The search for new green and efficient stabilizers is of great importance for the stabilization of nitrocellulose(NC). This is due to the shortcomings of traditional stabilizers, such as high toxicity. In this study, ...The search for new green and efficient stabilizers is of great importance for the stabilization of nitrocellulose(NC). This is due to the shortcomings of traditional stabilizers, such as high toxicity. In this study, reduced polyaniline(r-PANI), which has a similar functional structure to diphenylamine(DPA) but is non-toxic, was prepared from PANI based on the action with N_(2)H_(4) and NH_(3)-H_(2)O, and used for the first time as a potential stabilizer for NC. XPS, FTIR, Raman, and SEM were used to characterize the reduced chemical structure and surface morphology of r-PANI. In addition, the effect of r-PANI on the stabilization of NC was characterized using DSC, VST, isothermal TG, and MMC. Thermal weight loss was reduced by 83% and 68% and gas pressure release by 75% and 49% compared to pure NC and NC&3%DPA, respectively.FTIR and XPS were used to characterize the structural changes of r-PANI before and after reaction with NO_(2). The 1535 cm^(-1) and 1341 cm^(-1) of the FTIR and the 404.98 eV and 406.05 eV of the XPS showed that the -NO_(2) was generated by the absorption of NO_(2). Furthermore, the quantum chemical calculation showed that NO_(2) was directly immobilized on r-PANI by forming -NO_(2) in the neighboring position of the benzene ring.展开更多
Nitrocellulose,or cellulose nitrate,has received considerable interest due to its various applications,such as propellants,coating agents and gas generators.However,its high mechanical sensitivity caused many accident...Nitrocellulose,or cellulose nitrate,has received considerable interest due to its various applications,such as propellants,coating agents and gas generators.However,its high mechanical sensitivity caused many accidents during its storage and usage in ammunition.In this work,two kinds of insensitive step ladderstructured nitrocellulose(LNC)with different nitrogen contents were synthesized.The products were characterized by FT-IR,Raman,XRD,SEM,elemental analysis,TGA,DSC,accelerating rate calorimeter analysis(ARC),and drop weight test to study their molecular structure,thermal characteristics and desensitization performance.Compared with raw nitrocellulose,LNC has a sharper exothermic peak in the DSC and ARC curves.The H50values of the two kinds of LNC increased from 25.76 to 30.01 cm for low nitrogen content and from 18.02 to 21.84 cm for high nitrogen content,respectively.The results show that the ladder-structure of LNC which provides regular molecular arrangement and a soft buffer made with polyethylene glycol could affect the energy releasing process of LNC and reduce the sensitivity of LNC.Insensitive LNC provides an alternative to be used as a binder in insensitive propellants formulation.展开更多
A series of fullerene anisole derivative stabilizers was synthesized by nucleophilic substitution reaction using hexachlorofullerene and benzyl alcohol as raw materials to extend the service duration of nitrocellulose...A series of fullerene anisole derivative stabilizers was synthesized by nucleophilic substitution reaction using hexachlorofullerene and benzyl alcohol as raw materials to extend the service duration of nitrocellulose(NC)-based propellants.Single-crystal X-ray diffraction,nuclear magnetic resonance,highresolution mass spectrometry,Fourier transform infrared(FT-IR)spectroscopy,and UV-Vis spectroscopy were used to characterize the structures of the synthesized fullerene anisole derivative stabilizers.Methyl violet,differential scanning calorimetry test,isothermal weight loss,vacuum stability test,and adiabatic accelerated test were used to study their compatibility with NC and their ability to stabilize NC.The results show that the designed and synthesized novel fullerene anisole derivative stabilizer has good compatibility with NC,and their overall stabilizing effects on NC are better than those of the traditional stabilizers,diphenylamine(DPA),and N,N’-dimethyl-N,N’-diphenylurea(C2).The stabilizing effects was ranked as:3b>2d>2a>2c>C2>2b>DPA>NC.In addition,FT-IR analysis and electron spin resonance spectroscopy were applied to explore the stability mechanism of fullerene-based stabilizers to NC.The results reveal that the new fullerene stabilizer can adsorb and effectively eliminate the nitrogen oxide free radicals generated by NC degradation;therefore,it can forbid the autocatalytic degradation of NC and stabilize NC.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
In this study,to better understand the reaction mechanism between inorganic salts and nitrocellulose,CaCO_(3) and Li_(2)CO_(3) were evaluated with respect to their effects on the thermal degradation of NC in nitrogen ...In this study,to better understand the reaction mechanism between inorganic salts and nitrocellulose,CaCO_(3) and Li_(2)CO_(3) were evaluated with respect to their effects on the thermal degradation of NC in nitrogen atmosphere using TG/DSC at three different heating rates(2,5,10 K/min).The numerical relationship between activation energy(E)and conversion rate was obtained by FWO and KAS method,and it was discovered that CaCO_(3) could improve the thermal stability of NC.Activation energy values were calculated by Kissinger method,and it was found that NC that contain Li2CO3had the highest activation energy while NC containing CaCO3had the lowest E value.By combining the thermal analysis data with Malek method,the most probable mechanism model of thermal degradation is obtained as Sesták-Berggren model,which expression is f(α)=α^(m)(1-α)^(n).As a result of this study,there are certain guiding principles that can be applied to the pyrolysis reaction model and to the actual production process of nitrocellulose.展开更多
The transition metal complexes of triaminoguanidine(TAG-M,where M=Cobalt(Co)or Iron(Fe))have been prepared.The catalytic effect of these complexes on the thermolysis of energetic composite based on nitrocellulose and ...The transition metal complexes of triaminoguanidine(TAG-M,where M=Cobalt(Co)or Iron(Fe))have been prepared.The catalytic effect of these complexes on the thermolysis of energetic composite based on nitrocellulose and diethylene glycol dinitrate,has been investigated.Extensive characterization of the resulting energetic composites was carried out using scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and differential scanning calorimetry(DSC).Isoconversional kinetic analysis was performed to determine the Arrhenius parameters associated with the thermolysis of the elaborated energetic formulations.It is found that TAG-M complexes have strong catalytic effect on the thermo-kinetic decomposition of NC/DEGDN by decreasing the apparent activation energy and significantly increased the total heat release.The models that govern the decomposition processes are also studied,and it is revealed that different reaction processes are accomplished by introduction metal complexes of triaminoguanidine.Overall,this study serves as a valuable reference for future research focused on the investigation of catalytic combustion features of solid propellants.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.22305123)。
文摘The search for new green and efficient stabilizers is of great importance for the stabilization of nitrocellulose(NC). This is due to the shortcomings of traditional stabilizers, such as high toxicity. In this study, reduced polyaniline(r-PANI), which has a similar functional structure to diphenylamine(DPA) but is non-toxic, was prepared from PANI based on the action with N_(2)H_(4) and NH_(3)-H_(2)O, and used for the first time as a potential stabilizer for NC. XPS, FTIR, Raman, and SEM were used to characterize the reduced chemical structure and surface morphology of r-PANI. In addition, the effect of r-PANI on the stabilization of NC was characterized using DSC, VST, isothermal TG, and MMC. Thermal weight loss was reduced by 83% and 68% and gas pressure release by 75% and 49% compared to pure NC and NC&3%DPA, respectively.FTIR and XPS were used to characterize the structural changes of r-PANI before and after reaction with NO_(2). The 1535 cm^(-1) and 1341 cm^(-1) of the FTIR and the 404.98 eV and 406.05 eV of the XPS showed that the -NO_(2) was generated by the absorption of NO_(2). Furthermore, the quantum chemical calculation showed that NO_(2) was directly immobilized on r-PANI by forming -NO_(2) in the neighboring position of the benzene ring.
基金supported in part by the National Natural Science Foundation of China(No.22075146)。
文摘Nitrocellulose,or cellulose nitrate,has received considerable interest due to its various applications,such as propellants,coating agents and gas generators.However,its high mechanical sensitivity caused many accidents during its storage and usage in ammunition.In this work,two kinds of insensitive step ladderstructured nitrocellulose(LNC)with different nitrogen contents were synthesized.The products were characterized by FT-IR,Raman,XRD,SEM,elemental analysis,TGA,DSC,accelerating rate calorimeter analysis(ARC),and drop weight test to study their molecular structure,thermal characteristics and desensitization performance.Compared with raw nitrocellulose,LNC has a sharper exothermic peak in the DSC and ARC curves.The H50values of the two kinds of LNC increased from 25.76 to 30.01 cm for low nitrogen content and from 18.02 to 21.84 cm for high nitrogen content,respectively.The results show that the ladder-structure of LNC which provides regular molecular arrangement and a soft buffer made with polyethylene glycol could affect the energy releasing process of LNC and reduce the sensitivity of LNC.Insensitive LNC provides an alternative to be used as a binder in insensitive propellants formulation.
基金financial support received from the Natural Science Foundation of China(Grant No.51972278)Outstanding Youth Science and Technology Talents Program of Sichuan(Grant No.19JCQN0085)Open Project of State Key Laboratory of Environment-friendly Energy Materials(Southwest University of Science and Technology,Grant No.20fksy16)。
文摘A series of fullerene anisole derivative stabilizers was synthesized by nucleophilic substitution reaction using hexachlorofullerene and benzyl alcohol as raw materials to extend the service duration of nitrocellulose(NC)-based propellants.Single-crystal X-ray diffraction,nuclear magnetic resonance,highresolution mass spectrometry,Fourier transform infrared(FT-IR)spectroscopy,and UV-Vis spectroscopy were used to characterize the structures of the synthesized fullerene anisole derivative stabilizers.Methyl violet,differential scanning calorimetry test,isothermal weight loss,vacuum stability test,and adiabatic accelerated test were used to study their compatibility with NC and their ability to stabilize NC.The results show that the designed and synthesized novel fullerene anisole derivative stabilizer has good compatibility with NC,and their overall stabilizing effects on NC are better than those of the traditional stabilizers,diphenylamine(DPA),and N,N’-dimethyl-N,N’-diphenylurea(C2).The stabilizing effects was ranked as:3b>2d>2a>2c>C2>2b>DPA>NC.In addition,FT-IR analysis and electron spin resonance spectroscopy were applied to explore the stability mechanism of fullerene-based stabilizers to NC.The results reveal that the new fullerene stabilizer can adsorb and effectively eliminate the nitrogen oxide free radicals generated by NC degradation;therefore,it can forbid the autocatalytic degradation of NC and stabilize NC.
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the National Natural Science Foundation of China(NSFC,Grants No.52176114 and 52111530091)Jiangsu Funding Program for Excellent Postdoctoral Talent。
文摘In this study,to better understand the reaction mechanism between inorganic salts and nitrocellulose,CaCO_(3) and Li_(2)CO_(3) were evaluated with respect to their effects on the thermal degradation of NC in nitrogen atmosphere using TG/DSC at three different heating rates(2,5,10 K/min).The numerical relationship between activation energy(E)and conversion rate was obtained by FWO and KAS method,and it was discovered that CaCO_(3) could improve the thermal stability of NC.Activation energy values were calculated by Kissinger method,and it was found that NC that contain Li2CO3had the highest activation energy while NC containing CaCO3had the lowest E value.By combining the thermal analysis data with Malek method,the most probable mechanism model of thermal degradation is obtained as Sesták-Berggren model,which expression is f(α)=α^(m)(1-α)^(n).As a result of this study,there are certain guiding principles that can be applied to the pyrolysis reaction model and to the actual production process of nitrocellulose.
文摘The transition metal complexes of triaminoguanidine(TAG-M,where M=Cobalt(Co)or Iron(Fe))have been prepared.The catalytic effect of these complexes on the thermolysis of energetic composite based on nitrocellulose and diethylene glycol dinitrate,has been investigated.Extensive characterization of the resulting energetic composites was carried out using scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),and differential scanning calorimetry(DSC).Isoconversional kinetic analysis was performed to determine the Arrhenius parameters associated with the thermolysis of the elaborated energetic formulations.It is found that TAG-M complexes have strong catalytic effect on the thermo-kinetic decomposition of NC/DEGDN by decreasing the apparent activation energy and significantly increased the total heat release.The models that govern the decomposition processes are also studied,and it is revealed that different reaction processes are accomplished by introduction metal complexes of triaminoguanidine.Overall,this study serves as a valuable reference for future research focused on the investigation of catalytic combustion features of solid propellants.
