Conventional plasticizers deteriorate mechanical and viscoelastic properties of the propellants due to their migration upon aging and long-term storage,which affects reliability and safety properties during exploitati...Conventional plasticizers deteriorate mechanical and viscoelastic properties of the propellants due to their migration upon aging and long-term storage,which affects reliability and safety properties during exploitation.To address this issue,conventional plasticizer,dioctyl adipate(DOA),is replaced by reactive one,castor oil(CO).In addition,three different types of HTPB were used to obtain propellants with designed viscoelastic and mechanical properties.The CO increased propellants viscosity,without a significant impact on the propellant processability,regardless to the type of prepolymer.Conversely,mechanical properties were different depending on the type of resin,which were further analyzed by gel permeation chromatography(GPC).Addition of CO formed a denser polymer network and shifted T_(g) to higher values,compared to the compositions with DOA.The tensile strength of CO-containing propellants was lower at +20℃ and +50℃ compared to the reference compositions,while the strain at maximum load and strain at break were significantly increased with pronounced plastic deformation,especially for samples at -30℃.The inclusion of CO in the propellants composition gives more room for adjusting a wide range of mechanical properties.展开更多
Active volatile components in drug pair(DP)Herba Ephedrae-Ramulus Cinnamomi(HE-RC),single drug HE and RC were analyzed by gas chromatography/mass spectrometry(GC/MS),chemometric resolution method(CRM)and overall volum...Active volatile components in drug pair(DP)Herba Ephedrae-Ramulus Cinnamomi(HE-RC),single drug HE and RC were analyzed by gas chromatography/mass spectrometry(GC/MS),chemometric resolution method(CRM)and overall volume integration.By means of CRM,the two-dimensional data obtained from GC-MS instruments were resolved into a pure chromatogram and a mass spectrum of each chemical compound.In total,97,62,and 78 volatile chemical components in volatile oil of HE,RC,and DP HE-RC,were respectively determined qualitatively and quantitatively,accounting for 90.08%,91.62%,and 89.76% total contents of volatile oil of HE,RC,and DP HE-RC respectively.It is further demonstrated that the numbers of volatile components of DP HE-RC are almost the sum of those of two single drugs,but some relative contents of them are changed.Some new components,such as 1,6-dimethylhepta-1,3,5-triene,tetracyclo[4.2.1.1(2,5).0(9,10)]deca-3,7-diene,globulol and(E,E)-6,10,14-trimethyl-5,9,13-pentadecatrien-2-one are found in DP HE-RC because of chemical reactions and physical changes during decoction.展开更多
A GC-MS method for the determination of 27 organochlorine pesticides and 15 Pyrethroid pesticides in animal food is established.The method was based on Gel Permeation chromatography combined with solid-phase extractio...A GC-MS method for the determination of 27 organochlorine pesticides and 15 Pyrethroid pesticides in animal food is established.The method was based on Gel Permeation chromatography combined with solid-phase extraction for sample preparation.Rapid qualitative and quantitative analyses was carried out by gas chromatography-mass spectrometry under the selective-ion monitoring mode.The experimental results showed that the correlation coefficients were better than 0.99,the recoveries for spiked standards were 70%-104%,the relative standard deviations were 2.1%-15.9%.展开更多
基金the support of this research from the Serbian Ministry of Education,Science and Technological Development(Grant No.451-03-68/2023-14/200325)Ministry of Defense(Grant No.VA-TT/1/22-24)。
文摘Conventional plasticizers deteriorate mechanical and viscoelastic properties of the propellants due to their migration upon aging and long-term storage,which affects reliability and safety properties during exploitation.To address this issue,conventional plasticizer,dioctyl adipate(DOA),is replaced by reactive one,castor oil(CO).In addition,three different types of HTPB were used to obtain propellants with designed viscoelastic and mechanical properties.The CO increased propellants viscosity,without a significant impact on the propellant processability,regardless to the type of prepolymer.Conversely,mechanical properties were different depending on the type of resin,which were further analyzed by gel permeation chromatography(GPC).Addition of CO formed a denser polymer network and shifted T_(g) to higher values,compared to the compositions with DOA.The tensile strength of CO-containing propellants was lower at +20℃ and +50℃ compared to the reference compositions,while the strain at maximum load and strain at break were significantly increased with pronounced plastic deformation,especially for samples at -30℃.The inclusion of CO in the propellants composition gives more room for adjusting a wide range of mechanical properties.
基金Project (01962502) supported by the Natural Science Foundation of Hunan Province, China
文摘Active volatile components in drug pair(DP)Herba Ephedrae-Ramulus Cinnamomi(HE-RC),single drug HE and RC were analyzed by gas chromatography/mass spectrometry(GC/MS),chemometric resolution method(CRM)and overall volume integration.By means of CRM,the two-dimensional data obtained from GC-MS instruments were resolved into a pure chromatogram and a mass spectrum of each chemical compound.In total,97,62,and 78 volatile chemical components in volatile oil of HE,RC,and DP HE-RC,were respectively determined qualitatively and quantitatively,accounting for 90.08%,91.62%,and 89.76% total contents of volatile oil of HE,RC,and DP HE-RC respectively.It is further demonstrated that the numbers of volatile components of DP HE-RC are almost the sum of those of two single drugs,but some relative contents of them are changed.Some new components,such as 1,6-dimethylhepta-1,3,5-triene,tetracyclo[4.2.1.1(2,5).0(9,10)]deca-3,7-diene,globulol and(E,E)-6,10,14-trimethyl-5,9,13-pentadecatrien-2-one are found in DP HE-RC because of chemical reactions and physical changes during decoction.
文摘A GC-MS method for the determination of 27 organochlorine pesticides and 15 Pyrethroid pesticides in animal food is established.The method was based on Gel Permeation chromatography combined with solid-phase extraction for sample preparation.Rapid qualitative and quantitative analyses was carried out by gas chromatography-mass spectrometry under the selective-ion monitoring mode.The experimental results showed that the correlation coefficients were better than 0.99,the recoveries for spiked standards were 70%-104%,the relative standard deviations were 2.1%-15.9%.
