Recent Submissions

  • Evaluating Healthcare Governance Using Knowledge-based System to Enhance Quality Management

    Al Khamisi, Yousuf N.; Munive-Hernandez, J. Eduardo; Campean, I. Felician (2018-07)
    Governance perspective plays a vital role in the success of Quality Management in Healthcare Environment (QMHE). In fact QMHE has adopted and applied different quality tools and models in recent times, with some even developing their own quality‐based initiatives. This paper will present an original and novel approach (KB/ES coupled with GAP analysis) to evaluate the effectiveness of governance body in QMHE. The KB system inserts GAP for benchmarking and evaluating the current practices with the desired ones. The KB system will benchmark the current position of governance perspective as part of QMHE with the ideal benchmark one. The results will help healthcare practitioners to improve the governance boy’s gaps and take the correct decisions.
  • Developing a Discrete Event Simulation Methodology to support a Six Sigma Approach

    Hussain, Anees; Munive-Hernandez, J. Eduardo; Campean, I. Felician (2019)
    Competition in the manufacturing industry is growing at an accelerated rate due to globalization trend. This global competition urges manufacturing organizations to review and improve their processes in order to enhance and maintain their competitive advantage. One of those initiatives is the implementation of the Six Sigma methodology to analyze and reduce variation hence improving the processes of manufacturing organizations. This paper presents a Discrete Event Simulation methodology to support a Six Sigma approach for manufacturing organizations. Several approaches to implement Six Sigma focus on improving time management and reducing cycle time. However, these efforts may fail in their effective and practical implementation to achieve the desired results. Following the proposed methodology, a Discrete Event Simulation model was built to assist decision makers in understanding the behavior of the current manufacturing process. This approach helps to systematically define, measure and analyze the current state process to test different scenarios to improve performance. The paper is amongst the first to offer a simulation methodology to support a process improvement approach. It applies an action research strategy to develop and validate the proposed modelling methodology in a British manufacturing organization competing in global markets.
  • Developing a FMEA Methodology to Assess Non-Technical Risks in Power Plants

    Almashaqbeh, Sahar; Munive-Hernandez, J. Eduardo; Khan, M. Khurshid (2018-07)
    Risk Management is one of the most relevant approaches and systematic application of strategies, procedures and practices management that have been introduced in literature to identifying and analysing risks which exist through the whole life of a product or a process. As a quality management tool, the novelty of this paper suggests a modified Failure Modes and Effect Analysis (FMEA) for understanding the non-technical risk comprehensively, and to attain a systemic methodology by decomposing the risk for nine risk categories including an appropriate 84 Risk Indicators (RI's) within all those categories through the Life Cycle (LC) stages of power plants. These risk categories have been identified as: economic risks, environmental and safety health risks, social risks, technological risks, customer/demand risks, supply chain risks, internal and operational business process risks, human resources risks and management risks. These indicators are collected from literatures. The enhanced FMEA has combined the exponential and the weighted geometric mean (WGM) to calculate the Exponential Weighted Geometric Mean-RPN (EWGM-RPN). The EWGM-RPN can be used to evaluate the risk level, after which the high-risk areas can be determined. Subsequently, effective actions either preventive or corrective can be taken in time to reduce the risk to an acceptable level. However, in this paper the FMEA will not adapt an action plan. Due to that, all RPN's will be considered depending on the point scale (1 to 5) afterward, the results will be combined and extended later with AHP. This developed methodology is able to boost effective decision- making about risks, improve the awareness towards the risk management at power plants, and assist the top management to have an acceptable and preferable understanding of the organisation than lower level managers do who are close to the day-to-day (tactical plan). Additionally, this will support the organisation to develop strategic plans which are for long term. And the essential part of applying this methodology is the economic benefit. Also, this paper includes developed sustainability perspective indicators with a new fourth pillar, which is the technological dimension. The results of the analysis show that the potential strategic makers should pay special attention to the environmental and internal and operational business process risks. The developed methodology will be applied and validated for different power plants in the Middle East. An expanded validation is required to completely prove drawbacks and benefits after completing the Analytical Hierarchy Process (AHP) model.
  • Developing a Risk Assessment Model for non-Technical Risk in Energy Sector

    Almashaqbeh, Sahar; Munive-Hernandez, J. Eduardo; Khan, M. Khurshid (2018-07)
    Risk Management is one of the most relevant approaches and systematic applications of strategies, procedures and practices management that have been introduced in literatures for identifying and analysing risks which exist through the whole life of a product ,a process or services. Therefore, the aim of this paper is to propose a risk assessment model that will be implemented to the energy sector, particularly to power plants. This model combines the Analytic Hierarchy Process (AHP) technique with a new enhanced Balance Score Card (BSC). AHP is constructed to determine the weights and the priorities for all perspectives and risk indicators that involved in the BSC. The novelty in this paper is not only in using the BSC for risk assessment, but also, in developing a new BSC with six perspectives, which are sustainability perspective; economic; learning and growth; internal and operational business process; supply chain and customer/demand perspective. Another three contributions of this paper are firstly, including the sustainability dimension in BSC, and covering nine risk categories, which comprise 84 risk indicators that have been distributed across the six risk BSC perspectives. Secondly, assessing the non-technical risks in power plants and finally, this research will concentrate on the strategic level instead of the operational level where the majority of researches focus on latter but the former is far less researched. The created model will provide an effective measurement for the risks particularly, in the power plants sector. The results of this study demonstrate that the supply chain risks perspective is the keystone for the decision making process. Furthermore, these risk indicators with the new structure of BSC with six perspectives, help in achieving the organisation mission and vision in addition to affording a robust risk assessment model. The inputs of this model are composed from a previous stage using a modified Failure Mode and Effect Analysis (FMEA) (which has been used the Exponential Weighted Geometric Mean (EWGM)) to understand and analyse all risks, after which, the results of the developed FMEA which are the Risk Priority Numbers (RPN’s), have been used to build the AHP-BSC risk model. These risks are collected with difficulty from various literatures. This study will be validated in the next stage in power plants in the Middle East.
  • A System Dynamics Model for Supply Chain Risk Assessment

    Almashaqbeh, Sahar; Munive-Hernandez, J. Eduardo; Khan, M. Khurshid (2019-07)
    Risk assessment is a strategic approach for building resilient supply chains in different types of industries, including the energy sector. In case of an important event with a high level of the risk happening, it could jeopardize the operations of an organization. This could even interrupt the delivery of a product or service, damaging the profitability and reputation of the organization. This could also have a long-term effect on the strategic performance of the firm. Furthermore, key risks might be linked through causal interrelationships. Given the nature of a dynamic business environment, risk assessment also needs to consider the effect of time on those risks. Hence, it is important to understand the behaviour of a complex and dynamic system of interrelated risks to improve strategic decision making in the energy sector. This paper presents a System Dynamics model to assess risks with a supply chain perspective for power plants. The risk assessment model was validated with a case study of three power plants in the Middle East. The developed risk assessment model allowed to understand the long-term effect of risk on three performance indicators: availability of the power plant, efficiency, and operational and maintenance costs. The model provides a different approach to traditional risk assessment by proposing a dynamic modelling methodology.
  • A System Dynamics Model for Risk Assessment of Strategic Customer Performance Perspective in Power Plants

    Almashaqbeh, Sahar; Munive-Hernandez, J. Eduardo; Khan, M. Khurshid (2019-07)
    The energy sector is a dynamic business environment, power plants have to deal with several complex risks, including both technical and non-technical risks. Thus, unexpected risks can disrupt the energy generation processes, with a negative long-term impact. Furthermore, these risks are not isolated, as their impact may affect a series of interrelated risks. To add to this complexity, the assessment of those risks may change with time in a dynamic business environment. This situation makes strategic decision making less effective regarding the successful design of a risk management system. Understanding the dynamic behaviour of a complex system of interrelated risks in the energy sector is very important to achieve a more sustainable overall performance of the power plants. This paper presents a System Dynamics (SD) approach to capture the interdependencies of strategic non-technical risks associated to the customer performance perspective in a risk management system for the energy sector. Several approaches for risk assessment focus on technical risks related to equipment but fail to consider the complex interactions with other risks and neither consider the dynamic nature of the business environment. A system dynamics model with 15 risk factors was built to assist decision makers in understanding the behaviour for such risks affecting the customer performance perspective. The model was validated in a power plant in the Middle East. The model allowed to highlight the impact of mitigating the risk of policy and regulations on the availability risk of the power plant and on the risk factor related to operational and maintenance cost.
  • Using the Exponential Weighted Geometric Mean (EWGM) Method to Optimise the FMEA as a Risk Assessment Methodology

    Almashaqbeh, Sahar; Munive-Hernandez, J. Eduardo; Khan, M. Khurshid (2019)
    Failure Modes and Effect Analysis (FMEA) is a proactive, highly structured, and systematic approach for failure analysis. It has been also applied as a risk assessment tool, by ranking potential risks based on the estimation of Risk Priority Numbers (RPNs). This paper develops an improved FMEA methodology for strategic risk analysis. The proposed approach combines the Analytic Hierarchy Process (AHP) technique with the Exponential and Weighted Geometric Mean method (EWGM) to support risk analysis. AHP is applied to estimate the weights of three risk factors: Severity (S), Occurrence (O) and Detection (D), which integrate the RPN for each risk. The EWGM method is applied for ranking RPNs. Combining AHP with EWGM allows avoiding repetition of FMEA results. The results of the developed methodology reveal that duplication of RPNs has been decreased, and facilitating an effective risk ranking by offering a unique value for each risk. The proposed methodology focuses not only on high severity values for risk ranking but also it considers other risk factors (O and D), resulting in an enhanced risk assessment process. Furthermore, the weights of the three risk factors are considered. In this way, the developed methodology offers unique value for each risk in a simple way which makes the risk assessment results more accurate. This methodology provides a practical and systematic approach to support decision-makers in assessing and ranking risks that could affect long-term strategy implementation. The methodology was validated through the case study of a power plant in the Middle East, assessing 84 risks within 9 risk categories. The case study revealed that top management should pay more attention to key risks associated with electricity price, gas emissions, lost-time injuries, bad odor, and production.
  • Design and economic evaluation of solar-powered hybrid multi effect and reverse osmosis system for seawater desalination

    Filippini, G.; Al-Obaidi, M.A.; Manenti, F.; Mujtaba, Iqbal M. (2019)
    Reducing the cost of fresh water has always been a major concern in the desalination industry. A solar powered hybrid multi-effect distillation and reverse osmosis desalination plant (MED+RO) has been designed and optimised from an economical point of view in a previous work by the same authors. In the present study, the possibility of coupling the desalination plant with a photovoltaic (PV) solar farm is investigated, with the aim of generating electricity at low cost and in a sustainable way. A detailed mathematical model for the PV system has been implemented from the literature. Interestingly, the model can predict the cost of the PV system in terms of capital cost and electricity cost per kWh considering the input data of solar irradiation, duration of daylight and technical specification of a real solar module. Consequently, the solar PV model has been combined with the desalination model, which enables to estimate the cost of fresh water per cubic meter. Data about four locations, namely Isola di Pantelleria (IT), Las Palmas (ES), Abu Dhabi (UAE), and Perth (AUS), have been used to economically test the feasibility of installing the proposed plant, and especially of the PV solar farm.
  • Optimisation of several industrial and recently developed AJAM naphtha isomerization processes using model based techniques

    Jarullah, A.T.; Abed, F.M.; Ahmed, A.M.; Mujtaba, Iqbal M. (2019-07)
    Increasing the yield and research octane number (RON) of naphtha isomerization process are the most important issues in industries. There are many alternative industrial naphtha isomerization processes practiced around the world. In addition, AJAM is a new naphtha isomerization process proposed by the authors recently (Ahmed et al., 2018) where the isomerization reactor model was validated using real data of Baiji North Refinery (BNR) of Iraq. In this work, first, the performance of the AJAM Process is evaluated against 8 existing industrial isomerization processes in terms of RON, yield and the cost using model based optimisation techniques. To be consistent, we have used the same isomerization reactor model in all the industrial processes we evaluated here. Secondly, energy saving opportunity in the new AJAM process is studied using pinch technology.
  • Economic removal of chlorophenol from wastewater using multi-stage spiral-wound reverse osmosis process: simulation and optimisation

    Al-Obaidi, M.A.; Kara-Zaitri, Chakib; Mujtaba, Iqbal M. (2019-10)
    The successful use of Reverse Osmosis (RO) process has increased significantly in water desalination, water treatment and food processing applications. In this work, the economic feasibility of a multi-stage RO process including both retentate and permeate reprocessing for the removal of chlorophenol from wastewater is explored using simulation and optimisation studies. Firstly, a mathematical model of the process is developed based on the solution diffusion model, which was validated using experimental chlorophenol removal from the literature, is combined with several appropriate cost functions to form a full model package. Secondly, for a better understanding of the interactions between the different parameters on the economic performance of the process, a detailed process simulation is carried out. Finally, a multi-objective optimisation framework based on Non-Linear Programming (NLP) problem is developed for minimising the product unit cost, the total annualised cost, the specific energy consumption together with optimising the feed pressure and feed flow rate for an acceptable level of chlorophenol rejection and total water recovery rate. The results clearly show that the removal of chlorophenol can reach 98.8% at a cost of approximately 0.21 $/m³.
  • An Axiomatic Categorisation Framework for the Dynamic Alignment of Disparate Functions in Cyber-Physical Systems

    Byrne, Thomas J.; Doikin, Aleksandr; Campean, I. Felician; Neagu, Daniel (2019)
    Advancing Industry 4.0 concepts by mapping the product of the automotive industry on the spectrum of Cyber Physical Systems, we immediately recognise the convoluted processes involved in the design of new generation vehicles. New technologies developed around the communication core (IoT) enable novel interactions with data. Our framework employs previously untapped data from vehicles in the field for intelligent vehicle health management and knowledge integration into design. Firstly, the concept of an inter-disciplinary artefact is introduced to support the dynamic alignment of disparate functions, so that cyber variables change when physical variables change. Secondly, the axiomatic categorisation (AC) framework simulates functional transformations from artefact to artefact, to monitor and control automotive systems rather than components. Herein, an artefact is defined as a triad of the physical and engineered component, the information processing entity, and communication devices at their interface. Variable changes are modelled using AC, in conjunction with the artefacts, to aggregate functional transformations within the conceptual boundary of a physical system of systems.
  • Shape-controlled silver NPs for shape-dependent biological activities

    Sadeghi, F.; Yazdanpanah, A.; Abrishamkar, A.; Moztarzadeh, F.; Ramedani, A.; Pouraghaie, S.; Shirinzadeh, H.; Samadikuchaksaraei, A.; Chauhan, N.P.S.; Hopkinson, L.; Sefat, Farshid; Mozafari, M. (2017-09)
    The most important issue during synthesis of nanoparticles (NPs) is to avoid particle agglomeration and adhesion. There have been several attempts to use special substances such as organic surfactants, polymers and stable ligands for this purpose. In this study, silver NPs were synthesised with and without gelatin macromolecules, as a green natural biopolymer, which resulted in NPs with varying shapes and sizes. The effect of morphological characteristics on the antibacterial and antifungal properties of the synthesised NPs were studied, by comparing Gram-negative (Escherichia coli) versus Gram-positive (Staphylococcus aureus) bacteria as well as fungi (Candida albicans) by calculation of minimal inhibition concentration value. The results corresponded well with the assumptions on the effects of shape and size on the antibacterial and antifungal properties of the studied NPs.
  • Fullerene: biomedical engineers get to revisit an old friend

    Goodarzi, S.; Da Ros, T.; Conde, J.; Sefat, Farshid; Mozafari, M. (2017-10)
    In 1985, the serendipitous discovery of fullerene triggered the research of carbon structures into the world of symmetric nanomaterials. Consequently, Robert F. Curl, Harold W. Kroto and Richard E. Smalley were awarded the Noble prize in chemistry for their discovery of the buckminsterfullerene (C60 with a cage-like fused-ring structure). Fullerene, as the first symmetric nanostructure in carbon nanomaterials family, opened up new perspectives in nanomaterials field leading to discovery and research on other symmetric carbon nanomaterials like carbon nanotubes and two-dimensional graphene which put fullerenes in the shade, while fullerene as the most symmetrical molecule in the world with incredible properties deserves more attention in nanomaterials studies. Buckyball with its unique structure consisting of sp2 carbons which form a high symmetric cage with different sizes (C60, C70 and so on); however, the most abundant among them is C60 which possesses 60 carbon atoms. The combination of unique properties of this molecule extends its applications in divergent areas of science, especially those related to biomedical engineering. This review aims to be a comprehensive review with a broad interest to the biomedical engineering community, being a substantial overview of the most recent advances on fullerenes in biomedical applications that have not been exhaustively and critically reviewed in the past few years.
  • Global optimisation of the car front-end geometry to minimise pedestrian head injury levels

    Kianifar, Mohammed R.; Campean, I. Felician (2019)
    The paper presents a multidisciplinary design optimisation strategy for car front-end profile to minimise head injury criteria across pedestrian groups. A hybrid modelling strategy was used to simulate the car-pedestrian impact events, combining parametric modelling of front-car geometry with pedestrian models for the kinematics of crash impact. A space filling response surface modelling strategy was deployed to study the head injury response, with Optimal Latin Hypercube (OLH) Design of Experiments sampling and Kriging technique to fit response models. The study argues that the optimisation of the front-end car geometry for each of the individual pedestrian models, using evolutionary optimisation algorithms is not an effective global optimization strategy as the solutions are not acceptable for other pedestrian groups. Collaborative Optimisation (CO) multidisciplinary design optimisation architecture is introduced instead as a global optimisation strategy, and proven that it can enable simultaneous minimisation of head injury levels for all the pedestrian groups, delivering a global optimum solution which meets the safety requirements across the pedestrian groups.
  • The effect of WIN55, 212-2 on protein S100, matrix metalloproteinase-2 and nitric oxide expression of chondrocyte monolayer

    Abdeldayum, Ali I.A.; Youseffi, Mansour; Sefat, Farshid; Genedy, Mohamed A.; Abdul Jamil, M.M.; Javid, F. (2017-01)
    Studies have been conducted to highlight the anti-inflammatory and immunosuppressive properties of synthetic cannabinoids as well as their potential for cartilage repair. Various wound healing techniques can be used to investigate the mechanisms of chondrocyte repair in monolayers or three dimensional tissues constructs. In this work the effect of WIN55, 212-2 (WIN-2) on nitric oxide (NO) and matrix metalloproteinase-2 (MMP-2) expressed by wounded chondrocyte monolayers was investigated. Moreover, expression of collagen type-I and type-II, fibronectin and S100 proteins were detected using immunofluorescence and quantitatively verified using ELISA based techniques following treatment with 1 μM and 2 μM of WIN-2. Treating chondrocytes with 1 μM of WIN-2 significantly increased expression of collagen type-II, fibronectin and S100, and significantly reduced collagen type-I expressions as compared to the control groups. On the other hand, both concentrations of WIN-2 significantly reduced the expression of the inflammation markers NO and MMP-2 in a dose dependent manner. These findings highlight the potential use of the synthetic cannabinoids for improving cartilage healing properties as well as acting as an anti-inflammatory agent which could be used to enhance tissue engineering protocols aimed at cartilage repair.
  • Automotive IVHM: Towards Intelligent Personalised Systems Healthcare

    Campean, I. Felician; Neagu, Daniel; Doikin, Aleksandr; Soleimani, Morteza; Byrne, Thomas J.; Sherratt, A. (2019)
    Underpinned by a contemporary view of automotive systems as cyber-physical systems, characterised by progressively open architectures increasingly defined by their interaction with the users and the smart environment, this paper provides a critical and up-to-date review of automotive Integrated Vehicle Health Management (IVHM) systems. The paper discusses the challenges with prognostics and intelligent health management of automotive systems, and proposes a high-level framework, referred to as the Automotive Healthcare Analytic Factory, to systematically collect and process heterogeneous data from across the product lifecycle, towards actionable insight for personalised healthcare of systems.
  • Photolithographic structuring of stretchable conductors and sub-kPa pressure sensors

    Tuinea-Bobe, Cristina-Luminita; Lemoine, P.; Manzoor, M.U.; Tweedie, M.; D'sa, R.A.; Gehin, C.; Wallace, E. (2011-10-07)
    This paper presents a novel method to prepare stretchable conductors and pressure sensors based on the gold/polydimethylsiloxane (PDMS) system. The gold films were sputtered onto structured PDMS surfaces produced with a photolithographic surface treatment with the aim of reducing tensile strains in the gold film. Scanning electron microscopy (SEM) and atomic force microscopy analyses showed that these 3D patterns reduce cracks and delaminations in the gold film. Electrical measurements indicate that the patterns also protect the films against repeated tensile cycling, although the un-patterned samples remained conducting as well after the completion of 120 cycles. The extrapolated resistivity value of the patterned sample (4.5 × 10−5 Ωcm) compares well with previously published data. SEM micrographs indicate that the pattern features deflect the cracks and therefore toughen the gold film. However, x-ray photoelectron spectroscopy and contact angle analyses indicate that the patterning process also slightly modifies the surface chemistry. This patterning method was used to prepare capacitive strain gauges with pressure sensitivity (ΔZ/Z)/P of 0.14 kPa−1 in the sub-kPa regime. Such stretchable and potentially conformal low-pressure sensors have not been produced before and could prove advantageous for many smart fabric applications.
  • Multiple shape memory behavior of highly oriented long‐chain‐branched poly(lactic acid) and its recovery mechanism

    Li, J.; Zhao, X.; Ye, L.; Coates, Philip D.; Caton-Rose, Philip D. (2019-04)
    The shape memory effect of highly oriented long‐chain‐branched poly(lactic acid) (LCB‐PLA) prepared through solid‐phase die drawing technology was studied by comparison with PLA. When the recovery temperature increased from 60°C to 120°C, for PLA, only one‐step recovery at about 80°C can be observed and the recovery ratio was below 21.5%, while, for LCB‐PLA, multiple recovery behavior with high recovery ratio of 78.8% can be achieved. For oriented PLA, the recovery curve of the final sample showed the same trend with that of sample suffering just free drawing; while for oriented LCB‐PLA, the recovery curve of the final sample showed the same trend with that of sample suffering just die drawing. After shape recovery, the mechanical properties of LCB‐PLA showed a linear downward trend with the recovery temperature. Together with amorphous phase, the oriented mesomorphic phase, which formed during solid die drawing, can act as switching domains. And thus, upon heating, the chain segment of amorphous phase relaxed at first and triggered the first macroscopical shape recovery, leading to the decrease of long period (Lac) and the thickness of the amorphous layer (La). Then, with further increasing temperature, the oriented mesomorphic phase gradually relaxed resulting subsequently multi‐shape recovery, and the Lac and the La further decreased. Therefore, by regulating the recovery temperature of oriented LCB‐PLA, the shape recovery ratio and mechanical strength can be controlled effectively, and thus the self‐reinforced and self‐fastening effect can be achieved simultaneously for PLA as bone fixation material.
  • Novel rhodium on carbon catalysts for the oxidation of benzyl alcohol to benzaldehyde: A study of the modification of metal/support interactions by acid pre-treatments

    Wilde, C.A.; Ryabenkova, Yulia; Firth, I.M.; Pratt, L.; Railton, J.; Bravo-Sanchez, M.; Sano, N.; Cumpson, P.J.; Coates, Philip D.; Liu, X.; Conte, M. (2019-01-25)
    Rhodium nanoparticles or rhodium organometallic complexes are mainly used in catalysis for reduction or hydroformylation reactions. In this work instead, we explored the capabilities of Rh nanoparticles as an oxidation catalyst, applied to the oxidation of benzyl alcohol to benzaldehyde under very mild conditions (100 °C, and atmospheric pressure) as a model reaction. Here we report the preparation of novel Rh/C catalysts by using an impregnation protocol, with particular emphasis on the pre-treatment of the carbon supports by using HNO3 and HCl, as well as the characterization of these materials by using an array of methods involving TEM, XPS and XRPD. Our preparation method led to a wide Rh particle size distribution ranging from 20 to 100 nm, and we estimate an upper limit diameter of Rh nanoparticles for their activity towards benzyl alcohol oxidation to be ca. 30 nm. Furthermore, a HNO3 pre-treatment of the activated carbon support was able to induce a smaller and narrower particle size distribution of Rh nanoparticles, whereas a HCl pre-treatment had no effect or sintered the Rh nanoparticles. We rationalise these results by HNO3 as an acid able to create new nucleation sites for Rh on the carbon surface, with the final effect of smaller nanoparticles, whereas for HCl the effect of sintering was most likely due to site blocking of the nucleation sites over the carbon surface. The roles of acid centres on the carbon surfaces for the oxidation reaction was also investigated, and the larger their amounts the larger the amounts of by-products. However, by treatment with HNO3 we were able to convert neutral or basic carbons into supports capable to enhance the catalytic activity of Rh, and yet minimised detrimental effects on the selectivity of the oxidation to benzaldehyde.
  • Influence of the morphological structure of carbon nanotubes on the viscoelasticity of PMMA‐based nanocomposites

    Lin, X.; Li, K.; Gough, Timothy D.; Coates, Philip D.; Wang, D.; Zhang, L. (2018-07-15)
    The rheological behavior of polymeric nanocomposites provides major determination for their processability. In this work, three carbon nanotubes (CNTs) with varied geometries were adopted as nanofiller and then were introduced into poly(methyl methacrylate) (PMMA) matrix with different loadings (0.07–1.0 wt %). The different preparation routine led to varied CNTs dispersion states, on which the shear viscosity and the compressibility of their melts were proved to be sensitive. The technology for the preparation of their nanocomposites played a crucial role in controlling their rheological behavior. With melting blended bare CNTs, the dynamic shear viscosity of PMMA/CNTs increased with the increase of CNTs content, accompanied by aggregated CNTs in which no polymer matrix was entrapped. With the help of surface modification and pre‐mixing, well dispersed CNTs were obtained and a rather low aggregation rate ca. 0.029% was revealed. The well dispersed CNTs with an organic layer which was constructed by small molecules and presented lower viscosity. Such CNTs led to no remarkable clusters within polymer host and played the role of lubricant with an increased‐mobility layer, which can be reflected from the weighted relaxation time spectra.

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