The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mohsen Jahanshahi - One of the best experts on this subject based on the ideXlab platform.
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effect of nanoparticles on the micromechanical and surface properties of poly urea formaldehyde composite microcapsules
Composites Part B-engineering, 2014Co-Authors: Ghorbanzadeh M Ahangari, Abdolhosein Fereidoon, Mohsen Jahanshahi, N SharifiAbstract:Abstract Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea–formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite shell wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the shell wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the shell wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF shell behaves as a viscoelastic–plastic material.
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effect of nanoparticles on the morphology and thermal properties of self healing poly urea formaldehyde microcapsules
Journal of Polymer Research, 2013Co-Authors: Abdolhosein Fereidoon, Ghorbanzadeh M Ahangari, Mohsen JahanshahiAbstract:The preparation of microcapsules with adequate performance is required for the fabrication of self-healing composites. Self-healing microcapsules with improved morphology as well as thermal and water resistance were prepared by introducing either single-walled carbon nanotubes (SWCNTs) or aluminum oxide nanoparticles (nano-alumina) into a urea–formaldehyde resin (which acts as the wall material). The prepared microcapsules were studied using various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy (OM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact-angle measurements. Based on comparisons with traditional poly(urea–formaldehyde) microcapsules, the modified microcapsules exhibited a smoother surface. Our results indicate that the presence of the nanoparticles did not affect the core content of the microcapsules, which was approximately 78 wt.%. The average size of the traditional microcapsules was reduced from 168 μm to 115 and 95 μm for the SWCNT- and nano-alumina-modified microcapsules, respectively. In addition, the thermal resistance of the microcapsules was improved after modifying the capsule walls. After the microcapsules had been modified with SWCNTs, the water resistance of the capsules improved, and the contact angle increased from 44° to 50°.
Haiyan Li - One of the best experts on this subject based on the ideXlab platform.
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fabrication of microcapsules containing dual functional tung oil and properties suitable for self healing and self lubricating coatings
Progress in Organic Coatings, 2018Co-Authors: Haiyan Li, Zhike Li, Huaiyuan WangAbstract:Abstract Tung oil-loaded microcapsules with the protection of Poly(urea-formaldehyde) (PUF) shells were prepared by in-situ polymerization method. Microcapsules keep the spherical shape with core content of more than 80.0 wt%. The average diameter was approximately 105 μm. Microcapsules exhibit excellent thermal stability. Dual-functional coatings were prepared by incorporating tung oil-loaded microcapsules into epoxy. Self-healing and self-lubricating function of coatings were realized by the releasing of tung oil from microcapsules under the scarp or wear condition. Tung oil has excellent film-forming property when they contact with oxygen. self-healing anti-corrosion and self-lubricating anti-wear properties were evaluated by salt-immersed corrosion tests and wear tests. Results demonstrated the coatings have an excellent corrosion resistance performance, the corrosion resistance get better as the increasing of microcapsules content. Besides, epoxy coatings demonstrated a favorable self-lubricating performance with the add of microcapsules. The friction coefficient and wear rate were the lowest at the microcapsules content of 10 wt%, there were 17.3% and 78.6% decrease respectively compared to the pure epoxy. The self-healing and self-lubricating mechanism were also discussed.
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preparation and application of polysulfone microcapsules containing tung oil in self healing and self lubricating epoxy coating
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017Co-Authors: Haiyan Li, Huaiyuan Wang, Baohui WangAbstract:Abstract Polysulfone microcapsules containing tung oil were synthesized by a solvent evaporation method. The mean diameter and wall thickness of the synthesized microcapsules were approximately 130 μm and 9 μm, respectively. High thermal stability of the microcapsules with a thermal degradation onset temperature of 350 °C was obtained. The multi-functional coating was fabricated by incorporating the microcapsules containing tung oil into an epoxy matrix. The self-healing and self-lubricating functions were evaluated by corrosion and tribology test. 10 wt% microcapsules embedded in epoxy coating offered optimum results. The microcapsules showed excellent anticorrosion performance in scratched coatings, which was attributed to the formation of a cross-linked polymer film after tung oil was released from the damaged microcapsules. The frictional coefficient and wear rate of the self-lubricating coating decreased significantly as compared to the neat epoxy. The formation of a transfer film from releasing tung oil and the entrapment of wear particles in the cavities left by the ruptured microcapsules were the major antifriction mechanism.
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Preparation and characterization of self-healing Microcapsules with poly(urea-formaldehyde) grafted epoxy functional group shell
Journal of Applied Polymer Science, 2009Co-Authors: Rongguo Wang, Haiyan Li, Xiaodong He, Honglin Hu, Wenbo LiuAbstract:Microcapsules were prepared by in situ polymerization technology with poly(urea-formaldehyde) (PUF)-grafted gamma-glycidoxypropyltrimethoxy silane (KH560) copolymer as a shell material and dicyclopentadiene (DCPD) as core materials. The aim was to improve the interfacial bond between microcapsules and epoxy matrix in composites through the epoxy functional group in KH560. The microcapsulating mechanism was discussed and the process was explained. The morphology and shell wall thickness of microcapsules were observed by using scanning electron microscopy. The size of microcapsules was measured using optical microscope and the size distribution was investigated based on data sets of at least 200 measurements. The chemical structure and thermal properties of microcapsules were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectra, and thermogravimetric analysis. Results indicted that the PUF-graft KH560 microcapsules containing DCPD can be synthesized successfully; the epoxy functional group was grafted on the wall material. The microcapsule size is in the range of 40-190 mu m with an average of 125 mu m. The wall thickness of microcapsules sample is in the range of 2-5 mu m and the core content of microcapsules is about 60%. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1501-1506, 2009
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surface modification of self healing poly urea formaldehyde microcapsules using silane coupling agent
Applied Surface Science, 2008Co-Authors: Haiyan Li, Rongguo Wang, Honglin HuAbstract:Abstract Poly(urea-formaldehyde) (PUF) microcapsules, which are used as self-healing component of fibre reinforced resin matrix composites, were prepared by in situ polymerization method. The surface of PUF microcapsules was modified by using 3-aminopropyltriethoxy silane-coupling agent (KH550), and the interfacial interactions between PUF microcapsules and KH550 was also studied. Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectra (XPS) analyses showed that the silane-coupling agent molecular binds strongly to PUF microcapsules surface. Chemical bond (Si–O–C) was formed by the reaction between Si–OH and the hydroxyl group of PUF microcapsules, also there have chemical adsorption effect in the interface simultaneously because of the existence of hydrogen bond between Si–OH and the hydroxyl group of PUF microcapsules. Scanning electronic microscopy (SEM) observation showed that a thin layer was formed on the surface of modified PUF microcapsules. Additionally, fractured surface were observed under SEM to investigate the interfacial adhesion effect between PUF microcapsules and epoxy matrix. The result indicted that the silane-coupling agent play an important role in improving the interfacial performance between microcapsules and resin matrix.
Abdolhosein Fereidoon - One of the best experts on this subject based on the ideXlab platform.
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effect of nanoparticles on the micromechanical and surface properties of poly urea formaldehyde composite microcapsules
Composites Part B-engineering, 2014Co-Authors: Ghorbanzadeh M Ahangari, Abdolhosein Fereidoon, Mohsen Jahanshahi, N SharifiAbstract:Abstract Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea–formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite shell wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the shell wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the shell wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF shell behaves as a viscoelastic–plastic material.
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effect of nanoparticles on the morphology and thermal properties of self healing poly urea formaldehyde microcapsules
Journal of Polymer Research, 2013Co-Authors: Abdolhosein Fereidoon, Ghorbanzadeh M Ahangari, Mohsen JahanshahiAbstract:The preparation of microcapsules with adequate performance is required for the fabrication of self-healing composites. Self-healing microcapsules with improved morphology as well as thermal and water resistance were prepared by introducing either single-walled carbon nanotubes (SWCNTs) or aluminum oxide nanoparticles (nano-alumina) into a urea–formaldehyde resin (which acts as the wall material). The prepared microcapsules were studied using various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy (OM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact-angle measurements. Based on comparisons with traditional poly(urea–formaldehyde) microcapsules, the modified microcapsules exhibited a smoother surface. Our results indicate that the presence of the nanoparticles did not affect the core content of the microcapsules, which was approximately 78 wt.%. The average size of the traditional microcapsules was reduced from 168 μm to 115 and 95 μm for the SWCNT- and nano-alumina-modified microcapsules, respectively. In addition, the thermal resistance of the microcapsules was improved after modifying the capsule walls. After the microcapsules had been modified with SWCNTs, the water resistance of the capsules improved, and the contact angle increased from 44° to 50°.
Guozheng Liang - One of the best experts on this subject based on the ideXlab platform.
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preparation and properties of poly urea formaldehyde microcapsules filled with epoxy resins
Materials Chemistry and Physics, 2008Co-Authors: Li Yuan, Aijuan Gu, Guozheng LiangAbstract:Abstract The poly(urea–formaldehyde) (PUF) microcapsules filled with epoxy resins have potential for self-healing or toughening polymeric composites. A series of PUF microcapsules containing epoxy resins were synthesized by selecting different process parameters including surfactant type, surfactant concentration, adjusting time for pH value and heating rate. The effects of process parameters on the size and surface morphology of microcapsules were discussed. The storage stability, solvent resistance and the mechanical strength of microcapsules were investigated. The morphology of microcapsules was observed using scanning electron microscopy (SEM) and optical microscopy (OM). The results indicate that the formation of microcapsules is affected by the surfactant type. The size of microcapsules can be controlled by the surfactant concentration. The surface morphology of microcapsules can be adjusted by the surfactant concentration, the adjusting time for pH and the heating rate. The microcapsules prepared by using surfactant sodium dodecylbenzene sulfonate (SDBS) show good storage stability, excellent solvent resistance and appropriate mechanical strength.
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synthesis and characterization of microencapsulated dicyclopentadiene with melamine formaldehyde resins
Colloid and Polymer Science, 2007Co-Authors: Li Yuan, Guozheng Liang, Jianqiang XieAbstract:Microcapsules containing healing agents have been used to develop the self-healing polymeric composites. These microcapsules must possess special properties such as appropriate strength and stability in surrounding medium. A new series of microcapsules containing dicyclopentadiene (DCPD) with melamine–formaldehyde (MF) resin as shell material were synthesized by in situ polymerization technology. These microcapsules may satisfy the requirements for self-healing polymeric composites. The chemical structure of microcapsule was identified by using Fourier transform infrared (FTIR) spectrometer. The morphology of microcapsule was observed by using optical microscope (OM) and scanning electron microscope. Size distribution and mean diameter of microcapsules were determined with OM. The thermal properties of microcapsules were investigated by using thermogravimetric analysis and differential scanning calorimetry. Additionally, the self-healing efficiency was evaluated. The results indicate that the poly(melamine–formaldehyde) (PMF) microcapsules containing DCPD have been synthesized successfully, and their mean diameters fall in the range of 65.2∼202.0 μm when the adjusting agitation rate varies from 150 to 500 rpm. Increasing the surfactant concentration can decrease the diameters of microcapsules. The prepared microcapsules are thermally stable up to 69 °C. The PMF microcapsules containing DCPD can be applied to polymeric composites to fabricate the self-healing composites.
Ghorbanzadeh M Ahangari - One of the best experts on this subject based on the ideXlab platform.
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effect of nanoparticles on the micromechanical and surface properties of poly urea formaldehyde composite microcapsules
Composites Part B-engineering, 2014Co-Authors: Ghorbanzadeh M Ahangari, Abdolhosein Fereidoon, Mohsen Jahanshahi, N SharifiAbstract:Abstract Microcapsules containing self-healing agents have been used to repair microcracks in polymeric matrices. These microcapsules must possess special properties, such as appropriate strength and stability in the surrounding matrix. Herein, poly(urea–formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. The elastic modulus and hardness of the microcapsules with and without a nanocomposite shell wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with scanning electron microscopy (SEM), optical microscope (OM), as well as atomic force microscopy (AFM). The results demonstrated significant increases in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the shell wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from the AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the shell wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF shell behaves as a viscoelastic–plastic material.
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effect of nanoparticles on the morphology and thermal properties of self healing poly urea formaldehyde microcapsules
Journal of Polymer Research, 2013Co-Authors: Abdolhosein Fereidoon, Ghorbanzadeh M Ahangari, Mohsen JahanshahiAbstract:The preparation of microcapsules with adequate performance is required for the fabrication of self-healing composites. Self-healing microcapsules with improved morphology as well as thermal and water resistance were prepared by introducing either single-walled carbon nanotubes (SWCNTs) or aluminum oxide nanoparticles (nano-alumina) into a urea–formaldehyde resin (which acts as the wall material). The prepared microcapsules were studied using various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy (OM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact-angle measurements. Based on comparisons with traditional poly(urea–formaldehyde) microcapsules, the modified microcapsules exhibited a smoother surface. Our results indicate that the presence of the nanoparticles did not affect the core content of the microcapsules, which was approximately 78 wt.%. The average size of the traditional microcapsules was reduced from 168 μm to 115 and 95 μm for the SWCNT- and nano-alumina-modified microcapsules, respectively. In addition, the thermal resistance of the microcapsules was improved after modifying the capsule walls. After the microcapsules had been modified with SWCNTs, the water resistance of the capsules improved, and the contact angle increased from 44° to 50°.
