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  • Journal article
    Sorce F, Lowe C, Ngo S, Taylor Aet al., 2019,

    The effect of HMMM crosslinker Ccntent on the thermal-mechanical properties of polyester coil coatings

    , Progress in Organic Coatings, Vol: 137, ISSN: 0300-9440

    The thermosetting polyester-based coatings crosslinked with hexa(methylmethoxy)melamine (HMMM) used for coil coating sheet metal experience large deformations when formed into architectural cladding and white goods. Cracking of the 20-μm-thick coatings must not occur during forming, to prevent corrosion of the steel substrate, so the relationship between the composition and the thermal-mechanical properties is critical to develop highly formable and durable coatings, and to choose suitable forming conditions. Free films of coatings with 5 % to 30 % crosslinker content have been analysed. Dynamic mechanical analysis (DMA) showed that the glass transition temperature (Tg) and crosslink density increase with crosslinker content. Differential scanning calorimetry (DSC) has been used to measure the Tg from the thermal response, based solely on the chemical structure, and agrees well with the DMA.Tensile tests were performed at temperatures as a function of DSC Tg (Tg - 40 °C to Tg + 50 °C). There was little variation in Young’s modulus and strain to failure in the glassy region where the intermolecular forces dominate, but in the rubbery region governed by the covalent bonds a lower crosslinker content gave lower values. This indicates that the failure mechanism undergoes a transition with increasing temperature from being controlled by the brittle fracture stress to the yield stress. The addition of TiO2 pigment increased the modulus and apparent yield stress at low temperatures in the glassy region, and increased the strain to failure and failure stress in the rubbery region. Failure envelopes, normalising the tensile data with the DSC Tg and the crosslink density, show the dependence on crosslinker content and pigmentation. This allows the behaviour of coatings to be predicted from their structure, and enhanced coatings to be developed based on the required mechanical properties.
  • Journal article
    Zeeuw Van Der Laan A, Aurisicchio M, 2019,

    Archetypical consumer roles in closing the loops of resource flows for Fast-Moving Consumer Goods

    , Journal of Cleaner Production, Vol: 236, ISSN: 0959-6526

    After the depletion of their consumable components, Fast-Moving Consumer Goods (FMCGs) become obsolete. In an attempt to close the loop of resources (i.e. products, components or materials) FMCGs can be designed with revalorisation services. In these product-service systems (PSSs) consumers are assigned a key role in closing the loops of resource flows. To understand and define this role, we dissected eighteen examples of PSSs. From this analysis, four dimensions emerged that characterise distinct aspects of the PSSs: the form of obsolescence; the change of resources from obsolete to operative or recoverable; the prerequisite activities required of consumers for revalorisation; and the facilitators of activities (i.e. investments and incentives). These dimensions were used to model four data-driven archetypical roles of consumers named after the interaction between consumers and the resource in the obsolete state, namely keep, bring, consign or abandon obsolete components. The research concluded that revalorisation always takes place in designated locations. The roles that consumers fulfil in closed-loop PSSs involve carrying out activities to position resources in such locations. The roles always come at a cost, but PSSs can be designed to reduce it. PSSs can also be designed to induce a perceivable value of obsolete resources, which can be used to increase role fulfilment. This research presents a comprehensive understanding of the roles of consumers in the specific context of closed-loop FMCGs, identifies tactics to increase the fulfilment of these roles and suggests further research on behaviours and PSSs to understand the roles of other stakeholders in various type of PSSs.
  • Journal article
    Tsang WL, Taylor AC, 2019,

    Fracture and toughening mechanisms of silica- and core–shell rubber-toughened epoxy at ambient and low temperature

    , Journal of Materials Science, Vol: 54, Pages: 13938-13958, ISSN: 0022-2461

    The highly cross-linked thermosetting polymers used as adhesives and as the matrices of fibre composites for the construction of lightweight vehicles are very brittle, and finding effective toughening solutions for such engineering applications is a long-standing problem. An anhydride-cured thermosetting epoxy polymer has been modified by the addition of different wt% of silica nanoparticles, core–shell rubber particles and hybrids with equal wt% of both. The fracture energy was measured at ambient and low temperature (− 40 °C and − 80 °C) to understand the brittle fracture behaviour. The fracture and toughening mechanisms were identified by scanning electron microscopy of the fracture surfaces. Analytical models were used to predict the modulus and fracture energy; the predictions agreed very well with the measured values. Toughening using silica nanoparticles is especially efficient at low particle contents. This shows how epoxies can be toughened successfully for use in industrial and transport applications.
  • Conference paper
    Aurisicchio M, Zeeuw Van Der Laan A, Tennant M, 2019,

    Material-Service Systems for Sustainable Resource Management

    , EcoDesign 2019
  • Journal article
    Gesslbauer S, Savela R, Chen Y, White AJP, Romain Cet al., 2019,

    Exploiting noncovalent interactions for room-temperature heteroselective rac-lactide polymerization using aluminum catalysts

    , ACS Catalysis, Vol: 9, Pages: 7912-7920, ISSN: 2155-5435

    Whereas harnessing noncovalent interactions (NCIs) has largely been applied to late-transition-metal complexes and to the corresponding catalytic reactions, there are very few examples showing the importance of NCIs in early-transition-metal and main-group-metal catalysis. Here, we report on the effects of hydrogen bond donors in the catalytic pocket to explain the high activity and stereoselectivity of a series of aluminum catam complexes in rac-lactide ring-opening polymerization (ROP). Four original aluminum catam catalysts have been synthesized and fully characterized. Structure–activity relationships and isotope effects show the importance of the NH moieties of the ligand in rac-lactide ROP. Computational studies highlight beneficial hydrogen bonds between the ligand and the monomer. Overall, structural characterization of the catalysts and mechanistic, kinetic, and computational studies support the benefits of noncovalent interactions in the catalytic pocket.
  • Journal article
    Tsai SN, Carolan D, Sprenger S, Taylor ACet al., 2019,

    Fracture and fatigue behaviour of carbon fibre composites with nanoparticle-sized fibres

    , Composite Structures, Vol: 217, Pages: 143-149, ISSN: 0263-8223

    Fibre composites with thermoset polymer matrices are widely used. However, thermosets are very brittle, which can limit the applications of fibre composites. In this work, silica nanoparticles (SNPs) were used to modify two fibre sizings to improve the toughness of carbon fibre composites. Mode I interlaminar fracture and fatigue crack growth tests were conducted on the composites made using the silica nanoparticle-sized fibres. There was no significant change in the fatigue crack growth rate with the addition of SNPs. However, the addition of SNPs to either sizing increased the composite toughness. The fracture energy was significantly increased from 166 J/m 2 to 220 J/m 2 (increased by 33%) with only 0.89 wt% on fibre weight of SNPs. This is significantly more efficient than adding SNPs into the matrix, which can require addition of up to 20 wt% of SNPs [1], to achieve the same improvement in toughness.
  • Journal article
    Sorce F, Ngo S, Lowe C, Taylor Aet al., 2019,

    Quantification of coating surface strains in Erichsen cupping tests

    , Journal of Materials Science, Vol: 54, Pages: 7997-8009, ISSN: 0022-2461

    Thermosetting polyester-based coatings are used to produce pre-painted metal in the coil coating industry. The coated steel sheet is formed into white goods and architectural cladding, which involves large deformations of the metal and results in large strains in the coating. The Erichsen cupping test is a standard method used to assess the formability, ductility and adhesion of coatings, which induces similar strains to those experienced during forming. It is a qualitative and robust quality control method, but the behaviour of coatings during the test has never been previously studied quantitatively. Failure of coatings on sheet metal during forming is a strain-governed process, so understanding the behaviour of a coating in the Erichsen cupping test will allow the formability, material properties and chemical structure of the polymer to be linked more closely, enabling the development of better coatings. A finite element model has been developed to calculate the coating surface strains for any level of indentation during the test, and has been validated using the surface strains during cupping measured by digital image correlation. A master curve of the maximum strain versus the indentation depth (Erichsen index) has been determined. This allows the strain to failure of the coating on a substrate, a critical material property which is otherwise difficult and laborious to obtain, to be simply determined from the Erichsen test for the first time. The relationship between the Erichsen index and maximum surface strain presented here enables users to obtain this material property both from future tests and from the results of historic tests (as many coating suppliers and users have extensive databases of Erichsen test results stretching back many years). This novel framework provides a quantitative method to analyse the performance of coatings used in the coil industry, redeveloping a century-old technique.
  • Conference paper
    Zeeuw Van Der Laan A, Aurisicchio M, 2019,

    Designing Product-Service Systems to Close Resource Loops: Circular Design Guidelines

    , CIRP Lifecycle Engineering, Publisher: Elsevier BV, Pages: 631-636, ISSN: 2212-8271
  • Journal article
    Guild F, Kinloch AJ, Masania K, Sprenger S, Taylor Aet al., 2018,

    The fracture of thermosetting epoxy polymers containing silica nanoparticles

    , Strength, Fracture and Complexity, Vol: 11, Pages: 137-148, ISSN: 1567-2069

    An epoxy resin, cured with an anhydride, has been modified by the addition of silica nanoparticles. The particles were introduced via a sol-gel technique which gave a very well dispersed phase of nanosilica particles, which were about 20 nm in diameter, in the thermosetting epoxy polymer matrix. The glass transition temperature of the epoxy polymer was unchanged by the addition of the anoparticles, but both the modulus and toughness were increased. The fracture energy increased from 77 J/m2 for the unmodified epoxy to 212 J/m2 for the epoxy polymer containing 20 wt.% of nanosilica. The fracture surfaces were inspected using scanning electron and atomic force microscopy, and these microscopy studies showed that the silica nanoparticles (a) initiated localised plastic shear-yield deformation bands in the epoxy polymer matrix and (b) debonded and allowed subsequent plastic void-growth of the epoxy polymer matrix. A theoretical model for these toughening micro mechanisms has been proposed to confirm that these micromechanisms were indeed responsible for the increased toughness that was observed due to the presence of the silica nanoparticles in the epoxy polymer.
  • Journal article
    Pieri T, Nikitas A, Angelis-Dimakis A, 2018,

    Holistic assessment of carbon capture and utilization value chains

    , Environments, Vol: 5, ISSN: 2076-3298

    Carbon capture and utilization (CCU) is recognized by the European Union, along with carbon, capture and storage (CCS), as one of the main tools towards global warming mitigation. It has, thus, been extensively studied by various researchers around the world. The majority of the papers published so far focus on the individual stages of a CCU value chain (carbon capture, separation, purification, transportation, and transformation/utilization). However, a holistic approach, taking into account the matching and the interaction between these stages, is also necessary in order to optimize and develop technically and economically feasible CCU value chains. The objective of this contribution is to present the most important studies that are related to the individual stages of CCU and to perform a critical review of the major existing methods, algorithms and tools that focus on the simulation or optimization of CCU value chains. The key research gaps will be identified and examined in order to lay the foundation for the development of a methodology towards the holistic assessment of CCU value chains.

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