Bionanocomposites of Regenerated Cellulose Reinforced with Halloysite Nanoclay and Graphene Nanoplatelets: Characterizations and Properties

Abstract

In recent years, the development of environmentally friendly materials obtained from renewable resources has attracted immense interest due to the new sustainable development policies. Cellulose is a readily available, naturally occurring biodegradable, and biocompatible linear polysaccharide. Recently, room temperature ionic liquids have been used as solvents to produce regenerated cellulose (RC) due to their attractive properties such as good chemical and thermal stability, low flammability, low melting point, and ease of recycling. Polymer/ nanofiller nanocomposites are believed to have strong potential to widen polymer applications due to enhanced performance. It is also widely accepted that the incorporation of small amount of nanofiller (less than 5 wt%) into bio-based matrixes to produce nano-biocomposite materials with enhanced mechanical, permeability, and thermal properties. The tubular silica-based naturally occurring nanofiller, halloysite nanotubes (HNT), has been investigated due to its high surface area, unique geometry, and its potential to make the hydrogen bonding with polymers to disperse well in the matrix. Graphene nanoplatelets (GNP) have also attracted enormous attention among polymer engineers over the last few years due to its unique electrical, thermal, and mechanical properties. Single layer twodimensional GNP sheet is considered as the strongest material along with the high surface area and aspect ratio. The chapter aims to highlight the effect of the addition of two different types of nanofillers such as HNT and GNP to produce RC nanocomposites on selected properties.

PVA, PVA Blends, and Their Nanocomposites for Biodegradable Packaging Application

“…Richard Feynman was the first person to introduce the concept of nanotechnology at an American Physical Society conference in 1959 [16] . This technology aimed to use materials on a nanoscaled level at 1-100 nm to improve their performance by taking advantage of the high surface area (generally in excess of 750 m 2 /g) with unique properties [16] ; Whereas polymer composites have traditionally contained a mixture of polymers (thermoset, thermoplastic or elastomer) and micro-sized organic or nonorganic reinforcements or fillers [16,138,139] , polymer nanocomposite (PNCs) normally incorporate fillers on the nanoscaled level (10 -9 m) with high aspect ratios (i.e. length/ thickness >300).…”

“…The use of nanotechnology for biodegradable polymers offers excellent opportunities to enhance their properties with improved cost effectiveness [9,16,140] . PNCs with small filler loadings (≤ 5 wt%) can match the properties of conventional composite with 40-50 wt.% loading of classical fillers, leading to light-weight composite materials [9,16,138,140,141] . However, PNCs have several limitations in relation to material processing and property with the incorporation of nanofillers.…”

“…However, PNCs have several limitations in relation to material processing and property with the incorporation of nanofillers. Particle agglomeration during filler dispersion, high viscosity when using relatively high filler loadings and high modulus and low strength resulting from high brittleness are the main disadvantages of PNCs [138] , as illustrated in Figure 17. PVA is one of the most popular biodegradable polymers reinforced with nanofillers in order to enhance its thermal and barrier properties, especially for food packaging [30] .…”

“…Polymer/clay nanocomposites (PCNs) were studied for the first time in 1961 to make polymerised vinyl monomers intercalated into montmorillonite, which was further systematically developed and commercialised by Toyota Central Research Laboratories during the 1980s [4,135,136,138] . PCN is a class of hybrid material consisting of nanoclay fillers such as montmorillonite (MMT), halloysite nanotubes (HNTs), saponite and hectrite dispersed into organic polymers [8] .…”

“…In addition, Raheel et al [162] reported that the presence of exfoliated structures for PVA/MMT/GO nanocomposites were good evidence of the compatibility and excellent dispersion of nanofillers within PVA matrices due to the presence of many oxygen contained groups on GO surfaces. [40,138,163] . CNTs are widely used as reinforcing materials to improve overall composite properties such as high mechanical and thermal properties due to their strong C-C bonds [163,164] .…”