety, was used for this research. Sugars and protein from SF were separated using a simple lab based filtration technique. The sugars were then oxidized using H₂O₂, a benign oxidizing agent, to obtain aldehyde and carboxyl groups. The oxidized sugars containing these groups were then used to crosslink the reactive groups present in the protein separated from SF, mainly utilizing Maillard type chemistry. The resulting crosslinked (thermosetting) soy protein resin had enhanced mechanical and thermal properties and reduced moisture absorption. When reinforced with strong microfibrillated cellulose they can produce fully sustainable and biodegradable green composites. The novel scheme developed here may be extended to prepare biobased plastics with enhanced properties by crosslinking natural flours with similar composition (soluble sugars and protein).