Chapter 9 - Vinyl-ester composites reinforced with natural fibers and nanofillers

Abstract

When compared to their synthetic counterparts, natural fibers represent an environmentally friendly alternative by virtue of several attractive attributes that include lower density, lower cost, nontoxicity, ease of processing, renewability, and recyclability. In addition, the use of natural fibers in polymer matrix composites has the potential to produce materials with higher specific strength and specific modulus due to their low density. In this chapter, vinyl-ester resin matrix composites reinforced with recycled cellulose fiber (RCF) have been fabricated via a soaking method. Nanocomposites from both polymers reinforced with different concentrations (i.e., 1, 5, and 10wt%) of Cloisite 30B nanoclay platelets and halloysite nanotubes (HNTs) have been synthesized. Mechanical properties, such as flexural strength, impact toughness, fracture toughness, and the effect of water absorption on impact toughness were evaluated. Porosity, thermal stability, and flammability of these materials have also been investigated. Results indicate that flexural strength decreased for most samples due to the poor dispersion of nanofillers and the existence of micro-voids within the samples. In contrast, impact toughness and fracture toughness were improved for all reinforced samples. Water absorption has a positive effect in enhancing the impact toughness of the composites via plasticization at the crack tip. The addition of nanoclay platelets and halloysite nanotubes (HNTs) increased the porosities and improved the thermal stability flammability of all nanocomposites. The effects of RCF, Cloisite 30B nanoclays, and HNTs on the physical and mechanical properties are discussed.