| Chlorinated polyethylene(CPE) isobtained by random chlorination of polyethylene(PE),whose molecular chain is basically saturated and side chain is polar chlorine atom.Therefore,CPE has advantage in heat resistance aging resistance, cold resistance, oil resistance, weather resistance, chemical resistance, ozone resistance, free coloring, flame resistance, electrical insulation, mutual viscosity and so on,which makes CPE have a wide range of applications in many fields. But this structure also limits the rate of vulcanization and the choice of the curing system. Now peroxide curing system and thiadiazole system are common curing system in the market,but they have the shortcoming ofnon-vulcanization without mould and expensive cost respectively that restrict the application of materials to a varying extent.Therefore,study on the new curing system of CPE has a certain practical significance.The experiment was conducted by adopting conventional vulcanization and chlorinated polyethylene rubber(CM) under high temperature conditions,and mechanical properties of CM vulcanizate was tested.The result showed that CM vulcanizate displayed significant vulcanization behavior,which demonstrated the feasibility of CPE cured by sulfur. Through the comparison of mechanical properties, the effect of components on the curing process was studied. The result showed that Zn O、TMTD and Lead salt composite system play the most important role in curing. The structure of target product was characterized by Fourier transform infrared spectroscopy,which confirmed that theinteraction between Zinc Oxide and CPE produced double bond that provided the reaction conditions for sulfur curing system. The vulcanization of CPE by sulfur needed harsher condition in such a low content of double bonds in which TMTD was used as accelerator and curing agent at the same timeand was complete in a very short time.The presence of the stabilizer could absorb hydrogen chloride in the system, which restricted the formation of double bond to a certain extent,but the loss of the stabilizer could cause the degradation of materials, which would greatly reduce the mechanical properties of materials.The mechanism for the double bond reaction of CPE induced by ZnO was discussed.Using Lewis acid catalysis theory in the aging of PVC and elimination reaction mechanism of small molecule hydrocarbon in alkaline environment as the starting point,The curing characteristics of CPE compound added with ZnCl2 and Zn(OH)2 respectively were tested. The result showed that both substances contributed to the curing of CPE,the contribution of Zn(OH)2 is mainly at the early stage of vulcanization and the contribution of ZnCl2 is mainly at the late stage of vulcanization. It was found that the pretreatment of ZnO and CPE could shorten the curing time effectively and improve the efficiency of curing.The effects of the amount of ZnO,the pretreatment time and the pretreatment temperature on the curing behavior of the materials were studied.Differential scanning calorimetry(DSC) test showed that the reaction of double bond occurred at about 155 ℃.In this paper, the vulcanization of CPE at low temperature and pressure was successfully carried out by using the curing system.The mechanical properties of CPE could be up to application standard, which provided the possibility for steam curing of the material.Formulation design was carried outby usingrelated indicators of the vehicle hose products as the standard.Under this curing system,the effects of the amount and type of reinforcing agent,cross-linking agent and tackifier on dynamic performance of CPE under high temperature and temperature were studied,which provided theoretical basis for formulation design of the system. |
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