The cure kinetics of diglycidyl ether of bisphenol A (DGEBA) with hyperbranched poly (3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calori...The cure kinetics of diglycidyl ether of bisphenol A (DGEBA) with hyperbranched poly (3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry (DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible --P--O-- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Malek. It was found that the two-parameter autocatalytic model(Sestak-Berggren equation) is the most adequate one to describe the cure kinetics of the studied System at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.展开更多
A method of estimating the critical rate of temperature increase of thermal explosion for the first orderautocatalytic decomposition reaction system using non-isothermal DSC is presented. Information is obtained on th...A method of estimating the critical rate of temperature increase of thermal explosion for the first orderautocatalytic decomposition reaction system using non-isothermal DSC is presented. Information is obtained on theincreasing rate of temperature in nitrocellulose containing 13.54% of nitrogen when the first order autocatalytic decomposition converts into thermal explosion.展开更多
A method of estimating the critical rate of temperature rise for the thermal explosion of first order autocatalytic decomposition reaction systems by using non-isothermal DSC is presented. The information was obtained...A method of estimating the critical rate of temperature rise for the thermal explosion of first order autocatalytic decomposition reaction systems by using non-isothermal DSC is presented. The information was obtained on the increasing rate of temperature for the first order autocatalytic decomposition of nitrocellulose containing 13.86% nitrogen converting into the thermal explosion.展开更多
Two general expressions and their six derived formulae for estimating the critical temperature(Tb) of thermal explosion for energetic materials(EMs) were derived from the Semenov's thermal explosion theory and ei...Two general expressions and their six derived formulae for estimating the critical temperature(Tb) of thermal explosion for energetic materials(EMs) were derived from the Semenov's thermal explosion theory and eight non-isothermal kinetic equations via reasonable hypothesis. We can easily obtain the values of the initial temperature(T0i) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of EMs, the onset temperature(Tei), the exothermic decomposition reaction kinetic parameters and the values of Too and Te0 from the equation Toiorei=Tooore0+α1β1+α2β2+...+αL-2βi^L-2, i=1, 2, …, L and then calculate the values of Tb by means of the six derived formulae. The results obtained with the six derived calculating methods for six trinitromethyl explosives: bis(2,2,2- trinitroethyl-N-nitro) ethylene diamine(BTNEDA), 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate(TNETB), bis(2,2,2- trinitroethyl) formal(BNTF), bis(2,2,2-trinitroethyl-nitramine)(BTNNA), 2,2,2-trinitroethyl-2,2,2-trinitroethyl-N- nitroamino acetate(TNTNNA) and tetrakis [2,2,2-trinitroethyl] orthoester(TTNOE) agree well with each other.展开更多
Critical temperature(Tb) of thermal explosion for energetic materials is estimated from Semenov's thermal explosion theory and the non-isothermal kinetic equation da/dt=Aoexp(bT)[1+(T-T0)b][(a) deduced via r...Critical temperature(Tb) of thermal explosion for energetic materials is estimated from Semenov's thermal explosion theory and the non-isothermal kinetic equation da/dt=Aoexp(bT)[1+(T-T0)b][(a) deduced via reasonable hypotheses, where To is the initial point of the deviation from the baseline of DSC curve. The final formula is (Tb-Te0){ 1+1/[1+( Tb-T00)b]}=1. We can easily obtain the initial temperature(T0/) and onset temperature(Tci) from the non-isothermal DSC curves, the values of Too and Tc0 from the equation TOi or ei=T00 or c0+α1βi+a2βi^2+…+aL-2L-2βiL-2, i=1,2,…L, the value of b from the equation: In[β/(Tei-T0i)]=ln[A0/G(a)]+bTei, so as to calculate the value of Tb. The result obtained with this method coincides completely with the value of Tb obtained by Hu-Yang-Liang-Wu method.展开更多
A kinetic equation of non-isothermal crystamzation was derived by extending Avrami's equation to the non-isothermal situation. More crystallization information can be obtained from this kinetic equation. The curve...A kinetic equation of non-isothermal crystamzation was derived by extending Avrami's equation to the non-isothermal situation. More crystallization information can be obtained from this kinetic equation. The curves of non-isothermal and isothermal crystallizations were analysed and compared for poly (ethylene terephthalate) (PET), and the results were discussed.展开更多
A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene t...A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.展开更多
The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship...The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t 1/2 ( the half life of crystallization) and the appropriate temperature variable. The parameters such as the activation energy (Ed) for transport, the equilibrium melting temperature (T_m^0),the nucleation parameter (ψ),themaximum crystallization temperature (T_(e, max)), and the kinetic crystallizability (G) for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed.展开更多
The curing process of dendritic polymer PAMAM with bis-phenol A epoxy resin was investigated using isothermal differential scanning calorimetry(DSC),the mechanism of this reaction was autocatalytic.The data of two r...The curing process of dendritic polymer PAMAM with bis-phenol A epoxy resin was investigated using isothermal differential scanning calorimetry(DSC),the mechanism of this reaction was autocatalytic.The data of two reaction rate constants k1,k2 and reaction orders m,n were obtained from Kamal equation.The overall reaction order m+n was between 2.07 and 2.29,the apparent activation energies of E1 and E2 were 59.79 kJ/mol and 56.51 kJ/mol, respectively.The reaction entered into a diffusion controlled stage at the conversion of 50%,experimental data and theoretic curve had deviation at this time.The reaction conversion,at which the deviation occurred,decreased with lowering curing temperature.展开更多
通过合理假设,从谢苗诺夫(Semenov)热爆炸理论和8个非等温动力学方程,导出了估算含能材料(EMs)热爆炸临界温度(Tb)的2个通式和它们的6个派生式。从EMs的非等温DSC曲线可获得DSC曲线偏离基线的起始温度(T0)、onset温度(Tei)和放热分解反...通过合理假设,从谢苗诺夫(Semenov)热爆炸理论和8个非等温动力学方程,导出了估算含能材料(EMs)热爆炸临界温度(Tb)的2个通式和它们的6个派生式。从EMs的非等温DSC曲线可获得DSC曲线偏离基线的起始温度(T0)、onset温度(Tei)和放热分解反应的动力学参数。由方程T0ior ei=T00 or e0+a1βi+a2βi2+…+aL-2βiL-2,i=1,2,…,L可得到T00和Te0值,随后用6个派生式可计算Tb值。对1,4,5,8-四硝基-1,4,5,8-四氮杂双呋咱[3,4-c:3′,4′-h]十氢化萘,1,4,5,8-四氮杂双呋咱[3,4-c:3′,4′-h]十氢化萘,1,3,4-三硝基咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,1,3,4,8-四硝基咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,1,4,5,8-四硝基-1,4,5,8-四氮杂萘呋咱[3,4-b]十氢化萘,1,3,5-三硝基-1,3,5-三氮杂呋咱[3,4-f]环庚烷,由6个派生式所得的Tb值甚接近。展开更多
文摘The cure kinetics of diglycidyl ether of bisphenol A (DGEBA) with hyperbranched poly (3-hydroxyphenyl) phosphate(HHPP) as the curing agent was investigated by means of non-isothermal differential scanning calorimetry (DSC) at various heating rates. The results were compared with the corresponding results by using 1,3-dihydroxybenzene(DHB) as a model compound. The results show that HHPP can enhance the cure reaction of DGEBA, resulting in the decrease of the peak temperature of the curing curve as well as the decrease of the activation energy because of the flexible --P--O-- groups in the backbone of HHPP. However, both the activation energy of the cured polymer and the peak temperature of the curing curve are increased with DHB as a curing agent. The cure kinetics of the DGEBA/HHPP system was calculated by using the isoconversional method given by Malek. It was found that the two-parameter autocatalytic model(Sestak-Berggren equation) is the most adequate one to describe the cure kinetics of the studied System at various heating rates. The obtained non-isothermal DSC curves from the experimental data show the results being accordant with those theoretically calculated.
文摘A method of estimating the critical rate of temperature increase of thermal explosion for the first orderautocatalytic decomposition reaction system using non-isothermal DSC is presented. Information is obtained on theincreasing rate of temperature in nitrocellulose containing 13.54% of nitrogen when the first order autocatalytic decomposition converts into thermal explosion.
基金Supported by the Science and Technology Foundation of Shaanxi Key L aboratory of Physico- Inorganic Chemistry(No.2 9- 3,2 0 0 1) and the Science and Technology Foundation of Propellant and Explosive Combustion of China(No.5 14 5 5 0 10 1)
文摘A method of estimating the critical rate of temperature rise for the thermal explosion of first order autocatalytic decomposition reaction systems by using non-isothermal DSC is presented. The information was obtained on the increasing rate of temperature for the first order autocatalytic decomposition of nitrocellulose containing 13.86% nitrogen converting into the thermal explosion.
基金Supported by the National Natural Science Foundation of China(Nos.20573098, 50846021 and 69075036)
文摘Two general expressions and their six derived formulae for estimating the critical temperature(Tb) of thermal explosion for energetic materials(EMs) were derived from the Semenov's thermal explosion theory and eight non-isothermal kinetic equations via reasonable hypothesis. We can easily obtain the values of the initial temperature(T0i) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of EMs, the onset temperature(Tei), the exothermic decomposition reaction kinetic parameters and the values of Too and Te0 from the equation Toiorei=Tooore0+α1β1+α2β2+...+αL-2βi^L-2, i=1, 2, …, L and then calculate the values of Tb by means of the six derived formulae. The results obtained with the six derived calculating methods for six trinitromethyl explosives: bis(2,2,2- trinitroethyl-N-nitro) ethylene diamine(BTNEDA), 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate(TNETB), bis(2,2,2- trinitroethyl) formal(BNTF), bis(2,2,2-trinitroethyl-nitramine)(BTNNA), 2,2,2-trinitroethyl-2,2,2-trinitroethyl-N- nitroamino acetate(TNTNNA) and tetrakis [2,2,2-trinitroethyl] orthoester(TTNOE) agree well with each other.
基金Supported by the National Natural Science Foundation of China (No.20573098)
文摘Critical temperature(Tb) of thermal explosion for energetic materials is estimated from Semenov's thermal explosion theory and the non-isothermal kinetic equation da/dt=Aoexp(bT)[1+(T-T0)b][(a) deduced via reasonable hypotheses, where To is the initial point of the deviation from the baseline of DSC curve. The final formula is (Tb-Te0){ 1+1/[1+( Tb-T00)b]}=1. We can easily obtain the initial temperature(T0/) and onset temperature(Tci) from the non-isothermal DSC curves, the values of Too and Tc0 from the equation TOi or ei=T00 or c0+α1βi+a2βi^2+…+aL-2L-2βiL-2, i=1,2,…L, the value of b from the equation: In[β/(Tei-T0i)]=ln[A0/G(a)]+bTei, so as to calculate the value of Tb. The result obtained with this method coincides completely with the value of Tb obtained by Hu-Yang-Liang-Wu method.
文摘A kinetic equation of non-isothermal crystamzation was derived by extending Avrami's equation to the non-isothermal situation. More crystallization information can be obtained from this kinetic equation. The curves of non-isothermal and isothermal crystallizations were analysed and compared for poly (ethylene terephthalate) (PET), and the results were discussed.
文摘A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.
文摘The non-isothermal crystallization kinetics of poly(ethylene terephthalate) (PET) modified by poly (ethlene glycol) (PEG) were determined by DSC. The dual linear regression method was used to evaluate the relationship between the reciprocal of t 1/2 ( the half life of crystallization) and the appropriate temperature variable. The parameters such as the activation energy (Ed) for transport, the equilibrium melting temperature (T_m^0),the nucleation parameter (ψ),themaximum crystallization temperature (T_(e, max)), and the kinetic crystallizability (G) for the copolyesters were obtained. The influence of the PEG content in PET chains on the parameters characterizing crystallization kinetics and crystallization thermodynamics was discussed.
文摘The curing process of dendritic polymer PAMAM with bis-phenol A epoxy resin was investigated using isothermal differential scanning calorimetry(DSC),the mechanism of this reaction was autocatalytic.The data of two reaction rate constants k1,k2 and reaction orders m,n were obtained from Kamal equation.The overall reaction order m+n was between 2.07 and 2.29,the apparent activation energies of E1 and E2 were 59.79 kJ/mol and 56.51 kJ/mol, respectively.The reaction entered into a diffusion controlled stage at the conversion of 50%,experimental data and theoretic curve had deviation at this time.The reaction conversion,at which the deviation occurred,decreased with lowering curing temperature.
基金National Natural Science Foundation of China(No.20573098)Science and Technology Foundation of the National Defence Key Laboratory of Propellant and Explosive Combustion of China(9140C3501050701)
基金National Natural Science Foundation of China(No.20573098)Science and Technology Foundation of the National Defence Key Laboratory of Propellant and Explosive Combustion of China(9140C3501050701)
文摘通过合理假设,从谢苗诺夫(Semenov)热爆炸理论和8个非等温动力学方程,导出了估算含能材料(EMs)热爆炸临界温度(Tb)的2个通式和它们的6个派生式。从EMs的非等温DSC曲线可获得DSC曲线偏离基线的起始温度(T0)、onset温度(Tei)和放热分解反应的动力学参数。由方程T0ior ei=T00 or e0+a1βi+a2βi2+…+aL-2βiL-2,i=1,2,…,L可得到T00和Te0值,随后用6个派生式可计算Tb值。对1,4,5,8-四硝基-1,4,5,8-四氮杂双呋咱[3,4-c:3′,4′-h]十氢化萘,1,4,5,8-四氮杂双呋咱[3,4-c:3′,4′-h]十氢化萘,1,3,4-三硝基咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,1,3,4,8-四硝基咪唑烷酮[4,5-b]呋咱[3,4-e]哌嗪,1,4,5,8-四硝基-1,4,5,8-四氮杂萘呋咱[3,4-b]十氢化萘,1,3,5-三硝基-1,3,5-三氮杂呋咱[3,4-f]环庚烷,由6个派生式所得的Tb值甚接近。