Kai Qi,Zhenzhen Jin,Dan Wang,Zhenyu Chen,Xingpeng Guo,Yubing Qiu
The degradation of electrochemical activity is the inevitable and noticeable issue in the widespread applications of conducting polypyrrole (PPy), which involves chemical and electrochemical reactions in PPy natural degradation processes. Based on thorough insights into PPy degradation behavior, this work develops a method of theoretical derivation for the natural degradation kinetics model of PPy, which is verified in NaOH aqueous electrolytes and could be further generalized in other media. The kinetics model derives the rate equations of the chemical and electrochemical processes ( v c and v e ) in PPy degradation. The relationships of the electroactivity degradation rate constant ( k deg ) and rate constants of the chemical and electrochemical processes ( k c and k e ) as well as reaction orders of PPy n+ and OH − are established through theoretical deduction. The effects of doping anions in PPy, film thickness, and electrolyte temperature on the degradation kinetics are investigated through theoretical considerations and experimental findings. The degradation level and service failure time of PPy can be effectively predicted using the kinetics model. Establishing the degradation kinetics model would signal the new perspective and depth in comprehensive studies of PPy degradation, finally facilitating the optimization of performance management in PPy practical applications.
Shuai Wang,Anzhe Wang,Pan Gao,Rui Bai,Junjie Liu,Peng Zhou,Dazhao Liu
Strength prediction under the action of pores is crucial for the safety of ceramics. Here, a quantitative prediction model of pore-strength response under mode-I loading was developed based on the new mapping relationship between stress intensity factor and tip radius. The new model was proved to have great application after comparison and analysis of the pore-strength test data of three typical ceramics as well as the pertinent data as-reported in the literature. Results indicated that when the tip radius of pore ( ρ ) exceeds the critical value ( ρ c = K Ic 2 /(π σ 0 2 )), the stress intensity factor increases as a power function with increasing ρ , at which point the strength decay is significantly weakened, and when the ρ is lower than the ρ c , the pore can be equated to a crack problem. This work can not only forecast and assess the failure strength of ceramics containing pores, but also provide guidance for the design of extremely dependable ceramics.
危险品化学品经营许可证（带存储）