Polyurethane-modified Epoxy Research Articles

Modification and characterization of urethane acrylate oligomers used for UV-curable coatings

Nine modified urethane acrylate oligomers including polyether-modified polyurethane acrylate, epoxy-modified polyurethane acrylate and hyperbranched polyurethane acrylate have successfully been synthesized and characterized by Fourier transform infrared spectra. The properties of UV-cured films formed by these oligomers were also investigated. The effects of the molecular structure of the oligomers on the properties of cured film, including tack-free time, pencil hardness, impact resistance, adhesion and boiling water resistance, have been discussed. The results indicate that the UV-cured film with good performance can be designed by the modification of the molecular structure of the oligomer. Among the oligomers prepared in this paper, the cured film formed using HBPUA-50%OA as oligomer exhibits a relatively short tack-free time, high hardness, good impact resistance, great adhesion and boiling water resistance.

Waterborne epoxy-modified polyurethane-acrylate dispersions with nano-sized core-shell structure particles: synthesis, characterization, and their coating film properties

Abstract Waterborne epoxy-modified polyurethane-acrylate (EPUA) dispersions with nano-sized core-shell structure particles, with polyacrylate (PA) as core and epoxy-modified polyurethane (EPU) as shell, were successfully prepared via a two-step procedure. The waterborne EPU dispersions were first synthesized to serve as seeds, and then the butyl acrylate (BA) and methyl methacrylate (MMA) monomers were introduced into EPU particles to form polymeric core by radical polymerization under the assistance of ultrasonic treatment. Fourier transform infrared (FT-IR) spectroscopy revealed that the epoxy and PA components were successfully incorporated onto the chain of the PU and EPU to form EPU and EPUA, respectively. The transmission electron microscopy (TEM) photograph demonstrated that the EPUA particles have the core-shell structure. The as-prepared EPUA coating films exhibited good thermo-stability and mechanical properties, as revealed by thermogravimetric analysis (TGA) and tensile testing, respectively. The results of potentiodynamic polarization curves and immersion corrosion testing in 5 wt% NaCl aqueous solution both demonstrated that the anticorrosive properties of EPUA mainly depended on the mass content of PA, with the optimized value of 30 wt%.

PENGARUH 1,4-BUTANDIOL SEBAGAI POLIOL PADA MODIFIKASI EPOKSI MENGGUNAKAN POLIURETAN

Corrosion is a natural phenomenon causing degradation value and function of material. The use of paints and polymer coatings is the most popular method to protect material against corrosion. Polymer coatings used was an epoxy-based organic resin and polyurethane. Generally, those coating materials were used separately. This study carried out the modification of epoxy with polyurethane in order to obtain coating materials as a combination of epoxy and polyurethane. Expectedly, the chemical reaction between epoxy coating-material and polyurethane could improve the characteristics of the obtained coating materials. Synthesis of polyurethane-modified epoxy with 1,4-butanediol as the polyol (ETP-BTD) was conducted by reacting epoxy resin, tolonate and 1,4-butanediol simultaneously at 50 oC for 30 min with dibutyltindilaurate as catalyst. Functional group analysis of ETP-BTD was performed by Fourier Transform Infra Red (FTIR), tensile strength by Ultimate Testing Machine (UTM), adhesion by ASTM D4541 Portable Pull-off Adhesion Testers, water vapor transmission rate by ASTM E96 Desiccant Method and thermal stability was studied using Thermogravimetric Analysis (TGA). The FTIR analysis results showed that there are urethane bonds at 1716-1690 cm-1. These results showed that modification of epoxy using polyurethane increased the tensile strength and adhesion, and also decreased the water vapor transmission rate of epoxy. Keywords: epoxy, modification, polyol, polyurethane, 1.4-butanediol

Study on the Pulsed Flashover Characteristics of Solid-Solid Interface in Electrical Devices Poured by Epoxy Resin

In electrical devices poured by epoxy resin, there are a lot of interfaces between epoxy resin and other solid dielectrics, i.e. solid-solid interfaces. Experiments were carried out to study the flashover characteristics of two typical solid-solid interfaces (epoxy-ceramic and epoxy-PMMA) under steep high-voltage impulse for different electrode systems (coaxial electrodes and finger electrodes) and different types of epoxy resin (neat epoxy resin, polyether modified epoxy resin and polyurethane modified epoxy resin). Results showed that, the flashover of solid-solid interface is similar to the breakdown of solid dielectric, and there are unrecoverable carbonated tracks after flashover. Under the same distance of electrodes, the electric stress of coaxial electrodes is lower than that of finger electrodes; and after the flashover, there are more severe breakdown and larger enhanced surface conductivity at interface for coaxial electrodes, as compared with the case of finger electrode. The dielectric properties are also discussed.

Preparation and Characterization of Epoxy Resin Composite Modified by Flexible Polyurethane Resin

In this paper, under the effect of MD1041 cashew oil modified phenolic amine curing agent for epoxy resin, it successfully prepared polyurethane flexible resin modified epoxy resin composite materials by using polyurethane modified epoxy resin reinforced flexible resin. Modified composite material of the new preparation is characteristed by the method of the mechanical performance test, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC). The results show that the flexible resin has a strong effect on the toughness of modified epoxy resin composite materials. When the mass ratio of the flexible resin account for 5.9%,comprehensive mechanical properties of the modified composites is at the premium; when the mass ratio of flexible resin account for 3.1%, the thermal stability of the epoxy resin modified with flexible resin is at the best.

The Influence of Reactive Diluents on the Properties of UV Dual Cured Polyurethane-Modified Epoxy Monoacrylates Films

The UV-curable liquid compositions were developed with different oligomers (epoxy diacrylates, EDA; epoxy monoacrylates, EMA; or polyurethane-modified epoxy monoacrylates, PMEMA), reactive diluents and photoinitiators. Thin films were prepared by curing these mixtures using a high pressure mercury lamp. The change of absorption peaks of double bond and epoxy group were identified by Fourier Transform Infrared (FTIR) spectra during UV dual curing process. Gel content, mechanical, volume shrinkage and thermal characterizations of the UV-cured films were investigated. The gel content, youngs modulus and stress at break turned to maximum values as the degree of polymerization achieved the maximum value, except for the strain at break. The flexibility of UV dual cured films using PMEMA as oligomer was improved due to grafting of the soft chain segments (polyurethane). The volume shrinkage test indicated that the UV dual cured films exhibited lower internal stress and higher cohesive force than simple radical UV cured films. The thermogravimetric analysis of UV cured films revealed that UV dual cured films prepared from PMEMA showed excellent thermal stability.

Polyurethane-Modified Epoxy Monoacrylates Containing Two Different UV-Curable Groups: Preparation and Charaterization

Polyurethane-modified epoxy monoacrylates (PMEMA) containing two different UV- curable groups (double bond and epoxy groups) were synthesized. The changes of NCO groups during the synthesis process of PMEMA were measured by chemical titration method, and its Fourier Transform Infrared (FTIR) spectra were investigated. The results indicated that polyurethane chain segments can be grafted onto the epoxy monacrylates (EMA) by the reaction of NCO and OH groups. The FTIR of PMEMA showed that it contains both double bond of acrylic ester (UV radical curable) and epoxy groups (UV cationic curable).

Influence Factors Study on the Properties of Epoxy Resin Modified by Polyurethane

Polyurethane-modified epoxy resin was prepared with Polyurethane prepolymer(PUP). The effects of the PUP content and epoxy resin type on mechanical and thermal properties of materials were discussed. The results indicate that the tensile strength and impact strength of the material increase to maximum successively, and then decrease with the increasing addition of PUP. When the mass fraction of PUP was 15%, the tensile strength and the impact strength of materials were all the best. There were significant differences in mechanical and thermal properties of material for different epoxy, and the best results were cured epoxy TDE-85.

Fabrication and Mechanical Characterization of a Microscale Electrophoretic Polymer Based on MEMS Technology

Microscale polyurethane modified epoxy resin film has been fabricated using MEMS tehnologies in the present paper. The effect of different process conditions on the thickness of fabricated film was discussed. The microscale film shows smooth and uniform surface morphology. The tensile test of the film by DMA indicates its tensile strength and Young's modulus are approximately 55MPa and 1.8GPa, respectively. The fracture section of the film was characterized by SEM. In addition, the interface bonding strength of the fabricated film between Ni substrate is much higher than Parylene-C and SU-8. This microscale polymer film is promising in several smart MEMS fields, especially bio-MEMS structures.

Preparation of Novel Series of UV Dual Curable Polyurethane-Modified Epoxy Monoacrylates and their Films Properties

A new series of radical-cationic UV dual curable polyurethane-modified epoxy monoacrylates (PMEMA) was prepared. Radical-cationic UV dual curable were prepared with photosensitive resin (epoxy monoacrylates (EMA) or PMEMA), reactive diluents, radical and cationic photoinitiators. UV dual cured films of those liquid compositions were obtained by using a high pressure mercury UV lamp. FTIR spectra identified the change of C=C and epoxy groups absorption peaks during the UV-curing process. The effect of different modified oligomers on the gel content, water absorption, mechanical and thermal properties of radical-cationic UV dual cured films was investigated. The characteristic C=C (1635cm-1, 810cm-1) and epoxide (910cm-1, 772cm-1) absorption speaks were no longer detectable after UV dual cured. The gel contents of all samples using PMEMA as oligomers were beyond 97.0% and their water absorption values were about 0.80%. With the length of flexible polyurethane chain segments increased, the Young’s modulus and breaking strength of UV dual cured films decreased gradually, except for the relative elongation. The volume shrinkage test indicated that the UV dual cured films exhibited lower internal stress and higher cohesive force than single radical UV cured films. The results of thermogravimetric analysis (TGA) for the UV dual cured films indicated good thermal stability with no appreciable weight loss until well above 250°C.

Comparison of anti-corrosion properties of polyurethane based composite coatings with low infrared emissivity

Four polyurethane resins, pure polyurethane (PU), epoxy modified polyurethane (EPU), fluorinated polyurethane (FPU) and epoxy modified fluorinated polyurethane (EFPU), with similar polyurethane backbone structure but different grafting group were used as organic adhesive for preparing low infrared emissivity coatings with an extremely low emissivity near 0.10 at 8–14μm, respectively. By using these four resins, the effect of different resin matrics on the corrosion protection of the low infrared emissivity coatings was investigated in detail by using neutral salt spray test, SEM and FTIR. It was found that the emissivity of the coatings with different resin matrics changes significantly in corrosion media. And the results indicated that the coating using EFPU as organic adhesive exhibited excellent corrosion resistance property which was mainly attributed to the presence of epoxy group and atomic fluorine in binder simultaneously.

Synthesis, Characterization and Preliminary Investigation of Blood Compatibility of Novel Epoxy-modified Polyurethane Networks

To prepare elastomers with acceptable physical properties and good blood compatibility, polyurethane networks were synthesized via crosslinking reaction of epoxy-terminated polyurethane prepolymers (EUPs) and hexamethylene diamine. EUPs were prepared by reacting glycidol and NCO-terminated polyurethanes. All new materials were characterized by conventional spectroscopic methods and properties were evaluated and correlated to their structure. Cytotoxcicity evaluation for the films of samples based on mouse fibroblasts (L929) revealed that these elastomers posed no threat to these cells. In vitro platelet-rich plasma contact test showed reduced number of adhered platelets on the surface of the films, particularly for those with maximum crystallinity and microphase structures and high hydrophilicity. The results obtained implied the potential for the utilization of these elastomers in biomedical applications.

Composites of UHMWPE fiber reinforced PU/epoxy grafted interpenetrating polymer networks

Several polyurethane-modified epoxy resins (PU/DGEBA-g-IPNs) were synthesized and characterized through a series tests, including differential scanning calorimetry and mechanical property measurements, such as tensile, Izod, bending and shear strengths were investigated in the study. The PU/DGEBA-g-IPNs and neat DGEBA as matrices for UHMWPE fiber-reinforced and aramid fiber-reinforced composites were prepared for comparison of their mechanical properties. The degree of plasma treatment, the polyurethane content, and the type of polyol in the polyurethane within the matrix of the composite were investigated through mechanical and bulletproof testing.

Synthesis and Characterization of Polyurethane-Toughened Epoxy-Bismaleimide Matrices

Interpenetrating polymer networks of bismaleimide-modified polyurethane-epoxy systems were developed using chain-extended bismaleimide (BMI) and polyurethane-modified epoxy with 4,4′-diamino-diphenylmethane as curative. Infrared spectral analysis was used to confirm the polyurethane cross-linked epoxy (PU-EP). The chain-extended BMI was synthesized from a previously reported procedure and its structure and purity was confirmed by FTIR, 1H and 13C-NMR spectra. The prepared matrices were characterized by mechanical, water absorption, thermal and electrical studies. The results obtained from these studies indicate that the incorporation of polyurethane into epoxy increases the mechanical strength and water absorption behavior and decreases the thermal and electrical properties of epoxy resin. Whereas, the incorporation of chain-extended bismaleimide into a polyurethane-modified epoxy system increases the tensile and flexural properties, thermal stability, and electrical properties of epoxy resin and decreases the impact strength, water absorption behavior, glass transition temperature and heat distortion temperature according to its percentage content.

Damping properties of interpenetrating polymer networks of polyurethane-modified epoxy and polyurethanes

Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)-modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one-shot method. Two types of PU-modified epoxy: PU-crosslinked epoxy and PU-dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU-modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU-modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU-modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU-dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU-crosslinked epoxy/PU IPNs with 20 wt % of PU-crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999

Polyurethane-modified epoxy resin and their polymer particle filled epoxies

Hydroxyl-terminated polyurethane (HTPU) prepolymer and crystalline polymer particles were used to modify the toughness of diglycidyl ether of bisphenol-A (DGEBA) epoxy cured with diaminodiphenyl sulphone (DDS). For the crystalline polymers, poly(butylene terephthalate) (PBT) and poly(hexamethylene adipamide) (Nylon 6,6), with particle size under 401 μm were employed. The PU-modified epoxies exhibit a significantly improved fracture toughness. The β-relaxation of cured epoxy resin shows a more clear two-phase separation as the polyurethane content increases. Besides, the addition of crystalline polymer particles could further enhance the toughness of PU-modified epoxy at low particle content. Scanning electron microscopy (SEM) shows that PU-modified epoxy has a two-phase structure. The fracture properties of PBT particle filled epoxy are found to be better than those of Nylon 6,6 particle filled epoxy. Nevertheless, the toughening effect of these crystalline polymer particles is much less efficient than that of PU modification.

Synthesis and characterization of cryogenic adhesives based on epoxy‐modified polyurethane resin systems

AbstractPolyurethane adhesives containing the polyether backbone exhibit a good joint strength in cryogenic environments. In practice, many of the commercially available polyurethane adhesive systems contain free or chemically blocked isocyanates which have some limitations. This study presents the synthesis and characterization of a modified polyurethane type adhesive. Glycidol was used to convert the isocyanate‐terminated polyurethane prepolymer to glycidylterminated polyurethane prepolymer. A series of glycidyl‐terminated polyurethanes, based on polyoxypropylene glycol (PPG) soft segments having different molecular weights, were synthesized and their adhesive properties on aluminium were evaluated. The effect of the soft segment length on adhesion was examined.The adhesive properties at room temperature and cryogenic temperature are in line with the phenomenon observed in dynamical mechanical analysis (DMA) and in the phase separation behavior of the polyurethanes. Differential scaning calorimetry (DSC) was used to assess the phase separation content. An improvement in the adhesive strengths at room temperature is achieved by adding epoxy resins to the glycidyl‐terminated polyurethane resins.

Glycidyl‐terminated polyurethane modified epoxy resins: Mechanical properties, adhesion properties, and morphology

AbstractGlycidol was used to convert the isocyanate‐terminated polyurethane prepolymer to glycidyl‐terminated polyurethane prepolymer. The modified polyurethane not only offers some distinct advantages over the commercial polyurethane prepolymer, but also enhances the properties of the epoxy resins. The glycidyl‐terminated polyurethane modified epoxy resin proved to be superior to conventional epoxy resins in improving impact strength, fracture energy, and adhesion properties. The compatibility of the compounds in this glycidyl‐terminated PU/epoxy system was investigated using different preparation procedures. It was found that the synthesized glycidyl‐terminated polyurethane prereacted with curing agents, exhibited a lesser degree of phase separation, and can influence the mechanical properties of polymer blends. The results coincide with the phenomena observed in dynamic mechanical analysis and scanning election microscopy. © 1994 John Wiley & Sons, Inc.