Redispersed microfibrillated cellulose film properties and resource efficiency

Microfibrillated cellulose (MFC) is a bio-based material produced by disintegrating cellulose fibers into microscale fibrillar components. Owing to its biodegradability, renewable origin, and favorable oxygen and oil barrier as well as film-forming properties, MFC has potential for sustainable packaging applications. However, its broader utilization is limited by the high energy consumption associated with the fibrillation process. One approach to improving resource efficiency is to collect and reuse any off-specification MFC films, such as products having incorrect grammage, the presence of wrinkles, or excess material related to trimming. In this study, the redispersion of MFC films using an ultrasound-assisted disintegration method was investigated, with focus on film properties and energy efficiency. The results showed that ultrasound-enhanced treatment during recycling improved the UV barrier performance of MFC films, reducing UV transmittance by 24 to 35% compared to unrecycled reference films. Longer ultrasonication time increased the visible light transmittance 14% compared to the reference film with same thickness. In addition, tensile properties were enhanced, with increases of 36% in strain at break and 41% in tensile index. The findings demonstrate that recycling of MFC films does not compromise, and may even improve, mechanical and barrier properties, while enabling notable savings in raw materials, energy, and costs.