The Effect of Chemical and High-Pressure Homogenization Treatment Conditions on the Morphology of Cellulose Nanoparticles

Suxia Ren,Tingzhou Lei,Xiuxuan Sun,Qinglin Wu

doi:10.1155/2014/582913

Abstract

Cellulose nanoparticles were fabricated from microcrystalline cellulose (MCC) through combined acid hydrolysis with sulfuric and hydrochloric acids and high-pressure homogenization. The effect of acid type, acid-to-MCC ratio, reaction time, and numbers of high-pressure homogenization passes on morphology and thermal stability of the nanoparticles was studied. An aggressive acid hydrolysis was shown to lead to rod-like cellulose nanocrystals with diameter about 10 nm and lengths in the range of 50–200 nm. Increased acid-to-MCC ratio and number of homogenization treatments reduced the dimension of the nanocrystals produced. Weak acid hydrolysis treatment led to a network of cellulose nanofiber bundles having diameters in the range of 20–100 nm and lengths of a few thousands of nanometers. The high-pressure homogenization treatment helped separate the nanofiber bundles. The thermal degradation behaviors characterized by thermogravimetric analysis at nitrogen atmosphere indicated that the degradation of cellulose nanocrystals from sulfuric acid hydrolysis started at a lower temperature and had two remarkable pyrolysis processes. The thermal stability of cellulose nanofibers produced from hydrochloric acid hydrolysis improved significantly.

Highlights

As the most abundant and renewable biopolymer provided by nature, cellulose is attracting a lot of research effort in many scientific disciplines and continues to be a subject of intense studies for its utilization as functional materials
Cellulose nanofibers and nanocrystals were produced from microcrystalline cellulose through acid hydrolysis combined with high-pressure homogenization
(2) Increased acid-to-microcrystalline cellulose (MCC) ratio and homogenization treatment passes further reduced the dimension of the nanocrystals produced

Summary

Introduction

As the most abundant and renewable biopolymer provided by nature, cellulose is attracting a lot of research effort in many scientific disciplines and continues to be a subject of intense studies for its utilization as functional materials. Cellulose is a linear polymer consisting of D-anhydroglucose units joined together by β-1, 4-glycosidic linkages that gives rise to various crystalline domain formations [1]. These crystalline domains possess very high strength and modulus, approximately on the order or great than a comparable structural steel sample [1, 2]. The smallest discernible building block of cellulose I is a bundle of parallel glucan chains, typically with a square or close-to-square cross section known as a cellulose I fibril [2]. There are four methods commonly used to isolate bundles of cellulose fibers, that is, acid hydrolysis, enzymatic hydrolysis, mechanical shearing, and enzymatic hydrolysis combined with mechanical shearing and high-pressure homogenization [3,4,5]

Results

Discussion

Conclusion