The Experts below are selected from a list of 24579 Experts worldwide ranked by ideXlab platform
Yong Qiu - One of the best experts on this subject based on the ideXlab platform.
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toughening effect and flame retardant behaviors of phosphaphenanthrene phenylsiloxane bigroup macromolecules in epoxy thermoset
Macromolecules, 2018Co-Authors: Yong Qiu, Haisheng Feng, Shanglin Jin, Jianwei HaoAbstract:A series of novel phosphaphenanthrene/phenylsiloxane bigroup macromolecules (DDSi-n) were synthesized and applied to obtain high-performance epoxy Thermosets. DDSi-n macromolecules simultaneously enhanced the anti-impact and flame-retardant performance of epoxy Thermosets. The impact strength of the DDSi-n-containing thermoset (DDSi-n/EP) was maximally increased by nearly 140% in 8% DDSi-1/EP because of the flexible phenylsiloxane block and the polar phosphaphenanthrene group interacting with matrix in DDSi-n macromolecules. Meanwhile, the evidently elevated anti-ignition and self-extinguishing performance, the suppressed combustion heat, and the enhanced charring capability of DDSi-n/EP were all caused by the flame-retardant group synergistic effect of phosphaphenanthrene and phenylsiloxane groups of DDSi-n macromolecules in Thermosets. Compared with the individual phosphaphenanthrene or phenylsiloxane group in monogroup contrasts, the phosphaphenanthrene and phenylsiloxane groups in bigroup DDSi-n macro...
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Toughening Effect and Flame-Retardant Behaviors of Phosphaphenanthrene/Phenylsiloxane Bigroup Macromolecules in Epoxy Thermoset
Macromolecules, 2018Co-Authors: Yong Qiu, Haisheng Feng, Shanglin Jin, Jianwei HaoAbstract:A series of novel phosphaphenanthrene/phenylsiloxane bigroup macromolecules (DDSi-n) were synthesized and applied to obtain high-performance epoxy Thermosets. DDSi-n macromolecules simultaneously enhanced the anti-impact and flame-retardant performance of epoxy Thermosets. The impact strength of the DDSi-n-containing thermoset (DDSi-n/EP) was maximally increased by nearly 140% in 8% DDSi-1/EP because of the flexible phenylsiloxane block and the polar phosphaphenanthrene group interacting with matrix in DDSi-n macromolecules. Meanwhile, the evidently elevated anti-ignition and self-extinguishing performance, the suppressed combustion heat, and the enhanced charring capability of DDSi-n/EP were all caused by the flame-retardant group synergistic effect of phosphaphenanthrene and phenylsiloxane groups of DDSi-n macromolecules in Thermosets. Compared with the individual phosphaphenanthrene or phenylsiloxane group in monogroup contrasts, the phosphaphenanthrene and phenylsiloxane groups in bigroup DDSi-n macro...
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improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene triazine compounds in epoxy thermoset
Polymer International, 2017Co-Authors: Yong Qiu, Patrick Klack, Volker Wachtendorf, Zhen Liu, Bernhard SchartelAbstract:A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy Thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to Thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode.
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Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset
Polymer International, 2017Co-Authors: Yong Qiu, Patrick Klack, Volker Wachtendorf, Zhen Liu, Bernhard SchartelAbstract:A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy Thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to Thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode.
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pyrolysis route of a novel flame retardant constructed by phosphaphenanthrene and triazine trione groups and its flame retardant effect on epoxy resin
Polymer Degradation and Stability, 2014Co-Authors: Yong Qiu, Menglan Xu, Fei Xin, Guozhi Xu, Nan Sun, Yajun ChenAbstract:Abstract A novel flame retardant TGIC-DOPO, which was constructed by phosphaphenanthrene and triazine-trione groups, was synthesized via a controllable ring-opening addition reaction between 1,3,5-triglycidyl isocyanurate (TGIC) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The flame-retardant effect of TGIC-DOPO on an epoxy resin, diglycidyl ether of bisphenol-A (DGEBA), cured with 4,4′-diamino-diphenyl sulfone was investigated. The results of the limited oxygen index (LOI), UL94 vertical burning test, and cone calorimeter test indicated that the TGIC-DOPO imparted flame-retardant properties to DGEBA Thermosets. When the mass fraction of TGIC-DOPO reached 12wt.%, the DGEBA thermoset acquired a LOI value of 33.3%, UL94 V-0 rating, and the lower peak of heat release rate (pk-HRR) at 481 kW/m 2 . Specifically, the DGEBA thermoset with 6wt.% TGIC-DOPO had an LOI value of 33.3%, whereas the DGEBA thermoset with 10wt.% TGIC-DOPO had the highest LOI value of 35.2% among the specimens. Meanwhile, the time to ignition, pk-HRR, average of effective heat of combustion (av-EHC), and total heat release of the DGEBA thermoset were all negatively correlated with the mass fraction of TGIC-DOPO. Moreover, the average CO 2 and CO yields exhibited a downtrend with increasing mass fraction of TGIC-DOPO from 6wt.%. The reduction of av-EHC with increase of TGIC-DOPO content in Thermosets confirmed the free radical quenching effect of TGIC-DOPO in gaseous phase during combustion. The macromorphology, micromorphology and element content of the residues from the cone calorimeter test revealed the bi-phase flame-retardant effect of TGIC-DOPO. Furthermore, the pyrolysis route of TGIC-DOPO were investigated via Py-GC/MS, which disclosed that the decomposed TGIC-DOPO with double flame-retardant groups released various fragments with quenching effect on free radical chain reaction of combustion. The fragments enhanced the flame-retardant performance of DGEBA Thermosets both in gaseous and condensed phases. The flame-retardant performance of TGIC-DOPO was resulted by the quenching effect of TGIC-DOPO and the synergistic effect of phosphaphenanthrene and triazine-trione groups.
Zhiqiang Fan - One of the best experts on this subject based on the ideXlab platform.
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sonochemical transformation of epoxy amine thermoset into soluble and reusable polymers
Macromolecules, 2015Co-Authors: Yuqin Min, Binyang Du, Shuyun Huang, Yuxiang Wang, Xinghong Zhang, Zhijun Zhang, Zhiqiang FanAbstract:The degradation and reuse of epoxy Thermosets have significant impact on the environments. We report that an epoxy–amine thermoset embedded with Diels–Alder (DA) bonds was transformed into soluble polymers via sonochemistry under mild temperature (ca. 20 °C) for the first time. Sonication could effectively induce the position-oriented cleavage of DA bonds (i.e., retro-DA) of the fully swelled epoxy thermoset in dimethyl sulfoxide (DMSO), leading to the soluble polymers. Of importance, such sonochemical process could be regulated on demand via switching on-and-off of the sonication. The obtained soluble polymers could be recured to form epoxy–amine Thermosets via DA reaction. This sonochemical method might provide an unprecedented and efficient way to the controlled degradation and recycling of the epoxy Thermosets containing the dynamic covalent bonds likes DA groups.
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Sonochemical Transformation of Epoxy–Amine Thermoset into Soluble and Reusable Polymers
Macromolecules, 2015Co-Authors: Yuqin Min, Binyang Du, Shuyun Huang, Yuxiang Wang, Xinghong Zhang, Zhijun Zhang, Zhiqiang FanAbstract:The degradation and reuse of epoxy Thermosets have significant impact on the environments. We report that an epoxy–amine thermoset embedded with Diels–Alder (DA) bonds was transformed into soluble polymers via sonochemistry under mild temperature (ca. 20 °C) for the first time. Sonication could effectively induce the position-oriented cleavage of DA bonds (i.e., retro-DA) of the fully swelled epoxy thermoset in dimethyl sulfoxide (DMSO), leading to the soluble polymers. Of importance, such sonochemical process could be regulated on demand via switching on-and-off of the sonication. The obtained soluble polymers could be recured to form epoxy–amine Thermosets via DA reaction. This sonochemical method might provide an unprecedented and efficient way to the controlled degradation and recycling of the epoxy Thermosets containing the dynamic covalent bonds likes DA groups.
Yuqin Min - One of the best experts on this subject based on the ideXlab platform.
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sonochemical transformation of epoxy amine thermoset into soluble and reusable polymers
Macromolecules, 2015Co-Authors: Yuqin Min, Binyang Du, Shuyun Huang, Yuxiang Wang, Xinghong Zhang, Zhijun Zhang, Zhiqiang FanAbstract:The degradation and reuse of epoxy Thermosets have significant impact on the environments. We report that an epoxy–amine thermoset embedded with Diels–Alder (DA) bonds was transformed into soluble polymers via sonochemistry under mild temperature (ca. 20 °C) for the first time. Sonication could effectively induce the position-oriented cleavage of DA bonds (i.e., retro-DA) of the fully swelled epoxy thermoset in dimethyl sulfoxide (DMSO), leading to the soluble polymers. Of importance, such sonochemical process could be regulated on demand via switching on-and-off of the sonication. The obtained soluble polymers could be recured to form epoxy–amine Thermosets via DA reaction. This sonochemical method might provide an unprecedented and efficient way to the controlled degradation and recycling of the epoxy Thermosets containing the dynamic covalent bonds likes DA groups.
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Sonochemical Transformation of Epoxy–Amine Thermoset into Soluble and Reusable Polymers
Macromolecules, 2015Co-Authors: Yuqin Min, Binyang Du, Shuyun Huang, Yuxiang Wang, Xinghong Zhang, Zhijun Zhang, Zhiqiang FanAbstract:The degradation and reuse of epoxy Thermosets have significant impact on the environments. We report that an epoxy–amine thermoset embedded with Diels–Alder (DA) bonds was transformed into soluble polymers via sonochemistry under mild temperature (ca. 20 °C) for the first time. Sonication could effectively induce the position-oriented cleavage of DA bonds (i.e., retro-DA) of the fully swelled epoxy thermoset in dimethyl sulfoxide (DMSO), leading to the soluble polymers. Of importance, such sonochemical process could be regulated on demand via switching on-and-off of the sonication. The obtained soluble polymers could be recured to form epoxy–amine Thermosets via DA reaction. This sonochemical method might provide an unprecedented and efficient way to the controlled degradation and recycling of the epoxy Thermosets containing the dynamic covalent bonds likes DA groups.
Bernhard Schartel - One of the best experts on this subject based on the ideXlab platform.
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improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene triazine compounds in epoxy thermoset
Polymer International, 2017Co-Authors: Yong Qiu, Patrick Klack, Volker Wachtendorf, Zhen Liu, Bernhard SchartelAbstract:A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy Thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to Thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode.
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Improved flame retardancy by synergy between cyclotetrasiloxane and phosphaphenanthrene/triazine compounds in epoxy thermoset
Polymer International, 2017Co-Authors: Yong Qiu, Patrick Klack, Volker Wachtendorf, Zhen Liu, Bernhard SchartelAbstract:A siloxane compound (MVC) and a bi-group phosphaphenanthrene/triazine compound (TGD) were employed in epoxy Thermosets to explore high-efficiency flame retardant systems. With only 1wt% MVC and 3wt% TGD, an epoxy thermoset passed UL 94 V-0 rating test and achieved a limiting oxygen index value of 34.0%, exhibiting an excellent flame retardant effect. The MVC/TGD system not only decreased the peak value of heat release rate and effective heat of combustion but also imparted an improved charring ability to Thermosets, thereby outstandingly reducing the flammability of 1%MVC/3%TGD/EP. Compared with the fire performance of 4%TGD/EP and 4%MVC/EP, the MVC/TGD system showed an obvious flame retardant synergistic effect, mainly depending on the general improvement of flame inhibition, charring and barrier effects of the thermoset during combustion. Evolved gas analysis combinedwith condensed-phase pyrolysis product Analysis jointly revealed the details of the changed pyrolysis mode.
G. P. Johari - One of the best experts on this subject based on the ideXlab platform.
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Relaxations in Thermosets. XXV: Calorimetric studies of the curing kinetics of pure and rubber-containing epoxy-based Thermosets
Journal of Applied Polymer Science, 1993Co-Authors: S Wasserman, G. P. JohariAbstract:The curing kinetics of diglycidyl ether of bisphenol-A, with ethylene diamine, propylene diamine, and hexamethylene diamine, with 60 wt % amine-terminated butadiene acrylonitrile (ATBN) and without, have been measured under both isothermal and ramp-curing conditions. The phase separation of ATBN is undetectable by calorimetry, but has a significant effect on both the rate of curing and the extent of cure. In all cases, its presence decreases the extent of cure and lowers the Tg of the thermoset formed. The total heat of reaction for the curing is 445 ± 15 J/g and remains unaffected by both the presence of an elastomer and the increase in the molecular size of the curing agent. None of the formalisms available for the curing kinetics of epoxy-based Thermosets is consistent with the results for the neat Thermosets. The average activation energy for the reactions increases from 107 to 150 kJ/mol when ethylene diamine is replaced by hexamethylene diamine, but curing reaches near completion in a shorter time with the latter than with the former. The Tg of the latter thermoset is lower than that of the former and follows a decreasing trend with increase in the molecular size of the curing agent—an effect that is related to the increase in the length of cross-links in the network structure. © 1993 John Wiley & Sons, Inc.
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Relaxations in Thermosets. XXV. Calorimetric studies of the curing kinetics of pure and rubber‐containing epoxy‐based Thermosets
Journal of Applied Polymer Science, 1993Co-Authors: S Wasserman, G. P. JohariAbstract:The curing kinetics of diglycidyl ether of bisphenol-A, with ethylene diamine, propylene diamine, and hexamethylene diamine, with 60 wt % amine-terminated butadiene acrylonitrile (ATBN) and without, have been measured under both isothermal and ramp-curing conditions. The phase separation of ATBN is undetectable by calorimetry, but has a significant effect on both the rate of curing and the extent of cure. In all cases, its presence decreases the extent of cure and lowers the Tg of the thermoset formed. The total heat of reaction for the curing is 445 ± 15 J/g and remains unaffected by both the presence of an elastomer and the increase in the molecular size of the curing agent. None of the formalisms available for the curing kinetics of epoxy-based Thermosets is consistent with the results for the neat Thermosets. The average activation energy for the reactions increases from 107 to 150 kJ/mol when ethylene diamine is replaced by hexamethylene diamine, but curing reaches near completion in a shorter time with the latter than with the former. The Tg of the latter thermoset is lower than that of the former and follows a decreasing trend with increase in the molecular size of the curing agent—an effect that is related to the increase in the length of cross-links in the network structure. © 1993 John Wiley & Sons, Inc.
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Relaxations in Thermosets. XIII. Effects of post‐cure and aging on the sub‐Tg relaxations of nonstoichiometric epoxide‐based Thermosets
Journal of Polymer Science Part B, 1992Co-Authors: M. B. M. Mangion, M Wang, G. P. JohariAbstract:The dielectric permittivity and loss of diglycidyl ether of bisphenol-A (DGEBA) cured with greater than and less than the stoichiometric amounts of diaminodiphenyl methane (DDM) have been measured over a temperature range 77–350 K prior to curing and gelation, after curing at about 340 K and further aging for a predetermined period. The height of the γ-relaxation peak monotonically decreases during the post-cure period and becomes masked by the contributions from the β-relaxation peak, whose height, in turn, first increases on postcuring to a same maximum value for both nonstoichiometric Thermosets and then decreases. This decrease is attributed to physical aging effects. The β-relaxation peak shifts towards higher temperature on postcuring. Comparison between the changes in the dielectric properties of the saturated and starved Thermosets show that while the γ-relaxation process may be attributed to the motion of the epoxide dipolar groups of the unreacted DGEBA, the β-relaxation process is not attributable entirely to the motion of OH groups and of the unreacted amines in the thermoset. Explanations involving the chain and network packing in the structure of a thermoset are necessary for the observed behavior of the β-relaxation process in amine saturated and starved Thermosets.
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Relaxations in Thermosets. XIII. Effects of post-cure and aging on the sub-Tg relaxations of nonstoichiometric epoxide-based Thermosets
Journal of Polymer Science Part B, 1992Co-Authors: M. B. M. Mangion, M Wang, G. P. JohariAbstract:The dielectric permittivity and loss of diglycidyl ether of bisphenol-A (DGEBA) cured with greater than and less than the stoichiometric amounts of diaminodiphenyl methane (DDM) have been measured over a temperature range 77–350 K prior to curing and gelation, after curing at about 340 K and further aging for a predetermined period. The height of the γ-relaxation peak monotonically decreases during the post-cure period and becomes masked by the contributions from the β-relaxation peak, whose height, in turn, first increases on postcuring to a same maximum value for both nonstoichiometric Thermosets and then decreases. This decrease is attributed to physical aging effects. The β-relaxation peak shifts towards higher temperature on postcuring. Comparison between the changes in the dielectric properties of the saturated and starved Thermosets show that while the γ-relaxation process may be attributed to the motion of the epoxide dipolar groups of the unreacted DGEBA, the β-relaxation process is not attributable entirely to the motion of OH groups and of the unreacted amines in the thermoset. Explanations involving the chain and network packing in the structure of a thermoset are necessary for the observed behavior of the β-relaxation process in amine saturated and starved Thermosets.
