Cellulose Whisker/Epoxy Resin Nanocomposites

Abstract

New nanocomposites composed of cellulose nanofibers or "whiskers" and an epoxy resin were prepared. Cellulose whiskers with aspect ratios of ∼10 and ∼84 were isolated from cotton and sea animals called tunicates, respectively. Suspensions of these whiskers in dimethylformamide were combined with an oligomeric difunctional diglycidyl ether of bisphenol A with an epoxide equivalent weight of 185-192 and a diethyl toluenediamine-based curing agent. Thin films were produced by casting these mixtures and subsequent curing. The whisker content was systematically varied between 4 and 24% v/v. Electron microscopy studies suggest that the whiskers are evenly dispersed within the epoxy matrix. Dynamic mechanical thermoanalysis revealed that the glass transition temperature (T g ) of the materials was not significantly influenced by the incorporation of the cellulose filler. Between room temperature and 150°C, i.e., below T g , the tensile storage moduli (E′) of the nanocomposites increased modestly, for example from 1.6 GPa for the neat polymer to 4.9 and 3.6 GPa for nanocomposites comprising 16% v/v tunicate or cotton whiskers. The relative reinforcement was more significant at 185°C (i.e., above T g ), where E′ was increased from ∼16 MPa (neat polymer) to ∼1.6 GPa (tunicate) or ∼215 MPa (cotton). The mechanical properties of the new materials are well-described by the percolation model and are the result of the formation of a percolating whisker network in which stress transfer is facilitated by strong interactions between the whiskers.

Fate of Cellulose Nanocrystal Aerosols Deposited on the Lung Cell Surface In Vitro

“…1−4 CNCs offer benefits to a wide range of applications in different fields of science and technology; they show advantageous characteristics, such as high tensile strength and stiffness, and are thus useful as a filler in high-performance nanocomposites, 5,6 but are also applicable in mechano-adaptive materials, 7,8 water purification systems, 9 and other applications as a cost-effective alternative to carbon nanotubes (CNTs). 10 Therefore, the universal use of these inexpensive and easy to isolate materials and their consequential mass-scale production is only a matter of time, with a projected production volume of up to 1700 tons of cellulose nanofibers per year by 2017.…”

Nanocellulose and Its Application for Shape-Memory Materials

“…During this progress, self-interactions of NCs through hydrogen bonds of surface hydroxyls are "switched off" by competitive hydrogen bonding with the solvent [18,111]. When the solvent is evaporated, the interactions between the NCs are "switched on" and assembled into a percolating network.…”

Cellulose Nano Whiskers as a Reinforcing Filler in Polyurethanes

“…Softwood (SW) kraft pulp (Revol et al, 1994;Araki et al, 1998;Araki et al, 1999;Pu et al, 2007), SW sulfite pulp (Beck-Candanedo et al, 2005), hardwood (HW) ECF (elemental chlorine free) pulp (Beck-Candanedo et al, 2005), recycle pulp (Filson et al, 2009), cotton fiber (Revol et al, 1994;Dong et al, 1996;Dong et al, 1998;Araki et al, 2000;Hasani et al, 2008;Cao et al, 2009;Pei et al, 2010;Tang & Weder, 2010;Wang et al, 2010), sisal fiber (de Rodriguez et al, 2006;Tang & Weder, 2010), flax fiber (Cao et al, 2007), ramie fiber (Habibi et al, 2007;Habibi & Dufresne, 2008;Zoppe et al, 2009), wheat straw (Helbert et al, 1996), bamboo residue , bacterial microfibrils (Grunert & Winter, 2002), grass fiber (Pandey et al, 2009), tunicate cellulose (Favier et al, 1995;Angles & Dufresne, 2000;Sturcova et al, 2005;Ljungberg et al, 2006;Habibi et al, 2007;Siqueira et al, 2010;Tang & Weder, 2010), microcrystalline cellulose (MCC) Bondeson et al, 2006;Oksman et al, 2006;Bondeson & Oksman, 2007;Bai et al, 2009;Auad et al, 2010; have all been utilized as cellulose sources for whiskers. The most common preparation method employed is acid hydrolysis, including acid sulfuric and hydrochloric acid.…”