The electrocatalytic N 2 reduction reaction (ENRR) to ammonia has attracted much attention due to the mild operating conditions, in which the Nafion membrane is generally adopted to separate the ammonia from the anode products. However, it has been mentioned that the Nafion membrane allows ammonia to pass through and traps the ammonia to some extent, but powerful confirmation experiments and effective solutions are still lacking. Herein, it is experimentally confirmed that the use of the Nafion membrane in the ENRR is inappropriate, based on the results that the ammonia can pass through the membrane, be adsorbed on the membrane, and interact with the membrane. This causes a measurement error and accelerates the membrane degradation process, which is unfavorable for ammonia quantification and the long-term stability operation of the ENRR in practical application. Also, for the first time, a more accurate method to evaluate the activity of the ENRR electrocatalyst using a salt bridge to replace the Nafion membrane is presented.
A novel method was developed to determine the ultra-low glass transition temperature ( T g ) of materials through physical blending via differential scanning calorimetry . According to the Fox equation for polymer blends , a blend of two fully compatible polymers has only one T g . The single T g is a function of the T g s of the two simple polymers. Thus, the ultra-low T g of one material can be obtained from the T g s of another polymer and their blends. The error of T g measurements depends on the measurement error of the T g s for the blends and another polymer. The method was successfully applied to determine the T g s of acetyl tributyl citrate (ATBC), tributyl citrate (TBC) and poly(ethylene glycol)s (PEG)s with different molecular weights . The T g s for ATBC, TBC, PEG-4000 and PEG-800 were −57.0 °C, −62.7 °C, −76.6 °C and −83.1 °C, respectively. For all the samples, the standard deviation of measurements was less than 3.3 °C, and the absolute error of measurements was theoretically not more than 5.3 °C. These results indicate that this method has acceptable precision and accuracy.
Guixiang Xie,Yaqi Lu,Xiaochun Lu,Zhusen Zhang,Shuidong Lin
Thermogravimetric analysis (TGA) has been extensively applied in polymeric characterization and quality inspection, facilitating in-depth investigations of the microstructural thermal response characteristics of polymers, including thermal stability, composition analysis, and thermal decomposition mechanisms. Here, the impacts of six factors on the TG thermal analysis curves obtained during operation are systematically examined while analyzing their causes and recommending solutions. Furthermore, the thermal degradation kinetics of an ionomer formed by neutralizing an ethylene–methacrylic acid copolymer with metal ions (SGP membrane) used in laminated tempered glass is analyzed using the Arrhenius equation, Ozawa–Flynn–Wall hypothesis and Kissinger method. Kinetic parameters at 5% degradation are fitted and used to predict the service lifetime of the SGP membrane. The results indicate that the SGP membrane sample exhibits activation energyEa= 136.90 kJ/mol, reaction ordern= 1.65 and pre-factorA= e25.93. It can be seen that the service lifetime of the SGP membrane sample is 16 years at 80 °C and 1.65 years at 100 °C.
危险品化学品经营许可证（带存储）