Phenolic Epoxy Research Articles

A new strategy for preparing oligomeric ionic liquid gel polymer electrolytes for high-performance and nonflammable lithium ion batteries

In the present work, a new strategy is used to economically synthesize an oligomeric ionic liquid from conventional phenolic epoxy resin. This oligomeric ionic liquid is further blended with PVdF-co-HFP and organic liquid electrolyte to prepare a high performance, nonflammable gel polymer membrane. Although the liquid electrolyte uptake is low (< 50%) for this novel gel polymer electrolyte, it possesses high ionic conductivities of 2.0mScm−1 at 30°C and 6.6mScm−1 at 80°C, respectively. The AC impedance results show that the interfacial compatibility between this gel polymer electrolyte and the electrodes is good. These two factors result in high cell capacity under different charge/discharge rates. Further, excellent cell-cycle stability after being charged and discharged 100 cycles is also demonstrated with the columbic efficiency to be up to 99. Due to the existence of the oligomeric ionic liquid, this novel gel polymer electrolyte exhibits superior dimensional stability; that is, at high temperature (150°C) the dimensional change is less than 1%. Notably, the electrolyte’s limiting oxygen index can be as high as 29, meaning that it achieves the flame-retardant requirement under a normal atmosphere, which is essential to the safety of lithium ion batteries. These features allow this novel gel polymer electrolyte to function as a high performance and high safety lithium ionic conductor as well as a separator for lithium-ion batteries.

Evaluation of polymeric coatings on their efficiency of inhibiting the adhesion of inorganic scale

The use of polymer coatings allows modulating wettability and can contribute decisively to mitigate the formation of scale in pipes and equipment. In this work critical surface energy (CSE) and surface free energy (SFE) were determined for several polymer coatings (epoxy phenol novolac resins and fluoropolymers), aiming the evaluation of their antifouling capacity against brines reproducing formation waters from pre salt wells. Coatings with lower values for SFE and CSE presented the lowest degree of fouling as determined by wet analysis using inductively coupled plasma atomic emission spectroscopy (ICP - AES).

Investigation of soluble PEG-imidazoles as the thermal latency catalysts for epoxy-phenolic resins

Novel soluble PEG-imidazole compounds were synthesized and evaluated as thermal latent catalysts for the polymerization of diglycidyl ether of bisphenol A (DGEBA) under liquid–liquid or liquid–solid (≥ PEG1000) two phase systems. Soluble PEG-imidazole homogeneous catalysts were used to cure epoxy resin system for the investigation of their thermal latency and storage stability. From the results, the PEG200-imidazole catalyst showed better thermal latency than PEG400-imidazole, PEG600-imidazole and PEG1000-imidazole. Concerning the glass transition temperature (Tg), the use of novel PEG200-imidazole and PEG600-imidazole catalysts provided complete or near complete curing systems in the temperature range about 155 °C. Results from the cure activation energy and the viscosity-storage time of these catalysts, the order of thermally latent activity was PEG200-imidazole (1) > PEG400-imidazole (2) > PEG600-imidazole (3) > PEG1000-imidazole (4) > 1-cyanoethyl-2-ethyl-4-methylimidazole (2E4MZ-CN) > imidazole.

Coarse-grained molecular dynamics simulations of epoxy resin during the curing process

Motivated by the need to establish a multiscale understanding of the mechanical and thermal properties of polymers used for nano-, meso- and macro-composites, we are presenting an investigation of the cross-linking process (associated with curing) of an epoxy phenol novolac and bisphenol-A melt system via coarse-grained molecular dynamics simulations. In particular, we are focusing on the associated structural and physical behaviors of the melts of different cross-linking degree under Couette and Poiseuille flow conditions. At the nanoscale, we also investigated the stress, heat flux and temperature fields that are computable from the quantities of the coarse-grained model of the epoxy resin melt with the extended Hardy’s theory to multibody potentials. We have established that the epoxy resin chains tend to reorient along the direction of the imposed Couette flow, and the degree of alignment increases with the cross-linking degree and shear rate. The pronounced reorientation of cross-linked epoxy resin melts can be ascribed to the inter-bonded chains. This conformational change explains the shear thinning behaviors of cross-linked melts that initiate at low shear rates. The cross-linked melts under Poiseuille flow possess less pronounced velocity profiles, accompanied with the smaller temperature rise from the applied gravity force. Due to the size of the nanoscale channel height, the epoxy resin melts under Poiseuille flow can only be approximately predicted via the continuum theory. We have shown that the discrepancies between atomistic simulations and continuum predictions increase as the wall/epoxy interaction strength reduces. This study reveals the variations of important rheological properties during the cross-linking process and elucidates the roles played by the topological changes in the shear flow, thus can contribute to the design and manufacturing of the epoxy-resin based nanocomposites.

Study on the Phenolic - Epoxy Resin System

By blending the different ratio of the low viscosity of bisphenol A type epoxy resin with low viscosity ammonia catalytic phenolic resin, the performance of the resin systems were investigated by the gel time, viscosity, mechanical properties, heat resistance, flame retardance. In addition, DSC was used to detect the thermal property, and FT-IR monitored the reactive process of phenolic-epoxy resin. When the phenolic resin was mixed with 5% epoxy resin, the results were as follow: the gel time of 121 s at 150°C, viscosity of 7760 mPa·s at 30°C, flexural strength of 83.3 MPa, impact strength of 6.9 kJ/m2, tensile strength of 20 MPa, heat deflection temperature of 148.5°C, oxygen index of 34.5% and the apparent cure activation energy of 94.2kJ/mol. The resin systems had higher service temperature, low viscosity, excellent mechanical properties and service characteristics, and it could meet the requirements of fast pultrusion process.

Composite sandwich panel with multifunction of load bearing, heat insulation, and thermal protection

Integrative sandwich panels with multifunction of load bearing, thermal protection, and heat insulation are manufactured through co-injection resin transfer molding process. These panels have a polymethacrylimide foam core for heat insulation and two composite layers made of carbon/epoxy for load bearing and carbon/phenolic for thermal protection. In co-injection resin transfer molding process, the epoxy resin and phenolic resin are synchronously injected and cured in order to make integrative structures and improve the properties of the interface between different layers. The influence of main factors in the process of co-injection is investigated: the vacuum assistance is indispensable to improve the efficiency of manufacture and guarantee the properties of the products, volume fraction of carbon fiber plays the main role in determining size accuracy of the product, adjusting injection pressure is a simple and efficient way to adjust the infusion time of resin, while injection temperature has smaller influence in the features of manufacture. The mechanical properties of sandwich panels manufactured through co-injection resin transfer molding process and multi-step process are tested and compared to validate the advantage of the co-injection resin transfer molding process. The test shows that the in-plane compressive strength, three-point flexural strength, and interface shear strength are all improved by the co-injection resin transfer molding process. Co-injection resin transfer molding process is proved to be a feasible and efficient way to manufacture the integrative sandwich panel with good interface features.

Microphase separation in a cross-linked epoxy phenol polymer

The microphase separation on the surface of samples of a cross-liked epoxy phenol (EP) polymer produced by the curing of a composition containing an epoxy diane oligomer (EO) and a phenol formaldehyde oligomer (PO) has been investigated using electron microscopy with decoration by silver chloride. It has been shown that, in the cross-liked EP polymer, there is a quasi-lattice of mixed-type AgCl nanoparticles, which consists of two sublattices. The formation of simple lattices of particles is caused by the microphase separation according to the type of nucleation and growth of fractal clusters of the cross-liked EO; the spinodal decomposition in the binary system; and the formation of interpenetrating polymer networks represented by the superposition of two lattices of particles or two infinite phase clusters (cross-liked EO and PO, respectively).

Coarse-grained molecular dynamics simulations of the tensile behavior of a thermosetting polymer.

Using a previously developed coarse-grained model, we conducted large-scale (∼ 85 × 85 × 85 nm(3)) molecular dynamics simulations of uniaxial-strain deformation to study the tensile behavior of an epoxy molding compound, epoxy phenol novolacs (EPN) bisphenol A (BPA). Under the uniaxial-strain deformation, the material is found to exhibit cavity nucleation and growth, followed by stretching of the ligaments separated by the cavities, until the ultimate failure through ligament scissions. The nucleation sites of cavities are rather random and the subsequent cavity growth accounts for much (87%) of the volumetric change during the uniaxial-strain deformation. Ultimate failure of the materials occurs when the cavity volume fraction reaches ∼ 60%. During the entire deformation process, polymer strands in the network are continuously extended to their linear states and broken in the postyielding strain hardening stage. When most of the strands are stretched to their taut configurations, rapid scission of a large number of strands occurs within a small strain increment, which eventually leads to fracture. Finally, through extensive numerical simulations of various loading conditions in addition to uniaxial strain, we find that yielding of the EPN-BPA can be described by the pressure-modified von Mises yield criterion.

Influences of the molecular structure of carbon sources on the structure, morphology and performances of the Li3V2(PO4)3–C cathode for lithium ion batteries

The influences of carbon sources in the synthesis of Li3V2(PO4)3–C (LVP) by carbothermal reduction method have been investigated. All the Li3V2(PO4)3–C samples possess the typical monoclinic structure. Of all the samples, LVP-PR (phenolic resin) possesses the largest discharge capacities of 128.4 mA h g−1, 125.7 mA h g−1 and 103.9 mA h g−1 at 0.2 C, 2 C and 5 C respectively. Its charge transfer resistance has the lowest value of 59.04 Ω. These excellent electrochemical performances result from its maximum conductivity of 1.93 × 10−2 S cm−1. The intensity ratio of peaks 1350 cm−1 to 1580 cm−1 in Raman spectra of LVP-PR has the lowest value of 1.162. The appearance of needle-shaped crystallites in LVP-PR and LVP-ER (epoxy resin) shows that phenolic resin and epoxy resin possess a strong reduction ability. This is also verified by the size of the crystallite. All these are because of the structural differences of carbon sources. The certain amount of benzene rings in the phenolic resin enables LVP-PR to possess high conductivity. The space steric effect of the methyl in epoxy resin and the lack of conjugated π bonds in glucose decrease the conductivity of LVP-ER and LVP-GL.

A Coarse-Grained Model for Epoxy Molding Compound

We present a coarse-grained model for molecular dynamics simulations of an epoxy system composed of epoxy phenol novolac as epoxy monomer and bisphenol-A as the cross-linking agent. The epoxy and hardener molecules are represented as short chains of connected beads, and cross-linking is accomplished by introducing bonds between reactive beads. The interbead potential, composed of Lennard-Jones, bond stretching, and angle bending terms, is parametrized through an optimization process based on a particle swarm optimization method to fit certain key thermomechanical properties of the material obtained from experiments and previous full atomistic simulations. The newly developed coarse-grained model is capable of predicting a number of thermomechanical properties of the epoxy system. The predictions are in very good agreement with available data in the literature. More importantly, our coarse-grained model is capable of predicting tensile failure of the epoxy system, a capability that no other conventional molecular dynamic simulation model has. Finally, our coarse-grained model can speed up the simulations by more than an order of magnitude when compared with traditional molecular dynamic simulations.

A study of the thermal, dielectric, and flame-retarding characteristics of various bismaleimide blended with halogen-free epoxy resin

This work investigates various blends of a halogen-free epoxy resin (phenolic epoxy resin (703-H) and melamine phenol formaldehyde novolac (MPN) combined with different quantities of bismaleimide (BMI). The goal of this work was to optimize the thermal, flame-retarding, and dielectric properties by modifying the matrix with BMI. The polymerization of the matrices was studied with 13C nuclear magnetic resonance spectroscopy (13C-NMR) and fourier transform infrared spectroscopy (FTIR). The reaction kinetics and thermal stability were studied using dynamic mechanical analyzer (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The total reaction heat (ΔH) of 703-H/MPN was greater than that of 703-H/MPN/BMI blends. The total activation energy and the dielectric constant were both found to decrease with an increasing BMI content. The Ozawa model can be used to describe the 703-H/MPN/BMI reaction kinetics. The most excellent characteristics, such as the highest Tg of 205 °C, the highest limiting oxygen index (LOI) value of 41, and the lowest dielectric constant of 2.3, were obtained when the EEW ratio of 703-H/MPN was 1.0/0.5, with 0.5 EEW (epoxy equivalent weight) of BMI cured at 145 °C for 2 h.

A molecular dynamics study of tensile strength between a highly-crosslinked epoxy molding compound and a copper substrate

Presented in this paper is a numerical study based on classical molecular dynamics simulation to understand the deformation and failure behavior of an epoxy/copper bimaterial under pure tension normal to the interface. The epoxy considered is a highly cross-linked epoxy phenol novolac, and the copper substrate is a standard face-center-cubic single crystal with its (1,1,1) surface as the epoxy/copper interface. Stress versus displacement/strain curves are obtained to understand the bimaterial behavior and to predict the epoxy/copper interfacial tensile strength. It is found that the interfacial failure is brittle caused by simultaneous detachment of epoxy atoms from the copper substrate, and the interfacial tensile strength is almost unaffected by the unloading and reloading before the failure strength is reached. Effects of temperature, epoxy cross-link density, and epoxy functionality are also investigated. Findings of this study provide significant insights into the deformation and failure behavior mechanisms of the epoxy/copper bimaterial interface.

Enhancement of ablative and interfacial bonding properties of EPDM composites by incorporating epoxy phenolic resin

Effects of epoxy phenolic resin (EPR) on ablative and interfacial bonding properties of EPDM composites were evaluated. Ablative properties of EPDM composites were enhanced by two folds with incorporating 10phr EPR. This significant enhancement was attributed to positive effect of EPR on thermal stability and thermal insulating properties of EPDM composites as well as formation of compact char layer onto composites. Furthermore, interfacial shear strength of EPDM composites with carbon fiber/epoxy (CF/EP) composites was increased by 55.6% with incorporating 10phr EPR, due to interfacial chemical reaction of epoxide groups of EPR molecule from EPDM composites with amine group of hardener from CF/EP composites.

Degradation mechanism of lacquered tinplate in energy drink by in-situ EIS and EN

The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages: organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.

Influence of the isothermal cure temperature on the nanostructure and thermal properties of an epoxy layered silicate nanocomposite

The cure kinetics of triglycidyl p-amino phenol (TGAP) epoxy resin with a diamine (4,4-diamino diphenyl sulphone [DDS]), reinforced with montmorillonite (MMT), has been studied by differential scanning calorimetry. The isothermal cure reaction consists of two parts: a rapid intra-gallery reaction, attributed to homopolymerization of the TGAP catalyzed by the MMT and the extra-gallery cross-linking reaction of the TGAP with the DDS. Increasing cure temperature promotes the intra-gallery reaction, which should promote an exfoliated nanostructure; this is confirmed by transmission electron microscopy. These results indicate that this system (TGAP/DDS/MMT) is an excellent candidate for achieving exfoliated polymer-layered silicate nanocomposites and identifies a protocol for optimizing the degree of exfoliation. POLYM. ENG. SCI., 54:51–58, 2014. © 2013 Society of Plastics Engineers

Study on the Copolymer Properties of Phenolic Resin-Epoxy Resin

The properties of phenolic-epoxy copolymer were studied in this paper. DSC was used to detect the possibility of copolymerization between phenolic resin and epoxy resin. FT-IR monitored the reactive process of mixed resin in various temperature stages. DMA revealed that the copolymer possessed high moduli and glass transition temperatures. The result showed that phenolic-epoxy copolymer can react in appropriate proportion. It is better for the copolymer system to avoid rich epoxy without curing agent. The properties of the copolymer could be increased when sacrificed some excellent properties of phenolic and epoxy. The copolymer 70% phenolic &amp; 30% epoxy and 60% phenolic &amp; 40% epoxy posses higher service temperature, lower volumetric shrinkage and excellent mechanical properties.

Capacitive Deionization Performance of Activated Carbon Electrodes Prepared by a Novel Liquid Binder

A novel liquid binder, which is called AA in this paper, was synthesized with acrylic acid and azodiisobutyronitrile to prepare electrodes from activated carbon (AC, ACE) for capacitive deionization (CDI). The ACE prepared with AA (ACE-AA) was carbonized to improve its CDI performance. As a result, its wettability was significantly improved, and the specific capacitance was increased by a factor of 8. The optimization showed that electrodes with a mass fraction of AC of 35 wt% had the best CDI performance. Compared with ACEs prepared with phenolic resin (PR), polytetrafluoroethylene (PTFE) and epoxy resin (ER), electrodes prepared using AA binder showed improved flexibility, durability, wettability, and desalination ratio. Therefore, the ACE-AA seems to be a very promising carbon electrode for CDI.

Study on the Resin Curing Time and the Mechanical Properties of the Composites

In order to study the curing characteristics of common resins including bisphenol-A epoxy vinyl ester resin, phenolic epoxy vinyl ester resin and unsaturated polyester resin, the curing time of three resins was tested using cobalt naphthenate as accelerator and methyl ethyl ketone peroxide as curing agent. The results showed that the resin curing time reduces with the experimental temperature rising; in order to control the curing time at about 25 minutes when the experimental temperature is 23°C, the curing agent adding proportion of bisphenol-A epoxy vinyl ester resin, unsaturated polyester resin and phenolic epoxy vinyl ester resin are respective about 0.7%, 0.5% and 1.8%. The composites made by bisphenol-A epoxy vinyl ester resin have excellent tensile strength and composites made by phenolic epoxy vinyl ester resin have best bending strength.

Investigating the Properties of Modified Epoxy-Containing Oligomers

This work was devoted to the development of modified epoxy–phenol binders and reinforced plastics based on them (carbon-fibre-reinforced plastics). The composition of the binder was optimised using different types of modifier, and trial specimens of carbon-microfibre-reinforced plastics were manufactured. Their deformation and strength properties were investigated, and also the properties at the phase interface between binder and carbon fibre. It was shown that the use of the investigated modifiers makes it possible to increase the deformation and strength characteristics of the binders and of the carbon-fibre-reinforced plastics based on them.

Comparative characterization of chip to epoxy interfaces by molecular modeling and contact angle determination

An investigation of interfacial interaction has been performed between three epoxy molding compound materials and a native silicon dioxide layer (SiO2) usually found at chip surfaces. The epoxy materials were an industry oriented epoxy molding compound Epoxy Phenol Novolac (EPN), its filled variety EPNF (with silica particles) and a model aromatic epoxy11,3-Bis(2,3-epoxypropoxy)-benzene and a 1,2diamino(ethane)2 hardener in a 2:1 mixing ratio.1 (212). All systems are described in full in [1] and [2]. The free surfaces of the solid materials were experimentally analyzed by contact angle measurements of three different liquids (water, methylene-iodide (MI) and glycerol). Results are compared to interfacial energies obtained by analysis of the interfaces in bimaterial molecular models, yielding reasonable agreement. A qualitative prediction regarding the influence of water on the interfacial strength between chip and molding compound is attempted.