Paper and cardboard: The application of texture analysis on the latest developments

Due to increased environmental awareness, there is a growing trend in the packaging industry to produce high-performance biodegradable materials made from natural resources. The development of composites primarily made of natural fibres with a minor quantity of biopolymers has been a major goal in both academic and industrial research. Natural fibres are also chosen because of their various advantages, such as being more cost-effective, environmentally friendly, and comparable mechanical properties to synthetic fibres. However, their hydrophilic character leads to poor interfacial adherence with the matrix. Consequently, chemical treatment of the fibre’s surface appears to be required.  Unlike the bleaching process which is the most commonly used process in the packaging industrial sector, alkaline treatment is cost-effective and promotes only the partial removal of amorphous constituents, such as lignin, which is considered as the connecting material that holds the fibres together under hot compression, resulting in increased mechanical properties. However, the main issue with using chemically treated fibres alone are their low mechanical and water barrier properties. This can be avoided by employing a low quantity of biopolymers to coat the material's surface. Among the biopolymers, starch is one of the most promising renewable biopolymers because of its versatility, low cost, abundance, and biodegradability. Additionally, the mechanical, thermal and moisture protection properties of starch biopolymers can be further improved and adapted to meet specific needs by adding plasticisers and a crosslinking agent.