Acrylic emulsion resin is one of popular matrixes for both outside and inside coatings. It has low cost, high UV and weather resistance, good aesthetics and environmentally friendly. The introduction of inorganic additives in nanosize such as SiO2, TiO2, etc. into acrylic emulsion resin could improve the mechanical and thermal properties of the polymer matrix. The surface modification of nanoparticles can enhance the dispersibility of the nanoparticles in the polymer matrix. This paper presents the characteristics of nanosilica modified with different contents of tri(methoxysilyl)propyl methacrylate silane (MPTS) as a coupling agent and the effect of modified nanosilica on the abrasion resistance and thermal properties of acrylic emulsion resin. The infrared (IR) spectroscopy and thermo-gravimetric analysis (TGA) were used to evaluate the presence of MPTS on the surface of modified nanosilica. Grafting yield of MPTS on the surface of nanosilica was calculated from TGA diagrams. The obtained results showed that nanosilica was surface modified successfully by MPTS with a grafting yield of 47 % when using 3 wt.% of MPTS. After modification, the modified nanosilica became more hydrophobic and can disperse well in acrylic emulsion resin. The modified nanosilica improved significantly the abrasion resistance of acrylic coating as compared to neat acrylic resin and acrylic/unmodified silica nanocoating. The MPTS modified nanosilica has the potential to be applied as a reinforcing additive to acrylic emulsion resins to improve its abrasion resistance.
The effect of diane-epoxy resin (DE) and poly(tetrahydrofuran) divinyl ether (DVE) content on the photo crosslinking reaction of the DE/DVE system with triarylsulfonium salt (TAS) as photo-initiator were investigated. The results showed that increasing DVE content improved some of physico-mechanical properties of photocrosslinked coatings although the relative hardness and the speed of photocrosslinking reaction reduced. The results of the changes of functional groups, relative hardness and gel fraction as well as the physico-mechanical properties of UV-cured coatings based on DE/DVE/TAS system illustrated that suitable mass ratio of constituents was 80/20/5. The UV-cured coating based on the system DE/DVE/TAS = 80/20/5 cross-linked completely after 3.6 seconds UV-exposure and having good physico-mechanical properties: impact resistance reached 180 kg.cm; the flexibility obtained 1mm; the adhesion and relative hardness were point 1 and 0.7, respectively.
Effects of CaCO3 content on photocrosslinking and properties of UV‐curable coatings based on epoxy diacrylate resin (EDA), hexanediol diacrylate (HDDA) and photoinitiator I.184 have been studied. It was found that in investigated coatings with the weight ratio EDA/HDDA/I.184 = 50/50/3, CaCO3 content in the range of 10‐40 % provided fine and smooth films in used substrates. The presence of CaCO3 significantly reduced conversion of acrylate groups and quality of the UV‐cured coatings in comparison with the neat one. The increase of CaCO3 content slowed down the photocrosslinking process and inconsiderably affected to properties of investigated coatings in its range of 10‐20 %, but led to obvious decrease of their impact resistance and gloss in its further augment up to 40 %. Coating containing optimal CaCO3 content of 20 % from technical and economical points of view was determined to have gel fraction, relative hardness and gloss of 60o of 90 %; 0.94 %; 92.3 % after 2.4s of UV‐exposure, respectively.
Effect of dispersing auxiliaries, namely polyvinylpyrrolidone (PVP), Lauryl dodecyl sulfate sodium (SDS), nonionic surfactant op-10 (Op-10), C12-14 alcohol ethoxylate AE7 (AE7) and polyethylenimine (epomin) on the nanosilica dispersion into passive Cr(III) solution, pH = 1.5, were investigated by FT-IR, zeta potential, particle-size distribution and natural salt spray testing. The obtained results indicated that passive Cr(III)-nanosilica solution after 7-day fabrication was uniform, having no agglomeration if using SDS, PVP and AE7 agent. AE7 saw the best dispersion aid ability for dispersing nanosilica into passive Cr(III) solution in those dispersing auxiliaries studied. Conversion coating fabricated from passive Cr(III)-nanosilica-AE7 solution had a highest level of anticorrosion durability. White rust appeared on X-Cut position of sample fabricated from former solution after 9-day natural salt spray testing, which was the longest in all of samples. However, average particle size of nanosilica in passive Cr(III)nanosilica-AE7 solution was approximately 60 nm, which was quintuple initial average nanosilica size. Hence, AE7 could help nanosilica dispersion into passive Cr(III) solution but effect of AE7 was not strong enough to disperse nanosilica well into solution as well as maintaining the stability for new system.
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