Browsing by Author "Sachse, Sophia"

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    Assessment of nanoparticle release and associated health effect of polymer-silicon composites
    (2014-04-15) Zhu, Huijun; Irfan, Adeel; Sachse, Sophia; Njuguna, James
    The fast advancement in the nanotechnology and manufacturing of engineering nanomaterials has inevitably caused concerns over their impact on environment and human health. Little information is currently available on possible release of nanomaterials or/and nanoparticles (NP) from conventional and novel products and associated health effect. The NEPHH project funded under the EU FP7 programme is aimed to assess the environment and health impact of polymer-silicon nanocomposites in comparison to conventional polymer composites from life cycle perspective. As part of the NEPHH project, this study focused on assessing the possible release of NP during the application stage of conventional and nanoproducts. NP release was monitored during physical processing of polymer-silicon composites, and the toxicity of both the released NP and the raw silica nanomaterials that were used as fillers in nanocomposites was assessed in vitro using human lung epithelial A549 cells.
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    The effect of nanoclay on dust generation during drilling process of polyamide 6 nanocomposites
    (Hindawi Publishing Corporation, 2012-06-10T00:00:00Z) Sachse, Sophia; Silva, Francesco; Zhu, Huijun; Irfan, Adeel; Leszczynska, Agneska; Pielichowski, Krzysztof; Ermini, Valentina; Blazquez, Maria; Kuzmenko, Oleksandr; Njuguna, James A. K.
    During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the nano and ultrafine particle emission rates from these materials. In this study, influence of nanoclay on mechanical drilling of PA6 composites, in terms of dust generation has been reported. With the help of real-time characterization, submicrometer-sized particles (5.6-512 nm) size distribution and number concentration emitted from polyamide 6/nanoclay composites during mechanical drilling is studied. Total particle concentration for the PA6/nanoclay composites was 20,000 cm-3, while unreinforced panel measured a total concentration of approximately 400,000 cm-3. While the airborne particle concentration for the PA6/ nanoclay composites was 20 times lower than for the PA6 matrix, the concentration of deposited nanoparticles doubled for the nanocomposite. The results clearly shows that more particles in the size range between 175-350 nm are generated, during drilling of the nanocomposites and this particles deposit in a shorter time. It is likely that the presence of nanoclay in some way retains the formation of high quantity of airborne particles and promotes particle deposition.
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    In vitro analysis of nanoparticles released from polyamide nanomaterial composites during drilling process
    (2011-05-10T00:00:00Z) Irfan, Adeel; Sachse, Sophia; Njuguna, James A. K.; Zhu, Huijun; Crump, Derrick
    Nanomaterials provide a new avenue of progress into technological development. By manipulating materials on the very basic atomic and molecular levels the property of a given material can be specifically altered to suit the purpose of intended applications. However, nanomaterials (nanoparticles and nanolayers) have a more complex nature in physiochemical properties and surface reactivity than their larger counterparts. Therefore, the release of these nanomaterials as dust during crushing or drilling may lead to serious health hazards for humans and the surrounding environment. This study, supported by the NEPHH (Nanomaterial-related Environmental Pollution Health Hazards), addresses two important questions about nanomaterials: - Whether nanomaterials can be released from physical process of nanoproducts. - Toxicity potential of nanodusts generated from nanoproducts in comparison with reference products. Both questions address a massive gap in knowledge for toxicity and more specifically nanomaterial toxicity.
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    The Influence of Multiscale Fillers Rein forcement into Impact Resistance and Energy Absorption Properties of Polyamide 6 and Polypropylene Nanocomposite Structures
    (2013-09-01T00:00:00Z) Silva, Francesco; Njuguna, James A. K.; Sachse, Sophia; Pielichowski, Krzysztof; Leszczynska, Agneska; Giacomelli, Marco
    Three-phase composites (thermoplastic polymer, glass-fibres and nano-particles) were investigated as an alternative to two-phase (polymer and glass-fibres) composites. The effect of matrix and reinforcement material on the energy absorption capabilities of composite structures was studied in details in this paper. Dynamic and quasi-static axial collapse of conical structures was conducted using a high energy drop tower, as well as Instron universal testing machine. The impact event was recorded using a high-speed camera and the fracture surface was investigated with scanning electron microscopy (SEM). Attention was directed towards the relation between micro and macro fracture process with crack propagation mechanism and energy absorbed by the structure. The obtained results indicated an important influence of filler and matrix material on the energy absorption capabilities of the polymer composites. A significant increase in specific energy absorption (SEA) was observed in polyamide 6 (PA6) reinforced with nano-silica particles and glass-spheres, whereas addition of montmorillonite (MMT) caused a decrease in that property. On the other hand, very little influence of the secondary reinforcement on the energy absorption capabilities of polypropylene (PP) composites was found.
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    Nano-sized particles emission during drilling and low velocity impact of silica-based thermoplastic nanocomposites
    (Cranfield University, 2012-10) Sachse, Sophia; Njuguna, James; Zhu, Huijun
    During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. Driven by the certainty that by the integration of low nano ller amounts, existing material properties can be improved and moreover new material properties can be developed. Despite the clear bene t and therefore, increasing research, production and utilisation of nanomaterials, little is known about how nanocomposites will perform over their whole life cycle, especially in the usage and end of life phase. Under the in uence of environmental factors such as ultraviolet light, moisture, temperature and mechanical actions, nano-sized particles can be potentially released from nanocomposites and thus may have negative e ects on the human health and the environment. Within the scope of this work an extensive literature review has been conducted in which polymer nanocomposites are brie y introduced and release scenarios of engineered nano-sized particles from nanocomposites during their life cycle are discussed. In the experimental part of this work silica based polypropylene, polyamide and polyurethane composites were manufactured and particle exposure mechanism during mechanical processing and testing were monitored and analysed. A series of comprehensive physical characterisation techniques were utilised to assess particle size distribution, shape, and concentration in di erent mediums, once emitted by the solid composite materials. It was observed that during drilling of PA6 composites, the airborne particle emission rates were 10 times higher than those for the PP based composites. However, the characterisation of deposited particles showed exactly the opposite behaviour, were the total number of particles emitted by the PP based composites was 10-100 times higher than those of the PA6 based composites. To the best of our knowledge, this is the rst time such work has been reported in the literature. Further, the addition of secondary ller into a polymer/glass- bre composites changed the micro-mechanism during crash testing and therefore controlled the energy absorption characteristics of the composites. However, it was shown that once subjected to higher impact energies the geometric particle size of the released particles increased from approx. 25 nm for the 530 J to approx. 60 nm for the 1560 J impact. Additionally, the tensile modulus increased by 0.31 GPa and the speci c energy absorbed during impact test increased from 20.7 kJ to 22.6 kJ by using nano-SiO2 alternative to micro-SiO2 particles in PP/glass- bre matrix. Even though a respective enhancement in mechanical properties were observed by using nano llers over micro llers, no signi cant di erence in particle emission during impact test were measured. Further, it could be shown that during drilling and testing, nano-sized particles were released from all materials studied, regardless of whether they had nanoparticles integrated or not. In one particular case, the neat polymer matrix generated more nano-sized particles during drilling than the exfoliated PA6/nanoclay nanocomposite. Hence, the addition of nanoclay can have bene cial impact in terms of controlled particle release. However, in general the addition of nano llers increased the particle emission rates during drilling and impact testing of the nanocomposites. Further, the emitted nano-sized particles were not all free engineered pristine nanoparticles but also hybrid particles consisting of matrix/nano ller material. A signi cant set of data was obtained during this study and hence the outcomes sets an excellent foundation for risk assessment and life cycle analysis of silica based polypropylene, polyamide and polyurethane nanocomposites.
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    Nanocomposites for vehicle structural applications
    (2011-11-14T00:00:00Z) Njuguna, James A. K.; Silva, Francesco; Sachse, Sophia; Lin, T
    Advancements in the nanotechnology industry promise to offer improvements in capabilities across a spectrum of applications. This is of immense strategic importance to the high performance sector which has historically leveraged technological advances. The uses of polymer nanocomposites in structures have several predictable impacts on structural design and applications, primarily by providing a safer, faster, and eventually cheaper transportation in the future. In this chapter, special attention is focused on the reinforcement of key properties of polymer nanocomposites for potential high performance structural applications. Further insight is provided on developments in both theoretical and experimental investigations providing valuable fundamental elements in strength and stiffness, impact resistant and energy absorption performance, thermal properties, age and durability performance and structural health monitoring of polymer nanocomposites for vehicular structural needs. A brief overview of modeling and simulation of nano-reinforced materials is also given reflecting its importance in vehicular structures.
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    Safety assessment of novel polymer-silicon composites - from LCA perspective
    (Publications Office of the European Union, 2012-12) Zhu, Huijun; Irfan, Adeel; Sachse, Sophia; Njuguna, James
    The fast growing trend in the development of novel materials with potential applications in many industrial sectors has caused concerns over the environment and human health effect of the emerging activities and associated products. It is imperative that these concerns are addressed in a holistic manner as early as possible. As part of the NEPHH project, this study applied the LCA concept aiming to identify hazardous nanoparticles (NP) that could be released during the development and application of novel products, focusing on polymeric-silicon composites in recognition of their attractions to a wide range of industries, including construct engineering, automotive and aerospace.