Instead of the traditional isocyanate curing system as the binder of solid propellant, a triazole curing system has been developed by the reaction of azide group and alkynyl group due to a predominant advantage of avoiding to the interference of humidity. In this work, the propargyl-terminated polybutadiene (PTPB) was blended with glycidyl azide polymers (GAPs) to produce new composites under the catalysis of cuprous chloride at ambient temperature. The triazole-crosslinked network structure was regulated by changing the molar ratio of azide group in GAP versus alkynyl group in PTPB, and hence various crosslinked densities together with the composition changes of GAP versus PTPB cooperatively determined the mechanical properties of the resultant composites. Furthermore, the formed triazole-crosslinked network derived from the azide group in GAP and alkynyl group in PTPB resulted in the slight increase of glass transition temperatures and a-transition temperatures, and improved the miscibility between GAP and PTPB.

No abstract

An efficient way to synthesize α-FeOOH from pickling wastewater in a falling film tower was proposed for the first time. This method overcomes the shortcomings of the traditional air oxidation method, and its production efficiency is increased by 16 times. The purity of α-FeOOH synthesized from pickling wastewater can reach 96.3%, and the iron recovery rate is greater than 90%. At the same time, we have systematically studied its kinetics in the falling film tower. The reaction rate constant k at different temperatures was also determined with the activation energy E a = 32.2497 kJ/mol and the pre-exponential A = 47.4132 s −1 . In addition, based on the double-film theory, a corresponding macrokinetic model was established. Also, the Hatta number in the reaction system was obtained, which proved the excellent gas− liquid mass transfer performance in the falling film tower. This work provides a promising method for the efficient production of α-FeOOH and the recycling of pickling wastewater.

The aim of this study was to clarify the effects of acrylamide on mechanical and tribological properties of short carbon fiber-reinforced bisphenol-A-type epoxy composites. The short carbon fiber/epoxy-based composites with or without acrylamide were prepared by solution blending and moderate temperature-curing techniques. Obviously, the short carbon fiber resulted in the enhancement of flexural strength and modulus of the short carbon fiber/epoxy-based composites in contrast to the epoxy-based composites. When the loading-level of short carbon fiber was 8 parts (corresponding to 100 parts of the epoxy matrix), the short carbon fiber 8/epoxy composites containing the same loading-level of acrylamide showed the highest flexural strength and modulus. At the same time, it was found that the addition of acrylamide further improved strength, modulus of the short carbon fiber/epoxy-based composites. Furthermore, the friction coefficient values of the acrylamide-modified short carbon fiber 8/epoxy composites were lower than that without the addition of acrylamide. The worn morphologies observed by scanning electron microscope revealed that the wear mechanism of the acrylamide-modified short carbon fiber 8/epoxy composites was fatigue wear.

While designing a machine, special design requirements are influenced by various restraint factors in practice. The evaluation of its scheme usually features multi-levels, multi-attributes and a mixed type of both qualitative and quantitative indices. Therefore, this paper focused on the evaluation of the machine design scheme and provided an evaluation method of the machine design scheme based on information content measurement model. This model firstly performed an analysis of all the factors that influence the design application and brought about an evaluation index system on the basis of information independence. Secondly, the model obtained the entire information content of the scheme by establishing information content calculating models of multi-level evaluation indices, and achieved the optimization analysis of machine design scheme on the basis of different amount of information content. Finally, the paper examined the effectiveness of the model with the application example.