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  • 1.
    Banushi, Gersena
    et al.
    HafenCity University, Germany.
    Vega, Alberto
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Weidlich, Ingo
    HafenCity University, Germany.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Kim, Jooyong
    Korea District Heating Corporation, Korea.
    Jakubowicz, Ignacy
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Sällström, Jan Henrik
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Durability of District Heating Pipelines Exposed to Thermal Aging and Cyclic Operational Loads2021Ingår i: Journal of Pipeline Systems Engineering and Practice, ISSN 1949-1190, Vol. 12, nr 1, artikel-id 04020067Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fourth generation district heating networks (4GDH) must be designed for future energy systems, integrating renewable volatile energy sources, with lower operation temperatures, and consequent reduction of heat losses and increased energy efficiency. The lower levels of operating temperature and the greater amount of cyclic loading, influence aging, and the service life of 4GDH pipelines, differently from traditional district heating (DH) networks, and thus require proper investigation of the system response at the cross-sectional level. To evaluate the material durability of 4GDH pipelines, we have analyzed the behavior of the service steel pipe, the insulation foam, and their adhesive interaction, using an innovative analytical and experimental procedure. This paper describes the influence of traditional and future operational loading conditions on the performance of preinsulated bonded single-pipe systems, representing the majority of currently operating DH pipelines. The performed fatigue analysis of the steel service pipe showed that the lifetime of 4GDH pipelines is expected to increase because of the lower operating temperature, and the low impact of thermal loading volatility in the network, compared to conventional DH. The accelerated aging tests of DN 50/160 pipes demonstrated that the combined effect of cyclic mechanical loading and thermal aging accelerates the rate of chemical degradation of the PUR foam, leading to a faster deterioration of the mechanical adhesion strength. The shear strength tests of naturally aged DH pipes revealed that, besides the initial pipe system characteristics and aging period, the residual shear strength of the polyurethane (PUR) foam depends on the temperature history, decreasing with the level of operating temperature and amount of fluctuation. The obtained results give a better understanding of the performance of traditional and 4GDH pipelines in operation that need to be appropriately considered in the engineering design standards of DH networks toward a more sustainable and energy-efficient infrastructure. 

  • 2.
    Forsgren, Lilian
    et al.
    Chalmers University of Technology, Sweden.
    Noyan, Ezgi
    Chalmers University of Technology, Sweden.
    Vega, Alberto
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande. Chalmers University of Technology, Sweden.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Boldizar, Antal
    Chalmers University of Technology, Sweden.
    The thermo-oxidative durability of polyethylene reinforced with wood-based fibres2020Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 181, artikel-id 109374Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aiming at better understanding the ageing behaviour of cellulose composites, the accelerated thermo-oxidative ageing of polyethylene reinforced with two types of wood-based cellulose fibres was studied. Materials were prepared by extrusion mixing of either un-stabilized or stabilized polyethylene reinforced with 5 and 20 vol % cellulose content. The materials were extruded into strips and then aged at 90°C in circulating air. The effect of accelerated ageing up to 31 days was assessed by oxidation induction time and mechanical properties in tension. The results indicated that the added cellulose fibres did not increase the degradation of the composites during this ageing. Reinforcement with 20 % cellulose fibre having a 28 % lignin content together with 0.005 % Irganox 1010 antioxidant resulted in a remarkable improvement in the resistance against accelerated thermo-oxidation, compared to the pure polyethylene with added antioxidant. The findings of increased lifetime of LDPE by addition of wood-based reinforcement is of great interest, since the durability aspect is crucial to understand and predict before usage in commercial applications and especially as structural composites.

  • 3.
    Jakubowicz, Ignacy
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Enebro, Jonas
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Challenges in the search for nanoplastics in the environment—A critical review from the polymer science perspective2021Ingår i: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 93, artikel-id 106953Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nanoplastics (NPs), which we define in this paper as solid plastic particles with the size <1 μm, unintentionally produced from the degradation and fragmentation of larger plastic objects are probably the least known area of plastic litter but are suspected to pose the greatest risk to the environment. However, no NPs have been detected in natural environments to date. This review attempts to provide a critical overview from the polymer science perspective of the relevant scientific literature, which could facilitate finding secondary NPs in natural environments. The information on secondary NPs has been scarce due to the big challenges in sampling, separation, and detection of these nanoscale particles. This review highlights the most important challenges and obstacles and discusses the mechanisms of generation of secondary NPs. It provides also a critical overview on modern instrumentation, newly developed workflows, promising techniques for sampling and sample preparation, and detection methods including spectroscopies (Raman and FT-IR), microscopies (SEM and TEM) and mass spectrometry (GC–MS and ToF–SIMS). We conclude that finding NPs in natural environments is plausible yet uncertain, which drives towards the development of a methodology for collection, separation and identification of NPs in environmental matrices along with a thorough evaluation of the process of formation of secondary NPs, their fate and effects on living organisms and the environment. To find nanoplastics in natural environments it is important to know the process of their formation, their fate, and experimental constraints.

  • 4.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Johansson, Ulrika
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Durability of Poly (Vinyl Chloride)-Based Geomembranes in Aggressive Liquid Media. NORDTEST Technical Report 393.1997Rapport (Refereegranskat)
    Ladda ner fulltext (pdf)
    fulltext
  • 5.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Skrifvars, Mikael
    Åkesson, Dan
    Boldizar, Antal
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Enebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Berlin, Johanna
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Royne, Frida
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi.
    Ericson, Mats
    Svensson, Mats
    Lindgren, Martina
    Guide för bioplaster: från tillverkning till återvinning2016Rapport (Övrigt vetenskapligt)
  • 6.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Development of polymer matrix clay nanocomposites for industrial applications using high throughput methods2008Ingår i: Solid State Phenomena, Vol. 151, s. 35-42Artikel i tidskrift (Refereegranskat)
  • 7.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Development of polymer matrix clay nanocomposites for industrial applications using high throughput methods2009Ingår i: Solid State Phenomena, Vol. 151, s. 35-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of polymer-layered silicate nanocomposites (PNCs) includes a long list of different possible components such as polymers, nano-additives, and co-additives, together with surface chemistry and various processing conditions. This involves the investigation of a large number of parameters that influence PNC performance. Consequently, fairly extensive research and development work is necessary, and this constitutes an obstacle in the commercialization of nanotechnology. This paper, which is based on experience from research and development for an industrial application, presents a procedure composed of high throughput (HT) screening methods for speeding up the development of PNCs. Our task was to replace the existing conventional glass fibre-reinforced polypropylene (PP) used in the manufacture of pallets by a PP/montmorillonite nanocomposite. One of the most important HT tools was a 15 cm3 laboratory-scale twin-screw microcompounder equipped with a 3.5 cm3 shot volume injection moulder. The HT nature of the microcompounder was derived from three important abilities, namely the ability to quickly perform alterations of the formulation, to easily change the processing conditions, and to perform direct extrusion of the test samples suitable for the evaluation. Equally important was to determine the overall order and morphology of the system to provide a basic understanding of these materials and ultimately find the optimum mechanical properties. Thermo-gravimetric analysis (TGA) was used to measure the percentage of the organic modifier in the various commercially available organoclays, as well as the decomposition temperature of the organic modifier. The shape and dispersion of clay platelets in the polymer was made visible by high-resolution scanning electron microscopy (HR-SEM); moreover, the big advantage with this technique was the possibility to observe the compatibility between the clay particles and the polymer matrix. The improvement in flame retardancy by nanoclays was measured using a cone calorimeter, which gave valuable information about the time to flaming ignition, heat release rate, effective heat of combustion and smoke production rate.

  • 8.
    Jakubowicz, Ignacy
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Review and Assessment of Existing and Future Techniques for Traceability with Particular Focus on Applicability to ABS Plastics2024Ingår i: Polymers, E-ISSN 2073-4360, Vol. 16, nr 10, artikel-id 1343Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is generally recognized that the use of physical and digital information-based solutions for tracking plastic materials along a value chain can favour the transition to a circular economy and help to overcome obstacles. In the near future, traceability and information exchange between all actors in the value chain of the plastics industry will be crucial to establishing more effective recycling systems. Recycling plastics is a complex process that is particularly complicated in the case of acrylonitrile butadiene styrene (ABS) plastic because of its versatility and use in many applications. This literature study is part of a larger EU-funded project with the acronym ABSolEU (Paving the way for an ABS recycling revolution in the EU). One of its goals is to propose a suitable traceability system for ABS products through physical marking with a digital connection to a suitable data-management system to facilitate the circular use of ABS. The aim of this paper is therefore to review and assess the current and future techniques for traceability with a particular focus on their use for ABS plastics as a basis for this proposal. The scientific literature and initiatives are discussed within three technological areas, viz., labelling and traceability systems currently in use, digital data sharing systems and physical marking. The first section includes some examples of systems used commonly today. For data sharing, three digital technologies are discussed, viz., Digital Product Passports, blockchain solutions and certification systems, which identify a product through information that is attached to it and store, share and analyse data throughout the product’s life cycle. Finally, several different methods for physical marking are described and evaluated, including different labels on a product’s surface and the addition of a specific material to a polymer matrix that can be identified at any point in time with the use of a special light source or device. The conclusion from this study is that the most promising data management technology for the near future is blockchain technology, which could be shared by all ABS products. Regarding physical marking, producers must evaluate different options for individual products, using the most appropriate and economical technology for each specific product. It is also important to evaluate what information should be attached to a specific product to meet the needs of all actors in the value chain.

    Ladda ner fulltext (pdf)
    fulltext
  • 9.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jansson, Anna
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Ekendahl, Susanne
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Eriksson, Linda
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Lindblad, Catrin
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Development of test procedure for the determination of disintegrability of plastic materials under conditions simulating small scale composting2006Rapport (Refereegranskat)
    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 10.
    Jakubowicz, Ignacy
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Johansson, L.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Assessment of the potential risks of release of nanoclay particles into environment2007Ingår i: 7th World Congress: Enabling Technologies and New Markets, Nanocomposites 2007, Executive Conference Management Inc. , 2007Konferensbidrag (Refereegranskat)
  • 11.
    Malm, Annika
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad.
    Mokhlesi, Saeed
    Chalmers University of Technology, Sweden.
    Sernhed, Kerstin
    Lund University, Sweden.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Hållbar Samhällsbyggnad.
    Kartläggning av materialfördelning och skadestatistik av vatten- och fjärrvärmeledningar i Sverige som underlag till rekommendationer för datainsamling: Rapport framtagen inom ramen för projektet Pipestatus2016Rapport (Övrigt vetenskapligt)
  • 12.
    Petersen, Henrik
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Enebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Development of nanocomposites based on organically modified montmorillonite and plasticized PVC with improved barrier properties2016Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, nr 3, artikel-id 42876Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Montmorillonite (MMT) was organically modified with tributyl citrate (TBC). Organoclays (OMMTs) were processed with diisononyl phthalate (DINP)-plasticized polyvinyl chloride (PVC) to form polymer nanocomposites. The produced composite materials showed a contradictory change in properties to that expected of a layered silicate nanocomposite, with a decreased E-modulus and increased gas permeability compared with a material without OMMT. It was experimentally shown that the TBC modifier was extracted from the OMMT and was dispersed in the PVC/DINP matrix, whereupon the OMMT collapsed and formed micrometer-sized agglomerates. Further investigation revealed that TBC has a significant effect on the gas permeability and the E-modulus, even at low additions to a DINP-plasticized PVC. A PVC nanocomposite with the TBC acting as both the OM for MMT and as the primary plasticizer was produced. This material showed a significantly increased E-modulus as well as a decrease in gas permeability, confirming that it is possible to develop a nanocomposite based on plasticized PVC, if both the organo-modification of the MMT and the formulation of the matrix are carefully selected.

  • 13.
    Petersen, Henrik
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Enebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Organic modification of montmorillonite for application in plasticized PVC nanocomposites2015Ingår i: Applied Clay Science, ISSN 0169-1317, E-ISSN 1872-9053, Vol. 107, s. 78-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new type of organic compound for modifying clay minerals suitable for use in plasticized polyvinyl chloride was selected and studied. The theory of Hansen solubility parameters was used to predict the miscibility between potential organomodifiers and polyvinyl chloride. In a series of systematic experiments using four very different solvents (i.e., water, ethanol, tetrahydrofuran and chloroform) and three different types of Mt (i.e., Mt-Na+, Mt-PGV and Mt-Ca++), the importance of various parameters to the process of clay mineral intercalation was investigated. The effects of each combination were evaluated employing wide-angle X-ray diffraction and thermogravimetry. The results of swelling experiments on clay mineral in various solvents correlated well with the results of a theoretical preliminary study using Hansen solubility parameters. The extent of swelling followed the order H2O > EtOH > THF > chloroform. The d-spacing seemed to be little affected by the type of solvent used in the modification, while the type of Mt used was important to the intercalation results. Organomodification of Mt-Na+ increased the d-spacing by nearly 0.7 nm when tributyl citratewas used as a chelating agent. Similar modification of Mt-Ca++ showed an increase of 0.3 nm only. Furthermore, thermogravimetry and DTG curves showed significant structural differences between Mt-Na+ and Mt-Ca++.

  • 14.
    Petersen, Henrik
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Kemi och material. Chalmers University of Technology, Sweden.
    Jakubowicz, Ignacy
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Enebro, Jonas
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Kemi och material.
    Yarahmadi, Nazdaneh
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Solid-state organo-modification of montmorillonite for manufacturing of plasticized poly(vinyl chloride) nanocomposites2018Ingår i: Journal of Vinyl and Additive Technology, ISSN 1083-5601, Vol. 24, s. E146-E153Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The preparation of poly(vinyl chloride) (PVC) nanocomposites via direct melt processing is still posing problems mainly because of the lack of availability of suitable commercial organoclays and because of the low thermal stability of PVC. A new type of organic compounds for modifying montmorillonite (MMT), which is suitable for use in plasticized PVC, has been found earlier. The current study shows that it is possible to achieve partially exfoliated PVC nanocomposites with greatly improved mechanical properties using a method of liquid-solid–state intercalation of MMT when using tributyl citrate and diisononyl phthalate (DINP) plasticizers as organic modifiers. It is also shown that liquid mixed metal stabilizers have the ability to intercalate the clay at least when DINP is used. The observation raises questions regarding how this phenomenon can affect the thermal stability of PVC composites. J. VINYL ADDIT. TECHNOL., 24:E146–E153, 2018. © 2017 Society of Plastics Engineers.

  • 15.
    Puig von Friesen, Marc
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Energi och Bioekonomi, Klimatisering och installationsteknik.
    Arinder, Pernilla
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience, Microbiology.
    Lundin, Maria
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Kjellin, Mikael
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Kurkinen, Eva-Lotta
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Byggnadsfysik och innemiljö (ETi ).
    Thörnblom, Kristian
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Säkerställa vattenkvalitet vid 45˚C med avseende på Legionella: En förstudie för innovationsupphandling2014Rapport (Refereegranskat)
  • 16.
    Sjöstrand, Karin
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Rörcentrum.
    Kärrman, Erik
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Urban Water Management.
    Metod för val av vattenförsörjning i områden med vattenbrist: en handbok2014Rapport (Refereegranskat)
    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 17.
    Sterky, Karin
    et al.
    Chalmers University of Technology, sweden.
    Jacobsen, Harald
    INEOS ChlorVinyls AS, Norway.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Yarahmadi, Nazdaneh
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Hjertberg, Thomas
    Borealis AB, Sweden.
    Influence of processing technique on morphology and mechanical properties of PVC nanocomposites2010Ingår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 46, nr 6, s. 1203-1209Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study aims to compare the influence of processing techniques and procedures on the morphology and mechanical properties of polyvinyl chloride (PVC) nanocomposites. PVC nanocomposites with 5 phr montmorillonite (MMT) clay were prepared on a two-roll mill or in a microcompounder, both were either processed once or via a masterbatch containing 20 phr MMT. The MMT was treated with non-ionic surfactants and analysed by thermo gravimetric analysis and X-ray diffraction prior to being added. The final composites were analysed and tested using X-ray diffraction, scanning and transmission electron microscopy (SEM/TEM), tensile test, and Charpy impact test. The dispersion was found to be best in the roll milled samples prepared via the masterbatch and the elongation at break and impact strength was also better for the roll milled samples. E-modulus and tensile strength, on the other hand, were significantly better for the microcompounded samples despite the larger particle size. This can be explained by a higher degree of orientation in these samples. Finally, it must be stated that the change in properties are not satisfactory. Although we see an increase in E-modulus, the decreased impact properties are not acceptable. The main reason for this is the lack of compatibility between the clay particles as observed by high resolution SEM.

  • 18.
    Vega, Alberto
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Jakubowicz, Ignacy
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Cyclic axial loads and thermal ageing of district heating pipes2021Ingår i: Energy Reports, E-ISSN 2352-4847, Vol. 7, s. 105-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal ageing at elevated temperatures is the standard method to determine the service life of pre-insulated district heating pipes nowadays. However, DH pipes are also subjected to axial movements which can affect the adhesion strength between the polyurethane foam and the service pipe. This contact surface is usually exposed to the highest temperatures. In this project, DH pipes were aged at elevated temperatures and at the same time cyclic axial loads were applied. Two DH pipes were only exposed to thermal ageing at 130 and 140 °C, while two other similar pipes were also exposed to cyclic axial loads. The adhesion strength was evaluated as the function of ageing time using the RISE plug method. Any changes in the chemical structure of the PUR samples were also observed using Fourier transform infrared spectroscopy. Comparing the results in this investigation, we found that the degradation of the mechanically loaded pipes was significantly faster than the degradation observed in non-loaded pipes at the same ageing temperatures. The FTIR study revealed that cyclic mechanical loads accelerated the chemical degradation of the PUR foam during thermal ageing. This study shows how important it is to consider all influencing factors in accelerated ageing. The methods presented here should be considered as an alternative to thermal ageing at high temperatures because the combination of mechanical and thermal loads reproduces better the real operating conditions. It is even of bigger interest when energy from different sources will be connected to the fourth generation of DH networks, which can cause more temperature fluctuations.

  • 19.
    Vega, Alberto
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Jakubowicz, Ignacy
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Determining the useful life of district heating pipes: Correlation between natural and accelerated ageing2020Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 175, artikel-id 109117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    District heating (DH) systems constitute a smart and environmentally friendly solution for energy distribution in the heat sector in Europe. This technique is still expanding but already faces some issues such as status assessment of the current DH networks and the development of new generation networks for low-temperature DH. Therefore, it is essential to understand the ageing behaviour of pipes under operating conditions and to find the relevant parameters that control the degradation processes. Many factors affect the deterioration of DH pipes, especially the polyurethane foam, which makes it very complex to find a reliable prediction model. Models based on a linear Arrhenius relationship using results from high ageing temperatures seem to be incorrect. For this study, 10 pipes that have been in service for many years in Sweden and Norway were evaluated. The aim was to study the impact of natural ageing on the mechanical adhesion and chemical structure of the polyurethane foam, which affects the pipe's performance. A test method developed at the Research Institutes of Sweden (RISE), called RISE plug method, was used to study the mechanical adhesion strength. In addition, Fourier transform infrared spectroscopy was used to observe any change in the chemical structure. The results were compared with previous analyses of DH pipes exposed to accelerated ageing. This information helps to provide a better comprehension of the deterioration of the current generation of pre-insulated DH pipes and to improve the accelerated ageing methods used nowadays to predict the technical lifetime of DH pipes. Our results suggest that the lifetime of DH pipes has been underestimated when using artificial ageing at relatively high temperatures. The data collected from naturally aged pipes gave confirmatory information about their physical status compared with our laboratory tests. This study also suggests that infrared analyses could be used as an early indication of the degradation of the polyurethane foam at the interface with a steel pipe. 

  • 20.
    Vega, Alberto
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Yarahmadi, Nazdaneh
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Jakubowicz, Ignacy
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Optimal conditions for accelerated thermal ageing of district heating pipes2018Ingår i: Energy Procedia, ISSN 1876-6102, Vol. 149, s. 79-83Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Technical lifetime prediction of polymeric materials is often based on accelerated ageing tests at elevated temperatures. Samples are exposed to relatively high temperatures to accelerate the natural degradation processes. For district heating pipes, accelerated thermal ageing is the ordinary method used to determine the lifetime of pipes. According to the Standard EN 253:2009 + A1:2013, the district heating pipes shall be subjected to an accelerated thermal ageing for a long period of time at 160 °C or 170 °C. The lifetime is determined by extrapolation using the Arrhenius relationship. However, papers published recently have questioned this method, especially the high temperatures used for ageing of the pipes and the use of Arrhenius equation to describe the complicated degradation mechanisms, which can result in the erroneous estimation of the technical lifetime. Our investigation has shown the complexity of the pipe's degradation mechanisms. The behaviour of mechanical shear strength at elevated temperatures (T > 130 °C), suggests an alteration rather than an acceleration of the degradation mechanisms. Accelerated ageing tests should reproduce the proper natural ageing mechanisms. The analyses of PUR's thermal conductivity and its chemical structure by FTIR confirmed the degradation patterns

    Ladda ner fulltext (pdf)
    fulltext
  • 21.
    Vega, Alberto
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Yarahmadi, Nazdaneh
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Jakubowicz, Ignazy
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Determination of the long-term performance of district heating pipes through accelerated ageing2018Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 153, s. 15-22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lifetime of pre-insulated district heating pipes (DHPs) is commonly evaluated using the method described in the normative European Standard EN 253. This lifetime is normally calculated using an Arrhenius equation, which makes use of test results from accelerated ageing tests at elevated temperatures. In this investigation, long-term accelerated ageing tests of DHPs at elevated temperatures were carried out. The ageing behaviour, especially at the interface between steel pipe and polyurethane (PUR) foam, showed several routes of degradation. It is clearly demonstrated using measurements of shear strength, thermal conductivity and alterations of chemical structure by Fourier Transform Infrared spectroscopy that the results of accelerated ageing at 170 and 150 °C significantly diverge from those obtained from the ageing test at 130 °C. It is therefore concluded that accelerated ageing at commonly used high temperatures does not create an acceleration of degradation processes at the steel/PUR interface relevant for the DHP application, but rather a significant alteration in mechanism. This finding is of crucial importance for the use of EN 253 and the development of future methods for lifetime prediction of DHPs.

  • 22.
    Vega, Alberto
    et al.
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Yarahmadi, Nazdaneh
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Sällström, Jan
    RISE Research Institutes of Sweden, Samhällsbyggnad, Infrastruktur och betongbyggande.
    Jakubowicz, Ignacio
    RISE Research Institutes of Sweden.
    Effects of cyclic mechanical loads and thermal ageing on district heating pipes2020Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 182, artikel-id 109385Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lifetime of pre-insulated district heating pipes is commonly evaluated by thermal ageing at elevated temperatures and is calculated using the Arrhenius equation. In this investigation, the effects of a repetitive shear stress during thermal ageing of pipes were studied. The degradation of polyurethane foam, especially at the interface with a steel pipe was evaluated from measurements of the adhesion strength and of alterations in the chemical structure of polyurethane by Fourier transform infrared spectroscopy. The main conclusion was that the thermal degradation of mechanically stressed district heating pipes was significantly faster than that of non-loaded pipes aged at the same temperature. It was also shown that the faster degradation of the mechanically loaded pipes is mainly due not to fatigue but to accelerated chemical degradation of the polyurethane foam. The results suggest that this methodology should be considered as an accelerated test method in order to avoid overestimation of the lifetime of district heating pipes and to show better ageing characteristics of mechanically stressed pipes, especially those intended for use in the fourth generation district heating networks 

  • 23.
    Yarahmadi, Nazdaneh
    SP – Sveriges Tekniska Forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut *(2016-12-31).
    Recycling and durability of PVC materials focusing on pre- and post-consumer wastes from building products2003Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The potential for recycling various polymeric materials contained within buildings constructed in the late 1960s and 1970s in Sweden was investigated during the course of this work. Three residential blocks were studied to establish the quantity of materials available for recycling, to investigate the difficulty in and time needed for the dismantling of the buildings, the degree of purity of the materials, and the possibility of separating the materials. The focus of the experimental work was on studies of various types of polyvinyl chloride (PVC), which is the dominant polymeric material in the buildings. The important properties and the durability of new plasticised and rigid PVC materials were investigated, as well as the properties of older products collected from the buildings. The study had several facets. First, there was an investigation into the degradation processes that occur during the initial processing of virgin material and during reprocessing. Then there was examination of changes in properties during service life. Following this was the process of establishing the remaining lifetime of the used and reprocessed materials. Finally there was an investigation into fundamental degradation mechanisms that can take place during the long service life of PVC materials in buildings under various environmental conditions. In particular, stabiliser consumption and dehydrochlorination, depletion of plasticiser, and deterioration of the tensile properties were examined. Evaluation was carried out by means of physical and chemical analysis and characterisation was achieved on a molecular level, in addition to evaluation of the mechanical properties, including attempts at recycling some materials on the laboratory scale. Accelerated ageing of the materials was performed to simulate the natural service life conditions. The decisive degradation mechanisms in the new and model materials were mapped and compared with older materials. An attempt was also made at recovering energy from flooring.

  • 24.
    Yarahmadi, Nazdaneh
    RISE - Research Institutes of Sweden (2017-2019).
    Sustainable management of plastic waste from hospitals: Final report of the project2019Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This project has been performed within the strategic research program RE:Source, with funding from the Swedish Energy Agency and participating partners. We would like to send a warm thank to all participants for their dedication and commitment during the project. Without their contributions the success of this project would not have been possible.

    The big interest the project received nationally and in other Nordic countries shows the importance of the area, and we are looking forward to following up and expand this work further as a national, Scandinavian and/or European project in the future

    Ladda ner fulltext (pdf)
    fulltext
  • 25.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Jacubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Recycling of blends composed of petro- and bio-based plastics2015Ingår i: J Material Sci Eng, Vol. 4, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Growing public concern regarding the environment and strive towards use of renewable resources represent key drivers for governments, companies, and researchers to develop alternatives to petroleum-based plastics. Replacing petro based plastics by bio based needs a transition period during which both petro and bio based plastics will coexist on the market. At the same time demand for products made from recycled materials is rising, making recyclability an important attribute for many types of plastics. Polymer blends and alloys offer an interesting solution to obtain multipurpose materials with tailor-made properties. However, recycling of these inseparable mixtures is restricted by processing as well as thermodynamic issues. As a part of the project “Sustainable recycling of “green” plastics” a study on the recycling and other challenges related to blends of bio- and petro based plastics has been done. PLA blends with HDPE and with PC has been investigated along with PVC plasticized with a bio-based plasticizer. The work has been performed by simulation of pre- and postconsumer products recycling. High throughput laboratory methods and industrial scale processing were used. Effects of recycling were investigated using sensitive analytical tools as well as tests of mechanical strength.

  • 26.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Jacubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Vega, Alberto
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Livslängd för fjärrvärmerör : Fas I – Nedbrytningsmekanismer2017Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Dagens standard för prefabricerade fjärrvärmerör SS-EN253 innehåller olika testmetoder och krav där ett av de viktigaste är kravet på livslängd på minst 30 år vid en kontinuerlig driftstemperatur på 120 °C. Bestämningen av tekniska livslängden är baserad på mätningar av förändringar i skjuvhållfastheten efter accelererad termisk åldring. Den beräknade livslängden för ett fjärrvärmerör är baserad på extrapolering med hjälp av Arrhenius ekvation. Det finns en stor enighet kring uppfattningen att Arrhenius modellen inte ger en god överensstämmelse med de observerade åldringsdata och att det följaktligen saknas tillförlitliga metoder för livslängdsbestämning av fjärrvärmerör. Trots många forskningsrapporter finns det fortfarande skilda teorier om hur snabbt PURisoleringar bryts ner och vilka nedbrytningsmekanismer som dominerar. Syftet med det här projektet är att kartlägga de komplicerade sambanden och förstå vilka nedbrytningsprocesser som dominerar under olika betingelser och utifrån denna kunskap utveckla tillförlitliga metoder för livslängdsprediktering. Allt testmaterial utgjordes i denna studie av polyuretan (PUR) cellplastisolering som togs ut från nytillverkade fjärrvärmerör. Accelererad åldring genomfördes i luft och i kväveatmosfär vid 150 °C för upp till 8 veckor. Det visade sig att exponering i kväveatmosfär inte orsakar någon mätbar förändring av egenskaper. En motsvarande åldring i luft orsakar däremot stora förändringar i både dimensioner, viktförlust och färg. IR (infraröd) analys kunde också bekräfta att materialet bryts ner genom termo-oxidativa processer. Termo-oxidativ nedbrytning syns också i analyser av cellgassammansättningen. Materialet efter åldring i luft innehåller betydligt mindre halt cyklopentan samtidigt som fyra nya flyktiga ämnen kunde detekteras. Trots alla indikationer på materialets termooxidativa nedbrytning har böjhållfastheten inte förändrats hos materialet. Detta måste utredas vidare för att kunna förklara mekanismer bakom resultatet. Förutom beständighetsstudier av PUR materialet genomfördes långtidsåldring av fjärrvärmerör vid olika temperaturer. Resultaten av skjuvhållfasthet mätningar indikerar att det åtminstone finns tre olika faser i nedbrytningsprocessen. Initialt sjunker hållfastheten troligen på grund av fysikaliska effekter orsakade av de höga temperaturerna. Därefter ökar skjuvhållfastheten troligen beroende på sidoreaktioner och fortsatt tvärbindning. Det tredje steget är en termo-oxidativ nedbrytning som såsmåningom leder till förlust av vidhäftningen. Även värmeledningsförmågan ökar betydligt som ett resultat av nedbrytningsprocesser. Det finns behov av ytterligare forskning för att kunna föreslå en ny modell för livslängdsberäkningar baserade på experimentella resultat.

  • 27.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Determination of the suitable methods for recycling of old and new flooring materials - Mechanical recycling aand energy recovery2002Konferensbidrag (Övrigt vetenskapligt)
  • 28.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    MISTRA- Sustainable building, Experiences From a Cross-Disiplinary Research Program2002Rapport (Refereegranskat)
  • 29.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Polymeric materials in sustainable building2002Konferensbidrag (Övrigt vetenskapligt)
  • 30.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Polymeric materials in sustainable building MISTRA- sustainable building. Experiences from a cross-disciplinary research programme2002Rapport (Refereegranskat)
  • 31.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    PVC floorings as post-consumer products for mechanical recycling and energy recovery2003Ingår i: Polymer Degradation and Stability, Vol. 79, s. 439-448Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PVC floorings as post-consumer products for mechanical recycling and energy recovery

  • 32.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    The effects of heat treatment and ageing on the mechanical properties of rigid PVC2003Ingår i: Polymer Degradation and Stability, Vol. 82, s. 59-72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of heat treatment and ageing on the mechanical properties of rigid PVC

  • 33.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Enebro, Jonas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Polylactic acid and its blends with petroleum-based resins: Effects of reprocessing and recycling on properties2016Ingår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, nr 36, artikel-id 43916Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Environmental and economic reasons make the use of bioplastics and biocomposites increasingly coveted in sectors other than packaging. Recycling of all wasted or rejected durable plastics is highly desired and biobased plastics are no exception. Therefore, the investigation of pre- and post-consumer recycling of products made from biobased plastics is of great interest. Polylactic acid (PLA) and its blends have been chosen for this study because it is an excellent representative of mass-produced bioplastics for industrial applications. As part of the "Sustainable Recycling of 'Green' Plastics" project, the current study addresses the durability issues related to the reprocessing and post-consumer recycling of a PLA virgin resin and two commercially available blends of PLA namely one with polycarbonate (PC) and one with polyethylene (PE). The materials were investigated using methods that simulate post-processing and post-consumer recycling. Accelerated ageing was performed at elevated temperature and humidity to simulate the usage period of the materials. The materials were analyzed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and their mechanical strength was evaluated by tensile and impact testing. The flow properties of the materials were characterized by the melt flow index (MFI). Multiple processing of pure PLA did not affect the impact strength or the glass transition temperature (Tg), but caused crystallization and increase in the MFI, indicating that degradation occurred during processing. DSC thermograms of the blends revealed that the components in the blends were not miscible. Multiple processing of the blends did not significantly affect the elastic modulus of the materials, but affected the elongation at break. The results indicated that multiple processing of the PLA/HDPE blend caused increased dispersion and thus increased elongation at break, while the dominating mechanism in the PLA/PC blend was degradation that caused a decrease in elongation at break. Post-consumer recycling of the PLA/PC blend was simulated and the results clearly showed that ageing corresponding to one year of use caused a significant degradation of PLA. Pure PLA was severely degraded after only one ageing cycle. Although the PLA/PC blend showed some improved mechanical properties and resistance to degradation compared with pure PLA, one ageing cycle still caused a severe degradation of the PLA and even the PC was degraded as indicated by the formation of small amounts of bisphenol A.

  • 34.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Gevert, Thomas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Determination of potential for recycling of polymeric products found in buildings from the 1960s and 70`s1999Konferensbidrag (Övrigt vetenskapligt)
  • 35.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Gevert, Thomas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Determination of potential for recycling of polymeric products found in buildings from the 1960s and 70s - a case study1999Ingår i: International journal of low energy and sustainable buildings. http://www.ce.kth.se/bim/leas/journal.htm, Vol. 1Artikel i tidskrift (Övrigt vetenskapligt)
  • 36.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Gevert, Thomas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Effects of repeated extrusion on properties and durability of rigid PVC2001Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 73, nr 1, s. 93-99Artikel i tidskrift (Övrigt vetenskapligt)
  • 37.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Jakubowicz, Ignacy
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Gevert, Thomas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Effects of repeated Extrusion on the Properties and Durability of Rigid PVC2000Konferensbidrag (Övrigt vetenskapligt)
  • 38.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Sällström, Jan H
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    IMPROVED MAINTENANCE STRATEGIES FOR DISTRICT HEATING PIPE-LINES2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The main objective of this work was to establish factsand tools, which could help us to obtain and predictpresent and future technical status of pre-insulatedbonded district heating pipes in operation. In order tosimulate ageing of polyurethane (PUR) insulation anaccelerated thermal ageing method was used.Accelerated ageing was performed by applying threedifferent elevated temperatures to the service pipes.The effect of the diffusion of oxygen through the casingwas examined by ageing district heating pipes with twodifferent thicknesses of the casing pipes.The evaluation of the technical status of the pipes afterartificial or natural ageing was done by measuring theshear strength (adhesion) between the PUR foam andthe steel service pipe. The tangential shear strengthtest method was mainly used for evaluation of thestatus of the pipes. The SP plug test method, which isa cheaper and more practical method in the field, wasalso used, and the results were compared with thosefrom the tangential shear strength test method.In the framework for improved maintenance strategies,the failure mechanism was considered as loss ofadhesion between polyurethane and the service pipe.The deterioration of the adhesion was assumed to be athermo-oxidative process governed by an Arrheniusrelationship. A model of how the development of faultsrelated to adhesion and costs of heat losses in a districtheating distribution network was sketched.

  • 39.
    Yarahmadi, Nazdaneh
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Sällström, JH
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Improved maintenance strategies for district heating pipe lines2014Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The main objective of this work was to establish factsand tools, which could help us to obtain and predictpresent and future technical status of pre-insulatedbonded district heating pipes in operation. In order tosimulate ageing of polyurethane (PUR) insulation anaccelerated thermal ageing method was used.Accelerated ageing was performed by applying threedifferent elevated temperatures to the service pipes.The effect of the diffusion of oxygen through the casingwas examined by ageing district heating pipes with twodifferent thicknesses of the casing pipes.The evaluation of the technical status of the pipes afterartificial or natural ageing was done by measuring theshear strength (adhesion) between the PUR foam andthe steel service pipe. The tangential shear strengthtest method was mainly used for evaluation of thestatus of the pipes. The SP plug test method, which isa cheaper and more practical method in the field, wasalso used, and the results were compared with thosefrom the tangential shear strength test method.In the framework for improved maintenance strategies,the failure mechanism was considered as loss ofadhesion between polyurethane and the service pipe.The deterioration of the adhesion was assumed to be athermo-oxidative process governed by an Arrheniusrelationship. A model of how the development of faultsrelated to adhesion and costs of heat losses in a districtheating distribution network was sketched.

  • 40.
    Yarahmadi, Nazdaneh
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Vega, Alberto
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Jakubowicz, Ignacy
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Kemi och material.
    Accelerated ageing and degradation characteristics of rigidpolyurethane foam2017Ingår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 138, s. 192-200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The urgent need for revision of the normative test method (EN 253) for the lifetime prediction of district

    heating pipes requires a better understanding of the failure mechanisms involved. Therefore, various

    methods were used to study thermal degradation characteristics of rigid polyurethane (PUR) foam in

    both air and nitrogen atmosphere. Accelerated ageing in nitrogen caused insigni

    ficant changes, whereas

    ageing in air caused signi

    ficant changes in weight, dimensions, chemical structure and cell gas composition,

    indicating importance of the thermo-oxidative type of degradation. A clear indication of the

    thermo-oxidative type of degradation was the formation of new carbonyl groups in PUR together with

    the loss of CH

    2 groups after ageing in air. Another result of ageing in air was the loss of pentane and

    cyclopentane, and the formation of some new volatile compounds in the cells of PUR foam. However,

    despite a large difference in degradation characteristics between the samples aged in air and in nitrogen,

    no signi

    ficant difference in the flexural strength of PUR foam was recorded during the induction stage of

    the degradation process. Furthermore, it is shown that the signi

    ficant drop in shear strength, which

    re

    flects the adhesion force between PUR foam and steel pipe, observed during the early stage of

    accelerated ageing of district heating pipes is not caused by thermo-oxidative degradation.

  • 41.
    Yarahmadi, Nazdaneh
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Vega, Alberto
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Jakubowicz, Ignacy
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Determination of essential parameters influencing service life time of polyurethane insulation in district heating pipes2017Ingår i: Energy Procedia, Elsevier Ltd , 2017, s. 320-323Konferensbidrag (Refereegranskat)
    Abstract [en]

    Pre-insulated district heating pipes (DHP) have been in use during the last forty years. Many improvements and development have been done in the system. However, life-time prediction is still an uncertain issue. This paper is a part of a bigger project with the objective to determine mechanisms related to the deterioration of the mechanical and insulation properties of pre-insulated heating pipes as a result of ageing. The focus in this project is on degradation mechanisms of the PUR material at high temperatures. In this paper some results of the two types of exposure are presented. The first type comprises a condition where the new pipes are subjected to accelerated ageing at three different temperatures. The second type comprises condition, when the PUR material itself is aged in different atmospheres in order to identify different degradation mechanisms. The chosen ageing temperatures in the first condition were 130°C, (close to the supply temperature), 150°C and 170°C, (accelerated ageing temperature in EN 253 [1]). Changes in thermal insulation and the adhesion force between the PUR and the steel pipe were evaluated using the transient plane source (TPS) technique and the SP plug method respectively. The results of ageing show that the degradation of PUR is a multi-stage process composed of a rapid change in properties followed by a plateau phase which changes later to a gradual deterioration of the properties. The results of the PUR material exposure at 150°C in air and in nitrogen showed significant differences in the degradation characteristics between the two environments as were revealed by DSC and FTIR methods. © 2017 The Authors. Published by Elsevier Ltd.

  • 42.
    Yarahmadi, Nazdaneh
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Vega, Alberto
    RISE - Research Institutes of Sweden (2017-2019), Samhällsbyggnad, Energi och cirkulär ekonomi.
    Jakubowicz, Ignacy
    RISE - Research Institutes of Sweden (2017-2019), Biovetenskap och material, Kemi och material.
    Livslängd för fjärrvärmerör: Fas 1 - Nedbrytningsmekanismer2017Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Dagens standard för prefabricerade fjärrvärmerör SS-EN253 innehåller olika testmetoder och krav där ett av de viktigaste är kravet på livslängd på minst 30 år vid en kontinuerlig driftstemperatur på 120 °C. Bestämningen av tekniska livslängden är baserad på mätningar av förändringar i skjuvhållfastheten efter accelererad termisk åldring. Den beräknade livslängden för ett fjärrvärmerör är baserad på extrapolering med hjälp av Arrhenius ekvation. Det finns en stor enighet kring uppfattningen att Arrhenius modellen inte ger en god överensstämmelse med de observerade åldringsdata och att det följaktligen saknas tillförlitliga metoder för livslängdsbestämning av fjärrvärmerör. Trots många forskningsrapporter finns det fortfarande skilda teorier om hur snabbt PUR-isoleringar bryts ner och vilka nedbrytningsmekanismer som dominerar. Syftet med det här projektet är att kartlägga de komplicerade sambanden och förstå vilka nedbrytningsprocesser som dominerar under olika betingelser och utifrån denna kunskap utveckla tillförlitliga metoder för livslängdsprediktering.

    Allt testmaterial utgjordes i denna studie av polyuretan (PUR) cellplastisolering som togs ut från nytillverkade fjärrvärmerör. Accelererad åldring genomfördes i luft och i kväveatmosfär vid 150 °C för upp till 8 veckor. Det visade sig att exponering i kväveatmosfär inte orsakar någon mätbar förändring av egenskaper. En motsvarande åldring i luft orsakar däremot stora förändringar i både dimensioner, viktförlust och färg. IR (infraröd) analys kunde också bekräfta att materialet bryts ner genom termo-oxidativa processer. Termo-oxidativ nedbrytning syns också i analyser av cellgassammansättningen. Materialet efter åldring i luft innehåller betydligt mindre halt cyklopentan samtidigt som fyra nya flyktiga ämnen kunde detekteras. Trots alla indikationer på materialets termo-oxidativa nedbrytning har böjhållfastheten inte förändrats hos materialet. Detta måste utredas vidare för att kunna förklara mekanismer bakom resultatet.

    Förutom beständighetsstudier av PUR materialet genomfördes långtidsåldring av fjärrvärmerör vid olika temperaturer. Resultaten av skjuvhållfasthet mätningar indikerar att det åtminstone finns tre olika faser i nedbrytningsprocessen. Initialt sjunker hållfastheten troligen på grund av fysikaliska effekter orsakade av de höga temperaturerna. Därefter ökar skjuvhållfastheten troligen beroende på sidoreaktioner och fortsatt tvärbindning. Det tredje steget är en termo-oxidativ nedbrytning som såsmåningom leder till förlust av vidhäftningen. Även värmeledningsförmågan ökar betydligt som ett resultat av nedbrytningsprocesser. Det finns behov av ytterligare forskning för att kunna föreslå en ny modell för livslängdsberäkningar baserade på experimentella resultat.

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