Effects of pH on Nanofibrillation of TEMPO-Oxidized Paper Mulberry Bast Fibers

Jung Park,Chan-Woo Park,Nam-Hun Kim,Gu-Joong Kwon,Seung-Hwan Lee,Song-Yi Han

doi:10.3390/polym11030414

Abstract

TEMPO oxidation was conducted as a pretreatment to achieve efficient nanofibrillation of long paper mulberry bast fibers (PMBFs). The pH dependency of nanofibrillation efficiency and the characteristics of the resulting cellulose nanofibrils (CNFs) were investigated. As the pH increased, the negative value of the zeta potential of TEMPO-oxidized fibers increased. The increase in electrostatic repulsion at pH values of greater than 9 prevented the entanglement of long PMBFs, which was a drawback for defibrillation at acidic pH. With increasing pH, the CNF production yield was increased. The crystallinity index of TEMPO-oxidized CNFs from PMBFs was 83.5%, which was higher than that of TEMPO-oxidized CNFs from softwood fibers in the same conditions. The tensile strength of nanopaper from TEMPO-oxidized PMBF CNFs was 110.18 MPa, which was approximately 30% higher than that (84.19 MPa) of the TEMPO-oxidized CNFs from softwood fibers.

Highlights

Cellulose nanofibrils (CNFs) are eco-friendly natural polymers with biodegradability and excellent strength, and their applications in various fields have been reported [1,2,3,4,5]
paper mulberry bast fibers (PMBFs) were obtained from Andong Hanji (Andong-si, Gyeongsangbuk-do, Korea) and softwood fibers were obtained in the sheet form from Hankuk Paper (Gangnam-gu, Seoul, Korea)
The PMBFs were treated by chemical pulping and the softwood fibers were disintegrated using a lab disintegrator

Summary

Introduction

Cellulose nanofibrils (CNFs) are eco-friendly natural polymers with biodegradability and excellent strength, and their applications in various fields have been reported [1,2,3,4,5]. They are generally less than 100 nm in diameter and several micrometers in length and can be produced through various mechanical defibrillation processes, such as high-pressure homogenization [6,7], microfluidization [8,9], grinding [10,11,12], and ultrasonication [13,14,15]. Cavities create high localized temperature and pressure of approximately 5000–10,000 K and

Methods

Results

Conclusion