Ultraviolet Curable Polyurethane Research Articles

Characterization and prediction of the nonlinear creep behavior of 3D-printed polyurethane acrylate

While the potential application of 3D-printed polymers is remarkable because of the favorable mechanical properties of these materials and their feasibility for producing customized structural components, 3D-printed polymer materials are rarely used in load-bearing structures due to a lack of understanding of the mechanical behaviors of a printed part over a long service life. In this study, the creep behaviors of ultraviolet-curable polyurethane acrylate (UV-PUA) fabricated by using a digital light processing 3D printer was investigated through experimental testing and finite element simulations. Digital image correlation was used to monitor the creep deformations under various thermomechanical conditions. A one-dimensional creep constitutive model was developed to characterize the nonlinear viscoelastic responses of the 3D-printed UV-PUA by decoupling temperature and stress effects. The constitutive model was further implemented in an ABAQUS UMAT subroutine. The simulation results show that the numerical creep model describes well the creep deformations and predicts a reasonable creep life at low temperatures. The sensitivity of the creep behavior of the printed specimens to various types of initial damage was also studied using the developed constitutive model, and the model results were validated by the tensile test results. The results are in good agreement, which verifies the feasibility of numerical method implemented in UMAT for studying the mechanical properties of 3D printed polymers. • Creep behavior of a 3D-printed polymer was monitored using DIC technology. • A nonlinear temperature-dependent viscoelastic model was developed. • 3D constitutive models were developed and implemented in finite element analysis. • The developed model predicts well the creep behavior of the 3D-printed polymer.

A Highly Controlled Organic-Inorganic Encapsulation Nanocomposite with Versatile Features toward Wearable Device Applications.

Ultraviolet-curable polyurethane acrylate (PUA) materials can be used in a number of important applications spanning from microfluidics, surface patterning to wearable technology. For the first time, the potential of encapsulation of modified zirconia (ZrO2 ) nanoparticles is reported in PUA-based hybrid films aimed to facilitate profoundly enhanced hardness and refractive index. By successfully manipulating the interfacial reaction conditions between ZrO2 nanoparticles and PUA film, the PUA-based nanocomposites exhibit an ultrahigh hardness of 9 and superior refractive index of 1.64 (589.3 nm). The outcomes obtained pave the way for seamless application of nanozirconia/PUA as a potent encapsulating material that provides structurally morphable, water resistant, and optically transparent light emitting diodes toward wearables devices in healthcare.

Effect of Hydrophilic Bentonite as a Filler on Curing Performance of Pigmented UV Curable Polyurethane Acrylate Coating

The effect of hydrophilic bentonite incorporation on the curing performance of pigmented ultra violet (UV) curable polyurethane acrylate (PUA) coating was investigated. To the best of our knowledge, crock fastness and gloss properties of pigmented bentonite incorporated UV curable PUA coating have been examined for the first time. Fourier Transform Infrared (FTIR) spectroscopy analysis of the cured films showed that addition of both bentonite and pigment decreased the conversion of C=C. However a more significant drop was observed with the addition of pigment into the formulation. The drop of conversion with the incorporation of bentonite did not adversely affect the hardness and crock fastness values and hence the UV curing performance of the films. Bentonite particles were efficiently distributed in the film and intercalation was achieved owing to the ball milling process. Hardness of the cured films increased with the increase in energy levels. On the other hand, hardness decreased at higher pigment concentrations however, was not affected adversely by bentonite incorporation. Gloss was found to be enhanced with the addition of bentonite in both pigmented and unpigmented films. Significant improvement in crock fastness could not achieved with the addition of bentonite.

Enhancing the Flame Retardancy of UV Curable Polyurethane Acrylate Coated Films with Alumina Trihydrate Filling

In this study, the flame retardancy of ultra violet (UV) curable polyurethane acrylate (PU) coated films were enhanced. For this aim, alumina trihydrate (ATH) filling material was mixed with the pastes including a photoinitiator and a UV curable PU. ATH filling ratio was preciously adjusted to obtain a uniform coating. The coated films were cured with a UV curing system equipped with gallium (Ga) and mercury (Hg) lamps. The chemical changes and the curing degree of the UV cured films were examined by a Fourier Transform Infrared Spectrum (FTIR) and a pendulum hardness tester. The thermal properties of the UV cured films were evaluated using a Differential Scanning Calorimeter (DSC). Moreover, vertical flammability and limiting oxygen index (LOI) measurements were conducted in order to determine the burning behavior of the UV cured films. The successful curing of the films was evidenced by means of FTIR results. The addition of ATH slightly increased the hardness values of the films. DSC results showed that ATH addition not only increased the enthalpy values but also enhanced the flame retardant property of the coated films and maximum LOI was achieved as 31.5%.  

Preparation and Properties of UV-Curable Polyurethane-acrylate Coatings Based on Polyhedral Oligomeric Silsesquioxanes (POSS)

In order to develop ultraviolet (UV)-curable coatings applicable to pre-coated metal (PCM), organic-inorganic hybrid UV curable polyurethane (PU)-acrylates were prepared using cage type metacryl-polyhedral oligomeric silsesquioxane (POSS) as a reactive diluent. To investigate the effect of POSS content on the physical properties of organic-inorganic hybrid polyurethane-acrylate coatings for PCM in this study, prepolymer was prepared by using H12MDI in PCL and HPBD, and oligomers capped at the end of 2-HEMA were synthesized. This study investigated the viscosities of the synthesized oligomers and prepared coatings; the thermal properties, mechanical properties, and transmittance of the UV-cured films; and the surface energy, adhesive property, pencil hardness, and MEK rubbing of the UV-curable films coated on the metal plate.

Hydrophobic, transparent waterborne UV-curable polyurethane nanocomposites based on polycarbonate and PCL-PDMS-PCL reinforced with colloidal silica

Waterborne ultraviolet-curable polyurethane (WUPU) and its nanocomposites based on polycarbonate and α,ω-dihydroxy-[poly(e-caprolactone)-poly(dimethylsiloxane)-poly(e-caprolactone)] (PCL-PDMS-PCL) were synthesized using isophorone diisocyanate (IPDI), dimethyl propionic acid (DMPA), polycarbonate diol (PCD), PCL-PDMS-PCL, hydroxyethyl methacrylate (HEMA), and aqueous colloidal silica. The resulting WUPU materials were characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, dynamic light scattering (DLS), and rheometry. The effects of PCL-PDMS-PCL and silica on the colloidal, physicochemical, and surface properties of the WUPU and its nanocomposites were studied. It was found that incorporation of PCL-PDMS-PCL (10 wt%) significantly enhanced the Young’s modulus, tensile strength, surface hydrophobicity, and water resistance of the WUPU films due to microphase separation and better interfacial adhesion between the PDMS soft phase and urethane hard phase provided by the PCL blocks. Furthermore, incorporation of silica (10 wt%) further improved the modulus, tensile strength, and water resistance of the PCD-PCL-PDMS-PCL-WUPU films without degrading the high surface hydrophobicity or transparency, due to the homogeneous dispersion and network structure of the silica clusters in the WUPU matrix.

Ultraviolet-curable polyurethane acrylate nanocomposite coatings based on surface-modified calcium carbonate

Abstract Polyurethane acrylate/surface-modified colloidal calcium carbonate (PUA/SCaCO3) nanocomposite coatings were successfully prepared via a UV-curing technology. The structural and morphological features of the PUA/SCaCO3 nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), and wide angle X-ray diffraction (XRD). The physical properties were strongly dependent upon chemical and morphological structures that originated from differences in SCaCO3 loading. A critical SCaCO3 concentration was observed for the evolution of both the structure and physical properties of the PUA/SCaCO3 nanocomposites as a function of SCaCO3 content. The thermal stability was measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively, and displayed some enhancement with the incorporation of SCaCO3 into PUA. Although the nanomechanical properties increased up to 3 wt% SCaCO3 content, they decreased due to lack of interfacial interaction with high SCaCO3 loading. Most importantly, the water uptake and water vapor transmission rate (WVTR) varied from 5.51 to 1.78 wt% and 28.9 to 19.9 g/m2 day, respectively, exhibiting significant enhancement in water resistance. The results clearly reveal that the performance of UV-curable PUA/SCaCO3 nanocomposites is strongly dependent on organically-modified colloidal SCaCO3 nanoparticles.

UV Curable Polyurethane Dispersions Extended by a New Chain Extender

Ultraviolet (UV) curable waterborne polyurethane dispersions with comb branched structure were synthesized by prepolymer process. C=C bonds were incorporated into the branched chains of the polyurethane using chain extender, hence, the content of C=C bonds can be adjusted by the chain extender consumption. The chemical structure was identified by Fourier transform infrared spectroscopy (FTIR) and 1H NMR. Effects of the chain extender content on the microstructure, rheological behavior, thermal property, mechanical and other properties of the UV cured films were researched.

Properties of High Solid Content UV Curable Waterborne Polyurethane Dispersions with Different C=C Content

Ultraviolet (UV) curable waterborne polyurethane(WPU) dispersions based on isophorone diisocyanate(IPDI), polypropylene glycol(PPG), dimethylolproprionic acid(DMPA) and pentaerythritol triacrylate(PETA) were prepared by the conventional method of anionic aqueous polyurethane dispersions. The structure of the ultraviolet (UV) curable WPU dispersions was studied by FT-IR. Stability, dispersion particle size and zeta-potential of the WPU dispersions were characterized. Effect of temperature on viscosity of the dispersions with different C=C content was also investigated. Results showed that all UV curable WPU dispersions had high solid content (48wt%) and showed remarkable mechanical stability. The viscosity of the dispersions decreased with temperature increasing from 20°C to 60°C. When C=C content varied from 0 to 1.05meq/g, the dispersion particle size was under 300nm, zeta potentials were less than -48.9mV.

Patterning methods for polymers in cell and tissue engineering.

Polymers provide a versatile platform for mimicking various aspects of physiological extracellular matrix properties such as chemical composition, rigidity, and topography for use in cell and tissue engineering applications. In this review, we provide a brief overview of patterning methods of various polymers with a particular focus on biocompatibility and processability. The materials highlighted here are widely used polymers including thermally curable polydimethyl siloxane, ultraviolet-curable polyurethane acrylate and polyethylene glycol, thermo-sensitive poly(N-isopropylacrylamide) and thermoplastic and conductive polymers. We also discuss how micro- and nanofabricated polymeric substrates of tunable elastic modulus can be used to engineer cell and tissue structure and function. Such synergistic effect of topography and rigidity of polymers may be able to contribute to constructing more physiologically relevant microenvironment.

Modulus- and surface energy-tunable ultraviolet-curable polyurethane acrylate: properties and applications

Since the introduction of ultraviolet (UV)-curable polyurethane acrylate (PUA) materials in 2004, our group has extensively used the material in various applications ranging from nanopatterning, biomimetics, microfluidics, to tissue engineering. In this highlight, we aim to provide a brief overview of the properties and applications of PUA with particular focus on the ability of tuning modulus (20–320 MPa) and surface energy (20–60 mJ m−2). These unique features enable us to use the material in various patterning applications as a mold and a patterned film, respectively. In addition, one can benefit from several other features of PUA such as self-replication, partial curing, flexibility, biocompatibility, and transparency. These issues are also briefly described along with their applications.

UV curable polyester‐based polyurethane acrylate nanocoating

PurposeThe paper's aim is to synthesise ultraviolet (UV) curable polyurethane acrylate based on polyester polyol and to study change in its mechanical, chemical, optical and weather resistance properties with varying amount of nanosilica. It also seeks to determine its optimum loading levels for property maximisation.Design/methodology/approachNew UV curable polyurethane acrylate has been synthesised using polyester polyol, blend of isophorone diisocyanate and toluene diisocyanate and hydroxyl ethyl acrylate. This resin was incorporated with nanosilica (1‐3 per cent) on the basis of total solids. The newly synthesised material was characterised by fourier transform infrared spectroscopy, gel permeation chromatography, X‐ray diffraction and scanning electron microscopy. The mechanical, chemical and optical properties of the coating films were studied and compared.FindingsThe hardness, tensile strength and abrasion resistance show significant enhancement with increasing amount of nanosilica. It is also found that UV cured polyurethane acrylate nanocoating exhibited improved weather resistance. The optimum concentration of nanosilica for better performance is found to be 3 per cent of total solids. The improvement is the result of inherent nature of nanosilica.Research limitations/implicationsNanosilica used in present context is having 10 nm mean diameter and near about 600 m2/g surface area. Nanosilica having different particle size, surface area and surface modification can be used to improve more specific properties.Practical implicationsAddition of nanosilica particles to polyurethane acrylate coating is a simple and inexpensive method resulting in phenomenal increase in properties.Originality/valueThe new organic‐inorganic hybrid nanocoating with improved weather resistance was synthesised. These coatings could find applications in demanding fields such as automotive topcoats.

Preparation and characterization of the heat-resistant UV curable waterborne polyurethane coating modified by bisphenol A

In this study, the modified ultraviolet (UV) curable waterborne polyurethane was obtained from isophorone diisocyanate (IPDI), polyethylene glycol (PEG, MW=600), α,α-dimethylol propionic acid (DMPA), hydroxyethyl acrylate (HEA) and bisphenol A. The rigid moiety was introduced into the main chain of polyurethane to improve its heat-resist- ance. The copolymer structure was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal property and UV curable behavior of the coatings were investigated. The glass transition temperature (Tg) of the modified film was deter- mined by differential scanning calorimetry (DSC). Thermal gravimetric analysis (TGA) was employed to investigate the thermal stability of the modified film. The results show that the average particle diameters increased from 69.25 to 95.12 μm as the content of bisphenol A increased from 0.00 to 9.25%. The optimum bisphenol A dosage was 7.23% (wt%), the Tg of the modified film increased by 7.07°C and 5% weight-loss temperature (233°C) increased by 14°C. The optimum irradiation time was 10-20 minutes after the coatings being painted on an armor plate at room temperature and initiator dosage was 5% (wt%) of the latex.

Room Temperature Detachment Nanolithography Using a Rigiflex Polymeric Mold

We report on detachment nanolithography of an organic thin film at room temperature mediated by ultraviolet (UV) exposure. A nanopatterned, UV curable polyurethane acrylate (PUA) mold was placed on a spin-coated organic film made of 4,4'-bis[N-1-napthyl-N-phenyl-amino]biphenyl (NPB) under a low pressure (1-2 bar). A higher work of adhesion at the organic/mold interface induced detachment of the contacting layer on silicon or gold substrate, resulting in well-defined nanopatterns without a residual layer. The detachment was highly improved by a short-term UV exposure, rendering the film surface free from contaminant hydrocarbons with a lower cohesive force, as confirmed by Fourier transform infrared (FTIR) spectroscopy and measurements of contact angle of water.

A new UV curable waterborne polyurethane: Effect of C [dbnd]C content on the film properties

A new ultraviolet (UV) curable waterborne polyurethane was prepared by modifying the conventional method of anionic aqueous polyurethane. Acrylate groups were introduced into the side chains and the end of the polyurethane main chains using the dihydric acrylate named as PEDA and the single-hydroxyl acrylate named as HEA. The C C content in the chain of the polyurethane was raised effectively and the maximum C C content achieved by this method is 4.5 meq/g. The structure was confirmed by the Fourier transform infrared spectroscopy (FTIR). The effects of different C C content were studied by evaluating various properties of the film such as the MEK resistance, hardness, thermal stability and the tensile properties. The curing rule of the polyurethane for different C C content had been investigated during the curing process.

Effect of monoacrylate type in UV curable PU acrylate based bicontinuous polymer/liquid crystal networks

Polymer network liquid crystals (PNLC) have been prepared from ultraviolet-curable polyurethane acrylate (PUA) and a nematic liquid crystal mixture (BL002). Effects of monoacrylate type on film morphology, temperature-dependent off-state transmittance, and electro-optic performance of the film have been studied. Among three types of monoacrylates incorporated (EHA(2-ethyl hexyl acrylate), MMA (methylmethacryalte), NVP (N-vinylpyrrolidone)), EHA-based PUAs gave the greatest polymer–LC phase separation, lowest threshold (V10), and operating (V90) voltages, and the effect was more pronounced in monoacrylate/triacrylate systems than in monoacrylate/diacrylate systems. Contact angle measurement offers a clue to the observed morphology and electro-optic behavior. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1393–1399, 1998

Novel polyurethane–silicone hydrogels

AbstractPolyurethane hydrogels derived from polysiloxane‐based ultraviolet‐curable polyurethane prepolymers and hydrophilic monomers were prepared and their properties were evaluated. The polyurethane prepolymers used in this study contained different arrangements of hard and soft segments and were derived from isophorone diisocyanate, neopentyl glycol, diethylene glycol, 1,4‐butanediol, hydroxy‐terminated polydimethylsiloxane, and 2‐hydroxyethyl methacrylates. The hydrophilic monomers used were 2‐hydroxyethyl methacrylate and N,N‐dimethyl acrylamide. All compositions can be cured under ultraviolet (UV) and form hydrogels after hydration. The oxygen permeabilities of the hydrogels are much higher than those of nonsilicone hydrogels and decreased as the water contents increased. The tear strengths and moduli decreased as the water contents of the hydrogels increased. All hydrogels prepared showed good hydrolytic stability and did not absorb lysozyme. © 1995 John Wiley & Sons, Inc.