M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.I...M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.In this work,the reaction mechanism,thermodynamic analysis,and kinetics of the reaction between M-BPR and HO_(2)were investigated at the CCSD(T)/cc-pVDZ//B3LYP/6-311G(d,p)level of theory coupled with transition state theory.The calculated results indicate that the title reaction can occur on both singlet and triplet potential energy surfaces,and the formation of hydroperoxides and 3O_(2)via triplet state is the main reaction channel,while the other four singlet product channels are negligible due to the higher barrier heights.Additionally,the reaction rate constants are estimated by using the transition state theory over the temperature range of 258 K to 378 K,and reaction rate constants arc found to be negatively correlated with temperature.At 298 K,the total rate constant for the title reaction is 1.86×10^(-11)cm^(3)·molecule^(-1)·s^(-1).The calculated rate constants over the studied temperature range were used to fit the data and the three-parameter Arrhenius ex-studied is obtainted to be k(T)=4.22×10^(-15)·(T/300)^(1.44)·exp(2505/T).展开更多
The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xyl...The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xylene adipamide） （MXD6）/multiwalled carbon nanotube （MWCNT） composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.展开更多
基金the Anhui University of Traditional Chinese Medicine High Level Talent Support Program Project(No.2021rcybO1)the National Natural Science Foundation of China(No.42075113,No.91544228)Scientific Research Program of Higher Education Institutions in Anhui Province(2023AH050836).
文摘M-xylene bicyclic peroxy radical(M-BPR)is an important atmospheric intermediate formed by the oxidation of m-xylene,which plays an important role in the new particle formation and growth of secondary organic aerosol.In this work,the reaction mechanism,thermodynamic analysis,and kinetics of the reaction between M-BPR and HO_(2)were investigated at the CCSD(T)/cc-pVDZ//B3LYP/6-311G(d,p)level of theory coupled with transition state theory.The calculated results indicate that the title reaction can occur on both singlet and triplet potential energy surfaces,and the formation of hydroperoxides and 3O_(2)via triplet state is the main reaction channel,while the other four singlet product channels are negligible due to the higher barrier heights.Additionally,the reaction rate constants are estimated by using the transition state theory over the temperature range of 258 K to 378 K,and reaction rate constants arc found to be negatively correlated with temperature.At 298 K,the total rate constant for the title reaction is 1.86×10^(-11)cm^(3)·molecule^(-1)·s^(-1).The calculated rate constants over the studied temperature range were used to fit the data and the three-parameter Arrhenius ex-studied is obtainted to be k(T)=4.22×10^(-15)·(T/300)^(1.44)·exp(2505/T).
文摘The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xylene adipamide） （MXD6）/multiwalled carbon nanotube （MWCNT） composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.
