| 1. |
- Abolhasani, Hasanali, et al.
(författare)
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Development of self-healable acrylic water-based environmental-friendly coating as an alternative to chromates coatings
- 2023
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Ingår i: Progress in organic coatings. - : Elsevier B.V.. - 0300-9440 .- 1873-331X. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- In this study, different coating systems, including solvent-based epoxy and water-based acrylic resins, were evaluated for their potential as an alternative to chromate coatings in order to avoid Cr(VI) toxic hazards. The resins were used as either pigment-free coatings or were formulated with 20-wt% zinc/aluminum pigments. The coatings were subsequently applied on galvanized ST12 steel plates and their corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) evaluations. The effect of the binder and pigment type on the impact resistance of two different polymeric coatings was also evaluated. The results of impact tests revealed completely peeled film from the substrate for epoxy coatings. However, under the same experimental conditions, very few small cracks were created in water-based acrylic coatings for both pigmented and pigment-free cases. In addition, some other parameters such as drying time and coating cost were taken into account to select a good alternative to chromate coatings. The results of this work can facilitate the introduction of an inexpensive environmentally friendly acrylic coating as a promising self-healing alternative to chromate coating.
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| 2. |
- Anerao, Prashant, et al.
(författare)
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Biochar reinforced PLA composite for fused deposition modelling (FDM): A parametric study on mechanical performance
- 2023
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Ingår i: Composites Part C: Open Access. - : Elsevier B.V.. - 2666-6820. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Rice husk biochar was added to polylactic acid (PLA) to create a biocomposite filament suitable for the extrusion-based 3D printing process of fused deposition modelling (FDM). Taguchi L16 was used for experiment design, and the significance of process parameters was determined using variance analysis (ANOVA). For a 0.3-mm layer thickness, the addition of 5 wt.% biochar resulted in ultimate tensile strength and a modulus of elasticity of 36 MPa and 1103 MPa, respectively. The addition of biochar had a negative influence on flexural strength. The maximum flexural modulus was obtained with 3 % biochar, 100 % infill density, and 0.1 mm layer thickness. Particularly, 1 % biochar resulted in a considerable increase in impact strength, while a subsequent rise in biochar resulted in a decrease, probably due to the agglomeration effect. For 3D printed neat PLA, the average tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength observed were 19 MPa, 550 MPa, 54 MPa, 1981 MPa, and 25 KJ/m2, respectively. Additionally, considering the output of each test, a multicriteria decision-making model, namely, TOPSIS, has been utilized for ranking the mechanical performance. In order to optimise the mechanical properties of three-dimensional printed objects, the study suggests a layer thickness of 0.2 mm, an infill density of 100 %, and raster angle of 0° as the FDM process parameters.
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| 3. |
- Das, Oisik, et al.
(författare)
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Functionalised biochar in biocomposites: The effect of fire retardants, bioplastics and processing methods
- 2023
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Ingår i: Composites Part C: Open Access. - : Elsevier. - 2666-6820. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Fire retardants, although can impart fire-safety in polymeric composites, are detrimental to the mechanical properties. Biochar can be used, in conjunction with fire retardants, to create a balance between fire-safety and mechanical performance. It is possible to thermally dope fire retardants into the pores of biochar to make it functionalised. Thus, the current work is intended in identifying a composite having the combination of the most desirable fire retardant, bioplastic, and a suitable processing method. A comparison was made between two fire retardants (lanosol and ammonium polyphosphate), bioplastics (wheat gluten and polyamide 11), and composite processing methods (compression and injection moulding). It was found that wheat gluten containing ammonium polyphosphate-doped biochar made by compression moulding had the best fire-safety properties with the lowest peak heat release rate (186 kW/m2), the highest fire performance index (0.6 m2s/kW), and the lowest fire growth index (1.6 kW/ms) with acceptable mechanical properties compared to the corresponding neat bioplastic. Thus, for gluten-based polymers, the use of ammonium polyphosphate thermally doped into biochar processed by compression moulding is recommended to both simultaneously improve fire-safety and conserve the mechanical strength of the resulting biocomposites.
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| 4. |
- Edwin Samson, Ponnusamy, et al.
(författare)
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The effect of fiber orientation and stacking sequence on carbon/E-glass/epoxy intraply hybrid composites under dynamic loading conditions
- 2023
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Ingår i: Polymers for Advanced Technologies. - : John Wiley and Sons Ltd. - 1042-7147 .- 1099-1581. ; 34:1, s. 363-376
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the dynamic mechanical properties of hybrid intraply carbon/E-glass epoxy composites with different orientations and stacking sequences under different loading conditions with increasing temperature. A neat epoxy and five various hybrid composites such as Carbon (0°)/E-glass (90°), Carbon (45°)/E-glass (135°), Carbon (90°)/E-glass (0°), Carbon/E-glass (alternating layer), and Carbon/E-glass (alternating layer 45°) were manufactured. Three-point bending test and dynamic mechanical test were conducted to understand the flexural modulus and viscoelastic behavior (storage modulus, loss modulus, and loss tangent) of the composites. Dynamic mechanical test was performed with the dual cantilever method, at four different frequencies (1, 5, 10, and 20 Hz) and temperatures ranging from 30 to 150°C. The experimental results of storage modulus, loss modulus, and loss tangents were compared with the theoretical findings of neat epoxy and various hybrid composites. The glass transition temperature (Tg) increased with the increase in frequency. A linear fit of the natural log of frequency to the inverse of absolute temperature was plotted in the activation energy estimation. The interphase damping (tanδi) between plies and the strength indicator (Si) of the hybrid composites were estimated. It was observed that the neat epoxy had more insufficient storage and loss modulus and a high loss tangent at all the frequencies whereas hybrid composites had high storage and loss modulus and a low loss tangent for all the frequencies. Compared with other hybrid composites, Carbon (90°)/E-glass (0°) had higher strength and activation energy. The result of reinforcement of hybrid fiber in neat epoxy significantly increases the material's strength and stability at higher temperatures whereas decreasing free molecular movement.
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| 5. |
- Gao, Xu, et al.
(författare)
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Thermal History Effects on Decomposition Behavior and Pyrolysis Mechanism of Cellulose Nitrate
- 2023
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Konferensbidrag (refereegranskat)abstract
- Nitrocellulose is an important kind of energetic material produced by replacing hydroxyl of cellulose molecule to nitro, which has a wide application range in social life. During transportation and storage, inevitably the quality of the nitrocellulose will be affected due to external ambient heating. In this study, two kinds of NC samples, original and heated ones, were used as research objects and taken into DSC experiments under several constant heating rates to explore thermal history effects on its decomposition and combustion behavior. A series of calculation methods based on model fitting were main ways for research, so were model free methods. Numerical results by model fitting method showed that decomposition reaction of NC follows n-th reaction model. The comparison between experimental results of two kinds of samples claimed that thermal history had positive influence on heat flow, and increased the reaction order of decomposition process, and decreased the characteristic temperatures. So the thermal history made the decomposition reaction more difficult to take place and more stable. This study is obviously meaningful for the research of thermal pyrolysis process of NC after thermal history.
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| 6. |
- Ghomi, Erfan Rezvani, et al.
(författare)
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Synthesis of TiO2 nanogel composite for highly efficient self-healing epoxy coating
- 2023
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Ingår i: Journal of Advanced Research. - : Elsevier. - 2090-1232 .- 2090-1224. ; 43, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionOrganic coatings are the most effective and facile methods of protecting steel against corrosion, which shields it from direct contact with oxygen and moisture. However, they are inherently defective and susceptible to damage, which allows the penetration of the corrosive media into the underlying substrates. Self-healing coatings were developed to address this shortcoming.ObjectiveThe current research aims to develop a coating with superior self-healing ability via embedment of titanium dioxide (TiO2) nanogel composite (NC) in a commercial epoxy.MethodsThe TiO2 NC was prepared by efficient dispersion of TiO2 nanoparticles in copolymer gel of acrylamide (AAm) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) with the help of 3-(trimethoxysilyl) propyl methacrylate (MPS). The chemical structure, morphology, and thermal properties of the modified and functionalized nanoparticles were assessed by infrared spectroscopy, electron microscopy, X-ray diffraction, and thermogravimetric analysis, respectively. In addition, TiO2 nanoparticles, nano-TiO2 functionalized monomer (NTFM), and NTFM/AAm/AMPS in different weight percentages were incorporated into epoxy resin to prepare a self-healing coating.ResultsThe results confirmed the successful fabrication of the NC. In addition, the incorporation of 1 wt% NTFM/AAm/AMPS led to homogenous dispersion, enhanced anti-corrosive and self-healing performance with the healing efficiencies of 100% and 98%, which were determined by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods, respectively.ConclusionThe prepared NC was sensitive towards salt concentration, pH, which aids the quick reaction of the TiO2 NC to corrosive ions, once the cracks occur. In addition, this is a unique feature compared to the other self-healing mechanisms, especially, the encapsulation of healing agents, which can be effective as long as the healing agent is present.
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| 7. |
- Kohli, Isha, et al.
(författare)
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Pyrolysis of Automotive Shredder Residue (ASR): Thermogravimetry, In-Situ Synchrotron IR and Gas-Phase IR of Polymeric Components
- 2023
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Ingår i: Polymers. - : Multidisciplinary Digital Publishing Institute (MDPI). - 2073-4360. ; 15:17
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Tidskriftsartikel (refereegranskat)abstract
- This article reports the characterisation of pyrolysis of automotive shredder residue using in situ synchrotron IR, gas-phase IR, and thermal analyses to explore if the automotive shredder residue can be converted into value-added products. When heating to ~600 °C at different heating rates, thermal analyses suggested one- to two-stage pyrolysis. Transformations in the first stage, at lower temperatures, were attributed to the degradation of carbonyl, hydroxyl, or carboxyl functional stabilisers (aldehyde and ether impurities, additives, and stabilisers in the ASR). The second stage transformations, at higher temperatures, were attributed to the thermal degradation of the polymer char. Simultaneous thermal analyses and gas-phase IR spectroscopy confirmed the evolution of the gases (alkanes (CH4), CO2, and moisture). The synchrotron IR data have demonstrated that a high heating rate (such as 150 °C/min) results in an incomplete conversion of ASRs unless sufficient time is provided. The thermogravimetry data fit the linearised multistage kinetic model at different heating rates. The activation energy of reactions varied between 24.98 and 124.94 kJ/mol, indicating a surface-controlled reaction exhibiting high activation energy during the initial stages and a diffusion and mass transfer control showing lower activation energy at the final stages. The corresponding frequency factors were in the range of 3.34 × 1013–5.68 × 101 mg−1/min for different pyrolysis stages. The evolution of the functional groups decreased with an increase in the heating rate.
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| 8. |
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| 9. |
- Lin, Chia-Feng, et al.
(författare)
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High Leach-Resistant Fire-Retardant Modified Pine Wood (Pinus sylvestris L.) by In Situ Phosphorylation and Carbamylation
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:12, s. 11381-11396
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Tidskriftsartikel (refereegranskat)abstract
- The exterior application of fire-retardant (FR) timber necessitates it to have high durability because of the possibility to be exposed to rainfall. In this study, water-leaching resistance of FR wood has been imparted by grafting phosphate and carbamate groups of the water-soluble FR additives ammonium dihydrogen phosphate (ADP)/urea onto the hydroxyl groups of wood polymers via vacuum-pressure impregnation, followed by drying/heating in hot air. A darker and more reddish wood surface was observed after the modification. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, solid-state 13C cross-polarization magic-angle-spinning nuclear magnetic resonance (13C CP-MAS NMR), and direct-excitation 31P MAS NMR suggested the formation of C–O–P covalent bonds and urethane chemical bridges. Scanning electron microscopy/energy-dispersive X-ray spectrometry suggested the diffusion of ADP/urea into the cell wall. The gas evolution analyzed by thermogravimetric analysis coupled with quadrupole mass spectrometry revealed a potential grafting reaction mechanism starting with the thermal decomposition of urea. Thermal behavior showed that the FR-modified wood lowered the main decomposition temperature and promoted the formation of char residues at elevated temperatures. The FR activity was preserved even after an extensive water-leaching test, confirmed by the limiting oxygen index (LOI) and cone calorimetry. The reduction of fire hazards was achieved through the increase of the LOI to above 80%, reduction of 30% of the peak heat release rate (pHRR2), reduction of smoke production, and a longer ignition time. The modulus of elasticity of FR-modified wood increased by 40% without significantly decreasing the modulus of rupture.
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| 10. |
- Liu, Hao, et al.
(författare)
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Insights into wood species and aging effects on pyrolysis characteristics and combustion model by multi kinetics methods and model constructions
- 2023
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Ingår i: Renewable energy. - : Elsevier Ltd. - 0960-1481 .- 1879-0682. ; 206, s. 784-794
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Tidskriftsartikel (refereegranskat)abstract
- Considering the extensive application of wood materials in the construction and manufacturing, waste wood has potential of converting into new natural energy sources. In this study, cypress, pine and fir woods commonly used in China, as well as old samples for above each species (more than 200 years old) have been used to study the aging and species effects on their thermal stability and combustion models. To obtain the kinetic triplets of the pyrolysis process, all samples have been heated in a nitrogen atmosphere with heating rates of 5, 10, 15, and 20 K min−1. The kinetics parameters of pyrolysis throughout the conversion process were then calculated using isoconversional method, Coats-Redfern (CR), and masterplots methods. The reconstructed theoretical models have been then adjusted using the accommodation functions. The results of this study contribute to an increased understanding of the fire mechanism of waste woods, and implications concerning to provide scientific theoretical guidance for its feasibility as a new energy fuel more efficiently.
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