Study On The Interfacial Function Of Polyphosphazene Elastomer And Polyamide Material

For the fiber-reinforced composites,the interfacial properties between the reinforcing fibers and the rubber matrix are the key factors affecting their performance.The polydiaryloxyphosphazene(PDAP)and polydifluoroalkoxyphosphazene(PDFP)elastomers were synthesized.The interfacial properties between Kevlar fiber,nylon 6 fiber,polyimide fiber,polyethylene fiber or carbon fiber and polyphosphazene matrix material were studied.The main part of thesis includes the following key points.1.PDAP and PDFP elastomers were prepared from polydichlorophosphazene via nucleophilic substitution reaction.The structure was thoroughly characterized by NMR,GPC and DSC techniques.Meanwhile,the vulcanization and mechanical properties of the fiber-reinforced polyphosphazene composites were also studied.2.After the successful synthesis of PDAP and PDFP,the interfacial interaction and reinforcing effect between polyphosphazene materials and Kevlar fiber,nylon 6 fiber,PI fiber and PE fiber were conducted.From the single fiber pull-out experiments of several fiber materials in polyphosphazene rubber,the average peel force between amide group-containing Kevlar fiber and PDAP was about 18 N,and that of PDFP is 22 N.The average peel force between amide group-containing nylon 6 fiber and PDAP is about 14 N and that of PDFP is 18 N.However,the peel force for PI is only 5 N?6 N.When it comes to carbon fiber and PDAP/PDFP,the peel force is 10 N?11 N.Corresponding to the SEM results,it can be seen that Kevlar filaments are attached at the interface cracks,and polyphosphazene elastomer material is present to the surface of Kevlar fiber.As a result,the interfacial interaction between polyphosphazene and Kevlar fiber is high.While the surface of PI fibers and carbon fibers is relatively smooth with little polyphosphazene elastomer material attached to the surfaces.Therefore,the interfacial interaction between polyphosphazene and the carbon/PI fibers is weak.3.We peeled the four films from the coating of polyphosphazene elastomer of the interface.It was found that polyphosphazene elastomer material obviously adhered to the surface of Kevlar film and nylon 6 film which both contain the amide group.Through infrared spectroscopy,it was found that there is a P=N stretching vibration peak at 1250 cm-1 and a "red shift" phenomenon exists as a result of hydrogen bonding between the amide group and the polyphosphazene backbone.Hydrogen bonding increases the interfacial interaction between them which result in reinforcement on polyphosphazene elastomer materials.However,PI films and PE films showed no obvious attachment to polyphosphazene,and there was no corresponding absorption peak of phosphazene in the IR spectrum.4.The interfacial tension between the four films and different concentrations of polyphosphazene solution was studied using a fully automatic interfacial tension tester.It was found that Kevlar,nylon 6 and PDAP/PDFP possess strong interfacial forces.Moreover,Kevlar and nylon 6 have the optimum interfacial concentration with PDFP.At this concentration,Kevlar/nylon 6 with amide structure can generate the maximum interfacial force between them and PDFP.The optimum concentration of the PDFP solution corresponds to the strongest interfacial force between Kevlar and PDFP,and the concentration is 10 mg/ml.The optimum concentration of the PDFP solution corresponds to the strongest interfacial force between nylon 6 and PDFP,and the concentration is 7 mg/ml.However,no optimal interfacial concentration was found between Kevlar and nylon 6 with PDAP.5.The interfacial adhesion of polyphosphazene elastomers with four films in the aqueous phase was investigated by adhesion test attachments with dynamic contact angles.These results showed that adhesive strengths of Kevlar and nylon 6 films containing amide groups with polyphosphazenes are similar,and Kevlar and the PDAP/PDFP polyphosphazenes exert a force slightly higher than that of nylon 6,reaching 1.0 g to 1.2 g,compared with the latter force being 0.8 g?1.0 g.However,the adhesive force of PI and PE is only 0.3 g?0.6 g.6.It is considered that there exists hydrogen bonding between the amide groups and polyphosphazene,where the nitrogen and oxygen atoms of the polyphosphazene backbone interact with active hydrogen in amide groups.As a result,polyamide-fiber-reinforced polyphosphazene composites have greatly improved the interfacial properties,showing more excellent characteristics in physical properties and mechanical properties.