| UV curable coatings own the advantages of fast curing,environment-friendly,energy saving and coat saving compared with traditional coatings,and have developed fast in recent years.Nanocomposites prepared by adding nanoparticles into organic coatings can get enhanced properties,such as thermal stability and mechanical property.The UV curable nanocomposite coatings combine the advantages of UV curing technology and nanomaterials together,and propel the application of UV curable coatings.In this study,a series of UV curable epoxy acrylate(EA)nanocomposite coatings were prepared employing polyhedral oligomeric silsesquioxanes(POSS)and organic rectorite(OREC)as the nanoparticles.The microstructure,morphology,UV-curing process and properties of nanocomposite coatings were studied.UV curable EA/POSS nanocomposite coatings were prepared by adding Octa(vinyl)-POSS(Ov-POSS),Glycidyl-POSS(G-POSS)and Methacryl-POSS(M-POSS)into epoxy acrylate UV curable system,respectively.The FTIR analysis indicated that there are cross-links between POSS and polymer matrix,and the acryloyloxy of M-POSS can react with the carbon-carbon double bond of UV curable system through free radical polymerization.POSS aggregates were observed in all the three kind of EA/POSS nanocomposites by SEM,because of the high surface area and surface energy of POSS.G-POSS and M-POSS had better dispersion compared with Ov-POSS,and TEM analysis showed that the diameter of M-POSS aggregates are all less than 100nm.The addition of POSS enhanced the UV-curing rates at initial stage,and besides,G-POSS and M-POSS improved the final double bond conversion.The thermal property,optical property,corrosion resistance and mechanical property of EA/POSS nanocomposite coatings were studied.The results of glass transition temperature(Tg)showed that,the addition of Ov-POSS decreased the Tg of nanocomposites;the addition of G-POSS improved the Tg,and Tg reached to the maximum at the loading of 1wt%and then decreased with the increasing G-POSS loadings;because the chemical bond connections between M-POSS and polymer matrix increased the crosslinking density of nanocomposite costings,the Tg of EA/M-POSS nanocomposites were significantly improved,and nanocomposite containing 5wt%of M-POSS had the highest Tg.TGA analysis showed that POSS reduced the decomposition rate at the later period of thermal decomposition.UV-Vis spectra analysis showed that POSS didn't affect the transparency of nanocomposite coatings at visible region,Ov-POSS and G-POSS enhanced the UV absorption of coatings.EIS was employed to test the corrosion resistance of nanocomposite coatings,the results showed that the addition of POSS enhanced the shielding effect of coatings to electrolyte solution,thus improved the corrosion resistance of nanocomposite coatings.Mechanical properties tests showed that G-POSS and M-POSS didn't bring adverse effects on the hardness of nanocomposite coatings;the impact resistance and flexibility of nanocomposite coatings were improved with the increasing G-POSS loadings;M-POSS enhanced the impact resistance,but decreased the flexibility of nanocomposite coatings greatly.Epoxy acrylate coatings modified with organically modified rectorite were synthesized employing the UV curing technique.Two kinds of alkyl ammonium ions,a long-chain quaternary ammonium salt octadecyltrimethylammonium chloride(OTAC),and a quaternary ammonium salt with reactive functional groups[2-(methacryloyloxy)ethyl]trimethyl-ammonium chloride(MAOTMA),were used as surfactants to modify rectorite.FTIR and XRD analysis showed that both OTAC and MAOTMA were successfully intercalated into the REC interlayers via cation exchange process,and the shorter C-chain of MAOTMA lead to the lower interlayer spacing of MAOTMA-REC compared to OTAC-REC.Both EA/OTAC-REC and EA/MAOTMA-REC nanocomposites formed intercalated structure,and EA/OTAC-REC nanocomposites showed better intercalation effect and dispersion.The addition of OTAC-REC and MAOTMA-REC both decreased the UV-curing rates and final double bond conversion,but the final double bond conversions remained above 80%,even when the loadings of OREC reached up to 10wt%.The thermal property,optical property,corrosion resistance and mechanical property of EA/OREC nanocomposite coatings were studied.The results showed that,the addition of OTAC-REC and MAOTMA-REC both enhanced the Tg of nanocomposite coatings,and the Tg of EA/OTAC-REC nanocomposites was higher than that of EA/MAOTMA-REC nanocomposites.The nanocomposite with 3wt%loading of OTAC-REC had the highest Tg.TGA revealed that the thermal stability of nanocomposites was enhanced by OTAC-REC and MAOTMA-REC,and the thermal stability of EA/MAOTMA-REC nanocomposites was better than that of EA/OTACREC nanocomposites,which is probably because MAOTMA-REC can react with the acrylic resin through polymerization,and formed a strong bonding interaction.UV-Vis spectra analysis showed that OREC decreased the transparency of nanocomposite coatings.EIS analysis showed that,OTAC-REC enhanced the corrosion resistance of nanocomposite coatings effectively,and the nanocomposites with 3 and 5wt%of OTAC-REC have better permeability resistance and higher coating resistance;MAOTMA-REC also enhanced the permeability resistance of coatings,but its permeability resistance to electrolyte solution was far weaker than that of OTAC-REC.Mechanical properties tests showed that,OTAC-REC and MAOTMA-REC didn't bring adverse effects on the hardness of nanocomposite coatings;with the increasing OREC loadings,the degree of cross-cut test decreased slightly and the flexibility of nanocomposite coatings increased significantly.UV curable organic-inorganic heat resistant insulating coatings were prepared by adding various milled fillers into UV curable epoxy acrylate systems.SEM and dynamic light scattering system were employed to analysis the particle size of fillers before and after high-energy ball-milling process.The SEM images of the surface of nanocomposite coatings showed the fillers dispersed in polymer matrix evenly,and there were no agglomeration and other microdefects.The heat resistant insulating coatings had good adhesion,flexibility,hardness,degree of cross-cut and impact resistance.The insulation resistance of coatings with thickness of 5?m was 1420?·mm2,and the insulation resistance of coatings with thickness of 2?m was 955?·mm2.The coatings had a flat surface and showed no obvious defects after annealed at 600? and 750?.The insulation resistance and adhesion of annealed coatings were tested,the results proved the coatings have good heat resistance. |
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