Browsing by Author "Marchante, Veronica"

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    Aerogel/epoxy thermal coatings for carbon fibre reinforced plastic substrates
    (Taylor and Francis, 2019-01-20) Krishnaswamy, Suryanarayanan; Abhyankar, Hrushikesh; Marchante, Veronica; Huang, Zhaorong; Brighton, James
    The present work studies an aerogel/epoxy composite that was dip coated onto a carbon fibre substrate by adding the aerogel at the 1 h and the 1.5 mark of the epoxy cure. Both coatings show decrease in thermal conductivity values (39% and 47% respectively) when compared to a pure epoxy coating. The coatings’ reflectance spectra also provided further evidence for the existence of the nano-pores within the aerogel particles. The aerogel coating was modelled using material properties from literature and solved using finite element methods. The model, which validated using experimental data, was then used to predict the coating’s performance in cyclic thermal loads. Additionally, coatings on a single surface- top and bottom; were also modelled and compared with the double coating system wherein it was seen that the double coating system had the lowest rate of temperature change and fluctuations at steady-state in contrast to the bottom coating which, showed the fastest drop in temperature as well as the highest fluctuations at steady state conditions. The performance of the top coating was in the middle.
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    Chronological review of the catalytic progress of polylactic acid formation through ring opening polymerization
    (SCIENCEDOMAIN International, 2016-08-09) Dubey, Satya P.; Abhyankar, Hrushikesh; Marchante, Veronica; Brighton, James; Blackburn, Kim
    The disposal of a large amount of polymer waste is one of the major challenges of this century. Use of bio-degradable polymers obtained from sustainable sources presents a solution to this problem. Poly lactic acid (PLA), a bio-degradable polymer, can be synthesized from sustainable sources as corn, starch, sugarcane and chips. Ring opening polymerization (ROP) of Lactide (LA) monomer using metal/bimetallic catalyst (Sn, Zn or Al) is the preferred method for synthesis of PLA. However, the PLA synthesized using such catalysts may contain trace elements of the catalyst. These catalyst traces are known carcinogens and as such should be (ideally) eliminated from the process. Use of the organic catalyst instead of metallic catalysts, may be one of the prominent solutions. Organic catalysts require the higher energy of activation for the ROP reaction of LA. Such energy requirement can be achieved through the application of alternative energy during the reaction. Alternative energy sources such as LASER, Ultrasound and microwave are prominent options to implement and process the ROP of PLA. This paper is an effort to emphasize the chronological review and to establish the current state-of-the-art in the field of PLA research.
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    Development of CNC prototype for the characterization of the nanoparticle release during physical manipulation of nanocomposites
    (Taylor & Francis, 2016-02-18) Gendre, Laura; Marchante, Veronica; Abhyankar, Hrushikesh; Blackburn, Kim; Temple, Clive; Brighton, James L.
    This work focuses on the release of nanoparticles from commercially used nanocomposites during machining operations. A reliable and repeatable method was developed to assess the intentionally exposure to nanoparticles, in particular during drilling. This article presents the description and validation of results obtained from a new prototype used for the measurement and monitoring of nanoparticles in a controlled environment. This methodology was compared with the methodologies applied in other studies. Also, some preliminary experiments on drilling nanocomposites are included. Size, shape and chemical composition of the released nanoparticles were investigated in order to understand their hazard potential. No significant differences were found in the amount of nanoparticles released between samples with and without nanoadditives. Also, no chemical alteration was observed between the dust generated and the bulk material. Finally, further developments of the prototype are proposed.
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    Effect of extrusion and compression moulding on the thermal properties of nylon-6/silica aerogel composites
    (SAGE, 2017-10-03) Krishnaswamy, Suryanarayanan; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, Hrushikesh
    The article presents the effect of a lower extrusion speed and compression moulding processes on the thermal properties of polyamide 6 (PA-6)/aerogel composite. Scanning electron and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 r/min, extrusion at 5 r/min showed a better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites extruded at different speeds suffered significant damage. Nevertheless, the extruded samples did show a lower thermal conductivity compared to the virgin polymer. Further, it was observed that the sample extruded at 5 r/min had a lower damage coefficient value with an overall loss of around 33% to the aerogel structure when compared to the material extruded at 65 r/min, which endured a structural loss of 41% to the aerogel in it.
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    Effect of extrusion and compression moulding on the thermal properties of Nylon-6/Silica Aerogel Composites: Experimental Data
    (Cranfield University, 2017-10-05 16:38) Krishnaswamy, Surya; Tinsley, Lawrence; Marchante, Veronica; Addepalli, Sri; Huang, Zhaorong; Abhyankar, Hrushikesh
    The paper presents the effect of a lower extrusion speed and compression moulding on the thermal properties of PA-6/Aerogel composite. SEM/EDX and optical microscope images showed that although most of the aerogel was destroyed during extrusion at 65 rpm, extrusion at 5 rpm showed better retention of the aerogel structure. However, when subjected to moulding in a compression press, both composites suffered significant damage. Nevertheless, the final thermal conductivity and damage coefficient values did show an improvement in the thermal insulation properties of the samples extruded at 5 rpm compared to the samples extruded at 65 rpm and the virgin polymer (PA-6) with the former losing around 33% of the structure of the aerogel particles compared to 41% for the later.
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    Microwave energy assisted synthesis of poly lactic acid via continuous reactive extrusion: modelling of reaction kinetics
    (Royal Society of Chemistry, 2017-03-27) Dubey, Satya P.; Abhyankar, Hrushikesh; Marchante, Veronica; Brighton, James L.; Bergmann, Björn; Trinh, Giang; David, Chantal
    The most commonly used batch process to manufacture PLA is ring opening polymerization (ROP) of lactide monomer in a suitable solvent, in the presence of a metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts. However, this process does not lend itself to safer/cleaner and high throughput (and high volume) manufacturing. Continuous reactive extrusion of lactide monomer using a suitable reaction input has the potential to increase the throughput, and this route has been explored in the literature. In this work, reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3, were considered to perform ROP of lactide monomer using the microwave as an alternative energy (AE) source for activating and/or boosting the polymerization. Implementation of a microwave generator in a section of the extruder is one of the novelties of this research. A simulation model of ROP of PLA was formulated to estimate the impact of reaction kinetics and AE source on the polymerization process. Ludovic® software was used for the simulation of continuous reactive extrusion of the process. Experimental and simulated results were compared for the validation of the methodology. This work also highlights the advantages and drawbacks of most conventional metal catalysts, the effect of alternative energies on reaction mechanism, and safe and efficient production of PLA.
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    Modelling and validation of synthesis of poly lactic acid using an alternative energy source through a continuous reactive extrusion process
    (MDPI, 2016-04-22) Dubey, Satya P.; Abhyankar, Hrushikesh; Marchante, Veronica; Brighton, James L.; Blackburn, Kim; Temple, Clive; Bergmann, Björn; Trinh, Giang; David, Chantal
    PLA is one of the most promising bio-compostable and bio-degradable thermoplastic polymers made from renewable sources. PLA is generally produced by ring opening polymerization (ROP) of lactide using the metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in a suitable solvent. In this work, reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3 were considered to perform ROP of lactide. Ultrasound energy source was used for activating and/or boosting the polymerization as an alternative energy (AE) source. Ludovic® software, designed for simulation of the extrusion process, had to be modified in order to simulate the reactive extrusion of lactide and for the application of an AE source in an extruder. A mathematical model for the ROP of lactide reaction was developed to estimate the kinetics of the polymerization process. The isothermal curves generated through this model were then used by Ludovic software to simulate the “reactive” extrusion process of ROP of lactide. Results from the experiments and simulations were compared to validate the simulation methodology. It was observed that the application of an AE source boosts the polymerization of lactide monomers. However, it was also observed that the predicted residence time was shorter than the experimental one. There is potentially a case for reducing the residence time distribution (RTD) in Ludovic® due to the ‘liquid’ monomer flow in the extruder. Although this change in parameters resulted in validation of the simulation, it was concluded that further research is needed to validate this assumption.
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    Non-isothermal cure kinetics of aerogel/epoxy composites using differential scanning calorimetry
    (Taylor and Francis, 2019-02-11) Krishnaswamy, Suryanarayanan; Marchante, Veronica; Abhyankar, Hrushikesh; Huang, Zhaorong; Brighton, James
    The present work determines the non-isothermal cure parameters of aerogel/epoxy samples along with the effect of a wetting agent. The cure parameters were calculated using Kissinger and isoconversional methods after which the reaction was modeled with the Sestak–Berggren equation. It is seen that the composites had higher activation energy and frequency factor values compared to the pure resin, and similarities in cure parameters between the aerogel/epoxy composites with and without the wetting agent were seen. Hence, the former’s use is advocated due to its positive influence on the resin–aerogel interface without sacrificing the cure parameters.
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    A novel process-linked assembly failure model for adhesively bonded composite structures
    (Elsevier, 2017-04-24) Yazdani Nezhad, Hamed; Zhao, Yifan; Liddel, Paul D.; Marchante, Veronica; Roy, Rajkumar
    The globally growing market for polymer composites and their increasing use within aircraft structures has necessitated reliable bonding of composite laminates to prevent structural failure. However, knowledge behind the interaction between curing process parameters and the failure of polymer composite bonded joints is not keeping pace with the market. A novel nonlinear correlation analysis has been employed and applied to experimental data, to attentively quantify the effect of curing parameters on the failure of bonded composite assemblies. The materials (adherends and adhesive) and the bonding processes were selected from those used in assembly of composite aircraft structures.
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    Particle emission measurements in three scenarios of mechanical degradation of polypropylene-nanoclay nanocomposites
    (Elsevier, 2020-08-14) Blazquez, María; Marchante, Veronica; Gendre, Laura; Starost, Kristof; Njuguna, James; Schutz, Jurg A.; Lacave, José María; Egizabal, Ainhoa; Elizetxea, Cristina; Cajaraville, Miren P.
    Researchers and legislators have both claimed the necessity to standardize the exposure assessment of polymer nanocomposites throughout their life cycle. In the present study we have developed and compared three different and independent operational protocols to investigate changes in particle emission behavior of mechanically degraded polypropylene (PP) samples containing different fillers, including talc and two types of nanoclays (wollastonite-WO- and montmorillonite-MMT-) relative to not reinforced PP. Our results have shown that the mechanical degradation of PP, PP-Talc, PP-WO and PP-MMT samples causes the release of nano-sized particles. However, the three protocols investigated, simulating industrial milling and drilling and household drilling, have produced different figures for particles generated. Results suggest that it is not possible to describe the effects of adding nano-sized modifiers to PP by a single trend that applies consistently across all different protocols. Differences observed might be attributed to a variety of causes, including the specific operational parameters selected for sample degradation and the instrumentation used for airborne particle release characterization. In particular, a streamlined approach for future assessments providing a measure for released particles as a function of the quantity of removed material would seem useful, which can provide a reference benchmark for the variations in the number of particles emitted across a wider range of different mechanical processes.
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    Progress in environmental-friendly polymer nanocomposite material from PLA: synthesis, processing and applications
    (Elsevier, 2017-07-10) Dubey, Satya P.; Thakur, Vijay Kumar; Krishnaswamy, Suryanarayanan; Abhyankar, Hrushikesh; Marchante, Veronica; Brighton, James L.
    The disposal of large amounts of waste from daily use polymers is among one of the foremost concerns in the current era. Effective utilization of bio-renewable materials procured from natural sources has been proposed as a potential solution to this problem. Among such different polymers, Poly lactic acid (PLA) which is a bio-degradable polymer, resembles quite promotable features, which can be polymerized from sustainable sources as chips sugarcane, starch and corn. Ring-opening polymerization (ROP) of Lactide (LA) monomer considering catalysts such as Al, Sn or Zn is one of the efficient methods for the PLA synthesis. However, the PLA polymerized through this type of catalysts may contain trace elements of the catalyst. Due to their carcinogenic nature, the traces of such catalysts should be (ideally) removed from the synthesis process. The use of alternative energy (AE- UV, Microwave) sources could be a potential route. Alternative development of non-metal catalysts is best alternatives for the processing of PLA through ROP. PLA layer based composite materials are gaining huge interest due to their multiple application (food, medical etc.) as eco-friendly material. In this article, we review on the implementation of AE sources for PLA processing and to populate the current state-of-the-art associated with the PLA research, especially application in nanocomposite materials field.