Enhanced mechanical properties, water resistance, thermal stability, and biodegradation of the starch-sisal fibre composites with various fillers

The poor performance and high cost of the starch-sisal fibre composites with open-cell structures prevent their usage as biodegradable biomass to replace plastics. Therefore, inorganic fillers [talcum powder (TP), CaCO3 (CC)] and a bio-filler [eggshell powder (EP)] were added, and the resulting mechanical properties, water resistance, thermal stability and biodegradation characteristics were compared. Results show that the tensile strength of the EP-composite increases by 34% and the compressive strength of the CC-composite increases by 69% when compared with those of the non-filler (NF) composite. The mechanical properties of the composites improved because of the reduction of starch crystallinity and the formation of new hydrogen bonds. The EP-composite offered optimal cushioning owing to its uniform and dense open-cell structures. Besides, the CCand EP composites offered better thermal stability. The composites with fillers were more waterproof than the NF composite (by approximately 33%). After conducting biodegradability tests for 30 days, the EP-composite lost 67% of its mass, which was more than those associated with the TPand CC-composites and can be attributed to the presence of organic matter in the EP-composite. These results demonstrate the potential of EP to replace CC and TP for reinforcing the starch-fibre composites with open-cell structures. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

The addition of inorganic fillers and a bio-filler to starch-sisal fibre composites improved their mechanical properties, water resistance, thermal stability and biodegradation characteristics. Eggshell powder and calcium carbonate showed the most positive effects, with eggshell powder offering optimal cushioning and biodegradation performance.