| In the drawing process of glass fiber(GF),it usually should be coated by sizing agent,which can not only repair the large number of micro cracks on the surface of glass fiber,but also improve the interfacial compatibility between glass fiber and resin matrix and have a good interface.Adding nano-particles to sizing agent can improve the mechanical properties of composite and effects of energy transfer.Based on the stability principle of Pickering emulsion,using modified nano-SiO2 particles and surfactant as the mixed emulsifier system and phenolic epoxy vinyl ester resin(VE)as the primary resin,the film former emulsion was prepared by phase inversion emulsification method,which greatly decreased the amounts of emulsifier.The best emulsification conditions were as follows:the mass ratio of Cetyl trimethyl ammonium bromide(CTAB)and polyoxyethylene castor oil(EL-40)was 1:3,mass ratio of emulsifiers was 4%,addition of modified nano-SiO2 particles was 2%of resin weight,the using weight of KH-550 was 4%of SiO2 and shear rate was 8000r/min.The average particle size of the emulsion was 0.102μm.The sediment weight fraction was 88.1%.Compared with emulsion without nano-SiO2,the ability of acid and alkali resistance and heat resistance of the emulsion with nano-SiO2 particles were improved.Using the vinyl resin emulsion containing different amounts of nano-SiO2 particles as the main film former,choosing other sizing agent components through reasonable selection,four different sizing agent formulas were configured.When the sizing rate of glass fiber was 1%,compared with glass fiber coated with sizing agent formula without nano-SiO2 particles,the stiffness and cluster of glass fiber,the ability of corrosion resistance and fracture strength of glass fiber coated with nano-SiO2 particles in sizing agent formula were all improved obviously.By scanning electron microscope,surface of glass fiber coated with sizing agent formula with nano-SiO2 particles was covered with a layer of uniform nano particles.By energy dispersion spectrum analysis,the particles on the surface of glass fiber were confirmed to be modified nano-SiO2 particles.Interlaminar shear strength(ILSS)test of composite showed that the ILSS of desized GF/VE was minimum,24.86MPa.After coated with different sizing agent formula,ILSS of GF/VE composite had different degrees of improvement.Compared to the desized GF/VE composite,the ILSS of GF/VE which coated with sizing agent formula 1 without nano-SiO2 particles increased by 14%,up to 28.34MPa,which was slightly lower than commercial GF/VE(28.74MPa).ILSS of GF/VE composite coated with sizing agent formula 3 which contained 2%nano-SiO2 particles is highest,up to 31.74MPa,and increased by 12%compared with formula 1.This was mainly because of the added nano-SiO2 particles covered on the surface of glass fiber uniformly,which increased the roughness of glass fiber and the effective contact areas between glass fiber and resin matrix,enforced the mechanical chimeric role and finally increased the interface bonding strength and meanwhile the fracture surface was rough and had a large fracture area.The resin could penetrate in glass fiber smoothly and the interface bond between glass fiber and resin was very good,so that the bonding performance between glass fiber and resin was the best.On the contrary,interface debonding happened seriously between desized glass fiber and resin matrix.A lot of glass fiber was pulled out from the resin matrix with little resin fraction adhesion,which showed that there was a poor interface between desized glass fiber and resin matrix. |
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