A new aromatic diacid monomer containing pyridine unit,4-phenyl-2,6-bis[4-（4-carboxyphenoxy） phenyl]pyridine 3,was successfully synthesized in three steps,starting from 4-hydroxyacetophenone.The corresponding pyridi...A new aromatic diacid monomer containing pyridine unit,4-phenyl-2,6-bis[4-（4-carboxyphenoxy） phenyl]pyridine 3,was successfully synthesized in three steps,starting from 4-hydroxyacetophenone.The corresponding pyridine-containing polybenzimidazole was prepared via polycondensation of 3 with tetraaminodiphenyl ether（TADE） in poly（phosphoric acid）（PPA）.The resulting polybenzimidazole exhibits excellent solubility,good thermal stabilities and high thermal resistance.展开更多
Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but the...Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but these methods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAn (/JS=6, where n means carbon amount) was studied here. The effects of the addition of modifying agent on molecular weight, gel time and softening point were investigated. Optimal addition of DAn (10% phenol) was obtained by testing the initial and retained flexural strengths of the modified resin. FT-IR spectra showed that carbonyl shifts to higher wave number. With the use of TG, SEM and strength loss curves, the relation between initial and retained strengths was analysed. Tests on the heated deformation curve, before and after resin modification, show that PF-DA10 has the characteristic of higher initial and retained strengths together.展开更多
Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in...Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (η inh ), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.展开更多
The preparation of monodisperse colloidal microlatex particles of polystyrene and poly(styrene butene diacid) by the use of microwave radiation and under normal ambient pressure is reported. There is no surfactant in ...The preparation of monodisperse colloidal microlatex particles of polystyrene and poly(styrene butene diacid) by the use of microwave radiation and under normal ambient pressure is reported. There is no surfactant in the system.The total synthesis time has been reduced from more then 10h(conventional method) to less than 1 h(microwave mothod). The dynamic experimental results indicate that the reaction proecss is very sharp in comparison with conventional polymerization. No constant rate stage existed.展开更多
基金the research support from the Natural Science Foundation of Gansu Province(No. 096RJZA047)the State Key Laboratory of Applied Organic Chemistry of People's Republic of China
文摘A new aromatic diacid monomer containing pyridine unit,4-phenyl-2,6-bis[4-（4-carboxyphenoxy） phenyl]pyridine 3,was successfully synthesized in three steps,starting from 4-hydroxyacetophenone.The corresponding pyridine-containing polybenzimidazole was prepared via polycondensation of 3 with tetraaminodiphenyl ether（TADE） in poly（phosphoric acid）（PPA）.The resulting polybenzimidazole exhibits excellent solubility,good thermal stabilities and high thermal resistance.
文摘Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers, but these methods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAn (/JS=6, where n means carbon amount) was studied here. The effects of the addition of modifying agent on molecular weight, gel time and softening point were investigated. Optimal addition of DAn (10% phenol) was obtained by testing the initial and retained flexural strengths of the modified resin. FT-IR spectra showed that carbonyl shifts to higher wave number. With the use of TG, SEM and strength loss curves, the relation between initial and retained strengths was analysed. Tests on the heated deformation curve, before and after resin modification, show that PF-DA10 has the characteristic of higher initial and retained strengths together.
基金This project was supported by the Research Affairs Division of Arak University.
文摘Facile and rapid polycondensation reactions of N,N'-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence of a small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (η inh ), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported.
文摘The preparation of monodisperse colloidal microlatex particles of polystyrene and poly(styrene butene diacid) by the use of microwave radiation and under normal ambient pressure is reported. There is no surfactant in the system.The total synthesis time has been reduced from more then 10h(conventional method) to less than 1 h(microwave mothod). The dynamic experimental results indicate that the reaction proecss is very sharp in comparison with conventional polymerization. No constant rate stage existed.
