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The massive biomass availability generated by the common giant reed (Arundo donax L.) motivates the research for its possible industrial use for high-added-value products through a biorefinery approach. The literature demonstrates the potential of common cane to obtain different high-value compounds, such as levulinic acid, oligosaccharides, fermentable sugars, highly digestible fiber for animal feed, polyphenols, and natural fibers for composite materials, among others. Arundo can also provide valuable lignocellulosic fibers with an application as composite reinforcement, which is the aim of this review. The work is split into different sections: fiber obtaining, mainly done by mechanical procedures, fiber characterization (composition, thermal degradation, "mechanical properties", and crystallinity), and properties of composites with reed fiber. Most authors refer to producing board panels with insulating properties, followed by introducing reed fibers or ground materials in thermoset resins. Few papers focus on the production of thermoplastic composites with Arundo, which shows the opportunity for deepening research in this area. PRISMA flowchart has been followed to perform the literature review. Different sources have been used, and retrieved results have been combined to obtain the core studies assessed in this review, evaluating the options of using Arundo fibers to obtain polymer composites.

The massive availability of biomass generated by the common giant reed (Arundo donax L.) motivates the search for its possible industrial use for the generation of high added-value products through implementing a biorefinery approach. The literature demonstrates the potential of common cane to obtain different high-value compounds, such as levulinic acid, oligosaccharides, fermentable sugars, highly digestible fiber for animal feed, polyphenols, and natural fibers for composite materials, among others. The data shows the upward trend in Europe toward the generation of new green industries, grouped under the biorefinery concept. Therefore, this review summarizes the current knowledge on the use of Arundo to produce materials, fibers, and chemicals. Major environmental concerns related to this plant are also reviewed. Special attention has been paid to the potential use of Arundo to produce chemicals using green chemistry approaches, as a way to contribute to and advance the achievement of Sustainable Development Goals. Recommendations for future research are also outlined.

Large scale buoyant structures typical of offshore wave energy generation devices may be produced using the rotational foam moulding process. Due to the challenging environmental conditions these parts experience during their lifetime at sea, it is important that the structures are optimised to ensure acceptable mechanical performance. Foams containing large cells suffer a reduction in mechanical properties; therefore, an optimal foam contains small, evenly sized, and well distributed bubbles in large numbers. Due to the lower pressures used in the process, this can be challenging to achieve. Careful selection of material and processing conditions is required to achieve an optimal structure. A unique bench-based rig was used to observe developing foam structures. A camera was used to record the foam height change at intervals. Foam height change was obtained using digital image analysis. Several parameters were studied such as the polymer particle size or the mould pressure for example. In addition to the foam height change, foam density were analysed. It is found that mould pressure, polymer particle size, chemical blowing agent concentration, and polymer rheology may be used to control the foamed structures.

BACKGROUNDA valorization route of corn husks from agrarian practices was performed by liquefaction using glycerol as liquefaction solvent to obtain biopolyols used as bioadditive in starch blends with the aim to find a useful industrial application in polymer processing.RESULTSLow molecular weight liquefied products obtained from a practically total convert reaction can be used for composite formulations (OH number, 310 mg KOH/g; viscosity, 3.4 Pa.s; and molecular weight (MW), 549 g/mol). Concurrently, starch thermoplastic blends using different proportions of biopolyol (40, 30 and 20 wt %) as plasticizer were produced with maximum torque and plasticization energy ranging from 3.4 to 15.1 Nm and from 1.7 to 9.1 Nm/min. The starch/biopolyol (70/30) sheets obtained by thermo‐pressing showed similar properties to controls (starch/glycerol: 70/30) such as sensitivity to environment, retrodegradation, biodegradability and density, however, mechanical properties exhibited better performance compared to controls (Young's modulus, 14 MPa; strain at break, 33 %; and tensile strength, 1.2 MPa), which exhibit a material with major mechanical balance.CONCLUSIONThe adequacy in the conversion of corn husks into biopolyols that could be used as improved bio‐based plasticizer to obtain biodegradable blends was revealed in the results. Hence, this study demonstrates that liquefied corn husks residues are sustainable resources with suitable properties for polymer processing, which can be applied in bioplastics and be considered as a value‐added feature.

The interest in natural fibre reinforced composites is growing in industrial applications due to natural fibres being an attractive alternative to synthetic fibres. However, it is necessary to improve the fire behaviour of the material because natural fibres have a high combustibility. The objective of this work is to evaluate the fire resistance of polymer composites reinforced with natural fibre fabric, using magnesium hydroxide as flame retardant for the polymeric matrix and alkali treatment for the fibre. The types of fabric are banana, banana with cotton and linen; and long banana fibre has been used for the formation of a nonwoven. The fire test is carried out based on ISO 9773 standard and the effect of the additive has been studied, chemical treatment, type of fabric and number of layers. Through statistical analysis, it is concluded that the flame propagation speed has a decreasing relation with respect to the percentage, but it decreases the mechanical properties considerably. In addition, the number of layers and type of fabric influence the fire properties. Finally, it is concluded that composites reinforced with linen fabric have the best mechanical properties, but banana nonwoven with 60% additive has the best fire behaviour.

Petroleum-based polymers traditionally used for plastic packaging production have been shown to leach dangerous chemicals such as bisphenol-A (BPA). Bio-based polymers are potentially safer alternatives, and many can be sustainably sourced from waste streams in the food industry. This study assesses bio-based polymers undergoing food packaging development for migration of endocrine disrupting leachates at the level of estrogen, androgen and progestagen nuclear receptor transcriptional activity. Reporter gene assays were coupled with migration testing, performed using standardised test conditions for storage and temperature. Test samples include nine bio-based polymers and four inorganic waste additives mixed with a traditional petroleum-based polymer, polypropylene. Thermoplastic starch material, polybutylene succinate, polycaprolactone, polybutylene adipate terephthalate (PBAT), two polylactic acid (PLA)/PBAT blends, polyhydroxybutyrate (PHB) and eggshell/polypropylene (10:90) presented no significant reduction in metabolic activity or hormonal activity under any test condition. Polypropylene (PP) presented no hormonal activity. Metabolic activity was reduced in the estrogen responsive cell line after 10 days migration testing of eggshell/polypropylene (0.1:99.9) in MeOH at 40°C, and PP in MeOH and dH

This chapter discusses the issues of plastic, primarily microplastic pollution in freshwater and drinking water, with a focus on developing nations. Microplastics, generally defined as plastic particles with a size less than 5 mm, are beginning to gain attention as an emerging contaminant of concern. Whilst testing has recently begun on the contamination of freshwater and treated drinking water by microplastics in a number of developed regions, literature regarding microplastic pollution in the water of less economically developed countries is lacking. Microplastics pose a threat to human health, and therefore, it is important that cost-effective methods for the testing, detection, and removal of these plastic items from drinking water globally is considered with a higher level of urgency. It is argued that by achieving the aims laid out by the Sustainable Development Goals, particularly Goals 6 and 12, the threats from microplastic pollution will subside.

The diminishing supply of crude oil has led the polymer industry to continue to investigate the use of alternative polymer feedstocks. Agricultural waste streams (or low-value byproducts) often contain the building blocks for biopolymer production. One potential feedstock is poultry feathers. Global poultry production currently exceeds 50 billion birds per annum and is continuing to increase. Generating more than 6 million tonnes of feathers/keratin annually, it represents a viable resource for biopolymers. A barrier to industrial adoption has been scalability. This work aims to upscale the extrusion process by adapting to a larger extruder (capable of 3+ kg/h), which will also improve mix stability. Use of this system improved throughput to 0.8 kg/h. The pellets produced were then used in secondary processing (tube and sheet extrusion) to investigate the potential for targeted applications. Analysis on water uptake, morphology, and mechanical properties was conducted to characterize feather-based polymers. Mechanical properties (tensile strength 3.6 MPa and elongation 58%) were similar to those of other biopolymers (range between 0.3 and 10.6 MPa and 2 and 85%, respectively) yet were achieved using a lower plasticizer content (24% compared to 29–40%)/higher waste loading. Results proved that feather polymers could be produced on a large scale and used to produce a range of final applications using a material containing ∼70% waste product.

Rotational molding allows for obtaining hollow parts with good aesthetics and properties, having as main drawbacks the lack of pressure and the long cycle times, which limit the range of materials. Different fillers have been introduced in rotomolding to obtain composite materials assessed. This review has shown that glass fibers or particles are the most common material among them, although carbon fibers or clays have also been studied. In general terms, 10% loadings provide an increase in mechanical properties; higher loadings usually lead to a decrease in processability or final properties. When the filler consists of a micro- or nano-material, such as clay or graphene, lower loadings are proposed, generally not exceeding 3%. The use of fillers of an inorganic nature to obtain composites has not been as explored as the incorporation of lignocellulosic materials and even less if referring to waste materials or side streams from industrial processes. So, there is a broad field for assessing the processing and properties of rotomolded composites containing inorganic waste materials, including the study of the relationship between the ratio of filler/reinforcement and the final properties and also their preprocessing (dry blending vs. melting compounding).

With global oil supplies expected to deplete within the next century, novel processing techniques and material developments are becoming a necessity to ease the burden and, eventually, replace these unsustainable resources. Work has begun to replace plastics (polymers derived from crude oil) with sustainable biopolymers. Often these can be derived from waste sources or low value by-products. Poultry feathers represent one possible feedstock material for biopolymer development, however the understanding of their thermal processing and melt formation remains in its infancy. Moreover, transitioning from lab scale to industrial scale remains a significant challenge. This paper aims to carry out extrusion of feather-based polymers and further understand the method of polymer formation. A design of experiments (DOE) investigation was conducted to optimise composition and extruder set-up. Results demonstrate shearing forces, pressure and temperature were all key factors for stable feather polymer formation to occur. The investigation concluded that a feather mix (with a particle sizing of 212–500 µm) with propylene glycol, in a ratio of 70:30 respectively, processed at 125 °C represents an optimal set-up in terms of mechanical and processing properties. These outcomes develop a base-line technique for implementing feather-based polymers into the polymer industry. Characterisation (via Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry) showed minimal changes to the thermal properties or structures of produced samples outlining potential reprocessing capability. An estimation of polymer cost generation was conducted, showing a saving of 56% compared to pure polypropylene.

The use of renewable resources is becoming increasingly important if we are to address the negative impacts of petroleum-based polymers. Utilising renewable resources, such as agri-food wastes (AFWs), for biopolymer production offers the advantages of lower dependence on fossil fuels, resource recovery (generating added value), and waste management. AFWs are generated as by-products or residues at every stage of the food supply chain: harvest, processing, and post-consumption. AFWs are a significant societal challenge but their full potential as renewable resources remain unexploited. Hence, this study aimed to identify feedstocks that can provide a continuous supply of raw materials for the manufacture of biopolymers. Harvest and process wastes from major crops were assessed using information from published reports and government departments over the period 2013‐2017. The analysis was based on criteria focusing on the availability, characteristics, and market value of the identified AFWs. The analysis was conducted for the crops: wheat, barley, oats, rapeseed, sugar beet, carrots, and onions. Total AFW production in the UK over the reference period was estimated at 15 Mt dry matter/yr, to which wheat is the major contributor (≈7 Mt). The results show that harvest residues, e.g., straw, have medium to high theoretical availability and competing uses, whereas processing residues, e.g., onion peels, have low theoretical availability and cost but are well suited for biopolymer production. These findings provide valuable information about resources that will enable potential investors to conduct studies to accurately assess the practicality of valorising AFWs into biopolymers.

With oil supplies, needed for plastic production, decreasing dramatically, there is a clear driver for alterative polymers from sustainable resources. Poultry feathers, containing ∼90% keratin, are one source of natural polymer with huge potential for biopolymer production. However, the presence of crosslinks, known as disulphide bonds, hinders processability. This paper reviews techniques to enable breakage of disulphide bonds through use of reduction agents (sodium sulphite and sodium sulphate) and hydrolysis. Samples were analysed using FTIR and DSC to quantify achievable bond breakage, effect on thermal properties and changes in protein concentration. A review on the effect of particle size on disulphide bond breakage was also conducted, along with quantifying the reformation of bonds post-processing. Finally, a bicinchoninic acid (BCA) protein assay was used to quantify changes to soluble protein content, key to predicting if biopolymer formation can occur. The results showed a final disulphide bond breakage of between 48% and 67% was achievable using these techniques. It was also shown that disulphide bond content exhibited up to 60% bond reformation post treatment. These reductions in disulphide bonds increased the thermoplastic nature and apparent protein content. Despite achieving the highest bond breakage percentage, hydrolysis caused degradation of useful proteins, rendering the material unsuitable for biopolymer production. Results suggested that treatment with sodium sulphite (4.3% wt. of feathers) and use of a small particle size (0–100 µm), sufficiently altered the properties of raw feathers to enable feather biopolymer production.

Increased poultry production worldwide has led to higher generation of poultry waste materials. To date, these materials have limited uses and often end up in landfill. Research has begun to investigate new applications for these waste materials, particularly as fillers and functional additives with a range of polymers. With oil supplies diminishing, use of an otherwise waste material to mitigate depletion rates represents a solution that will positively impact two global industries. This paper presents a technoeconomic analysis to determine the feasibility of using three abundant poultry waste materials, bone, meal and feathers, within the polymer industry, quantifying the energy, cost and carbon implications compared to conventional polymers and the potential oil savings compared to use as a bioenergy resource. Given the complexity of such an approach the assumptions involved have been detailed. Concurrently, compositional analysis yielded a detailed breakdown of each material (minerals and organic content), which was used to determine their potential as fillers in polymer processing. Calculations concluded that use as a polymer filler, in loadings up to 40% wt. for bone and meal and 60% wt. for feathers, provided high energy, carbon and cost savings to both the polymer and poultry industries. Crude oil savings were 5 times higher than use as a bioenergy source, showing the potential of poultry waste streams as polymer additives.

Typically, packaging films used for modified atmosphere packaging are multi-layered structures with high barrier properties, but these are difficult to recycle and therefore unsustainable. Lower barrier properties would allow a reduction in barrier layer thickness and therefore a reduction of raw materials or enable the use of alternative materials like bioplastics. The aim of this paper is to propose a model that determines the minimum permeability requirements to maintain shelf-life of red meat in high oxygen modified atmosphere packaging, therefore, providing the basis for the development of a new film. A mathematical model was developed to predict Pseudomonas spp. (spoilage bacteria particularly sensitive to changes in carbon dioxide) growth and headspace gas dynamics; predictions were validated against 15 published datasets that varied meat product, temperature, permeability of the packaging and initial headspace composition. The bias and accuracy factors comparing the model to the experimental maximum specific growth rate were 0.8426 and 1.2063 respectively, indicating a fail-safe model. Using response surface methodology, an empirical equation was developed for use as a decision support tool. To maintain shelf life, carbon dioxide permeability of 1.7 × 10-6 m3m-2h-1 atm-1 was required, higher than currently recommended permeabilities (approximately 1 × 10-8 m3m-2h-1 atm-1); this implies a clear potential for alternative films or a reduction in barrier layer thickness.

The world is facing increasing economic, environmental, and social sustainability challenges. Agri-Food supply chains play an intrinsic part in these as both, heavy users of natural resources and a supplier of essential resources satisfying societal needs. In the context of the circular economy, focusing on Reduce, Reuse and Recycle, (3R waste hierarchy) is no longer sufficient. Here an extension is proposed through rethinking the system, redesigning its infrastructure, processes and products, replacing traditional technologies, materials and energy sources with more effective ones and repurposing or recontextualising the use of products, components and by-products. While principles behind these ‘Rs’ are generally known, their application is industry and material/product-specific. Within the Agri-Food supply chain it is subject to strict food safety regulations, packaging requirements, ethical considerations, etc. In this paper, we explore ‘R’ principles discussed in the academic literature, identify ‘8Rs’ concept applicable to biological (e.g., crops, prepared food) and technical flows (e.g., packaging) that appear at Agri-Food producers and discuss their role in enabling and enhancing circularity in bio- and techno-sphere. We present applications of these ‘Rs’ in four cases relevant to the Agri-Food sector.

Bio-based plastics are produced from bio-based raw materials such as sugar cane, potatoes, corn, and agricultural and slaughterhouse waste. The evolution of the bio-based plastics market is affected by the stakeholders involved owing to their role in production processes, environmental guidelines and purchasing decisions. It is therefore imperative to understand the perceptions of stakeholders in order to inform the development of the bio-based plastics sector. This novel exploratory study investigates the perceptions and opinions of three stakeholder groups: environmental professionals and plastic processors; university students; and consumers in Belfast, Northern Ireland. During the focus groups (25 participants in total), samples of bio-based plastics, including starch-based monolayer and multilayer, and polyethylene terephthalate (PET), were presented. A qualitative analysis using the framework method revealed that environmental professionals and plastic processors were aware of both the benefits of bio-based plastics, such as a reduction in use of fossil fuels; and the challenges, which include the utilisation of agricultural land for biomass substrates and possible contamination of current conventional plastic recycling streams. Although there was a general lack of knowledge among students and consumers about bio-based plastics, they conveyed their beliefs that the use of agricultural waste will lead to closed-loop systems, resulting in a balanced approach to production and waste management. Some students and consumers, raised concerns about contamination of food by bio-based packaging prepared from slaughterhouse waste. However, these participants supported the use of slaughterhouse waste in the production of bio-based plastics for non-food contact items. The students and consumers and some of the environmental professionals and plastic processors were reluctant to pay more for bio-based plastics. The results indicate that manufacturers of bio-based plastics could benefit from informing consumers about the environmental impacts of beginning-of-life parameters, such as production processes and feedstocks, by using life cycle assessment parameters. This should be incorporated into information provided on labelling using standards from neutral organisations. This research could inform future communication strategies around bio-based plastics with both the public and industry.

Polymer foams are essential for the manufacture of low cost, lightweight, buoyant structures typical of offshore energy generation devices. Careful balancing of material and processing conditions is essential to achieving a mechanically optimal cellular structure. To date, a convenient method for optimising rotationally moulded polymer foams has not been demonstrated. An offline experimental method was developed, and a preliminary study conducted, analysing the influence of processing and material parameters, such as polymer particle size or chemical blowing agent (CBA) concentration, on polymer cellular structures. The density of each sample was analysed, and image analysis software used to compare the amount of cell deterioration in each specimen cross-section. The method was found to be capable of indicating appropriate levels of each variable, offering a quicker route to foam optimality based on minimising density and preventing cell deterioration.

Plastics are used in a wide range of applications generating significant waste streams. This is driving policy interventions to increase circularity, reduce waste and improve resource efficiency. However, information on plastic waste flows is not widely available across regions and nations. With an overarching aim to make recommendations for supporting the transition to a circular plastics economy in Northern Ireland, this study used quantitative uncertainties to conduct regional material flow analysis and geospatial mapping to identify local hotspots. It was observed that 149 ± 11 kilo tonnes of plastic waste were produced in Northern Ireland (79.2 kg/capita) in 2018. Reuse and recovery for recycling reached up to 35%, while 62% of plastic waste was landfilled with the remainder (3%) incinerated. This study found that there are increasing amounts of plastic waste locked in sectors with long product lifetimes, such as the construction sector with 21.3 kilo tonnes for 2018. It is therefore important to consider the processing capacities and environmental impacts of plastic waste management, not only for current plastic waste flows but also for tackling possible future growth of these flows. The results indicate that there is a need for a holistic all-island approach for effective plastic waste management in both Northern Ireland and the neighbouring Republic of Ireland. Furthermore, stricter enforcement of existing waste management rules and regulations could prevent need for additional policies to support a circular economy. This research provides robust scientific data to aid the transition to a circular economy for plastics in the region.

Medical devices destined for insertion into the body must be sterilised before implantation to prevent infection or other complications. Emerging biomaterials, for example bioresorbable polymers, can experience changes in their properties due to standard industrial sterilization processes. Gamma irradiation is one of the most reliable, large scale sterilization methods, however it can induce chain scission, cross-linking or oxidation reactions in polymers. sterilization at low temperature or in an inert atmosphere has been reported to reduce the negative effects of gamma irradiation. The aim of this study was to investigate the impact of low temperature sterilization (at −80 °C) when compared to sterilization at ambient temperature (25 °C) both in inert atmospheric conditions of nitrogen gas, on poly(lactide co-glycolide) (PLGA).PLGA was irradiated at −80 and 25 °C at 40kGy in a nitrogen atmosphere. Samples were characterised using differential scanning calorimetry (DSC), tensile test, Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC).The results showed that the molecular weight was significantly reduced as was the glass transition temperature, an indication of chain scission. FTIR showed small changes in chemical structure in the methyl and carbonyl groups after irradiation. Glass transition temperature was significantly different between irradiation at −80 °C and irradiation at 25 °C, however this was a difference of only 1 °C. Ultimately, the results indicate that the sterilization temperature used does not affect PLGA when carried out in a nitrogen atmosphere.

Life cycle analyses of novel food packaging materials do not often account for the environmental impact of a change in shelf-life, which can result in misleading comparisons. This paper established a methodology for comparative life cycle analyses, whereby the direct effects of the lidding films were compared whilst ensuring the indirect effects of the wasted food portion remained stable. Global warming potential and non-renewable energy use were analysed for a conventional (low-density polyethylene/ethylene vinyl alcohol) versus a biodegradable (polyhydroxyalkanoate/butenediol vinyl alcohol) multilayer lidding film for modified atmosphere packaging of minced beef. Two methodologies were investigated. The first (metric one) changed the barrier layer thickness in the biodegradable film to match the carbon dioxide transmission rate with that of a conventional film. The second (metric two) changed the barrier layer thickness to match a carbon dioxide transmission rate predicted by a mathematical model to ensure the same shelf-life as the conventional film. Using metric two over metric one resulted in 1) a thinner film 2) 2.3 times lower global warming potential. When using sugar beet as the biopolymer feedstock and the current UK disposal system, the biodegradable film had 135% higher global warming potential than the conventional film. By incorporating waste products and better farming practices, the global warming potential of the biodegradable film could be up to 92% lower than that of the conventional film. This work demonstrates how shelf-life can be incorporated into life cycle analyses and the importance of accounting for it, in particular when evaluating biodegradables which often have higher permeabilities.

The original version of this article unfortunately contained a mistake. E. Themistou was missing from the author group and so is now included with this erratum.

Process-induced degradation of clinically relevant resorbable polymers was investigated for two thermal techniques, filament extrusion followed by fused deposition modelling (FDM). The aim was to develop a clear understanding of the relationship between temperature, processing time and resultant process-induced degradation. This acts to address the current knowledge gap in studies involving thermal processing of resorbable polymers. Poly(DL-lactide-co-glycolide) (PDLGA) was chosen for its clinically relevant resorption properties. Furthermore, a comparative study of controlled thermal exposure was conducted through compression moulding PDLGA at a selected range of temperatures (150-225 °C) and times (0.5-20 min). Differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) were used to characterise thermally induced degradation behaviour. DSC proved insensitive to degradation effects, whereas GPC demonstrated distinct reductions in molecular weight allowing for the quantification of degradation. A near-exponential pattern of degradation was identified. Through the application of statistical chain scission equations, a predictive plot of theoretical degradation was created. Thermal degradation was found to have a significant effect on the molecular weight with a reduction of up to 96% experienced in the controlled processing study. The proposed empirical model may assist prediction of changes in molecular weight, however, accuracy limitations are highlighted for twin-screw extrusion, accredited to high-shear mixing. The results from this study highlight the process sensitivity of PDLGA and proposes a methodology for quantification and prediction, which contributes to efforts in understanding the influence of manufacture on performance of degradable medical implants.

In this study, bone tissue engineered scaffolds fabricated via powder-based 3D printing from hydroxyapatite (HA) and calcium sulphate (CaSO4) powders were investigated. The combination of using a fast resorbing CaSO4 based powder and the relatively slower HA powder represents a promising prospect for tuning the bioresorption of 3D printed (3DP) scaffolds. These properties could then be tailored to coincide with tissue growth rate for different surgical procedures. The manufactured scaffolds were infiltrated with poly(ε‑caprolactone) (PCL). The PCL infiltrated the inter-particle spacing within the 3DP structures due to the nature of a loosely-packed powder bed and also covered the surface of ceramic-based scaffolds. Consequently, the average compressive strength, compressive modulus and toughness increased by 314%, 465% and 867%, respectively. The resorption behaviour of the 3DP scaffolds was characterised in vitro using a high-throughput system that mimicked the physiological environment and dynamic flow conditions relevant to the human body. A rapid release of CaSO4 between Day 0 and 28 was commensurate with a reduction in scaffold mass and compressive properties, as well as an increase in medium absorption. In spite of this, HA particles, connected by PCL fibrils, remained within the microstructure after 56 days resorption under dynamic conditions. Consequently, a high level of structural integrity was maintained within the 3DP scaffold. This study presented a porous PCL-HA-CaSO4 3DP structure with the potential to encourage new tissue growth during the initial stages of implantation and also offering sufficient structural and mechanical support during the bone healing phase.

The chemical compositions of calcium phosphate materials are similar to that of bone making them very attractive for use in the repair of critical size bone defects. The bioresorption of calcium phosphate occurs principally by dissolution. To determine the impact of composition and flow conditions on dissolution rates, calcium phosphate tablets were prepared by slip casting of ceramic slips with different ratios of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). Dissolution was evaluated at pH4 using both a static and dynamic flow regime. Both the composition of the HA:β-TCP tablet and flow regime noticeably influenced the rate of dissolution; the 50:50 HA:β-TCP composition demonstrating the greatest level of dissolution, and, exposure of the ceramic specimens to dynamic conditions producing the highest rate of dissolution. Understanding the impact of phase composition and flow condition with respect to the dissolution of calcium phosphate will aid in the development and improvement of materials for bone substitution.

The application of synthetic cancellous bone has been shown to be highly successful when its architecture mimics that of the naturally interconnected trabeculae bone it aims to replace. The following investigation demonstrates the potential use of marine sponges as precursors in the production of ceramic based tissue engineered bone scaffolds. Three species of natural sponge, Dalmata Fina (Spongia officinalis Linnaeus, Adriatic Sea), Fina Silk (Spongia zimocca, Mediterranean) and Elephant Ear (Spongia agaricina, Caribbean) were selected for replication. A high solid content (80 %wt), low viscosity (126 mPas) hydroxyapatite slurry was developed, infiltrated into each sponge species and subsequently sintered, producing a scaffold structure that replicated pore architecture and interconnectivity of the precursor sponge. The most promising of the ceramic tissue engineered bone scaffolds developed, Spongia agaricina replicas, demonstrated an overall porosity of 56-61% with 83% of the pores ranging between 100 and 500 microm (average pore size 349 microm) and an interconnectivity of 99.92%.

Key to various bone substitute scaffold production techniques is the development of free-flowing ceramic slurry with optimum rheological properties. The aim is to achieve a colloidal suspension with as high a solid content as possible while maintaining a low viscosity which easily penetrates the pores of relevant sacrificial templates. The following investigation describes the optimization of a hydroxyapatite slip and demonstrates its potential application in scaffold production. Using predominantly spherical particles of hydroxyapatite of between 0.82 μm and 16.2 μm, coupled with a 2 wt % addition of the anionic polyelectrolyte, ammonium polyacrylate, an 80 wt % (55.9 vol %) hydroxyapatite solid loaded slip with a viscosity of approximately 126 mPa s has been developed. Its ability to infiltrate and replicate porous preforms has been shown using polyurethane foam. The enhanced particle packing achieved has allowed for the production of scaffolds with highly dense and uniform grain structures. The results represent a significant improvement in current slurry production techniques and can be utilized to develop high-density ceramic bone substitute scaffolds.

Bone tissue engineering may provide an alternative to autograft, however scaffold optimisation is required to maximize bone ingrowth. In designing scaffolds, pore architecture is important and there is evidence that cells prefer a degree of non-uniformity. The aim of this study was to compare scaffolds derived from a natural porous marine sponge (Spongia agaricina) with unique architecture to those derived from a synthetic polyurethane foam. Hydroxyapatite scaffolds of 1 cm3 were prepared via ceramic infiltration of a marine sponge and a polyurethane (PU) foam. Human foetal osteoblasts (hFOB) were seeded at 1x105 cells/scaffold for up to 14 days. Cytotoxicity, cell number, morphology and differentiation were investigated. PU-derived scaffolds had 84-91% porosity and 99.99% pore interconnectivity. In comparison marine sponge-derived scaffolds had 56-61% porosity and 99.9% pore interconnectivity. hFOB studies showed that a greater number of cells were found on marine sponge-derived scaffolds at than on the PU scaffold but there was no significant difference in cell differentiation. X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS) showed that Si ions were released from the marine-derived scaffold. In summary, three dimensional porous constructs have been manufactured that support cell attachment, proliferation and differentiation but significantly more cells were seen on marine-derived scaffolds. This could be due both to the chemistry and pore architecture of the scaffolds with an additional biological stimulus from presence of Si ions. Further in vivo tests in orthotopic models are required but this marine-derived scaffold shows promise for applications in bone tissue engineering.

The production of complex inorganic forms, based on naturally occurring scaffolds offers an exciting avenue for the construction of a new generation of ceramic-based bone substitute scaffolds. The following study reports an investigation into the architecture (porosity, pore size distribution, pore interconnectivity and permeability), mechanical properties and cytotoxic response of hydroxyapatite bone substitutes produced using synthetic polymer foam and natural marine sponge performs. Infiltration of polyurethane foam (60 pores/in2) using a high solid content (80wt %), low viscosity (0.126Pas) hydroxyapatite slurry yielded 84-91% porous replica scaffolds with pore sizes ranging from 50?m - 1000?m (average pore size 577?m), 99.99% pore interconnectivity and a permeability value of 46.4 x10-10m2. Infiltration of the natural marine sponge, Spongia agaricina , yielded scaffolds with 56- 61% porosity, with 40% of pores between 0-50?m, 60% of pores between 50-500?m (average pore size 349 ?m), 99.9% pore interconnectivity and a permeability value of 16.8 x10-10m2. The average compressive strengths and compressive moduli of the natural polymer foam and marine sponge replicas were 2.46±1.43MPa/0.099±0.014GPa and 8.4±0.83MPa /0.16±0.016GPa respectively. Cytotoxic response proved encouraging for the HA Spongia agaricina scaffolds; after 7 days in culture medium the scaffolds exhibited endothelial cells (HUVEC and HDMEC) and osteoblast (MG63) attachment, proliferation on the scaffold surface and penetration into the pores. It is proposed that the use of Spongia agaricina as a precursor material allows for the reliable and repeatable production of ceramic-based 3-D tissue engineered scaffolds exhibiting the desired architectural and mechanical characteristics for use as a bone 3 scaffold material. Moreover, the Spongia agaricina scaffolds produced exhibit no adverse cytotoxic response.

Transdermal drug delivery offers certain advantages over conventional oral or parenteral administration. However, transdermal delivery is not available to many promising therapeutic agents, especially high molecular weight hydrophilic compounds. This is due to the excellent barrier property of the superficial skin layer, the stratum corneum (SC). Only drugs with very specific physicochemical properties (molecular weight < 500 Da, adequate lipophilicity, and low melting point) can be successfully administered transdermally. Of the several active approaches used to enhance the transport of drugs through the SC, the use of microneedles (MNs) has recently been shown to be very promising and has attracted considerable attention by researchers from both industry and academia. MNs, when used to puncture skin, will by-pass the SC and create transient aqueous transport pathways of micron dimensions and enhance the transdermal permeability. However, for effective performance of these MNs in drug delivery applications, irrespective of the type, material, height and density, it is imperative that they penetrate into the skin with the greatest possible accuracy and reproducibility. Due to the inherent elasticity and irregular surface topography of the skin, it remains a major challenge to the reproducibility of MN penetration. Therefore, in order to achieve uniform and reproducible MN penetration into skin, an external source of assistance could be very useful. Accordingly, this review deals with various innovative applicator designs developed by industry and research centres in the context of effective application of MN arrays for transdermal drug delivery, as disclosed in the recent patent literature.

The aim of this study was to increase understanding of the mechanism and dominant drivers influencing phase separation during ram extrusion of calcium phosphate (CaP) paste for orthopaedic applications. The liquid content of extrudate was determined, and the flow of liquid and powder phases within the syringe barrel during extrusion were observed, subject to various extrusion parameters. Increasing the initial liquid-to-powder mass ratio, LPR, (0.4–0.45), plunger rate (5–20 mm/min), and tapering the barrel exit (45°–90°) significantly reduced the extent of phase separation. Phase separation values ranged from (6.22 ± 0.69 to 18.94 ± 0.69 %). However altering needle geometry had no significant effect on phase separation. From powder tracing and liquid content determination, static zones of powder and a non-uniform liquid distribution was observed within the barrel. Measurements of extrudate and paste LPR within the barrel indicated that extrudate LPR remained constant during extrusion, while LPR of paste within the barrel decreased steadily. These observations indicate the mechanism of phase separation was located within the syringe barrel. Therefore phase separation can be attributed to either; (1) the liquid being forced downstream by an increase in pore pressure as a result of powder consolidation due to the pressure exerted by the plunger or (2) the liquid being drawn from paste within the barrel, due to suction, driven by dilation of the solids matrix at the barrel exit. Differentiating between these two mechanisms is difficult; however results obtained suggest that suction is the dominant phase separation mechanism occurring during extrusion of CaP paste. Graphical Abstract

Plastics are used in a variety of applications because of durability and versatility. However, there are concerns associated with the production and end-of-life of plastics. Plastics consume 7% of world oil production and put pressure on resource supply. Moreover, plastics do not degrade biologically resulting in waste management issues. Within this context, our group focuses on: (1) Studying the scale of the problem and developing plastics flow maps for Northern Ireland; (2) Developing bio-based plastics to decrease use of non-renewable resources; (3) Manufacturing recycled plastics using plastic waste; (4) Performing life cycle assessment of solutions to compare with the baseline; ensuring sustainability in plastics economy.

Plastics are used in a wide range of applications due to affordability, durability and versatility. However, there are concerns related to end of life of plastics, resulting in increasing scientific scrutiny, media campaigning and growing public awareness. This has stimulated policy-makers to introduce changes aiming to reduce plastic consumption and production. There is an estimated global stockpile of about 8.3 billion tonnes of plastic waste with the EU generating around 26 million tonnes annually. According to recent estimates, the amount of plastic waste generated in UK was 2.6 million tonnes and 0.12 million tonnes in North Ireland (N Ireland) in 2017. Out of the total plastic waste, only 47 thousand tonnes were used in N Ireland for recycling and recovery. Moreover, approximately 75% of plastic waste arisings are from municipal waste streams, which can be reduced by incorporating changes in the ways plastics are used in household activities.The UK Plastics Pact (2018), which aims to transform the UK packaging plastic sector and, the Single Use Plastics Guidelines (Directive EU/2019, on the reduction of the impact of certain plastic products on the environment) which proposes a ban on the single use plastics for which alternatives exist, are going to play a key role in transition of the plastics economy in N Ireland. However, there is a dearth of studies giving details of existing plastics economy in N Ireland. To this end, the present research aims towards understanding the scale of the plastics problem in N Ireland to encourage innovations in the plastics sector. The specific objectives of the study are to investigate: (1) an overview of the plastic waste production; (2) the current legislation and guidelines to improve the circularity of the plastics life cycle; (3) the stakeholders involved in recycling and producing plastics from post manufacturing plastic waste; (4) future work and proposed improvements in N Ireland. In N Ireland, plastic recyclers and collectors, such as Bryson recycling, Cherry Pipes Ltd, Plaswire Ltd, Emerald Isle Ltd, RiverRidge Ltd, Shabra Plastics and Recycling Ltd, and Van Werven Ltd, recycle plastic waste from municipal arisings, farms, complex post manufacturing arisings. However, a closed loop of plastics economy is yet to be achieved in N Ireland. Potential solutions to achieve a closed loop are to, produce biodegradable plastics, incorporate recycled plastics with virgin plastics, so as to reduce use of virgin plastics, incentives to reduce plastic waste to both consumers and industries, energy recovery from plastic waste, design of products from recycled plastics and carbon foot-printing of various recycling methods.