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1. A Curing System of Benzoxazine with Amine: Reactivity, Reaction Mechanism and Material Properties | |||
SUN Jiaqin,QU Jiehao,WEI Wei,SHU Ling,LIU Xiangdong | |||
Chemistry 23 December 2014 | |||
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Abstract:Five commercially available amines: m-phenylenediamine (A1), m-xylylenediamine (A2), isophorone diamine (A3), trimethylhexamethylenediamine (A4), and 4,4'-diaminodiphenyl sulfone (A5), were examined as a nucleophilic hardener for bis-benzoxazine monomers based on aniline paired with bisphenol-A (BA-a) or bisphenol-F (BF-a). The reactivity and reaction mechanism of their reactive mixture with BA-a were investigated using FTIR and NMR spectroscopy, DSC, and HPLC techniques. It is found that BA-a cured with amines is much faster than the ring-opening polymerization of bulk BA-a upon heating at 120℃ or 150℃. The possible reaction mechanism was supported by the experimental results and includes three successive steps: (i) nucleophilic substitution at the carbon atom (O-C-N) in the oxazine ring by the amine, (ii) thermal decomposition of the resulting aminomethanaminium structure, and (iii) electrophilic addition of the newly formed iminium ion with the aromatic ring to form stable aminomethylphenol structures. These findings are helpful to improve thermosetting resins in terms of their chemical structure, material properties, and processability. | |||
TO cite this article:SUN Jiaqin,QU Jiehao,WEI Wei, et al. A Curing System of Benzoxazine with Amine: Reactivity, Reaction Mechanism and Material Properties[OL].[23 December 2014] http://en.paper.edu.cn/en_releasepaper/content/4625175 |
2. Magnetochromic Effect of Superparamagnetic Fe3O4 | |||
LI Ziheng,ZHAO Jun,LI Gen,QI Ping,WANG Wenquan | |||
Chemistry 08 December 2011 | |||
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Abstract:Superparamagnetic Fe3O4 are synthesized by high-temperature hydrothermal synthesis method and the magnetochromic effect is studied. Results show that the magnetochromic is controlled by external magnetic field and Coulomb force of Fe3O4 colloidal nanocrystal clusters (CNCs). The pH value can lead to the changing of charges and the Coulomb force of CNCs. Therefore the interparticle spacing of CNCs is changed. When under external magnetic field, an ordered nanostructure is formed. The magnetochromic is a combined effect of external magnetic field and pH value of solution. Using the magnetochromic method to study the interaction of nanoparticles is important for guiding the preparation of ordered nano-assemlbly. | |||
TO cite this article:LI Ziheng,ZHAO Jun,LI Gen, et al. Magnetochromic Effect of Superparamagnetic Fe3O4[OL].[ 8 December 2011] http://en.paper.edu.cn/en_releasepaper/content/4449911 |
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