Investigations on the effect of Sol-Gel coated coir fiber reinforcement in PP/EPDM composites

• Published in: European polymer journal 2024-05, Vol.212, p.113081, Article 113081
• Main Authors: K.M, Praveen, Pillin, Isabelle, Kervoelen, Antoine, Grohens, Yves, Thomas, Sabu
• Format: Article
• Language: English
• Subjects: Critical fiber length; Fiber debonding; Fiber pullout; Impact toughening; Non-isothermal crystallization kinetics; PP/EPDM blends
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2024.113081

•The study addresses the growing need to improve the energy absorption properties of natural fiber-reinforced polymer composites.•Coir fibers are subjected to plasma pre-treatment and coated with highly hydrophobic fluoroalkyl functional siloxane (FAS) to enhance their compatibility with the polymer matrix.•The newly developed composites exhibit significantly enhanced strain energy absorption, resulting in improved Izod impact energies while maintaining tensile and flexural properties.•Morphological examinations using scanning electron microscopy (SEM) reveal key mechanisms for energy absorption, including fiber pull-out, fiber fracture, and fiber–matrix debonding in FAS-coated fiber-filled composites.•The study highlights the crucial role of FAS-coated coir fibers in impacting tensile, flexural, and impact behaviors, emphasizing their remarkable hydrophobicity. There has been an increasing demand to enhance the energy absorption characteristics of natural fiber-reinforced polymer composites, especially when employed in structural applications. This study focuses on the development of coir fiber-based polypropylene (PP)/ethylene-propylene-diene rubber (EPDM) composites, in which fibers are pre-treated with plasma and coated with extremely hydrophobic fluoroalkyl functional siloxane (FAS). The melt blending technique is employed for the fabrication of these composites. To determine the appropriate length of the coir fibers for composite use, a critical length experiment is conducted. The composition of the composites is set by using 100 parts per hundred (pph) of polypropylene and 7.5 pph of EPDM, while varying the coir fiber content from 10 pph to 40 pph. The newly developed composites exhibit a greater capacity for strain energy absorption, resulting in improved Izod impact energies without significant compromise to the tensile and flexural properties. The impact-fractured specimens were examined using scanning electron microscopy (SEM) and the morphology images reveal key energy absorption mechanisms. Rheological analysis indicates shear-thinning behavior, while DSC analysis shows a lag effect in crystallization. The nucleation activity study shows that the coating (FAS-coated) might not be providing the desired nucleation effect, hindering the nucleation sites for crystallization. TGA analysis indicates that high stability at elevated temperatures achieved for FAS coated coir based composites.