In the pharmaceutical industry, coatings have a very important place in manufacturing and product development. Solid dosage forms like tablets, pellets, granules etc. are typically coated in order to control the drug release within the body, and also to protect against external factors like moisture or attrition. This is often achieved through dry coating with fine powders, since this provides reduced environmental concerns (no volatile organic solvents emitted) and lower energy consumption (no subsequent drying or evaporation operations required). However, the dry coating process is wasteful in terms of coating powder used and energy input, since when the coating uniformity does not meet the requirement, the entire batch is disposed of. To mitigate this, an excess of coating powder is often used, with excessive energy input to ensure all solids are sufficiently coated. We aim to address these problems by determining for a given combination of substrates and powder coatings: (i) How is coating of a single powder layer influenced by particle properties? (ii) How should a mixer operate to provide uniform coating across the entire batch? (iii) What is the minimum energy input to ensure uniform product coating? In this research we will determine how coating is achieved on the fundamental, particle level, by controlling and manipulating the distribution of particle physical (size, shape) and surface (roughness, interface energy) properties and characterising the resulting coating quality. Coating powders are typically extremely fine and cohesive, and hence are prone to agglomerating to form large clusters. Industrial powder coating requires these coating powder agglomerates to be consistently broken down to single particles and precisely delivered to the host. We will establish how the process can be tailored to enhance the ability of the system to achieve this for any powder. By determining the underlying principles of powder coating, and the influences of material properties and process parameters, we will create a regime map for dry powder coating, which will enable industry to tune coating operations to minimise powder and energy use.

In the pharmaceutical industry, coatings have a very important place in manufacturing and product development. Solid dosage forms like tablets, pellets, granules etc. are typically coated in order to control the drug release within the body, and also to protect against external factors like moisture or attrition. This is often achieved through dry coating with fine powders, since this provides reduced environmental concerns (no volatile organic solvents emitted) and lower energy consumption (no subsequent drying or evaporation operations required). However, the dry coating process is wasteful in terms of coating powder used and energy input, since when the coating uniformity does not meet the requirement, the entire batch is disposed of. To mitigate this, an excess of coating powder is often used, with excessive energy input to ensure all solids are sufficiently coated. We aim to address these problems by determining for a given combination of substrates and powder coatings: (i) How is coating of a single powder layer influenced by particle properties? (ii) How should a mixer operate to provide uniform coating across the entire batch? (iii) What is the minimum energy input to ensure uniform product coating? In this research we will determine how coating is achieved on the fundamental, particle level, by controlling and manipulating the distribution of particle physical (size, shape) and surface (roughness, interface energy) properties and characterising the resulting coating quality. Coating powders are typically extremely fine and cohesive, and hence are prone to agglomerating to form large clusters. Industrial powder coating requires these coating powder agglomerates to be consistently broken down to single particles and precisely delivered to the host. We will establish how the process can be tailored to enhance the ability of the system to achieve this for any powder. By determining the underlying principles of powder coating, and the influences of material properties and process parameters, we will create a regime map for dry powder coating, which will enable industry to tune coating operations to minimise powder and energy use.

Many industrial processing operations depend on feed materials that are fine powders with poor handling characteristics, which have to be rectified by granulation to form coarser granules. Generally wet granulation is employed, in which a binder is added to the powder in a mixer usually in batch processes. Continuous Twin Screw Granulation (TSG) has considerable potential, eg in the pharmaceutical sector, because of the flexibility in throughput and equipment design, reproducibility, short residence times, smaller liquid/solid ratios and also the ability to granulate difficult to process formulations. However, there remain significant technical issues that limit its widespread use and a greater understanding of the process is required to meet regulatory requirements. Moreover, encapsulated APIs (Active Pharmaceutical Ingredients) are of increasing interest and the development of a TSG process that did not damage such encapsulates would significantly extend applications. Experimental optimisation of TSG is expensive and often sub-optimal because of the high costs of APIs and does not lead to a more generic understanding of the process. Computational modelling of the behaviour of individual feed particles during the process will overcome these limitations. The Distinct Element Method (DEM) is the most widely used method but has rarely been applied to the number of particles in a TSG extruder (~ 55 million) and such examples involve simplified interparticle interactions e.g. by assuming that the particles are smooth and spherical and any liquid is present as discrete bridges rather than the greater saturation states associated with granulation. The project will be based on a multiscale strategy to develop advanced interaction laws that are more representative of real systems. The bulk and interfacial properties of a swelling particulate binder such as microcrystalline cellulose will be modelled using Coarse-grained Molecular Dynamics to derive inputs into a meso-scale Finite Discrete Element Method model of formulations that include hard particles and a viscous polymeric binder (hydroxypropylcellulose). Elastic particles (e.g. lactose and encapsulates) with viscous binder formulations will be modelled using the Fast Multi-pole Boundary Element Method. These micro- and meso-scale models will be used to provide closure for a DEM model of TSG. It will involve collaboration with the Chinese Academy of Science, which has pioneered the application of massively parallel high performance computing with GPU clusters to discrete modelling such as DEM, albeit with existing simpler interaction laws. An extensive experimental programme will be deployed to measure physical inputs and validate the models. The screw design and operating conditions of TSG for the formulations considered will be optimised using DEM and the results validated empirically. Optimisation criteria will include the granule size distribution, the quality of tablets for granules produced from the lactose formulation and the minimisation of damage to encapsulates. The primary benefit will be to provide a modelling toolbox for TSG for enabling more rapid and cost-effective optimisation, and allow encapsulated APIs to be processed. Detailed data post-processing will elucidate mechanistic information that will be used to develop regime performance maps. The multiscale modelling will have applications to a wide range of multiphase systems as exemplified by a large fraction of consumer products, catalyst pastes for extrusion processes, and agriculture products such as pesticides. The micro- and mesoscopic methods have generic applications for studying the bulk and interfacial behaviour of hard and soft particles and also droplets in emulsions. The combination of advanced modelling and implementation on massively parallel high performance GPU clusters will allow unprecedented applications to multiphase systems of enormous complexity.

Manufacture Using Advanced Powder Processes - MAPP Conventional materials shaping and processing are hugely wasteful and energy intensive. Even with well-structured materials circulation strategies in place to recondition and recycle process scrap, the energy use, CO2 emitted and financial costs associated are ever more prohibitive and unacceptable. We can no longer accept the traditional paradigm of manufacturing where excess energy use and high levels of recycling / down cycling of expensive and resource intensive materials are viewed as inevitable and the norm and must move to a situation where 100% of the starting material is incorporated into engineering products with high confidence in the final critical properties. MAPP's vision is to deliver on the promise of powder-based manufacturing processes to provide low energy, low cost, and low waste high value manufacturing route and products to secure UK manufacturing productivity and growth. MAPP will deliver on the promise of advanced powder processing technologies through creation of new, connected, intelligent, cyber-physical manufacturing environments to achieve 'right first time' product manufacture. Achieving our vision and realising the potential of these technologies will enable us to meet our societal goals of reducing energy consumption, materials use, and CO2 emissions, and our economic goals of increasing productivity, rebalancing the UK's economy, and driving economic growth and wealth creation. We have developed a clear strategy with a collaborative and interdisciplinary research and innovation programme that focuses our collective efforts to deliver new understanding, actions and outcomes across the following themes: 1) Particulate science and innovation. Powders will become active and designed rather than passive elements in their processing. Control of surface state, surface chemistry, structure, bulk chemistry, morphologies and size will result in particles designed for process efficiency / reliability and product performance. Surface control will enable us to protect particles out of process and activate them within. Understanding the influence between particle attributes and processing will widen the limited palette of materials for both current and future manufacturing platforms. 2) Integrated process monitoring, modelling and control technologies. New approaches to powder processing will allow us to handle the inherent variability of particulates and their stochastic behaviours. Insights from advanced in-situ characterisation will enable the development of new monitoring technologies that assure quality, and coupled to modelling approaches allow optimisation and control. Data streaming and processing for adaptive and predictive real-time control will be integral in future manufacturing platforms increasing productivity and confidence. 3) Sustainable and future manufacturing technologies. Our approach will deliver certainty and integrity with final products at net or near net shape with reduced scrap, lower energy use, and lower CO2 emissions. Recoupling the materials science with the manufacturing science will allow us to realise the potential of current technologies and develop new home-grown manufacturing processes, to secure the prosperity of UK industry. MAPP's focused and collaborative research agenda covers emerging powder based manufacturing technologies: spark plasma sintering (SPS), freeze casting, inkjet printing, layer-by-layer manufacture, hot isostatic pressing (HIP), and laser, electron beam, and indirect additive manufacturing (AM). MAPP covers a wide range of engineering materials where powder processing has the clear potential to drive disruptive growth - including advanced ceramics, polymers, metals, with our initial applications in aerospace and energy sectors - but where common problems must be addressed.