Polymer Flow Induced Crystallisation in Computational Fluid Dynamics

Aims:
In semi-crystalline polymers flow can drastically enhance the rate of crystallisation and so has a profound effect on product strength, toughness, permeability, surface texture, transparency as well as the capacity to be recycled. The aim of this project is to develop a predictive tool for flow induced crystallisation in polymers building upon recent progress made in the EPSRC grant EP/P005403/1. The objectives are to construct a numerical simulation of flow induced crystallisation in complex flow geometries and test its predictions against published experimental observations of flow induced crystallisation in polymer melts.

Methodology:
Developing a practical model for flow-induced crystallisation in polymers is challenging as this is an intrinsically multiscale modelling problem. Flow drastically enhances the rate at which polymers crystallise and has a profound effect on their morphology, as flow distorts the configuration of polymer chains and this distortion breaks down the kinetic barriers to crystallisation. Moreover all commercial polymers are made up of a blend of polymers of widely differing molecular weights. The project will build upon two recent advances in the theory of polydisperse polymer melts: the PolySTRAND model, which provides an efficient method for calculating the reduction in the energy barrier to nucleation due to flow induced changes in polymer conformation; and the Rolie-double-poly (RDP) constitutive model that provides a prediction for the rheology and polymer conformation of polydisperse polymers by taking account of the interactions between molecules of different lengths. Coupling these two models will therefore provide a means to predict the onset of crystallisation in a flowing polymer melt. This will be implemented within the CFD software package OpenFOAM enabling simulations of flow induced crystallisation in complex flow geometries.

Potential Impact:
Polymer processing is a multi-billion pound, world-wide industry, manufacturing products used on a daily basis. This vital sector of the economy will gain a significant competitive advantage from an improved understanding of how polymers crystallise during processing, as it will enable stronger, lighter, more durable and more easily recycled plastic products.

Expected Deliverables:
The project will deliver an integrated mathematical model for flow-induced crystallisation in polydisperse polymer melts based upon recent advancements in the molecular theory of polymers. By implementing this as a module with the widely used OpenFOAM software this will provide a tool that will be accessible and computationally cheap enough to be used in industry.

The CDT in Molecules to Product has the potential to make a real impact as a consequence of the transformative nature of the underpinning 'design and supply' paradigm. Through the exploitation of the generated scientific knowledge, a new approach to the product development lifecycle will be developed. This know-how will impact significantly on productivity, consistency and performance within the speciality chemicals, home and personal care (HPC), fast moving consumer goods (FMCG), food and beverage, and pharma/biopharma sectors.
UK manufacturing is facing a major challenge from competitor countries such as China that are not constrained by fixed manufacturing assets, consequently they can make products more efficiently and at significantly lower operational costs. For example, the biggest competition for some well recognised 'high-end' brands is from 'own-brand' products (simple formulations that are significantly cheaper). For UK companies to compete in the global market, there is a real need to differentiate themselves from the low-cost competition, hence the need for uncopiable or IP protected, enhanced product performance, higher productivity and greater consistency. The CDT is well placed to contribute to addressing this shift in focus though its research activities, with the PGR students serving as ambassadors for this change. The CDT will thus contribute to the sustainability of UK manufacturing and economic prosperity.
The route to ensuring industry will benefit from the 'paradigm' is through the PGR students who will be highly employable as a result of their unique skills-set. This is a result of the CDT research and training programme addressing a major gap identified by industry during the co-creation of the CDT. Resulting absorptive capacity is thus significant. In addition to their core skills, the PGR students will learn new ones enabling them to work across disciplinary boundaries with a detailed understanding of the chemicals-continuum. Importantly, they will also be trained in innovation and enterprise enabling them to challenge the current status quo of 'development and manufacture' and become future leaders.
The outputs of the research projects will be collated into a structured database. This will significantly increase the impact and reach of the research, as well as ensuring the CDT outputs have a long-term transformative effect. Through this route, the industrial partners will benefit from the knowledge generated from across the totality of the product development lifecycle. The database will additionally provide the foundations from which 'benchmark processes' are tackled demonstrating the benefits of the new approach to transitioning from molecules to product.
The impact of the CDT training will be significantly wider than the CDT itself. By offering modules as Continuing Professional Development courses to industry, current employees in chemical-related sectors will have the opportunity to up-skill in new and emerging areas. The modules will also be made available to other CDTs, will serve as part of company graduate programmes and contribute to further learning opportunities for those seeking professional accreditation as Chartered Chemical Engineers.
The CDT, through public engagement activities, will serve as a platform to raise awareness of the scientific and technical challenges that underpin many of the items they rely on in daily life. For example, fast moving consumer goods including laundry products, toiletries, greener herbicides, over-the-counter drugs and processed foods. Activities will include public debates and local and national STEM events. All events will have two-way engagement to encourage the general public to think what the research could mean for them. Additionally these activities will provide the opportunity to dispel the myths around STEM in terms of career opportunities and to promote it as an activity to be embraced by all thereby contributing to the ED&I agenda.