Cellulose Nanocomposites of Cellulose Nanofibers and Molecular Coils

Doug Henderson,Robert M Briber,Howard Wang,Yimin Mao,Liangbing Hu,Xin Zhang

doi:10.3390/jcs5080200

Abstract

All-cellulose nanocomposites have been produced from cellulose nanofiber (CNF) suspensions and molecular coil solutions. Morphology and small-angle neutron scattering studies show the exfoliation and dispersion of CNFs in aqueous suspensions. Cellulose solutions in mixtures of ionic liquid and organic solvents were homogeneously mixed with CNF suspensions and subsequently dried to yield cellulose composites comprising CNF and amorphous cellulose over the entire composition range. Tensile tests show that stiffness and strength quantities of cellulose nanocomposites are the highest value at ca. 20% amorphous cellulose, while their fracture strain and toughness are the lowest. The inclusion of amorphous cellulose in cellulose nanocomposites alters their water uptake capacity, as measured in the ratio of the absorbed water to the cellulose mass, reducing from 37 for the neat CNF to less than 1 for a composite containing 35% or more amorphous cellulose. This study offers new insights into the design and production of all-cellulose nanocomposites.

Highlights

This study presents the production and characterization of nanocomposites composed of two model cellulose components, cellulose nanofibers (CNFs) and amorphous cellulose (AC), over the entire composition range
Cellulose macrofibers swell upon oxidation and lose integrity at longer times, while the average distance between individual nanofibers increases roughly proportional to the average diameter of macrofibers, indicating uniform oxidation of elementary fibrils
Cellulose solutions in mixtures of ionic liquid EMIMAc and organic solvent DMSO were homogeneously mixed with CNF suspensions and subsequently dried to yield all-cellulose nanocomposites

Summary

Introduction

All-cellulose composite (ACC), composed only of different forms of neat cellulose, is an interesting subject of research as it provides better understanding of the limitations and opportunities of biomass technologies for a sustainable future, as well as potential solutions for hybrid composite technologies as an intermediate step [6,7,8,9,10]. Other routes for production of cellulose composites have been experimented through either incorporating fibers to cellulose solutions or partially dissolving fibers using solvents including N-methyl morpholine N-oxide (NMMO) [15], ionic liquids [16,17,18], N,N-dimethyl acetamide (DMAc) and LiCl [13,19,20,21], or others [22,23], followed by coagulation to regenerate cellulose II, resulting in cellulose composites containing a myriad of structures resulting in interlinked bulk and interfacial properties [12,23,24,25,26]

Methods

Results

Discussion

Conclusion