Nanocellulosic fillers for waterborne wood coatings: reinforcement effect on free-standing coating films

Marcel Kluge,Stefan Pinkl,Cordt Zollfrank,Albert Rössler,Wolfgang Gindl-Altmutter,Stefan Veigel,Ute Henniges

doi:10.1007/s00226-017-0892-y

Abstract

Coatings fulfill an important function in providing functionality and service life to wood surfaces. In the present study, the potential of nanocellulosic fillers toward improving waterborne wood coating mechanics is evaluated using free-standing coating films. At 2% filler content, significant improvements in static and dynamic mechanical properties were observed. The extent of these improvements was different depending on whether high-aspect-ratio cellulose nanofibrils of short cellulose nanocrystals were used. Chemical surface modification of cellulose nanofibrils did not provide further improvement. The water–vapor sorption properties of the coating films, which were also evaluated, did not show significant effects due to addition of nanocellulose, while optical transparency slightly decreased.

Highlights

The exposure of wood surfaces to external effects such as moisture, heat, ultraviolet radiation or mechanical stress can result in a deterioration of its properties
Nanocellulose may either be used in the form of long fibrils termed cellulose nanofibrils (CNF) produced by mechanical fibrillation of wood pulp, or in the shape of cellulose nanocrystals (CNC), which are produced by an additional acid hydrolysis step, resulting in higher crystallinity and lower aspect ratio compared to CNF
Fourier transform infrared spectroscopy (FTIR) spectra shown in Fig. 2 indicate significant changes in the chemistry of CNF after acetylation

Summary

Introduction

The exposure of wood surfaces to external effects such as moisture, heat, ultraviolet radiation or mechanical stress can result in a deterioration of its properties. The potential of nanocellulosic fillers toward improving waterborne wood coating mechanics is evaluated using free-standing coating films. At 2% filler content, significant improvements in static and dynamic mechanical properties were observed.

Results

Conclusion