The Experts below are selected from a list of 459 Experts worldwide ranked by ideXlab platform

Xiaogang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and characterization of novel polyimides from 4 4 bis 5 amino 2 pyridinoxy Diphenyl ether 4 4 bis 5 amino 2 pyridinoxy Diphenyl thioether and 4 4 bis 5 amino 2 pyridinoxy Diphenyl Sulfone
    RSC Advances, 2014
    Co-Authors: Yue Guan, Daming Wang, Zhen Wang, Guodong Dang, Chunhai Chen, Hongwei Zhou, Xiaogang Zhao
    Abstract:

    To investigate the difference of the –O–, –SO2– and –S– groups affecting the thermal, mechanical, optical properties and water uptake of polyimides (PIs), we prepared 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl ether (BAPDE), 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl Sulfone (BAPDS) and 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl thioether (BAPDT) with 2-chloro-5-nitropyridine and 4,4′-thiodiphenol, 4,4′-oxydiphenol, 4,4′-sulfonylbisphenol, respectively. Two series of novel PI-(1,3,5) and PI-(2,4,6) were synthesized from BAPDE, BAPDS and BAPDT with two aromatic dianhydrides: 4,4-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-thioDiphenyl tertracaboxylic dianhydride (TDPA), through a typical two-step polymerization method. The resulting polyimides exhibited solubility in polar solvents, such as DMAc, NMP, DMF, DMSO and m-cresol at room temperature. These polyimides with inherent viscosities of 0.84–1.26 dL g−1 exhibited high enough molecular weight to give tough and flexible thin films by solution casting. The glass transition temperature (Tg) values measured by differential scanning calorimetric and thermal stabilities based on 5% weight loss temperature of PI films varied from 226 to 305 °C and from 453 to 483 °C, respectively. Interestingly, the influence of oxygen and sulfur-connected ether linkage in diamine and dianhydride on Tg exhibits the reverse order. The polyimides also have good mechanical properties, tensile strengths of 101–114 MPa, tensile modulus of 2.8–3.2 GPa, and elongations at break of 8.8–33.3%. The cutoff wavelengths and transparency of PI films were in the ranges of 338–400 nm and 72–84% at 500 nm, respectively. The water uptakes of the resulting PI films were in the range of 0.5–1.4%.

Shuo Tang - One of the best experts on this subject based on the ideXlab platform.

  • high performance flame retardant epoxy resin based on a bi group molecule containing phosphaphenanthrene and borate groups
    Polymer Degradation and Stability, 2018
    Co-Authors: Shuo Tang, Lijun Qian, Yong Qiu, Yuping Dong
    Abstract:

    Abstract A flame retardant named ODOPB-Borate constructed by phosphaphenanthrene (DOPO) and borate groups was synthesized via esterification reaction between boric acid and 10-(2,5-dihydroxyphenyl)-10-H-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB). The molecular structure of ODOPB-Borate was characterized and verified. To research the group synergistic effect of phosphaphenanthrene and borate groups, ODOPB-Borate was incorporated into epoxy resin, diglycidyl ether of bisphenol-A (DGEBA), cured by 4,4-diamino-Diphenyl Sulfone (DDS). ODOPB-Borate increased the LOI and particularly improved the UL94 classification of epoxy resin thermosets, and also reduced the heat release of epoxy thermosets. Further, the decrease of total mass loss value of thermoset containing ODOPB-Borate revealed that ODOPB-Borate facilitated the EP composites to form more residue. The analyzed pyrolysis route of ODOPB-Borate revealed that ODOPB part mainly exerted quenching effect in gas phase and the borate part mostly remained in condensed phase and promoted charring effect and smoke suppressing effect. The synergistic effect from phosphaphenanthrene and borate groups endowed epoxy resins with flame retardancy. Moreover, ODOPB-Borate also increased the glass transition temperature and impact strength of epoxy resin.

  • gas phase flame retardant effects of a bi group compound based on phosphaphenanthrene and triazine trione groups in epoxy resin
    Polymer Degradation and Stability, 2016
    Co-Authors: Shuo Tang, Lijun Qian, Xinxin Liu, Yuping Dong
    Abstract:

    A flame retardant TAD constructed by phosphaphenanthrene and triazine-trione groups was synthesized via addition reaction between triallyl isocyanurate (TAIC) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Then, the molecular structure and thermal stability of TAD were characterized. To research its flame-retardant behaviors, TAD was incorporated into epoxy resin, diglycidyl ether of bisphenol-A, cured by 4,4′-diamino-Diphenyl Sulfone (DDS). TAD obviously increased the LOI values and UL94 rating of epoxy resin thermosets. TAD also reduced the values including peak of heat release rate (pk-HRR), total heat release (THR), average effective heat of combustion (av-EHC), average CO2 yield and total mass loss (TML), and increased average CO yields of epoxy thermosets. Further, the different decrease ratio of av-EHC and TML from thermoset containing TAD reveals that TAD exerted more gas-phase flame-retardant effect than condensed-phase effect. The opinion also was testified by the TAD/EP residues with loosen morphology from the cone calorimeter test. The analyzed pyrolysis route of TAD reveals that phosphaphenanthrene group mainly exerted quenching effect and the triazine-trione group exerted gas dilution effect. The excellent flame-retardant performance of TAD is resulted by the group synergistic effect from the two typical flame-retardant groups: phosphaphenanthrene and triazine-trione.

Zhen Wang - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and characterization of novel polyimides from 4 4 bis 5 amino 2 pyridinoxy Diphenyl ether 4 4 bis 5 amino 2 pyridinoxy Diphenyl thioether and 4 4 bis 5 amino 2 pyridinoxy Diphenyl Sulfone
    RSC Advances, 2014
    Co-Authors: Yue Guan, Daming Wang, Zhen Wang, Guodong Dang, Chunhai Chen, Hongwei Zhou, Xiaogang Zhao
    Abstract:

    To investigate the difference of the –O–, –SO2– and –S– groups affecting the thermal, mechanical, optical properties and water uptake of polyimides (PIs), we prepared 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl ether (BAPDE), 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl Sulfone (BAPDS) and 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl thioether (BAPDT) with 2-chloro-5-nitropyridine and 4,4′-thiodiphenol, 4,4′-oxydiphenol, 4,4′-sulfonylbisphenol, respectively. Two series of novel PI-(1,3,5) and PI-(2,4,6) were synthesized from BAPDE, BAPDS and BAPDT with two aromatic dianhydrides: 4,4-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-thioDiphenyl tertracaboxylic dianhydride (TDPA), through a typical two-step polymerization method. The resulting polyimides exhibited solubility in polar solvents, such as DMAc, NMP, DMF, DMSO and m-cresol at room temperature. These polyimides with inherent viscosities of 0.84–1.26 dL g−1 exhibited high enough molecular weight to give tough and flexible thin films by solution casting. The glass transition temperature (Tg) values measured by differential scanning calorimetric and thermal stabilities based on 5% weight loss temperature of PI films varied from 226 to 305 °C and from 453 to 483 °C, respectively. Interestingly, the influence of oxygen and sulfur-connected ether linkage in diamine and dianhydride on Tg exhibits the reverse order. The polyimides also have good mechanical properties, tensile strengths of 101–114 MPa, tensile modulus of 2.8–3.2 GPa, and elongations at break of 8.8–33.3%. The cutoff wavelengths and transparency of PI films were in the ranges of 338–400 nm and 72–84% at 500 nm, respectively. The water uptakes of the resulting PI films were in the range of 0.5–1.4%.

  • synthesis and properties of polyimides from isomeric bis dicarboxylphenylthio Diphenyl Sulfone dianhydrides
    Polymer, 2005
    Co-Authors: Jingling Yan, Zhen Wang, Lianxun Gao, Mengxian Ding
    Abstract:

    Abstract 4,4′-Bis(3,4-dicarboxyphenylthio)Diphenyl Sulfone dianhydride(4,4′-PTPSDA) and 4,4′-bis(2,3-dicarboxyphenylthio)Diphenyl Sulfone dianhydride(3,3′-PTPSDA) were synthesized from chlorophthalic anhydrides and bis(4-mercaptophenyl)Sulfone. Their structures were determined via IR spectra, 1 H NMR and elemental analysis. A series of polyimides were prepared from isomeric PTPSDAs and aromatic diamines in 1-methyl-2-pyrrolidinone (NMP) via the conventional two-step method. Polyimides based on 4,4′-PTPSDA and 3,3′-PTPSDA have good solubility in polar aprotic solvents and phenols. The 5% weight-loss temperatures of isomeric polyimides were near 500 °C in N 2 . DMTA and DSC analyses indicated that the glass-transition temperatures of polyimides from 3,3′-PTPSDA are higher than those of polyimides from 4,4′-PTPSDA. The wide-angle X-ray diffraction showed that all polyimides are amorphous. The polyimides from 3,3′-PTPSDA showed higher permeability but lower permselectivity compared with those from 4,4′-PTPSDA.

Yue Guan - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and characterization of novel polyimides from 4 4 bis 5 amino 2 pyridinoxy Diphenyl ether 4 4 bis 5 amino 2 pyridinoxy Diphenyl thioether and 4 4 bis 5 amino 2 pyridinoxy Diphenyl Sulfone
    RSC Advances, 2014
    Co-Authors: Yue Guan, Daming Wang, Zhen Wang, Guodong Dang, Chunhai Chen, Hongwei Zhou, Xiaogang Zhao
    Abstract:

    To investigate the difference of the –O–, –SO2– and –S– groups affecting the thermal, mechanical, optical properties and water uptake of polyimides (PIs), we prepared 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl ether (BAPDE), 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl Sulfone (BAPDS) and 4,4′-bis(5-amino-2-pyridinoxy)Diphenyl thioether (BAPDT) with 2-chloro-5-nitropyridine and 4,4′-thiodiphenol, 4,4′-oxydiphenol, 4,4′-sulfonylbisphenol, respectively. Two series of novel PI-(1,3,5) and PI-(2,4,6) were synthesized from BAPDE, BAPDS and BAPDT with two aromatic dianhydrides: 4,4-oxydiphthalic anhydride (ODPA), and 3,3′,4,4′-thioDiphenyl tertracaboxylic dianhydride (TDPA), through a typical two-step polymerization method. The resulting polyimides exhibited solubility in polar solvents, such as DMAc, NMP, DMF, DMSO and m-cresol at room temperature. These polyimides with inherent viscosities of 0.84–1.26 dL g−1 exhibited high enough molecular weight to give tough and flexible thin films by solution casting. The glass transition temperature (Tg) values measured by differential scanning calorimetric and thermal stabilities based on 5% weight loss temperature of PI films varied from 226 to 305 °C and from 453 to 483 °C, respectively. Interestingly, the influence of oxygen and sulfur-connected ether linkage in diamine and dianhydride on Tg exhibits the reverse order. The polyimides also have good mechanical properties, tensile strengths of 101–114 MPa, tensile modulus of 2.8–3.2 GPa, and elongations at break of 8.8–33.3%. The cutoff wavelengths and transparency of PI films were in the ranges of 338–400 nm and 72–84% at 500 nm, respectively. The water uptakes of the resulting PI films were in the range of 0.5–1.4%.

Yuping Dong - One of the best experts on this subject based on the ideXlab platform.

  • high performance flame retardant epoxy resin based on a bi group molecule containing phosphaphenanthrene and borate groups
    Polymer Degradation and Stability, 2018
    Co-Authors: Shuo Tang, Lijun Qian, Yong Qiu, Yuping Dong
    Abstract:

    Abstract A flame retardant named ODOPB-Borate constructed by phosphaphenanthrene (DOPO) and borate groups was synthesized via esterification reaction between boric acid and 10-(2,5-dihydroxyphenyl)-10-H-9-oxa-10-phosphaphenanthrene-10-oxide (ODOPB). The molecular structure of ODOPB-Borate was characterized and verified. To research the group synergistic effect of phosphaphenanthrene and borate groups, ODOPB-Borate was incorporated into epoxy resin, diglycidyl ether of bisphenol-A (DGEBA), cured by 4,4-diamino-Diphenyl Sulfone (DDS). ODOPB-Borate increased the LOI and particularly improved the UL94 classification of epoxy resin thermosets, and also reduced the heat release of epoxy thermosets. Further, the decrease of total mass loss value of thermoset containing ODOPB-Borate revealed that ODOPB-Borate facilitated the EP composites to form more residue. The analyzed pyrolysis route of ODOPB-Borate revealed that ODOPB part mainly exerted quenching effect in gas phase and the borate part mostly remained in condensed phase and promoted charring effect and smoke suppressing effect. The synergistic effect from phosphaphenanthrene and borate groups endowed epoxy resins with flame retardancy. Moreover, ODOPB-Borate also increased the glass transition temperature and impact strength of epoxy resin.

  • gas phase flame retardant effects of a bi group compound based on phosphaphenanthrene and triazine trione groups in epoxy resin
    Polymer Degradation and Stability, 2016
    Co-Authors: Shuo Tang, Lijun Qian, Xinxin Liu, Yuping Dong
    Abstract:

    A flame retardant TAD constructed by phosphaphenanthrene and triazine-trione groups was synthesized via addition reaction between triallyl isocyanurate (TAIC) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Then, the molecular structure and thermal stability of TAD were characterized. To research its flame-retardant behaviors, TAD was incorporated into epoxy resin, diglycidyl ether of bisphenol-A, cured by 4,4′-diamino-Diphenyl Sulfone (DDS). TAD obviously increased the LOI values and UL94 rating of epoxy resin thermosets. TAD also reduced the values including peak of heat release rate (pk-HRR), total heat release (THR), average effective heat of combustion (av-EHC), average CO2 yield and total mass loss (TML), and increased average CO yields of epoxy thermosets. Further, the different decrease ratio of av-EHC and TML from thermoset containing TAD reveals that TAD exerted more gas-phase flame-retardant effect than condensed-phase effect. The opinion also was testified by the TAD/EP residues with loosen morphology from the cone calorimeter test. The analyzed pyrolysis route of TAD reveals that phosphaphenanthrene group mainly exerted quenching effect and the triazine-trione group exerted gas dilution effect. The excellent flame-retardant performance of TAD is resulted by the group synergistic effect from the two typical flame-retardant groups: phosphaphenanthrene and triazine-trione.