| 1. |
- Alipour, Nazanin, et al.
(författare)
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Qualitative characterization of nanoclay particle emissions from PP nanocomposites after thermal degradation
- 2015
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Ingår i: 20th International Conference on Composite Materials, ICCM 2015. - : International Committee on Composite Materials.
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Konferensbidrag (refereegranskat)abstract
- The use of nanomaterials in polymeric materials is a rapidly expanding field, and the polymer nanocomposites are being introduced into various markets. But there is still little known about the fate of nanocomposites and nanoparticles during service life and end-of-life of the materials. To avoid possible environmental, health and safety problems, simulating different scenarios for nanoparticles release from the polymer matrix plays a key role in commercialization of these advanced materials. The polymer/nanoclay nanocomposites show superior material properties in comparison with the pure polymers, such as improved mechanical properties, heat resistance, flame retardancy and decreased gas permeability. Polypropylene (PP) nanocomposites have attracted a considerable interest due to the material's low cost, low density and extensive production volumes. In this study, in order to obtain reliable results regarding the release of nanoclays from PP nanocomposites, homogenous composite with predetermined content of nanoclay was produced and characterized to obtain information regarding content, dispersion and size of the nanoclays in the matrix. The PP nanocomposite was degraded under controlled conditions and the surface morphology as well as oxidation of the material was characterized with scanning electron microscopy (SEM) and infrared spectroscopy during degradation. A prototype environmental chamber was designed in order to collect nano-sized particles in a controlled manner and subsequent characterization of the released or formed particles was performed with transmission electron microscopy (TEM) and the exposed nanocomposite was analysed with thermogravimetric analysis (TGA).
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| 2. |
- Alipour, Nazanin, et al.
(författare)
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Release of micro- and nanoparticles from a polypropylene/clay nanocomposite, a methodology for controlled degradation and evaluation
- 2021
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 319
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Tidskriftsartikel (refereegranskat)abstract
- A methodology was developed for qualitative assessment and characterisation of particle losses from nanocomposites during service life. The methodology can be generalised to other systems where the material fragments during ageing and can be extended to quantitative analysis. A chamber was constructed for ageing of selected materials, which enabled effective collection and subsequent analysis of released particles. A combination of scanning and transmission electron microscopy and energy dispersive X-ray spectroscopy was found to be suitable for characterising particles in terms of size, shape and content. The methodology was tested on a common nanoclay composite with polypropylene as the matrix. There was no need for physical/mechanical wear to generate particles, slow flow of air and elevated temperature led to cracking and fragmentation of the material, and subsequent release of nanocomposite particles containing embedded or protruding clay. The release of pure clay particles and polypropylene particles was also detected. Using the methodology, it was observed that even in ‘mild’ degradation conditions (pure thermo-oxidation with no wear), fillers and nanocomposite particles can be released to the environment, which is an environmental and health concern. © 2021 The Authors
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| 3. |
- Apel, Christina, et al.
(författare)
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Safe-and-sustainable-by-design: State of the art approaches and lessons learned from value chain perspectives
- 2024
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Ingår i: Current Opinion in Green and Sustainable Chemistry. - Stockholm : IVL Svenska Miljöinstitutet. - 2452-2236. ; 45, s. 100876-100876
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Tidskriftsartikel (refereegranskat)abstract
- Safe-and-sustainable-by-design (SSbD) is central in the European Chemicals Strategy for Sustainability, yet a common understanding of what SSbD is in concept and in practice isstill needed. A comparison of current SSbD descriptions and approaches was made and lessons learned were derived from value chain discussions (packaging, textile, construction,automotive, energy materials, electronics, and fragrances value chains) to help provide input on how to implement SSbD in practice.Five important building blocks were identified:design, data, risk and sustainability governance, competencies, and social and corporate strategic needs. Other lessons learned include the identification of the biggest safety andsustainability challenges in a lifecycle-thinking approach towards the development of purpose-driven innovations, and connecting trans-disciplinary experts to the innovation process, already from the early phases. A clear understanding of what SSbD is and how to implement the SSbD framework is needed with clear procedures and incentives to support the industrial sector, especially SMEs.
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| 4. |
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| 5. |
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| 6. |
- Atari Jabarzadeh, Sevil, et al.
(författare)
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Image Analysis Determination of the Influence of Surface Structure of Silicone Rubbers on Biofouling
- 2015
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Ingår i: International Journal of Polymer Science. - : Hindawi Limited. - 1687-9422 .- 1687-9430.
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on how the texture of the silicone rubber material affects the distribution of microbial growth on the surface of materials used for high voltage insulation. The analysis of surface wetting properties showed that the textured surfaces provide higher receding contact angles and therefore lower contact angle hysteresis. The textured surfaces decrease the risk for dry band formation and thus preserve the electrical properties of the material due to a more homogeneous distribution of water on the surface, which, however, promotes the formation of more extensive biofilms. The samples were inoculated with fungal suspension and incubated in a microenvironment chamber simulating authentic conditions in the field. The extent and distribution of microbial growth on the textured and plane surface samples representing the different parts of the insulator housing that is shank and shed were determined by visual inspection and image analysis methods. The results showed that the microbial growth was evenly distributed on the surface of the textured samples but restricted to limited areas on the plane samples. More intensive microbial growth was determined on the textured samples representing sheds. It would therefore be preferable to use the textured surface silicone rubber for the shank of the insulator.
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| 7. |
- Atari Jabarzadeh, Sevil, et al.
(författare)
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Use of essential oils for the prevention of biofilm formation on silicone rubber high voltage insulators
- 2015
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Ingår i: Polymers from Renewable Resources. - : Rapra Technology Ltd.. - 2041-2479 .- 2045-1377. ; 6:4, s. 119-136
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Tidskriftsartikel (refereegranskat)abstract
- The prevention of biofilm formation on high voltage insulators is important to avoid changes in the surface properties of the material and the subsequent failure of the application. Antimicrobial silicone rubber samples were prepared by the addition of thymol and eugenol to Sylgard 184 to determine the possibility of using natural antimicrobial agents present in essential oils in materials used for high voltage insulators. The antimicrobial effects of thymol and eugenol were studied for different fungal strains and for green algae identified in the biofilms formed on insulators in Tanzania, Sri Lanka and Sweden. It was successfully demonstrated that samples containing high amount of eugenol and different concentrations of thymol could inhibit the fungal growth of strains from Sri Lanka and Tanzania and the growth of green algae. The growth of strains from Sweden was also suppressed. The addition of eugenol to the material resulted in a noncrosslinked system and therefore, the antimicrobial effect of the additive in the material could not be assessed. The addition of thymol did not significantly influence the thermal and mechanical properties of Sylgard184. Although thermal analysis revealed that a large amount of the antimicrobial agent was lost during sample preparation, the materials were effective against microbial growth, even at low thymol concentrations.
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| 8. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Biofilm formation on silicone materials containing various antimicrobial agents
- 2010
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Konferensbidrag (refereegranskat)abstract
- The colonisation of microorganisms and subsequent biofilm formation on the surface of polymeric high voltage insulators affect the surface properties and can lead to failure of the insulators. In this study, silicone materials were prepared with different antimicrobial agents. The materials were analysed for the changes in the physical, chemical, surface and mechanical properties before and after biological growth test. Microorganisms used for the biological tests were fungi defined in the international standard test ISO 846 for electrical applications (Aspergillus niger van Tieghem, Penicillium funiculosum Thom, Paecilomyces variotii Bainier, Chaetomium globosum Kunze: Fries, Aspergillus terreus Thom, Aureobasidium pullulans (de Bary) Arnaud & Penicillium ochrochloron Biourge) and algae isolated from insulators in Sri Lanka and Tanzania (Chlorella vulgaris var. Autotrophica + various bacterial strains). Fungi growth test was performed by inoculation of the fungi on the surface of the materials and incubation in an oven at 28°C and 98% humidity for a specific period. Algae growth test was performed by inoculation on the material surface and subsequent incubation in room temperature under a constant fluorescent lamps for a specific period. The results indicated that some of the samples could prevent the biofilm formation on the surface of the materials while the microbial growth was unaffected on the pure silicone rubber.
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| 9. |
- Atarijabarzadeh, Sevil, et al.
(författare)
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Biofilm formation on silicone nanocomposites containing different antimicrobial agents
- 2010
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Konferensbidrag (refereegranskat)abstract
- In this study three types of clay/silicon nanocomposites were prepared. Clay was modified with two different antimicrobial agents (p-aminobenzoic acid and partially aminated poly(vinylbenzyl chloride) and used for preparation of the nanocomposites, which aimed to show antimicrobial properties and also easy dispersion of the clay into the polymeric matrix. Reference nanocomposites were made through the modification of the clay with a siloxane surfactant to make an easy dispersion of the clay into the silicone rubber. Nanocomposites were studied for resistancy against biological attack according to the international standard tests. Growth test results indicated that some of the nanocomposites can inhibit biological growth more than pristine nanocomposites. Modified clay was studied with x-ray diffraction technique. Materials were also studied with scanning electron microscopy before and after biological growth to analyse the biofilm formation on the surface.
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| 10. |
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