Query: epoxy hydroxyl UV

title: Toughness modification of cationic UV cured cycloaliphatic epoxy resin by hydroxyl polymers with different structures
abstract: In this work, cationic UV curable epoxy expansive matrix composites based on cycloaliphatic epoxy resin (CE) were prepared using trarysulfonium hexafluorophosphate salt as photoinitiator, and hyperbranched polyester terminated with 6 hydroxy groups (H2004) or linear hydroxy ended polytetramethylene ether glycol (PTMG) as toughness modifiers. Effects of H2004 and PTMG on the UV curing kinetics, mechanical and thermal properties were systematically compared. An acceleration phenomenon was observed by real time FTIR characterisation during the UV curing of CE/H2004, which may be attributed to the hydroxy group participation of H2004 based on an activated monomer mechanism. However, the epoxy group conversion in the CE/PTMG composite decreased during UV irradiation owing to the random coil morphology of PTMG. Thermal mechanical properties of the CE/H2004 composite were investigated by dynamic mechanical thermal analysis, which revealed that the glass transition temperature (Tg) decreased slightly as the H2004 dosage increased, in contrast to the Tg of the CE/PTMG composite, which increased as the PTMG content rose. Compared with CE, the thermal stability of CE/H2004 and CE/PTMG was less, but toughness was improved dramatically by increasing the content of H2004 or PTMG. At concentrations of H2004 and PTMG of 20% and 30% respectively, the impact strength was improved from 1.14 J/cm2 for CE to 4.62 J/cm2 for CE/H2004 and 10.44 J/cm2 for CE/PTMG. This was further elucidated by fracture surface analysis with a scanning electron microscope.

title: Epoxy composite coating corrosion protection properties reinforcement through the addition of hydroxyl terminated hyperbranched polyamide non covalently assembled graphene oxide platforms
abstract: This paper presents the role of GO particle functionalization by different contents of hydroxyl terminated hyper branched polyamide on the epoxy coating corrosion protection properties. Raman spectroscopy, UV visible analysis, and field emission scanning electron microscopy (FE SEM) methods were applied to study the HB/GO interactions and morphology at different ratios. Then, by electrochemical impedance spectroscopy (EIS) and accelerated corrosion test (salt spray) the Epoxy GO and Epoxy HB/GO 0.25, 0.5, 1.0 and 2.5 systems corrosion protection properties were investigated. Results obtained from Raman spectroscopy, UV Visible analysis, and FE SEM measurement proved that the GO sheets were successfully modified by HB molecules. SEM results evidenced that the GO particle dispersion quality in the epoxy matrix was significantly improved after modification by HB. Pull off results revealed significant improvement in the epoxy film adhesion to the steel surface in the presence of HB/GO. Results disclosed that the epoxy composite coating reinforced with HB/GO 0.5 and 1.0 showed the largest impedance >1010 ohm cm2) and lowest delamination values. Generally, the modified GO sheets significantly improved the epoxy coating corrosion protection properties due to the role of HB in improving the dispersion state (proved by SEM results) and interfacial interactions between the GO and epoxy matrix.

title: A Novel Hydroxyl Epoxy Phosphate Monomer Enhancing the Anticorrosive Performance of Waterborne Graphene/Epoxy Coatings
abstract: Herein, we report the synthesis of a novel hydroxyl epoxy phosphate monomer (PGHEP) as an efficient dispersant for graphene to enhance the compatibility of the graphene in epoxy resin. Raman spectroscopy, Ultraviolet visible spectroscopy (UV vis) and X ray photoelectron spectroscopy (XPS) studies were confirmed the p p interactions between PGHEP and graphene. Well dispersed states of PGHEP functionalized graphene (G) sheets in water were analyzed by transmission electron microscopy (TEM) atomic force microscopy (AFM) and scanning electron microscopy (SEM) Further, microstructure of prepared G/waterborne epoxy coatings containing 0.5 1.0 wt. of PGHEP functionalized G sheets were also observed with the help of SEM and TEM. The PGHEP functionalized G sheets dispersed composite coatings displayed enhanced corrosion resistance compared with pure epoxy resin, these coatings have higher contact angle, lower water absorption as evident from the results of electrochemical impedance spectroscopy (EIS) and salt spray tests. The superior corrosion protection performances of G/epoxy coatings were mainly attributed to the formed passive film from uniformly dispersed PGHEP functionalized G sheets which act as physical barrier on the steel surface. Therefore, this work provides a novel bio based efficient dispersant for G sheets and an important method for preparing G/waterborne epoxy coatings with superior corrosion resistance properties.

title: High performance waterborne UV curable polyurethane dispersion based on thiol acrylate/thiol epoxy hybrid networks
abstract: Synthesis, characterization, and film performance of waterborne thiol acrylate/thiol epoxy hybrid coatings are highlighted in this article. A dimer acid modified epoxy (DME) polyol, containing both hydroxyl and epoxy functional groups, was prepared by reacting epoxy resin (EEW 190 g/equi) with dimer fatty acid at 2:1 molar ratio. Further, a base UV curable polyurethane acrylate dispersion (UV PUD) with a pendant epoxy functional group, was prepared by reacting polyol (DME) isophorone diisocyanate, and dimethylol propionic acid and end capped with hydroxyethyl methacrylate with subsequent dispersion in water. Prepared intermediates were characterized for the parameters relevant to the study by physical, spectroscopic, and chemical methods. UV curable thiol acrylate/thiol epoxy hybrid coatings were prepared by blending UV PUD with trimethylolpropane tris(3 mercaptopropionate) (TMPMP) at four different thiol ratios (0, 0.3, 0.6, and 1.0) with respect to acrylate/epoxy groups. Cured films of the hybrid coating were identified by FTIR spectroscopy. The impact of thiol ratio on film performance was evaluated in terms of mechanical, chemical, thermal, and coating properties. The gel content measurements confirm that the addition of TMPMP increased the double bond conversion along with the epoxy group. Evaluation of cured samples shows the significant improvement in storage modulus, glass transition temperature, tensile strength, and hardness with increase in thiol ratio. The cured films possessed excellent water and acid resistance <4% even after 28 days of immersion. Moreover, the notable improvement was alkali resistance of cured films, i.e. as thiol ratio was increased from 0 to 1, weight loss in alkaline environment deceased from 49.5 to 4.5% after 28 days. Better properties of the thiol acrylate/thiol epoxy hybrid films will allow it as a potential application in low volatile high performance coatings.

title: Flame resistance, physical and mechanical properties of UV cured hybrid coatings containing low hydroxyl content sols via an anhydrous sol gel process
abstract: As one of a series of our studies, starting with silica sol (TM2) and Si P binary sol (SP5) two series of low hydroxyl content sols (LHCSs) were synthesized using an anhydrous sol gel method. The stable storage time of LHCS containing hybrid coatings was improved relative to that of hybrid coatings containing TM2 and SP5. The flame resistance and thermal stability of UV cured hybrid coatings consisting of LHCS, epoxy acrylate of bisphenol A (SM6104) and tripropylene glycol diacrylate (TPGDA) were investigated by means of thermogravimetric analysis (TGA) limit oxygen index (LOI) cone calorimetry and a flammability test. The results indicated that the flame resistance of LHCS containing hybrid coatings was further improved over that of hybrid coatings containing TM2 and SP5. The improvements mainly included a longer ignition time and lower combustion heat. Hybrid coatings applied on the surface of wooden floors could offer long lasting and significant protection against fire, showing outstanding practical value. In addition, the physical and mechanical properties of LHCS containing hybrid coatings were negatively affected by the decrease of hydroxyl group contents and the Ti containing component. A UV curable phosphorus containing resin (RAYLOK 1722) was introduced into the hybrid coatings containing LHCS. However, hybrid coatings containing RAYLOK 1722 showed only a small improvement in flame resistance, and their physical and mechanical properties were damaged by RAYLOK 1722.

title: Polyols from epoxidized soybean oil and alpha hydroxyl acids and their adhesion properties from UV polymerization
abstract: Two types of biobased polyols, ESOGA and ESOLA, were synthesized from epoxidized soybean oil (ESO) with glycolic acid (GA) and lactic acid (LA) respectively, using a solvent free/catalyst free method. An ESO epoxy conversion rate of over 93% was achieved for both polyols. ESOGA has a weight /number average molecular weight (Mw/Mn) of 27,700/3900 g/mol and average hydroxyl functionality (fOH) of 12.9, and ESOLA has Mw/Mn of 8800/3000 g/mol and fOH of 11.7. The structures of the polyols were further characterized with Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. Rheology and thermal properties were studied with a rheometer and a differential scanning calorimeter. The polyols were polymerized with ESO to adhesive polymers using UV light in the presence of cationic photoinitiator. The curing rate decreased as the amount of polyol increased for resins based on ESOGA and ESOLA (EGA and ELA) With the same amount of polyol, ELA resins cured faster than EGA resins. The peel strength and tack of EGA and ELA adhesives increased significantly as the ratio of polyol in the resin increased. ELA exhibited obviously higher peel strength and tack than EGA with the same amount of polyol. All resin tapes exhibited high static shear values (20,000+min) Overall, both ESOGA and ESOLA exhibited great potential as polyols for pressure sensitive adhesive applications.

title: Polyester amide hyperbranched polymer as an interfacial modifier for graphene oxide nanosheets: Mechanistic approach in an epoxy nanocomposite coating
abstract: Graphene Oxide nanosheets (GO) are synthesized through modified Hummer's method using expandable graphite. Consequently, the synthesized GO is surface functionalized by the aid of a polyester amide hyperbranched polymer (HB) possessing hydroxyl end groups. The characteristics of the surface modified GO are assessed by Fourier transform infrared spectroscopy (FT IR) X ray diffraction (XRD) UV VIS spectroscopy and thermo gravimetric analysis (TGA) The results show that HB molecules have been adsorbed on the GO surface and the d spacing of the GO lamellae has been increased from 11.058 A to 13.763 A. Subsequently, the modified GOs are impregnated into an epoxy resin at various loadings and dispersed utilizing mechanical agitation and complementary sonication process. The dispersions are mixed and cured with stoichiometric amount of a polyamidoamine based curing agent and applied on glass substrates to form 75 100 mm thick free standing films. Viscoelastic behavior are then evaluated by dynamic mechanical analysis (DMA) The results show that storage (E' modulus is enhanced and the glass transition temperatures (Tg) increases as GO and its modified counterparts are impregnated. Also, among the nanocomposites, coatings prepared by HB/GO 0.5 and HB/GO 1 show better improved properties indicating there exists an optimum ratio of GO/HB in which maximum surface modification has occurred.

title: Different toughening strategies for UV cured epoxy resins
abstract: Owing to their outstanding properties, epoxy resins are widely used in different industries and recently used in novel applications such as semiconductors and lithographic inks. Due to their low fracture toughness, Toughening of epoxy is widely discussed in literature during last decades. Many toughening agents including organic and inorganic materials are used to accomplish this purpose. The objectives of this research are to synthesize and use different toughening agents and study the influence of these modifiers on the mechanical and thermal properties in general and the fracture toughness in particular of the UV cured cycloaliphatic epoxy resins. Particularly, we desired to improve the fracture toughness of modified epoxies cured via UV light without sacrificing their thermal and other mechanical properties. Polymeric molecules or ceramic nanoparticles have been introduced; (1) Hyperstar polymers based on hyperbranched polyester core with or without hydroxyl reactive groups in their arms (2) reactive core/shell polymeric nanoparticles prepared by seeded emulsion polymerization (3) reactive or nonreactive diblock copolymer prepared via ATRP and based on polyethylene oxide and (4) commercial alumina nanoparticles as inorganic particles. The effect of the addition of these toughening agents on the rate of UV curing process and glass transition temperature, Tg, have been investigated. Subsequently, the morphology of the facture surfaces has been studied carefully using FE SEM. The stress intensity factor, KIC, measurements which is an indicator for fracture toughness was evaluated in terms of single edge notch three point bending (SENB) Cationic UV curing technique was utilized for the preparation of the modified epoxy composites. Specifically, the cationic photopolymerization of cycloaliphatic epoxy is known to proceed through nucleophilic attack of neutral monomer to oxonium cation, which is active chain end of the polymerization. The UV induced polymerization technique is a solvent free method occurring at room temperature which is eco friendly. It is indeed a polymerization process used for industrial applications because of the high production rate and the low energy consumption compared to thermal processes. The rapid UV curing process helps to maintain good dispersion of modified particles avoiding further aggregation that could occur during longer thermal treatment

title: A novel photocurable modified epoxy resin for high heat resistance coatings
abstract: In this paper, in order to further improve the heat resistance of UV curing epoxy cresol novolac (EOCN) 2,2 bis(hydroxymethyl)propionic acid (DMPA) was firstly introduced to open epoxy groups in EOCN and then the hydroxyl groups reacted with acryloyl chloride to make sure the resin has sufficient UV curing double bonds. Compared with the system that uses acrylic acid to open epoxy group and the secondary hydroxyl group reacting with unsaturated anhydride, up to 1.5 times double bonds were potentially introduced. The structure of the resins was characterized by FT IR and 1H NMR. Influences of double bond content on thermal behavior, photopolymerization kinetic behavior, and basic properties of the cured films were investigated. Thermal performance analysis demonstrated that the glass transition and the initial decomposition of the cured films were increased with the rising proportion of acryloyl group. Moreover, doping of abundant acryloyl chloride caused a significant increase of unsaturated double bond conversion, though the initial photopolymerization rates declined. Cured films with less acryloyl chloride modified showed better adhesive. For solvent resistant test, with the increase of the acryloyl group, the cured film displayed good resistance to strong acids and alkalis. These attractive features give this process potential applications in soldering ink and protective coatings.

title: Study on the UV curable waterborne alicyclic epoxy acrylates
abstract: Alicyclic epoxy acrylate(EA)were prepared with alicyclic epoxy resin and acrylic acid.The waterborne alicyclic epoxy acrylates were synthesized with hydroxyl group of EA and the maleic anhydride(MA).The effects of main parameters,such as reaction tempreture,reaction time and the weight of catalys and inhibitors on rate of conversion were discussed.Thus the optimization of preparation of the product was obtained.The structure of the product was characterized by FT IR.