An investigation into the properties of starch-based foams

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis reports research to investigate the mechanical, thermal and acoustic properties of biodegradable foams in block forms based on wheat starch and developed at Brunel University’s School of Engineering & Design, in order to exploit the potential environmental benefits of this renewable and biodegradable class of materials. Two emergent novel technologies have been developed based on a combination of the extrusion foaming of starch in conjunction with the natural adhesive characteristics of moistened starch to produce block foams. Regular Packing & Stacking (RPS), and Compression Bonded Loosefill (CBL), are foam fabrication technologies which have both demonstrated the potential to produce bulk foams based on wheat starch with unique structures and properties - a new class of foam materials in the form of macro-composites reinforced by a network of high-density bonding interfaces. This thesis, as part of a Department of Trade & Industry/Technology Strategy Board funded project, reports an investigation into the following areas to address the scientific and technical issues involved in the further development of the materials and their applications. - The basic properties of the raw materials used in the manufacture of CBL and RPS foams are outlined and the fabrication and preparation of these starch-based foams are described. The limitations of these production techniques are discussed with preliminary work and suggestions made for their enhancement. - Research into the mechanical properties of the CBL and RPS foams includes compression, tensile, creep and dynamic impact tests, whilst the mechanical behaviour of the foams subject to high temperature and high humidity conditions is also reported. - Research into the thermal properties of CBL and high density RPS foams includes testing of the material’s thermal conductivity. This aspect of the research also involved a case study detailing the use of RPS in a commercial thermal insulation application. - Research into the acoustic properties of CBL and RPS foams includes tests for sound absorption coefficient and sound transmission loss. - Data obtained from these tests are benchmarked against data pertaining to the mechanical, thermal and acoustic properties of conventional polymer foams in order to provide a basis on which to identify the potential cushioning, thermal insulation and acoustic insulation applications of the starch-based materials. The research has demonstrated the following: - Potential cushioning applications include those limited to the range of static loads within the capabilities of the materials, taking into account the resilience of CBL and RPS which is likely to be compromised by successive impacts. - Tensile forces tend to exploit weaknesses in the macrostructure of these materials. By implication the behaviour of the materials under shear forces would be expected to be similarly compromised. - CBL and RPS exhibited dimensional shrinkage, density increase and significantly reduced mechanical properties under conditions of high temperature and humidity. This suggests that neither CBL nor RPS foams would be suitable for applications in regions where tropical conditions may be encountered unless used in conjunction with other protective materials which would not acutely increase the environmental burden of the products. - Low-density RPS and CBL foams exhibit lower thermal conductivities and hence higher thermal insulation properties compared to many commercially available polymer foams of similar densities. As such these foams have the potential to be used in applications in which a measure of thermal insulation is required. A case study based on an existing commercial application in which the temperature of chilled products must be maintained over a 24 hour period reinforced these findings. - The performance of CBL and RPS starch foams would not provide sufficient functionality to be employed in applications in which dedicated acoustic performance is required, although their sound absorption capabilities may facilitate overall marketability for applications in which a degree of acoustic performance is required if used in conjunction with other materials which demonstrate good acoustic performance. It is anticipated that this work will make significant contributions toward advances in the development of these novel technologies, specifically in terms of establishing an understanding of the properties of the starch-based materials and in identifying potential applications. The research results should thus provide a fundamental element in the basis for the industrial development of these renewable and biodegradable materials.This study is funded by the UK Government Department of Trade & Industry (Technology Strategy Board) Project “Lightweight Eco-Composites Based on Renewable Raw Materials” (TP/2/MS/6/1/10118)

Examination of the effects of solids content on thickened gold mine tailings sedimentation and self-weight consolidation

Abstract: Thickening is being increasingly adopted by the mining industry because of its economic and environmental attributes, such as decreased amounts of water released following deposition and a smaller footprint of the tailings site. This study presents an assessment of the continuous process of sedimentation and the self-weight consolidation of slurry and thickened mine tailings. The results of a series of settling column tests performed with specimens with solids contents between 50 % and 72 % are presented and discussed. Lower solids contents that are more characteristic of slurry tailings were also included to cover a wide range of settling behavior. High-precision monitoring of pore water pressure was used to identify the transition from sedimentation to self-weight consolidation, which likely occurs between solids contents of 65 % and 68 % for this material, and it highlighted the fact that the combination of these two settlement processes accelerates ue dissipation. The displacement results for the tailings–water interface corroborate values in the technical literature related to the settlement of suspensions. Equilibrium was reached within a narrow time range (i.e., 400 to 500 min) despite the wide range of initial solids content in the slurries tested (i.e., 50 % S to 65 % S)

Impacts of Electric Road Systems on the German and Swedish Electricity Systems—An Energy System Model Comparison

This study analyses the impacts of electrification of the transport sector, involving both static charging and electric road systems (ERS), on the Swedish and German electricity systems. The impact on the electricity system of large-scale ERS is investigated by comparing the results from two model packages: 1) a modeling package that consists of an electricity system investment model (ELIN) and electricity system dispatch model (EPOD); and 2) an energy system investment and dispatch model (SCOPE). The same set of scenarios are run for both model packages and the results for ERS are compared. The modeling results show that the additional electricity load arising from large-scale implementation of ERS is mainly, depending on model and scenario, met by investments in wind power in Sweden (40–100%) and in both wind (20–75%) and solar power (40–100%) in Germany. This study also concludes that ERS increase the peak power demand (i.e., the net load) in the electricity system. Therefore, when using ERS, there is a need for additional investments in peak power units and storage technologies to meet this new load. A smart integration of other electricity loads than ERS, such as optimization of static charging at the home location of passenger cars, can facilitate efficient use of renewable electricity also with an electricity system including ERS. A comparison between the results from the different models shows that assumptions and methodological choices dictate which types of investments are made (e.g., wind, solar and thermal power plants) to cover the additional demand for electricity arising from the use of ERS. Nonetheless, both modeling packages yield increases in investments in solar power (Germany) and in wind power (Sweden) in all the scenarios, to cover the new electricity demand for ERS

Role of IFN-gamma and IL-6 in a protective immune response to Yersinia enterocolitica in mice

<p>Abstract</p> <p>Background</p> <p><it>Yersinia </it>outer protein (Yop) H is a secreted virulence factor of <it>Yersinia enterocolitica </it>(Ye), which inhibits phagocytosis of Ye and contributes to the virulence of Ye in mice. The aim of this study was to address whether and how YopH affects the innate immune response to Ye in mice.</p> <p>Results</p> <p>For this purpose, mice were infected with wild type Ye (pYV⁺) or a YopH-deficient Ye mutant strain (Δ<it>yopH</it>). CD11b⁺cells were isolated from the infected spleen and subjected to gene expression analysis using microarrays. Despite the attenuation of Δ<it>yopH in vivo</it>, by variation of infection doses we were able to achieve conditions that allow comparison of gene expression in pYV⁺and Δ<it>yopH </it>infection, using either comparable infection courses or splenic bacterial burden. Gene expression analysis provided evidence that expression levels of several immune response genes, including IFN-γ and IL-6, are high after pYV⁺infection but low after sublethal Δ<it>yopH </it>infection. In line with these findings, infection of IFN-γR^-/-and IL-6^-/-mice with pYV⁺or Δ<it>yopH </it>revealed that these cytokines are not necessarily required for control of Δ<it>yopH</it>, but are essential for defense against infection with the more virulent pYV⁺. Consistently, IFN-γ pretreatment of bone marrow derived macrophages (BMDM) strongly enhanced their ability in killing intracellular Ye bacteria.</p> <p>Conclusion</p> <p>In conclusion, this data suggests that IFN-γ-mediated effector mechanisms can partially compensate virulence exerted by YopH. These results shed new light on the protective role of IFN-γ in Ye wild type infections.</p

A global Arnoldi method for the model reduction of second-order structural dynamical systems

Abstract In this paper we consider the reduction of second-order dynamical systems with multiple inputs and multiple outputs (MIMO) arising in the numerical simulation of mechanical structures. In commercial software for the kind of application considered here, modal reduction is commonly used to obtain a reduced system with good approximation abilities of the original transfer function in the lower frequency range. In recent years new methods to reduce dynamical systems based on (block) versions of Krylov subspace methods emerged. This work concentrates on the reduction of second-order MIMO systems by the global Arnoldi method, an efficient extension of the standard Arnoldi algorithm for MIMO systems. In particular, a new model reduction algorithm for second order MIMO systems is proposed which automatically generates a reduced system of given order approximating the transfer function in the lower range of frequencies. It is based on the global Arnoldi method, determines the expansion points iteratively and the number of moments matched per expansion point adaptively. Numerical examples comparing our results to modal reduction and reduction via the block version of the rational Arnoldi method are presented

Promoting collaboration between livestock and wildlife conservation genetics communities

The collaboration between livestock and wildlife conservation genetics communities has the potential to help promote shared priorities, with respect to emerging technologies and new analytical approaches such as next generation sequencing incorporating adaptive variation. The GLOBALDIV Consortium recently organized an international workshop held at the Ecole Polytechnique Fédérale de Lausanne (Switzerland) including a whole-day session with contributions aimed at taking stock of the situation regarding the extent of information and methodology exchange between the two communities. Discussions permitted the identification of potential benefits of further promoting cooperation in the context of genetic monitoring in particular, a central concept to current concerns for both the livestock and wildlife conservation communitie