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Publications (8 of 8) Show all publications
Akhlaghi, S., Pourrahimi, A. M., Hedenqvist, M., Sjöstedt, C., Bellander, M. & Gedde, U. (2016). Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils. Polymer degradation and stability, 123, 69-79
Open this publication in new window or tab >>Degradation of carbon-black-filled acrylonitrile butadiene rubber in alternative fuels: Transesterified and hydrotreated vegetable oils
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2016 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 123, p. 69-79Article in journal (Refereed) Published
Abstract [en]

The deterioration of acrylonitrile butadiene rubber (NBR), a common sealing material in automobile fuel systems, when exposed to rapeseed biodiesel and hydrotreated vegetable oil (HVO) was studied. The fuel sorption was hindered in HVO-exposed rubber by the steric constraints of bulky HVO molecules, but it was promoted in biodiesel-exposed rubber by fuel-driven cavitation in the NBR and by the increase in diffusivity of biodiesel after oxidation. The absence of a tan δ peak of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was made possible in biodiesel-aged rubber by the detachment of bound rubber from particle surfaces. The HVO-exposed NBR showed a small decrease in strain-at-break due to the migration of plasticizer from the rubber, and a small increase in the Young’s modulus due to oxidative crosslinking. A drastic decrease in extensibility and Payne-effect amplitude of NBR on exposure to biodiesel was explained as being due to the damage caused by biodiesel to the continuous network of bound rubber-carbon black. A decrease in the ZnO crystal size with increasing exposure time suggested that the particles are gradually dissolved in the acidic components of oxidized biodiesel. The Zn2+ cations released from the dissolution of ZnO particles in biodiesel promoted the hydrolysis of the nitrile groups of NBR.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Acrylonitrile butadiene rubber, Biodiesel, Bound rubber degradation, HVO
National Category
Other Chemistry Topics Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-181471 (URN)10.1016/j.polymdegradstab.2015.11.019 (DOI)000368204100007 ()2-s2.0-84949575368 (Scopus ID)
Note

QC 20160202

Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2017-11-30Bibliographically approved
Ghorbani, F. M., Kaffashi, B., Shokrollahi, P., Akhlaghi, S. & Hedenqvist, M. S. (2016). Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(Caprolactone)/chitosan blends. Materials science & engineering. C, biomimetic materials, sensors and systems, 59, 980-989
Open this publication in new window or tab >>Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(Caprolactone)/chitosan blends
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2016 (English)In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 59, p. 980-989Article in journal (Refereed) Published
Abstract [en]

The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zeiler fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Poly(caprolactone), Chitosan, Hydroxyapatite nano-particles, Morphology, Rheology
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-180584 (URN)10.1016/j.msec.2015.10.076 (DOI)000367107400115 ()2-s2.0-84946887862 (Scopus ID)
Note

QC 20160121

Available from: 2016-01-21 Created: 2016-01-19 Last updated: 2017-11-30Bibliographically approved
Akhlaghi, S., Hedenqvist, M. S., Brana, M. T., Bellander, M. & Gedde, U. W. (2015). Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel. Polymer degradation and stability, 111, 211-222
Open this publication in new window or tab >>Deterioration of acrylonitrile butadiene rubber in rapeseed biodiesel
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2015 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 111, p. 211-222Article in journal (Refereed) Published
Abstract [en]

The deterioration of acrylonitrile butadiene rubber (NBR) exposed to rapeseed biodiesel at 90 degrees C was studied. The oxidation of biodiesel and NBR during ageing was monitored by H-1 NMR and infrared spectroscopy, HPLC and titration methods. The oxidation of biodiesel was impeded in the presence of NBR, but promoted in biodiesel-exposed rubber. This was explained as being due to the migration of stabilizer from the rubber to biodiesel, the diffusion of dissolved oxygen from biodiesel into NBR and the absorption of oxidation precursors of biodiesel by the rubber. The resemblance between the anomalous sorption kinetics of biodiesel in NBR and the equilibrium benzene uptake by the aged rubbers revealed that biodiesel caused a network defect in NBR, resulting in a gradual increase in the equilibrium swelling. The cleavage of crosslinks was implausible since the Young's modulus of the rubber at low strains, disregarding an initial decrease, increased with increasing exposure time. The appearance of 'naked' carbon black particles in the scanning electron micrographs of the aged rubbers and a drastic decrease in the strain-at-break of NBR after exposure to biodiesel suggests that internal cavitation was caused by the attack of biodiesel on the acrylonitrile units of NBR.

Keywords
Biodiesel, Acrylonitrile butadiene rubber, Oxidation, Degradation mechanism
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-161639 (URN)10.1016/j.polymdegradstab.2014.11.012 (DOI)000348949000025 ()2-s2.0-84919779987 (Scopus ID)
Note

QC 20150317

Available from: 2015-03-17 Created: 2015-03-13 Last updated: 2017-12-04Bibliographically approved
Akhlaghi, S., Gedde, U. W., Hedenqvist, M. S., Brana, M. T. C. & Bellander, M. (2015). Deterioration of automotive rubbers in liquid biofuels: A review. Renewable & sustainable energy reviews, 43, 1238-1248
Open this publication in new window or tab >>Deterioration of automotive rubbers in liquid biofuels: A review
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2015 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, p. 1238-1248Article, review/survey (Refereed) Published
Abstract [en]

Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.

Keywords
Biofuels, Rubbers, Automobile fuel system, Degradation
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-161100 (URN)10.1016/j.rser.2014.11.096 (DOI)000348880600097 ()2-s2.0-84919799253 (Scopus ID)
Funder
Swedish Energy Agency, 2011-006737
Note

QC 20150318

Available from: 2015-03-18 Created: 2015-03-09 Last updated: 2017-12-04Bibliographically approved
Arasteh, R., Naderi, A., Kaptan, N., Maleknia, L., Akhlaghi, S. & Nazockdast, H. (2014). Effects of Fiber Spinning on the Morphology, Rheology, Thermal, and Mechanical Properties of Poly(trimethylene terephthalate)/Poly(ethylene terephthalate) Blends. Advances in Polymer Technology, 33(S1), 21443
Open this publication in new window or tab >>Effects of Fiber Spinning on the Morphology, Rheology, Thermal, and Mechanical Properties of Poly(trimethylene terephthalate)/Poly(ethylene terephthalate) Blends
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2014 (English)In: Advances in Polymer Technology, ISSN 0730-6679, E-ISSN 1098-2329, Vol. 33, no S1, p. 21443-Article in journal (Refereed) Published
Abstract [en]

The morphology, thermal behavior, rheological, and mechanical properties of poly(trimethylene terephthalate) (PTT)/poly(ethylene terephthalate) (PET) blend fibers were investigated. The scanning electron microscopy studies revealed the formation of a microfibrillar network of the PET within the PTT matrix after the fiber-spinning process. Differential scanning calorimetry results demonstrated that although the thermal characteristics of the amorphous phase were unaffected by the fiber-spinning process, the melting and crystallization behavior of the blends was altered by the elongation flow imposed during the melt spinning. The viscoelastic behavior of the PTT/PET blends was also studied by a steady shear rate and dynamic sweep rheological experiments before and after the spinning process. The induced morphology and crystallization reordering resulting from the fibrillation process are shown to have a remarkable effect on the complex viscosity profile of the PTT/PET fibers, particularly in the blend containing 30 wt% PET. The mechanical testing showed that tenacity and Young's modulus of the PTT fibers increased with the addition of PET up to 30 wt%.

Keywords
Blending, Fibers, Fibrillar network, Polyesters, Rheology
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-159382 (URN)10.1002/adv.21443 (DOI)000346980600007 ()2-s2.0-84920160792 (Scopus ID)
Note

QC 20150203

Available from: 2015-02-03 Created: 2015-01-29 Last updated: 2017-12-05Bibliographically approved
Amanizadeh, F., Akhlaghi, S., Mobarakeh, H. S., Gedde, U. W. & Hedenqvist, M. S. (2014). Starve fed emulsion copolymerization of vinyl acetate and 1-hexene at ambient pressure. Polymer international, 63(10), 1850-1855
Open this publication in new window or tab >>Starve fed emulsion copolymerization of vinyl acetate and 1-hexene at ambient pressure
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2014 (English)In: Polymer international, ISSN 0959-8103, E-ISSN 1097-0126, Vol. 63, no 10, p. 1850-1855Article in journal (Refereed) Published
Abstract [en]

A novel emulsion copolymer of vinyl acetate (VAc) and 1-hexene was synthesized at ambient pressure. The feeding technique, initiation system and reaction time of the copolymerization were optimized based on molecular characteristics such as the weight contribution of 1-hexene in the copolymer chains and glass transition temperature (T-g) as well as on bulk properties like minimum film-formation temperature (MFFT) and solid content. According to nuclear magnetic resonance spectroscopy and differential scanning calorimetry results, the combination of starve feeding and redox initiation, within a reaction time of 4h, effectively led to the copolymerization at ambient pressure between highly reactive polar VAc monomers and non-polar 1-hexene monomers of low reactivity. The copolymer showed a lower T-g and MFFT, and a reasonable solid content compared to the poly(vinyl acetate) (PVAc) homopolymer. The consumption rate, hydrolysis of acetate groups and chain transfer reactions during the polymerization were followed using infrared spectroscopy. Based on the results, the undesirable reactions between the VAc blocks were hindered by the neighbouring 1-hexene molecules. Tensile testing revealed an improvement in the toughness and elongation at break of VAc-1-hexene films compared to PVAc films.

Keywords
emulsion copolymerization, vinyl acetate, 1-hexene, ambient pressure
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-153844 (URN)10.1002/pi.4709 (DOI)000341810400013 ()2-s2.0-84908234866 (Scopus ID)
Note

QC 20141013

Available from: 2014-10-13 Created: 2014-10-09 Last updated: 2017-12-05Bibliographically approved
Kaptan, N., Jafari, S. H., Mazinani, S., Akhlaghi, S., Fazilat, H., Gedde, U. W., . . . Monfared, A. (2014). Thermal Behavior and Degradation Kinetics of Compatibilized Metallocene-Linear Low Density Polyethylene/Nanoclay Nanocomposites. Polymer-plastics technology and engineering (Softcover ed.), 53(9), 890-902
Open this publication in new window or tab >>Thermal Behavior and Degradation Kinetics of Compatibilized Metallocene-Linear Low Density Polyethylene/Nanoclay Nanocomposites
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2014 (English)In: Polymer-plastics technology and engineering (Softcover ed.), ISSN 0360-2559, E-ISSN 1525-6111, Vol. 53, no 9, p. 890-902Article in journal (Refereed) Published
Abstract [en]

Morphology, thermal degradation and kinetics of metallocene-linear-low-density polyethylene (m-LLDPE)/m-LLDPE-graft-maleic anhydride (m-LLDPE-g-MA)/nanoclay nanocomposites were compared with m-LLDPE/nanoclay, m-LLDPE-g-MA/nanoclay and m-LLDPE/m-LLDPE-g-MA systems. X-ray diffraction measurements revealed intercalated and "highly intercalated'' morphologies for the nanocomposites. Thermogravimetric analysis demonstrated that although thermal degradation of m-LLDPE systems were delayed upon the inclusion of nanoclay in air, an inverse effect was perceived for the nanoclay under inert atmosphere. This conclusion was supported by kinetic analysis in terms of reaction order and activation energy. The results obtained from kinetics models also put forward the contribution of m-LLDPE-g-MA, as a compatibilizer, to the thermal stability enhancement through intermolecular cross-linking augmentation.

Keywords
Metallocene-linear low-density polyethylene, Nanocomposites, Thermal degradation kinetics, Thermal stability
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-148198 (URN)10.1080/03602559.2014.886055 (DOI)000337591700003 ()2-s2.0-84901608589 (Scopus ID)
Note

QC 20140805

Available from: 2014-08-05 Created: 2014-08-04 Last updated: 2017-12-05Bibliographically approved
Arabasadi, Z., Khorasani, M., Akhlaghi, S., Fazilat, H., Gedde, U. W., Hedenqvist, M. S. & Shiri, M. E. (2013). Prediction and optimization of fireproofing properties of intumescent flame retardant coatings using artificial intelligence techniques. Fire safety journal, 61, 193-199
Open this publication in new window or tab >>Prediction and optimization of fireproofing properties of intumescent flame retardant coatings using artificial intelligence techniques
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2013 (English)In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 61, p. 193-199Article in journal (Refereed) Published
Abstract [en]

A multi-structured architecture of artificial intelligence techniques including artificial neural network (ANN), adaptive neuro-fuzzy-inference-system (ANFIS) and genetic algorithm (GA) were developed to predict and optimize the fireproofing properties of a model intumescent flame retardant coating including ammonium polyphosphate, pentaerythritol, melamine, thermoplastic acrylic resin and liquid hydrocarbon resin. By implementing ANN on heat insulation results of coating samples, prepared based on a L16 orthogonal array, mean fireproofing time (MFPT) values were properly predicted. The predicted data were then proved to be valid through performing closeness examinations on fuzzy inference systems results regarding their experimental counterparts. However, the possible deviations tapped into phenomena like foam detachment and char cracking were alleviated by ANFIS modeling embedded with pertinent fuzzy rules based on the sole and associative practical role of used additives. The contribution of each intumescent coating component on the formulation with optimized fireproofing behavior was then explored using GA modeling. A similar optimization procedure was also conducted using conventional Taguchi experimental design but the GA based optimized intumescent coating was found to exhibit higher MFPT value than that suggested by the Taguchi method.

Keywords
Artificial intelligence techniques, Flame retardant, Genetic algorithm, Intumescent coating
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-133152 (URN)10.1016/j.firesaf.2013.09.006 (DOI)000327365700020 ()2-s2.0-84884824213 (Scopus ID)
Note

QC 20131029

Available from: 2013-10-29 Created: 2013-10-28 Last updated: 2017-12-06Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7348-0004

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