Wood-based barriers for wood-based materials

Paper/wood-based materials suffer from poor barrier and moisture-sensitive properties (left figure). By learning how nature (plants/fruits) create moisture and gas barriers, we have developed crosslinked barrier biopolyesters (representing the cutin layer in plants) with also a process that yields a rough wax-like outer layer, similar to what is observed in plants, giving high surface hydrophobicity (right figure (1)). These are obtained from glycerol and hydroxy fatty acids or diacids. In cuticals, the cutin layer also contain intracuticular wax-particles and phenolic compounds. What these do to the barrier function is not known. However, aromatic species are generally beneficial for barrier properties (2). In the strive to fully mimic natural cuticles the idea is to also incorporate these components to the new barriers. The focus of the project will be 1) to create the full cuticle structure, 2) analyse the effects on the barrier and physical properties of the different cuticle components. By mimicking the full cuticle, it will be possible to understand fully the mechanisms behind natural barriers, and to be able to tailor-make cuticle-based barrier layers on wood-based materials (e.g paper and board). For a future successful implementation of cuticle barriers in e.g. packaging materials, it is also important to have readily available biosources and a sustainable efficient process for conversion of these into barrier materials. The focus will be on wood-based sources, including readily available bark (suberin with fatty acids and aromatic compounds, middle figure), resin and lignin, and glycerol (from rapeseed diesel production) (3-7). Hence, in the project we will also consider 3) ways of efficiently producing the new barrier materials from readily available sources.