The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Qiang Zhang - One of the best experts on this subject based on the ideXlab platform.
-
preparation and characterization of novel melamine modified poly Urea Formaldehyde self repairing microcapsules
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010Co-Authors: Xiaomei Tong, Mingzheng Yang, Ting Zhang, Qiang ZhangAbstract:Abstract Microcapsules with adequate performance are required for self-healing materials. Novel self-repairing microcapsules with better heat resistance and water resistance were prepared by introducing melamine to Urea–Formaldehyde resin as wall material. The as-synthesized microcapsules were studied by various characterizations techniques, including scanning electron microscope (SEM), optical microscope (OM), particle size analyzer (PSA), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angle meter. Spherical poly(Urea–Formaldehyde) microcapsules (mean size: 96 μm) and melamine modified poly(Urea–Formaldehyde) microcapsules (mean size: 46 μm, wall thickness: ∼3 μm) were obtained when the amount of melamine was 6–8 wt% and the amount of core materials was 75 wt%. After modified by melamine, the water-resistance of microcapsule is improved and contact angle increases from 43° to 50°. The heat resistance, solvent resistance, acid resistance and alkali resistance are improved because of triazine ring in melamine, which resulting in long storage time for microcapsule at room temperature.
Michael R. Kessler - One of the best experts on this subject based on the ideXlab platform.
-
In situpoly(Urea-Formaldehyde) microencapsulation of dicyclopentadiene
Journal of Microencapsulation, 2020Co-Authors: Eric Brown, Michael R. Kessler, Nancy R. Sottos, Scott R. WhiteAbstract:Microencapsulated healing agents that possess adequate strength, long shelf-life and excellent bonding to the host material are required for self-healing materials. Urea-Formaldehyde microcapsules containing dicyclopentadiene were prepared by in situ polymerization in an oil-in-water emulsion that meet these requirements for self-healing epoxy. Microcapsules of 10–1000 μm in diameter were produced by appropriate selection of agitation rate in the range of 200–2000 rpm. A linear relation exists between log(mean diameter) and log(agitation rate). Surface morphology and shell wall thickness were investigated by optical and electron microscopy. Microcapsules are composed of a smooth 160–220 nm inner membrane and a rough, porous outer surface of agglomerated Urea-Formaldehyde nanoparticles. Surface morphology is influenced by pH of the reacting emulsion and interfacial surface area at the core-water interface. High yields (80–90%) of a free flowing powder of spherical microcapsules were produced with a fill co...
-
synthesis and characterization of melamine Urea Formaldehyde microcapsules containing enb based self healing agents
Macromolecular Materials and Engineering, 2009Co-Authors: Xia Sheng, Michael R. KesslerAbstract:Microcapsules for self-healing applications were produced with a melamine-Urea-Formaldehyde (MUF) polymer shell containing two different healing agent candidates, 5-ethylidene-2-norbornene (ENB) and ENB with 10 wt.-% of a norbornene-based crosslinking agent (CL), by in situ polymerization in an oil-in-water emulsion. Relatively neat outer surfaces with minor roughness were observed on the MUF microcapsules under optical and scanning electron microscopy. Shell thickness of the capsules ranged from 700 to 900 nm. Particle size analysis of the microcapsules showed narrow size distributions with a mean diameter of 113 μm for ENB-filled and 122 μm for ENB + CL-filled microcapsules at an agitation rate of 500 rpm. The microcapsules were found to be thermally stable up to 300 °C and exhibited a 10 to 15% weight loss when isothermally held at 150 °C for 2 h from thermogravimetric analysis. Overall, these MUF microcapsules exhibited superior properties compared to the Urea-Formaldehyde (UF) microcapsules used extensively for self-healing composites to date. In addition, the manufacturing process of MUF microcapsules is much simpler than those made from UF. Additional advantages of MUF microcapsules for self-healing composites are discussed.
-
in situ poly Urea Formaldehyde microencapsulation of dicyclopentadiene
Journal of Microencapsulation, 2003Co-Authors: E N Brown, Michael R. Kessler, Nancy R. Sottos, Scott R. WhiteAbstract:Microencapsulated healing agents that possess adequate strength, long shelf-life and excellent bonding to the host material are required for self-healing materials. Urea-Formaldehyde microcapsules containing dicyclopentadiene were prepared by in situ polymerization in an oil-in-water emulsion that meet these requirements for self-healing epoxy. Microcapsules of 10–1000 μm in diameter were produced by appropriate selection of agitation rate in the range of 200–2000 rpm. A linear relation exists between log(mean diameter) and log(agitation rate). Surface morphology and shell wall thickness were investigated by optical and electron microscopy. Microcapsules are composed of a smooth 160–220 nm inner membrane and a rough, porous outer surface of agglomerated Urea-Formaldehyde nanoparticles. Surface morphology is influenced by pH of the reacting emulsion and interfacial surface area at the core-water interface. High yields (80–90%) of a free flowing powder of spherical microcapsules were produced with a fill co...
Jianbo Qu - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis of Wood Lignin-Urea-Formaldehyde Resin Adhesive
Advanced Materials Research, 2012Co-Authors: Zhe Wang, Jianbo QuAbstract:Lignin-Urea-Formaldehyde resin adhesive was synthesized with alkali lignin from gramineae waste pulping liquor. Alkali lignin was purified and hydroxymethylated with HCHO and then crosslinked with Urea-Formaldehyde resin, polyvinyl alcohol and melamine. Results showed that lignin content in purified alkali lignin was 86.91%, both binding strength and free HCHO content of Urea-Formaldehyde resin synthesized from hydroxymethylated lignin reached the optimum value. The proper lignin amount for preparing resin was 30%, and the binding strength at this condition was 4.56MPa, and free Formaldehyde content was 0.049%.
-
Synthesis of Wood Lignin-Urea-Formaldehyde Resin Adhesive
Advanced Materials Research, 2012Co-Authors: Zhe Wang, Jingwen Xue, Jianbo Qu, Wenxia LiuAbstract:Lignin-Urea-Formaldehyde resin adhesive was synthesized with alkali lignin from gramineae waste pulping liquor. Alkali lignin was purified and hydroxymethylated with HCHO and then crosslinked with Urea-Formaldehyde resin, polyvinyl alc. and melamine. Results showed that lignin content in purified alkali lignin was 86.91%, both binding strength and free HCHO content of Urea-Formaldehyde resin synthesized from hydroxymethylated lignin reached the optimum value. The proper lignin amt. for prepg. resin was 30%, and the binding strength at this condition was 4.56MPa, and free Formaldehyde content was 0.049%. [on SciFinder(R)]
Zhe Wang - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis of Wood Lignin-Urea-Formaldehyde Resin Adhesive
Advanced Materials Research, 2012Co-Authors: Zhe Wang, Jianbo QuAbstract:Lignin-Urea-Formaldehyde resin adhesive was synthesized with alkali lignin from gramineae waste pulping liquor. Alkali lignin was purified and hydroxymethylated with HCHO and then crosslinked with Urea-Formaldehyde resin, polyvinyl alcohol and melamine. Results showed that lignin content in purified alkali lignin was 86.91%, both binding strength and free HCHO content of Urea-Formaldehyde resin synthesized from hydroxymethylated lignin reached the optimum value. The proper lignin amount for preparing resin was 30%, and the binding strength at this condition was 4.56MPa, and free Formaldehyde content was 0.049%.
-
Synthesis of Wood Lignin-Urea-Formaldehyde Resin Adhesive
Advanced Materials Research, 2012Co-Authors: Zhe Wang, Jingwen Xue, Jianbo Qu, Wenxia LiuAbstract:Lignin-Urea-Formaldehyde resin adhesive was synthesized with alkali lignin from gramineae waste pulping liquor. Alkali lignin was purified and hydroxymethylated with HCHO and then crosslinked with Urea-Formaldehyde resin, polyvinyl alc. and melamine. Results showed that lignin content in purified alkali lignin was 86.91%, both binding strength and free HCHO content of Urea-Formaldehyde resin synthesized from hydroxymethylated lignin reached the optimum value. The proper lignin amt. for prepg. resin was 30%, and the binding strength at this condition was 4.56MPa, and free Formaldehyde content was 0.049%. [on SciFinder(R)]
Xiaomei Tong - One of the best experts on this subject based on the ideXlab platform.
-
preparation and characterization of novel melamine modified poly Urea Formaldehyde self repairing microcapsules
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2010Co-Authors: Xiaomei Tong, Mingzheng Yang, Ting Zhang, Qiang ZhangAbstract:Abstract Microcapsules with adequate performance are required for self-healing materials. Novel self-repairing microcapsules with better heat resistance and water resistance were prepared by introducing melamine to Urea–Formaldehyde resin as wall material. The as-synthesized microcapsules were studied by various characterizations techniques, including scanning electron microscope (SEM), optical microscope (OM), particle size analyzer (PSA), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angle meter. Spherical poly(Urea–Formaldehyde) microcapsules (mean size: 96 μm) and melamine modified poly(Urea–Formaldehyde) microcapsules (mean size: 46 μm, wall thickness: ∼3 μm) were obtained when the amount of melamine was 6–8 wt% and the amount of core materials was 75 wt%. After modified by melamine, the water-resistance of microcapsule is improved and contact angle increases from 43° to 50°. The heat resistance, solvent resistance, acid resistance and alkali resistance are improved because of triazine ring in melamine, which resulting in long storage time for microcapsule at room temperature.
