The Study Of Reactive End Groups Liquid Fluoroelastomer Curing And Properties

Fluoroelastomer exhibits a series of excellent performances such as good resistance to chemical reagents oil and thermostability, which is a kind of rubber with self-extinguishing function. Now fluoroelastomer has been used widely in defense, cars, aerospace, petrochemical and other fields. Liquid fluoroelastomer not only has these advantages but also can be processed easily. Therefore, studying the curing of liquid fluoroelastomer is very meaningful. In this article at the basic of the prepared carboxyl and hydroxyl-terminated liquid fluoroelastomer by our laboratory. The curing behaviors and properties of liquid fluoroelastomer were studied. For the curing of carboxyl-terminated liquid fluoroelastomer, we chose polycarbodiimide as the crosslinking for the aim of curing under low temperature. For the curing of hydroxyl-terminated liquid fluoroelastomer, we chose the way of introducing hydroxyl-terminated liquid fluoroelastomer in polyurethane. The curing processes were studied by IR, GPC and DSC. The solvent resistance mechanical properties and heat resistance of the cured product were studied. The main results were as follow.The curing system of polycarbodiimide and carboxyl-terminated liquid fluoroelastomer were characterized by IR spectrum and DSC methods. The results showed that the curing system could react under temperature from room temperature to 50 ℃. The best curing condition was determined. The effect of added amount of curing agent on mechanical properties and solvent resistance were analyzed, and the results showed that the properties were best when the quality of polycarbodiimide and the quality of carboxyl group content of liquid fluoroelastomer were in the ratio of 100:1. Under the optimum radio, the effect of molecular weight and carboxyl group content of liquid fluoroelastomer on mechanical properties were analyzed. Liquid fluoroelastomer with the high molecular weight and carboxyl group content had good properties after being cured. High and low temperature resistance performance was studied by DMTA and TGA.The product, carboxyl-terminated liquid fluoroelastomer, and MDI were characterized by IR spectrum and DSC methods. The results showed that the product was what we expected. The optimum conditions of synthesis of fluorinated polyurethane performed polymer were as follow. Under the protection of N2, ethyl acetate was used as solvent, and the amount of catalyst was 50ppm, and the reaction was carried out for four hours at 80 degrees.When the reaction of modified polyurethane system and hydroxyl-terminated liquid fluoroelastomer was considered, the effects of added amount of hydroxyl-terminated liquid fluoroelastomer and different synthesis methods of prepolymer on the properties of modified polyurethane were analyzed. Performance studies included static and dynamic mechanical properties, heat resistance, and water resistance, crystallinity, etc. The results indicated that the optimum of addition amount of hydroxyl-terminated liquid fluoroelastomer was that the ratio of the amount of hydroxyl terminated liquid hydroxyl group to the amount of the hydroxyl group of PTMG was 1:6. Static mechanical properties and dynamic mechanical properties were better by the way of XPHF.