Kruger Inc Discloses Manufacturing Method for Nano-Crystalline Cellulose Film

Kruger Inc (Montreal, CA) researchers have devised a method to transform wood pulp into nano-crystalline cellulose film.  

Examples of some of the end uses for nano-crystalline cellulose  film include  (i) Aeronautics and Transportation for providing lighter components, better physical characteristics and longer life; (ii) Health & Science providing digestible/non-toxic film for digestive system; compatible film for chemical encapsulation; (iii) Electronics including film having polarization characteristics; film that is more affordable than carbon based products; (iv) Paper & Wood products including super resistant wood flooring varnishes; lightweight paper and others.

According to inventors Stephane Rousseau and Balazs Tolnai in U.S. Patent Application 20100124651, the  method of manufacturing nano-crystalline cellulose film includes the steps of (i) providing a suspension comprising nano-crystalline cellulose; (ii) uniformly dispensing the suspension onto at least one non-permeable sheet; (iii) drying the suspension using at least one non-contact drying apparatus; (iv) placing a semi-permeable sheet on the opposing surface of the suspension to the non-permeable sheet providing a sandwiched film configuration; (v) further drying the sandwiched film using at least one drying apparatus; (vi) removing the non-permeable sheet and the semi-permeable sheet from the sandwiched film; (vii) optionally further drying the gelled nano-crystalline film. 

Cellulose is a semi-crystalline high-molecular weight homopolymer contained in virtually all plants. Its semi-crystalline nature implies it has ordered crystalline regions as well as disordered amorphous regions. Subjecting cellulose to degradation via acid hydrolysis yields a suspension of cellulose crystals because the amorphous regions are preferentially hydrolized. Depending on the hydrolysis conditions, cellulose can be degraded into crystals that are between the micron and nanometer ranges--typically, nanocrystals would result from further hydrolyzing, and subjecting microcrystals to high shear forces.

Nanocrystalling cellulose has a size distribution that is species-dependent, but the typical range of crystal edge dimensions is 1-100 nm and that of crystal lengths is 20-2000 nm. Even though the tensile properties of nano-crystalline cellulose are an order of magnitude below those of carbon nanotubes, which is currently the strongest known structural material, they are sufficiently high to justify its inclusion into engineered biocomposite materials.

Currently, both pure nano-crystalline cellulose films and nano-crystalline cellulose-based composite films have only been produced on a laboratory scale, and have not been commercially isolated. The challenges and uncertainties associated with the commercial production of both pure and composite nano-crystalline cellulose films are numerous, and include: the films' lack of flexibility, their low release coefficients, their behaviour under tension, their drainage characteristics and their response to impingement drying. The method developed at Kruger overcomes many of these difficulties.