Eco-friendlier and sustainable natural-based additives for poly(vinyl chloride)-based composites

This work presents novel natural-based and solvent-free additives for poly(vinyl chloride) (PVC), namely calcium soaps, obtained for the first time from naturally occurring epoxidized soybean and linseed oils (ESO/ELO); and biogenic calcium carbonate, obtained from chicken eggshells (EG) after different acid and/or thermal pre-treatments. Results show that these additives were able to: i) reduce the concentration of volatile organic compounds released from PVC films, including alcohols, aldehydes, esters and phthalates (97,95,90 and 84% chromatographic peak area reduction, respectively), originating safer materials; ii) improve the long-term thermal stability of PVC-based materials, while maintaining their mechanical performance and when compared to control samples formulated with a high-performance commonly employed solvent-based thermal stabilizer. Films formulated with ESO-based calcium soaps and with EG powders treated with acid and thermal treatment (200 °C) presented the best performance in terms of heat aging and long-term thermal stability. The former also slightly improved the thermomechanical properties of the films indicating that these additives are also working as secondary plasticizers for PVC. This work gives an important contribution towards the safety and sustainability of high-performance PVC-based materials, by allowing the substitution of commercially available thermal stabilizers by new eco-friendlier and safer alternatives obtained from renewable sources.