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From paper to Micro-Fibrillated Cellulose (MFC): challenges, uses, impact

12/12/2014

Whilst the majority of collected recyclable paper is utilised to produce more paper, a significant amount is instead used for energy generation, or even sent to landfill because increases in recycling rates leads to a reduction in quality.

What is MFC?

Micro-Fibrillated Cellulose (MFC), also known as cellulose nanofibres or nanocellulose (also encompassing cellulose nanocrystals and bacterial nanocellulose), is a material with a high aspect ratio – typically 3-20 nanometres wide and up to several micrometres long. MFC has high strength and stiffness values, and is both bio-based and biodegradable. MFC’s excellent mechanical properties, its high surface area- derived from the nano-scale dimensions- and its ability to form a strong entangled nano-porous network make it a promising material for bio-composite production. In addition, recent studies have proved the significant barrier properties of MFC, opening the door to other applications such as films, or paper coatings.

Commercial interest in nanocellulose (including MFC) is rapidly increasing based on the substantial environmental and economic benefits that can bring into various applications. Forestry experts FP Innovations estimate the market to be worth $250 million in North America alone by 2020.

 

 

 

 

 

 


Comparison of regular cellulose fibres and microfibrillated cellulose fibres (scale bar 50µm)

How is MFC produced?

Cellulose fibres are present everywhere since they are the main constituents of green plants. MFC is produced through the fibrillation of these cellulose fibres into the nano-scale elements which they are made of. Production usually requires intensive mechanical energy which can be moderately reduced through chemical and enzymatic pre-treatments. However, depending on the type and purity of the fibres used as raw material, the efficiency of these pre-treatments can be largely diminished.

What are the challenges associated with MFC production?

Conventionally, MFC production is very energy intensive. New processing techniques are currently under development to reduce the high energy consumption and produce new types of MFC materials on an industrial scale. An additional challenge is associated with public acceptance. Similar to other nanomaterials, safety of MFC has been questioned, however recent studies have shown processing of MFC does not cause significant exposure to fine particles during friction grinding or spray drying. Additionally no evidence of inflammatory effects or cytotoxicity on mouse or human macrophages have been observed after exposure to MFC.

How is MFC produced in the INNOBITE project?

Typically, most MFC is obtained from pure cellulose extracted from wood. The INNOBITE project is obtaining MFC from highly recycled paper and wheat straw.

First, a specialty pulp is produced subjecting the pulps to an alternative oxidation process in combination with specific mild mechanical treatments resulting in an exceptional decrease of the energy consumption of MFC production. The production of MFC from recycled newspaper proved to be possible with a Masuko Supermass Colloider device although the mechanical properties of the final material were not as high as expected. The cause could be found in the presence of unknown additives and inks that affect the production and rheological behaviour during isolation. Currently the project is dealing with the removal of these impurities, what is expected to improve the final properties of the MFC.

What is MFC used for in the INNOBITE Project?

MFC can be used to produce films or nanopaper which, along with lignin-based thermosetting resin, is being used in the preparation of thermosetting bio-composites for the manufacture of indoor panels (partitions) with excellent environmental credentials.

Additionally, MFC is compounded with lignin-based thermoplastic resin and the subsequent bio-composite extruded to produce profiles for outdoor decking and fencing.

What impact can successful production of MFC in the INNOBITE project have?

The methods for MFC production within the INNOBITE project should enable more sustainable production of indoor panelling, fencing and decking profiles.

Additionally, the technology being developed within the INNOBITE project will allow a paper-recycling mill to easily diversify into an MFC producer, which based on the promising properties of MFC as a high performance additive, will afford the paper mill the opportunity to provide MFC to a promising and expanding market.

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