Fluorinated Epoxy Resin Research Articles

Estrogenic activity research of a novel fluorinated bisphenol and preparation of an epoxy resin as alternative to bisphenol A epoxy resin

A low estrogenic activity bisphenol 3,5-bis(trifluoromethyl)phenylhydroquinone (BTFMHQ) and its corresponding epoxy resin (BTFMEP) were synthesized via a multi-step procedure including the Meerwein arylation reaction, and followed by nucleophilic reaction. The chemical structures of two monomers were confirmed by their 1H NMR spectra. After curing, the properties of this fluorinated epoxy resin were measured and compared with the commercial epoxy resin diglycidyl ether of bisphenol A (DGEBA). As the result, BTFMEP exhibited good dimensional stability, excellent hydrophobic and low dielectric properties. Furthermore, BTFMEP showed a high glass transition temperature of 142 °C and a lower coefficient thermal expansion (CTE = 55.03 ppm/°C) than that of DGEBA (CTE = 60.71 ppm/°C). Moreover, BTFMEP exhibited the contact angle of 99.6°, which satisfied the standard of hydrophobic material. In addition, BTFMEP showed lower dielectric properties than DGEBA, because the introduction of side groups with high fluorine content into the material improved the electronegativity of epoxy material and reduced the polarizability of molecules efficiently. Herein, we believe the novel epoxy resin (BTFMEP) has a wide application prospect as the alternative to DGEBA.

Preparation and properties of novel fluorinated epoxy resins cured with 4-trifluoromethyl phenylbenzimidazole for application in electronic materials

A novel 3-trifluoromethyl phenylhydroquinone epoxy monomer (3-TFMEP) and a novel 4-trifluoromethyl phenylbenzimidazole (4-TFMBI) curing agent both with trifluoromethyl moieties were synthesized via a multi-step procedure. Their chemical structures were confirmed by FT-IR and 1H NMR spectra. Herein, we employed 3-TFMEP as the epoxy matrix, and 4-TFMBI as the curing agent or the curing accelerator. Next, we prepared a series of epoxy resins with four kinds of different curing system as 3-TFMEP/Methylhexahydrophthalicanhydride(Mehhpa)/2-methylimidazole (2-MI), 3-TFMEP/Mehhpa/4-TFMBI, 3-TFMEP/2-MI and 3-TFMEP/4-TFMBI in order to investigate the variation of the properties with different curing agents and curing accelerators. The result showed that no matter whether 4-TFMBI was used as the curing agent or as the curing accelerator, the epoxy resin cured with 4-TFMBI exhibited high mechanical and thermal stabilities, as well as low dielectric constant and dielectric loss. In particular, 3-TFMEP/4-TFMBI possessed the highest Td5% (the decomposition temperature of 5% weight loss) of 374 °C, 131 °C higher than 3-TFMEP/Mehhpa/2-MI. Additionally, the storage modulus of 3-TFMEP/Mehhpa/4-TFMBI was 3266 MPa at 25 °C, which was much higher than other kinds of cured epoxy resins. Moreover, 3-TFMEP/4-TFMBI possessed the lowest dielectric constant of 3.38 at 107 Hz among these cured epoxy resins. Therefore, we believed that this novel fluorinated epoxy resin cured with 4-TFMBI containing 3-trifluoromethyl moieties have a great potential for application in the electronic packaging material field.

Influence of the curing temperature on the diffusion rate of the perfluorinated alkyl chains of a modified epoxy resin

Perfluorononanoic acid (F17) was grafted to an epoxy resin. The virgin epoxy resin and the fluorinated epoxy resin were cured at various temperatures. Both air-resin and substrate-resin interfaces of the cured materials were characterized in terms of: (i) free surface energy, (ii) surface composition, evaluated using angle-resolved X-ray photoelectron spectroscopy (AR-XPS). Fluorine proportion was quantified at probing depths of about 4.5 and 9nm. The curing temperature highly influenced the diffusion of the perfluorinated chains towards both interfaces. Depending on the curing conditions, very low free surface energies (17mJ/m2) due to high fluorine concentrations (fluorine/carbon ratio=0.6) were measured at the air-resin interface. However, the F17 diffusion towards the substrate was also observed and led to important fluorine concentrations (F/C up to 0.4). Finally, a two-step curing procedure was used for monitoring the F17 diffusion during the curing, illustrated by an accumulation of fluorine atoms at both interfaces. A non-linear relation was highlighted between the surface energy drop and the fluorine content measured by AR-XPS.

Advanced studies on synthesis and cure reaction of fluorinated epoxy resin

Fluorinated epoxy resins (FERs) were extensively studied for applications in electronic packaging, optical waveguides, and antifouling coatings. This research focuses on the synthesis and characterization of FER following a polycondensation reaction between fluorinated bisphenol and epichlorohydrin. Cure reaction was monitored using dispersive Raman spectroscopy and by calculation of the oxirane groups conversion. After one short postcuring stage, the decomposition temperatures of fluoroepoxy showed increased values with 28–35°C for the samples cured at 50°C. The resultant materials showed excellent fracture morphology, while the presence of fluorine was revealed by energy-dispersive X-ray and X-ray photoelectron spectroscopic techniques. Hydrophobic surface was evidenced through the surface energy resulted from contact angle measurements.

Moisture effect on surface fluorinated epoxy resin for high-voltage DC applications

Charge accumulation under high-voltage DC is a major concern in the transmission system as its presence distorts the local electric field. By performing chemical treatment on the polymeric insulation via fluorination process, the charge dynamics of the treated material can be modified. Surface fluorination treatment has been proven to be an effective tool to enhance the dielectric properties. The treatment slightly improves the surface conductivity value and enhances the surface potential decay rate, which helps to prevent the accumulation of surface charge and consequently improve the breakdown strength of epoxy samples. However, the authors suspected the introduction of a fluorinated layer on top of the epoxy sample may have the capacity to absorb moisture from the environment. The increase in the surface conductivity by the fluorination treatment may not come from the fluorine layer itself, but rather from the absorbed moisture in the surface layer. The loss of moisture from the surface may lead to a dip in dielectric performance of the treated materials. Hence, a study on the moisture effect on the surface fluorinated epoxy resin was designed. The fluorinated samples were characterised by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) to analyse the morphology as well as the concentration of elements in the treated materials. The samples then were dried in vacuum oven at 105°C and/or inside nitrogen gas chamber at room temperature for 24 hours to forcefully dry out the absorbed surface moisture. The measurements of surface DC conductivity and surface potential decay were taken before and after the drying process. It has been found that the fluorination treatment on epoxy resins did give rise to high moisture content on the surface which plays an important contribution towards the dielectric enhancement properties.

Evolutions of surface characteristics and electrical properties of the fluorinated epoxy resin during ultraviolet irradiation

The photoinduced evolutions of surface physicochemical characteristics and electrical properties of the fluorinated epoxy resin have been investigated. Cured epoxy resin sheets were surface fluorinated in a laboratory vessel using a F2/N2 mixture with 12.5% F2 by volume at 0.1 MPa and 95 °C for 30 min. The fluorinated epoxy sample together with the unfluorinated (original) one for a comparison were exposed to ultraviolet (UV) radiation with wavelengths of 320 to 390 nm. During UV exposure, the evolution of surface physicochemical characteristics was investigated by attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, and the sessile drop technique. The corresponding evolution of surface electrical properties was evaluated by measurements of surface potential decay and surface conductivity. These results have shown that the crosslinking reaction rather than photodegradation occurred for the fluorinated sample, compared to a continuous degradation of the original sample during the UV exposure. These results also indicate that surface conduction and its sensitivity to humidity increased very significantly with UV exposure time for the original sample, while the opposite changes in surface conduction and its moisture sensitivity with the exposure time were found for the fluorinated sample. A relationship between the evolutions of surface electrical properties and surface physicochemical characteristics has been established.

Surface fluorinated epoxy resin for high voltage DC application

Charge accumulation under high voltage DC is a major concern in the transmission system as its presence distorts the local electric field. By performing chemical treatment on polymeric insulation via fluorination process, the charge transport characteristics of the material can be modified. In doing so, excellent surface properties of fluoropolymers can be attained without compromising the bulk properties of the original polymeric insulation. The change in chemical components at the surface of polymeric insulation should lead to a corresponding change in electrical properties at the surface and so suppress charge accumulation. In this paper, epoxy resin samples were formulated and treated with various surface fluorinating conditions. The samples then were characterised by scanning electron microscope (SEM), Raman spectroscopy and DC surface conductivity measurements. The surface potential decay measurement was performed and the result shows that there is a significant change in surface potential decay measurement with the introduction of surface fluorinated layer. The pulsed electroacoustic (PEA) measurement was used to further explain the decay mechanisms responsible for the observed phenomena. Surface DC flashover test using a pair of finger electrodes had also been conducted. It has been found that the introduction of fluorinated surface layer on epoxy resins plays an important role in improving the surface dielectric properties as apparent from the experimental results.

Surface Electrical Properties of Fluorinated Epoxy Resin and Influence of Ambient Humidity

As-prepared epoxy resin samples were surface fluorinated using a F2/N2 mixture. The fluorination resulted in a remarkable increase in surface conductivity of the epoxy sample by over three orders of magnitude. Corona charges deposited on the fluorinated surface could not be stored even at room temperature. Obvious dependence of surface conductivity and steady state surface current on ambient humidity was found for the fluorinated sample. ATR-IR analysis and SEM imaging of surface and cross-section demonstrated substantial changes in surface layer chemical composition and morphology due to the fluorination, which are responsible for the changes in surface electrical properties.

Gradient and weather resistant hybrid super‐hydrophobic coating based on fluorinated epoxy resin

ABSTRACTA weather resistant super‐hydrophobic coating that can offer good substrate adhesion and yet to be easily processed at large scale can be of practical use in emerging fields of self‐cleaning and anti‐icing paint, combing all these properties together remains challenging task. Here we describe a composite coating composed of a fluorinated epoxy resin emulsion with embedded in situ surface‐modified dual‐scale nano‐silica, which displayed durable super‐hydrophobicity and excellent adhesive strength. The as‐prepared coating possesses water contact angle of 158.6 ± 1°, sliding angle around 3.8 ± 0.2° which remain stable even under acidic/alkaline, heat/cool, and accelerated aging treatment. The results demonstrate that surface roughness had a micron‐ and nanometer scale distribution with increased particle loading beyond 40 wt %. Through quantitative comparison of surface Attenuated Total Reflection (ATR) with bulk FT‐IR transmission spectra, a gradient coating with surface enrichment of hydrophobic groups was determined. The air‐side fluorinated polysiloxane‐rich layer endows coating with weather‐resistance and ultra‐hydrophobicity while bottom epoxy resin layer enhances substrate adhesion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40955.

Fluorinated epoxy resin as a low adhesive mould for composite material

The aim of this work is to decrease the adhesion between a cured modified epoxy-based substrate and an in situ cured virgin epoxy-based piece. The effect of perfluorinated additives on the non-adhesion output is investigated through an adapted pull-off test. It appears that additive migration initiates the surface fluorination. Longer the fluorinated chain is, higher the surface fluorination is and weaker the adhesion strength is. The weak chemical affinity between these two epoxy resins is shown to be mainly responsible for these results leading to an adhesive rupture.

Synthesis and properties of methyl hexahydrophthalic anhydride‐cured fluorinated epoxy resin 2,2‐bisphenol hexafluoropropane diglycidyl ether

ABSTRACTThe fluorinated epoxy resin, 2,2‐bisphenol hexafluoropropane diglycidyl ether (DGEBHF) was synthesized through a two‐step procedure, and the chemical structure was confirmed by 1H nuclear magnetic resonance (NMR), 13C NMR, and Fourier transform infrared (FTIR) spectra. Moreover, DGEBHF was thermally cured with methyl hexahydrophthalic anhydride (MHHPA). The results clearly indicated that the cured DGEBHF/MHHPA exhibited higher glass transition temperature (Tg 147°C) and thermal decomposition temperature at 5% weight loss (T5 372°C) than those (Tg 131.2°C; T5 362°C) of diglycidyl ether of bisphenol A (DGEBA)/MHHPA. In addition, the incorporation of bis‐trifluoromethyl groups led to enhanced dielectric properties with lower dielectric constant (Dk 2.93) of DGEBHF/MHHPA compared with cured DGEBA resins (Dk 3.25). The cured fluorinated epoxy resin also gave lower water absorption measured in two methods relative to its nonfluorinated counterparts. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2801–2808, 2013

Rapid potential decay on surface fluorinated epoxy resin samples

Epoxy resin samples were surface fluorinated using a F2/N2 mixture with 12.5% F2 by volume at 50 °C and 0.1 MPa for different times of 10, 30, and 60 min. Surface potential measurements at room temperature and different relative humidity levels of 20% to 60% on the surface fluorinated epoxy samples charged by corona discharge showed a low initial surface potential and a rapid potential decay, depending on the ambient humidity and fluorination time, in comparison with the charged unfluorinated epoxy sample. Surface conductivity measurements at the different relative humidity levels further indicated a higher surface conductivity of the fluorinated samples than the unfluorinated sample by over three orders of magnitude and an increase or decrease in surface conductivity with the ambient humidity or fluorination time, in accordance with the results of surface potential measurements. Attenuated total reflection infrared analyses and scanning electron microscope surface and cross section observations on the un...

Surface properties of the epoxy resin modified by a novel functional fluorinated oligomer

A novel dicarboxyl-terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA) was synthesized through metal-free anionic polymerization and hydrolysis reaction. Chemical structures of CTHFA were characterized by gel permeation chromatography and 1H NMR. Two types of CTHFA with different chain lengths were initially used as an efficient surface modifier to improve the surface properties of epoxy resin, at the content of CTHFA ranging between 0 and 8 wt%. We minimized the amounts of the CTHFA used to achieve a high hydrophobic surface that was not obviously affected by the thermal properties of the epoxy resin. Surface properties and surface composition of the designed fluorinated epoxy resin were investigated by the contact angle and X-ray photoelectron spectroscopy (XPS). Modified epoxy resin with 5 wt% CTHFA containing longer chain length showed excellent hydrophobic surface properties (a high water contact angle about 115° and low surface energy 14.12 mN/m2) while the modified epoxy resin with 5 wt% CTHFA containing shorter chain length did not. XPS analyses indicated that the 5 wt% of fluorinated CTHFA epoxy resin with long macromolecular-chain enhanced more fluorinated groups’ migration to the surface than the fluorinated CTHFA-modified epoxy resin with short macromolecular-chain at the same content. Moreover, thermal properties of CTHFA-modified epoxy resin were also investigated.

Preparation and Characterization of Fluorinated Epoxy Resin Emulsion for Waterborne Coatings

Under the action of initiator(BPO), the α-methyl acrylic acid (α-MAA), butyl hexafluorobutyl methacrylate (HFMA) and other monomers are graft copolymerized into epoxy molecular. By adding N, N-dimethyl ethanolamine, fluorine-containing water-based epoxy resin emulsion can be prepared. By orthogonal experiments, the amount of acrylic monomer, BPO dosage, grafting temperature and other optimum conditions can be determined. Infrared spectroscopy (FT-IR) characterization confirms acrylic monomers successfully grafted to the epoxy resin molecules. The study focuses on the effect of different content of HFMA on modified emulsion particle size and contact angle of coating. The results shows that the introduction of HFMA monomer made the smallest average particle size of emulsion low to 165 nm, and the contact angle against water is increased by 20°. After determining the conventional and environmental performance of the emulsion, the results shows that this preparation of epoxy resin emulsion can fully meet the requirements of waterborne coatings.

Synthesis and properties of novel fluorinated epoxy resins based on 1,1-bis(4-glycidylesterphenyl)-1-(3′-trifluoromethylphenyl)-2,2,2-trifluoroethane

A novel fluorinated epoxy resin, 1,1-bis(4-glycidylesterphenyl)-1-(3′-trifluoromethylphenyl)-2,2,2-trifluoroethane (BGTF), was synthesized through a four-step procedure, which was then cured with hexahydro-4-methylphthalic anhydride (HMPA) and 4,4′-diaminodiphenyl-methane (DDM). As comparison, a commercial available epoxy resin, bisphenol A diglycidyl ether (BADGE), cured with the same curing agents was also investigated. We found that the BGTF gave the exothermic starting temperature lower than BADGE no mater what kind of curing agents applied, implying the reactivity of the former is higher than the latter. The fully cured fluorinated BGTF epoxy resins have good thermal stability with glass transition temperature of 170–175 °C and thermal decomposition temperature at 5% weight loss of 370–382 °C in nitrogen. The fluorinated BGTF epoxy resins also showed the mechanical properties as good as the commercial BADGE epoxy resins. The cured BGTF epoxy resins exhibited improved dielectric properties as compared with the BADGE epoxy resins with the dielectric constants and the dissipation factors lower than 3.3 and dissipation 2.8 × 10 −3, respectively, which is related to the low polarizability of the C–F bond and the large free volume of CF 3 groups in the polymer. The BGTF epoxy resins also gave low water absorption because of the existence of hydrophobic fluorine atom.

Grafting of Epoxy Resin on Surface-modified Poly(tetrafluoroethylene) Films

An epoxy/PTFE composite was prepared by curing the epoxy resin on the surface-modified PTFE film. Surface modification of PTFE films was carried out via argon plasma pretreatment, followed by UV-induced graft copolymerization with glycidyl methacrylate (GMA). The film composite achieved a 90°-peel adhesion strength above 15 N/cm. The strong adhesion of the epoxy resin to PTFE arose from the fact that the epoxide groups of the grafted GMA chains were cured into the epoxy resin matrix to give rise to a highly crosslinked interphase, as well as the fact that the GMA chains were covalently tethered on the PTFE film surface. Delamination of the composite resulted in cohesive failure inside the PTFE film and gave rise to an epoxy resin surface with a covalently-adhered fluoropolymer layer. The surface composition and microstructures of the GMA graft-copolymerized PTFE (GMA-g-PTFE) films and those of the delaminated epoxy resin and PTFE film surfaces were characterized by X-ray photoelectron spectroscopy (XPS), water contact angle and scanning electron microscope (SEM) measurements. The delaminated epoxy resin surfaces were highly hydrophobic, having water contact angles of about 140°C. The value is higher than that of the pristine PTFE film surface of about 110°. The epoxy resin samples obtained from delamination of the epoxy/GMA-g-PTFE composites showed a lower rate of moisture sorption. All the fluorinated epoxy resin surfaces exhibited rather good stability when subjected to the Level 1 hydrothermal reliability tests.

Fluorination of epoxy surfaces by a physical method

To enhance the surface hydrophobicity of epoxy polymers, a simple physical method for the simultaneous surface fluorination during curing of epoxy resins was proposed and evaluated. Curing of epoxy resins against a polytetrafluoroethylene (PTFE) mold gave rise to fluorinated epoxy polymer surfaces due to the anchorage of PTFE molecules on the epoxy polymer surface. The modified epoxy surfaces were characterized using contact-angle measurements and X-ray photoelectron spectroscopy (XPS). The fluorinated epoxy resin surfaces are highly hydrophobic, exhibiting contact angles of similar magnitude to that of the pristine PTFE film surface. The PTFE mold can be used repeatedly to give fluorinated epoxy surfaces with large contact angles. Aging and solvent extraction tests indicated that the fluorinated epoxy surfaces were very stable. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 296–304, 2000

Influence of humidity on refractive index of polymers for optical waveguide and its temperature dependence

Humidity dependence of the refractive index of deuterated polymethylmethacylate (d-PMMA) is examined at a wavelength of 1.3 μm using the return loss method. The refractive index of d-PMMA increases as humidity increases at room temperature, while it decreases as humidity increases at temperatures higher than 60 °C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swelling. Some hydrophobic polymers, such as silicone resin and fluorinated epoxy resin were affected by humidity to a lesser degree than d-PMMA.

A highly fluorinated epoxy resin. III. Behavior in composite and fiber‐coating applications

AbstractThe behavior of a highly fluorinated epoxy resin used as a composite matrix material with AS‐4 fibers and as an AS‐4 fiber coating was studied. The composite mechanical properties were obtained, and the adhesion of the matrix to the fibers was evaluated. Comparisons of uncoated and fluoropolymer coated AS‐4 fibers using single fibers embedded in an Epon 828 matrix were made. Substantial improvement in fiber critical length, and therefore fiber‐matrix adhesion, was observed.

Highly fluorinated epoxy resin. II. Behavior in blend applications

AbstractThe behavior of a highly fluorinated epoxy resin blended with Epon 828 was studied. The two resins are immiscible, resulting in 10–20‐μm spherical domains and a surface layer of fluorinated resin. A B stage for the blend providing for good ply lamination is indicated. The mechanical properties of the blend were commensurate with the Epon phase.