Sustainable hot-melt adhesives based on soybean protein isolate and polycaprolactone

Abstract

The combination of synthetic biodegradable thermoplastic with natural vegetable proteins is an alternative poorly explored that might have advantages mostly in reducing the final environmental impact and cost of the adhesive. This article deals with the development and characterization of potentially biodegradable hot-melt adhesives (HMA) based on soy protein isolate and polycaprolactone (PCL), with castor oil (CO) as a plasticizer/ compatibilizing agent and pine rosin (PR) as a tackifier. Results revealed the potential of replacing the non-renewable bioplastic PCL by biogenic SPI up to 50% w/w, without impairing significantly the adhesive strength. The addition of CO had a detrimental effect on the target properties, whereas the incorporation of pine rosin remarkably improved the adhesive strength. Based on the overall results, PCL-SPI based HMAs have potential as adhesives for lignocellulosic substrates, with the additional benefit of having a high biobased content and being potentially biodegradable.