Influence of viscoelastic behavior in flame retardancy of thermoplastic starch multicomponent systems loaded with leather waste

The utilization of natural fibers obtained from leather industrial wastes contributes to a circular economy and aids to the reduction in the usually high loadings of mineral flame-retardant additives employed to impart the flame retardancy in polymer systems. The present work investigates the relationship between viscoelastic properties and flame retardancy of thermoplastic starch multicomponent systems loaded with leather waste, aluminum trihydroxide used as flame-retardant additive, and bentonite clay. Different blending temperatures and rotational speeds during extrusion process are tested for the multicomponent systems. Rheological, morphological, flammability, thermal analysis, and tensile mechanical test are also used to characterize the obtained multicomponent systems. A detailed investigation of the viscoelastic properties through Han, Cole–Cole, and van Gurp–Palmen diagrams indicated that the fibers have to be well dispersed in the polymer matrix forming a network structure and that the material has to exhibit viscoelasticity to a moderate level, i.e., not too viscous and not too elastic as observed in the VGP diagram in order to impart the flame retardancy effect in the multicomponent system. These multicomponent systems with enhanced properties are a promising and sustainable alternative to traditional high-loaded flame-retardant systems taking advantage of the landfill disposal in local areas where leather wastes are a problem the great attention contributing to a circular economy.