Rheology of high solids Microfibrillated cellulose and miner al suspensions at high shear rates

Microfibrillated cellulose (MFC) is a wood pulp material where the fibril bundles are partially separated from each other, giving a high surface area product that attracts great interest as a sustainable reinforcing material. FiberLean Technologies Ltd has developed a novel, reliable, and scalable process to produce MFC by grinding a variety of cellulose species in water with a range of different mineral types; this product is an MFC- mineral composite material known as FiberLean.
With the decline in printing and writing paper grades, many paper mills are looking to convert their graphic paper machines to produce liner board or other packaging products. White printable top layers for packaging and other paper grades are conventionally produced as a seperate sheet before being couched, pressed, and dried together with the base layer. As a consequence, manufacturing these two-ply papers requires the additional construction of a complete paper machine wet-end section that is a major rebuilt and investment. The top layer of these multilayer grades typically comprises of a lightly refined hardwood Kraft fibre with 10%- 20% filler with the main objective of this layer being to optically cover tha base layer and achieve a high brightness surface suitable for printing. A solution to this costly papermachine upgrade is to apply a low weight FiberLean coating at low solids content (7.5%-10%) directly on the still consolidating base layer at the wet-end section of a paper machine using a coating applicator positioned above the wire. The mineral content of this novel coating can be as high as 80% mineral with the MFC acting as a binder holding the white layer from penetrating into the low solids content base. The two layers can then be pressed and dried simultaneously using the existing paper machine components upgrading single layer paper machines to two ply printable paper grades with a substantially lower cost investment.
By optimising this methodology of applying an even FiberLean ply at the wet-end of a paper machine, the utilisation of the same principal can contribute in the development of new aqueous based sustainable barrier layers for packaging applications. These MFC based layers could be used as a pre-coat for moisture, gas and grease barrier coating applications by closing up the highly porous surface of the base paper and allowing an impovement in the barrier coating holdout. This could allow lighter barrier coatweights to be applied without compromising the target properties of the end product. Furthermore, the smooth, low porosity FiberLean ply can on its own act as a barrier for moisture and grease creating numerous possibilities for this application.

The beneficiaries of the research and training of the CDT will be UK industry, the graduates of the programme, the wider academic community, and consumers :

(i) UK industry: the formulation sector is wide and diverse, and our industry partners are world-leading in a number of areas; foods (PepsiCo, Mondelez, Unilever), HPC (P+G, Unilever), fine chemicals (Johnson Matthey, Innospec), pharma (AstraZeneca, Pfizer, Imerys) and aerospace (Rolls-Royce). All projects are cocreated with industry, and cofunded - the majority will be EngD students based in company sites. Industry will benefit in a number of ways: (i) from a supply of trained graduates in this critical area, with > 90% of graduates of the programme to date getting jobs in formulation companies, and (ii) through participation in industry-academia research projects in which students work within the company on projects of practical value, (iii) through the synergy possible between companies in different non-competitive sectors (we have current projects between Mondelez and P+G, and Johnson Matthey and Unilever resulting from CDT linkages). We will also work with Catapult Centres, including the National Formulation Centre at CPI and the MTC at Coventry, to enhance the industry relevance of the CDT and train students in modern manufacturing methods.

(ii) Graduates of the programme: students are trained in a critical area where graduates are in short supply, obtain training and experience of the issues involved in industrial and collaborative research, present their work at external and internal meetings and get good jobs (>90% within formulation companies). Many of our graduates are now reaching senior positions in industry, and one, Dr Stewart Welch of Rolls Royce, is now the representative of Rolls-Royce on our Industrial Management Committee. In the next 5 years we will build at least 50 new projects with companies, creating EngD and PhD graduates, a new generation of leaders for the formulation industries.

(iii) Wider academic community in the UK and elsewhere. We will ensure that students on the programme write papers (as many as possible with industrial co-authors) on formulation projects. This is a vital part of the CDT, as it both ensures and demonstrates the academic quality of the programme. We have published extensively in areas such as; soft solid mixing processes (Unilever, Johnson Matthey; see Hall et al., Chem.Eng. Res. Des. 91, 2156-2168, 2013); food materials for enhanced mouthfeel, low-salt and low-sugar delivery, (Pepsico, Nestle, Mondelez; such as Moakes et al RSC Advances 5, 60786-60795, 2015); design of innovative cleaning strategies (Unilever, GSK, Heineken, P+G; Food Bioprod. Proc., 93, 269-282, 2015); characterisation of domestic cleaning processes (washing machines and dishwashers) to minimise water usage (P+G; Chem.Eng Sci., 75, 14, 2012); in-vitro models for formulated product breakdown and nutrient and drug delivery in the mouth, stomach and GI tract; EngD work followed up by BBSRC and industry funding (Eur J Nutr. 55, 2377-2388, 2016); dynamics of spray driers (P+G, AIChE J 61 1804-1821 2015; Chem. Eng. Sci. 162, 284-299, 2017), and ways to reduce waste in soyamilk production (Unilever; Innovative Food Science & Emerging Technologies, 41, 47-55, 2017).

(iv) consumers: many of the companies we work with are involved in Fast Moving Consumer Goods, where research has direct consumer benefit, for example in the creation of low fat foods that have high-fat mouthfeel. In addition, the overall aim of the programme is to develop sustainable formulated products and processes; such materials will be better for the environment and consumers.