Ultrasounds welding of nanocellulosic materials

International audienceThe interest for cellulose nanocrystals and nanofibrils is exponentially increased since last decade thanks to their industrialization. In addition to their low density, high aspect ratio, high stiffness and Young’s modulus and chemically reactive surface, this material is well known for its high specific surface. Thanks to these particular properties, cellulose nanomaterials can be used within a wide variety of applications. Coating is one of the promising applications for nanocellulose mainly for barrier applications in packaging. Indeed new bio-based but also high performance solutions are expected in food packaging. Unfortunately, up to now, high barrier solutions can be provided but they always require a layer of thermosealing polymer which is usually fossil based. These multilayer materials are also more complicate to handle when end of life is considered. One solution would be to propose cellulosic materials which could be welded easily. Except thermosealing, ultrasounds welding have been developed in plastic industry last years.This study is a proof of concept that nanocellulosic materials can be welded by ultrasounds. Several nanocellulosic materials were firstly designed and characterized, i.e. from classic cellulose nanocrystals and nanofibrils to functionalized CNC by esterification with lauric acid. Than model films were prepared and welded by ultrasounds. Process parameters were optimized and successful welding were obtained and mechanically characterized. These very positive results have been patented and open the doors for new solutions in welding of biobased materials