Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

Hongxiang Xie,Xianghao Yang,Haishun Du,Chuanling Si

doi:10.1155/2018/7923068

Abstract

The recent strategies in preparation of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) were described. CNCs and CNFs are two types of nanocelluloses (NCs), and they possess various superior properties, such as large specific surface area, high tensile strength and stiffness, low density, and low thermal expansion coefficient. Due to various applications in biomedical engineering, food, sensor, packaging, and so on, there are many studies conducted on CNCs and CNFs. In this review, various methods of preparation of CNCs and CNFs are summarized, including mechanical, chemical, and biological methods. The methods of pretreatment of cellulose are described in view of the benefits to fibrillation.

Highlights

Cellulose is the most abundant natural polymer and can be sustainably produced from various biomass
This is because cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are gained by disintegration of raw cellulose materials into nanosize particles, while bacterial cellulose (BC) and electrospun cellulose nanofibers (ECNFs) are produced by a build-up of nanofibers from low molecular weight sugars by bacteria and electrospinning, respectively
The results showed that CNCs with the length of approximately 239–336 nm were obtained, and CNFs could be gained by the further mechanical fibrillation of fibrous cellulosic solid residue [99]

Summary

Introduction

Cellulose is the most abundant natural polymer and can be sustainably produced from various biomass. NCs include cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), bacterial cellulose (BC), and electrospun cellulose nanofibers (ECNFs). This review will focus on CNCs and CNFs, while BC and ECNFs will not be covered. CNCs are highly crystalline and usually have a length less than 500 nm, while CNFs are made up of amorphous and crystalline cellulose chains and have a length of up to several microns. Both of them have immense potential in the manufacture of renewable and biodegradable materials [6, 7].

Preparation of Cellulose Nanocrystals

Method

Production of Cellulose Nanofibrils

Findings

Conclusions