| Ethylene-tetra-fluoro-ethylene(ETFE)insulated wire and cable has the advantages of high temperature resistance,radiation resistance,light weight,etc.,which is becoming one of the main varieties of aerospace cables.However,compared with polytetrafluoroethylene(PTFE),ETFE also has shortcomings such as low temperature resistance and poor mechanical properties,while the existing irradiated cross-linked ethylene-tetrafluoroethylene copolymer(XETFE)is unable to meet requirement of use because of insufficient degree of cross linking.The fundamental reason is that none of the existing cross-linking sensitizers can meet the processing requirements of ETFE under extreme conditions.In this paper,we have prepared a novel cross-linked sensitizer(HLC)and explored the effect of different concentration HLC and irradiation dose on XETFE.1.The novel sensitizer HLC was prepared by structural analysis of Triallyl Cyanurate(TAC)and Triallyl Isocyanurate(TAIC).The successful preparation of HLC can be proved by analysis of FT-IR and 1H-NMR.Based on the result of DSC,HLC melting point and self-polymerization temperature have risen apparently to150 ? and 350 ? respectively,which can meet the processing requirements of ETFE compared with the marketing sensitizers TAC and TAIC.According to the results of TG,the structure of HLC is stable,the volatilization is greatly reduced,and the decomposition temperature is 400?.HLC effectively solve the problems of the existing sensitizers in terms of self-polymerization,thermal stability,high temperature volatilization,etc.,which provides the feasibility for the irradiation crosslinking of ETFE.2.We have investigated the different between HLC and existing sensitizers(TAC?TAIC and TMAIC)in the market.Moreover,the tests results of mechanical properties,thermal stability,melting crystallization behavior and thermal weight proved that the new sensitizer HLC can promote the irradiation crosslinking of ETFE.Though,both the existing sensitizer TAC ? TAIC and TMAIC can promote thecrosslinking of ETFE irradiation to varying degrees,it still leads to its general crosslinking effect due to its insufficient self-polymerization and thermal stability,which can not meet the existing requirements.3.We have studied the effect of the concentration of the new sensitizer HLC and irradiation dose on ETFE irradiation cross-linking.Through the analysis of the mechanical properties,thermal stability,melting crystallization behavior and thermal load of the material,it was found that XETFE(ETFE-2% HLC-10)obtained under the conditions of HLC dosage of 2wt% and irradiation dose of 10 Mrad is the best.The mechanical performance analysis results show that the tensile strength of ETFE-2%HLC-10 rises to 43 Mpa,and the elongation at break remains 225%;the results of thermogravimetric analysis show that the initial decomposition temperature is increased to 461.25 °C,which is 23 °C higher than ETFE-10.The melting crystallization behavior results show that the melting point,enthalpy of melting ?Hf and crystallization of ETFE-2%HLC-10 are significantly reduced,which proves that the degree of cross-linking has been greatly improved.Thermal load test results show that even under high load weight(40 times),the sample ETFE-2% HLC-10 will not break after being stretched to 10 cm.When placing the sample after the load test at300 ° C after 5 minutes,the sample will quickly rebound to the original length of 5cm,while ETFE obtained under other conditions will break. |
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