Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resista...Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.展开更多
NaA zeolite with average particle size of 1 μm was successfully synthesized by microwave heating. Influences of pre-crystallization time, microwave power and microwave heating time on the synthesis of NaA zeolite wer...NaA zeolite with average particle size of 1 μm was successfully synthesized by microwave heating. Influences of pre-crystallization time, microwave power and microwave heating time on the synthesis of NaA zeolite were investigated. The as-synthesized sample was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and particle size distribution （PSD）. Thermal and flame retardant properties as intumescent flame retardant （IFR） in chloroprene rubber （CR） system, such as thermogravimetry （TG）, limiting oxygen index （LOI）, burning rate （BR） and specific extinction area （SEA） were further investigated by adding NaA zeolite particles to CR. Experimental results show that the thermal stability and LO1 value increased while BR and SEA decreased by adding 5 phr NaA zeolite into the 40 phr IFR filled CR system.展开更多
基金funded by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(No.N2023J053).
文摘Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.
基金the financial support of the National Natural Science Foundation of China (No. 20976057)
文摘NaA zeolite with average particle size of 1 μm was successfully synthesized by microwave heating. Influences of pre-crystallization time, microwave power and microwave heating time on the synthesis of NaA zeolite were investigated. The as-synthesized sample was characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and particle size distribution （PSD）. Thermal and flame retardant properties as intumescent flame retardant （IFR） in chloroprene rubber （CR） system, such as thermogravimetry （TG）, limiting oxygen index （LOI）, burning rate （BR） and specific extinction area （SEA） were further investigated by adding NaA zeolite particles to CR. Experimental results show that the thermal stability and LO1 value increased while BR and SEA decreased by adding 5 phr NaA zeolite into the 40 phr IFR filled CR system.
