News

The extraction of valuable materials & INNOBITE products

12/12/2014

The project has entered its final year. Read on for an overview of the project research so far…

The extraction of valuable materials 

The INNOBITE project focused on two processes which needed to be successfully developed to provide materials for the production of INNOBITE’s innovative construction materials: 

1)    the isolation of silica, lignin and cellulose pulp from wheat straw at industrial level through an integrated biorefinery approach, and

2)    the production of a speciality cellulose pulp, and subsequent isolation of micro-fibrillated cellulose (MFC), from recovered paper and wheat straw pulp.

There has been good progress made in developing an industrial method for extracting silica from the wheat straw feedstock, a biorefinery step which has never been implemented before. The new industrial step for silica extraction has been integrated into an existing biorefinery process (without interfering with the lignin and cellulose pulp production) and is being considered for patenting – more information is to become available at a later date.

A specialty pulp has been produced at pilot scale, initially from thermomechanical pulp (the major newspaper pulp component) and wheat straw pulp through an alternative chemical process. Processing conditions on both chemical and mechanical treatments have been optimized over a large number of trials, with the aim of minimizing the final MFC production cost, with special focus on decreasing the energy consumption. Work has also been undertaken to upscale technologies from laboratory to industrial scale including modifying existing industrial techniques to better suit production of MFC. Under those conditions, MFC of a high quality has been successfully isolated.

Recovered newspaper pulp characterization showed a high content of impurities, yet the MFC has been successfully obtained at lab scale. The production of MFC from recycled newspaper proved to be viable with a Masuko Supermass Colloider device. However, 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 effect the production and rheological behaviour during isolation. Work is currently ongoing to overcome said challenge.

 

INNOBITE Products

Thermosetting (TS) biocomposites

In order to enable production of INNOBITE’s final construction products, several steps have been finalized, while upscaling towards the final prototype is currently being undertaken. First, modelling the behaviour of the TS bio-composites has been carried out, setting up the ideal composition of the predefined system after considering both processing and final product characteristics. Based on this data, a satisfactory resin system has been developed by formulating a bio-epoxy resin containing wheat straw lignin originating in the integrated biorefinery process mentioned previously. In parallel, MFC films, successfully prepared from wheat straw pulp, have been prepared and used to reinforce that polymeric matrix creating a new TS biocomposite with remarkable properties. Four-layer lignin-based epoxy/MFC biocomposites, with MFC content up to 50%wt, have been produced at lab scale (10x15cm2) with the Hand lay-up technique. The composites have been subsequently tested for their mechanical properties with promising results and their environmental credentials (biobased carbon content and biodegradability) are currently being assessed.

Thermoplastic (TP) biocomposites

Originally, the work in this area started by using commercial lignin-based TP resin and commercial silica particles, from which biocomposites with improved impact strength and good particle dispersion were obtained. A new wheat straw lignin-based TP matrix was then developed within the project (Figure 1), which showed exceptional properties: less sensitivity to shear and heat than commercial grades and less tendency to produce incrustations on the processing equipment, all of which makes this new material especially suitable for extrusion. This matrix was then combined, first with commercial silica (Figure 2) and, after the development of the integrated biorefinery process containing the silica-extraction step, also with wheat straw silica. Currently, material properties are being further improved by optimisation of silica particle size. Future work will include determination of properties such as surface hardness, water absorption and biodegradability which are expected to meet the project objectives.

Figure 1 New wheat straw lignin TP resin production process

Figure 2 Lignin based thermoplastic matix containing commercial silica particles

 

 

 

 

 

Working in parallel, the first profile extrusion trials have been successfully performed with commercial lignin-based TP material (Figure 3). The work continues by utilising materials obtained through the project’s previous developments including silica and lignin from the new biorefinery process and MFC based on recycled paper. Also, co-extruded profiles with wheat straw silica/lignin-based TP compound at the outer and recycled paper based cellulose fibres/ lignin-based TP in the inner layer will be produced.

 Figure 3 Thermoplastic lignin based composite profiles

 

 

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