Influence of thickness and moisture content on the mechanical properties of microfibrillated cellulose (MFC) films
Microfibrillated cellulose (MFC) films with a layered structure and controlled thickness were successfully prepared, from bamboo processing resides as the source material, using ultrasonication followed by simple vacuum filtration. The effects of thickness and moisture content on the mechanical properties of the films were then investigated. It was shown that tensile stress and elongation at break were notably affected by the thickness of the MFC film, where the tensile stress and elongation at break of the film increased from 124 to 179 MPa and 0.9 to 5.5 %, respectively, as film thickness increased from 7.4 to 205.4 μm. However, no notable effect of thickness was observed on the Young’s modulus (~10.8 GPa). It was also found that moisture content has a significant impact on the tensile properties of MFC films, in lowering the Young’s modulus from 12 to 2 GPa and tensile stress from 180 to 90 MPa, and increasing the elongation at break from 4.2 to 17.5 %, as moisture content increased from 3 to 60 %. This is due to the effect of water in softening MFC films, resulting in a reduction in strength and increase in flexibility.