Diglycidyl Ether Of Bisphenol F Research Articles

Resin-Cement Blend Enhances Wellbore Integrity

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 213763, “Use of Innovative Resin-Cement Blend To Enhance Wellbore Integrity,” by Wajid Ali, Faisal A. Al-Turki, and Athman Abbas, SPE, TAQA Well Services, et al. The paper has not been peer reviewed. _ A major challenge occasionally faced during a well’s life cycle is the buildup of sustained casing pressure (SCP). Compromised cement-sheath integrity is one of the primary reasons for such a pressure buildup. Meeting this challenge requires development of an isolation material that can enhance the mechanical properties of cement. This paper presents the laboratory testing and application of a resin-cement system in a scenario where potential high-pressure influx was expected across a water-bearing formation. The resin-cement system was designed to be placed as a tail slurry to provide enhanced mechanical properties compared with a conventional slurry. Introduction The objectives of this study were to investigate the use of new systems at different densities with epoxy resin as an additive and to demonstrate value added in terms of improved mechanical properties and bonding. The resin used in this study is diglycidylether of bisphenol-F, a linear epoxy resin formed by reacting bisphenol-F with a suitable amount of epichlorohydrin and hydroxide. Amines are used as curing agents for epoxy resins. The curing mechanism is a step-growth polymerization. The curing is observed initially by an increase in viscosity and then by hardening. The final product’sproperties, in terms of compressive strength and viscosity, also are affected by the type and concentration of the amine. Aliphatic amines produce more-flexible types of epoxy resins compared with aromatic amine curing agents. Aromatic amines will produce a stronger, harder epoxy resin. Experimental Study Cement Slurry Preparation and Testing. The cement slurry was formulated and mixed with a maximum speed of 12,000 rev/min for 15 seconds and then at 4,000 rev/min for 35 seconds. To condition the cement slurry, an atmospheric consistometer was used. A viscometer was used to measure rheological properties. Thickening time tests also were conducted. Fluid-loss measurements (dynamic and static) were performed on the prepared cement slurry. Dynamic fluid loss can affect rheology and thickening time of cement slurries. Static fluid loss can result in reduction in cement slurry and allow formation fluids to enter the cement slurry. Separation of water is observed when a cement slurry is allowed to stand for a period before it sets. To determine the extent of water separation, a free water test was performed to determine the extent of water separation. The test was conducted by allowing cement slurry to stand in a 250-mL graduated cylinder for 2 hours. The cement slurry was poured into a cylindrical cell and lowered into a curing chamber. While maintaining pressures and temperatures, the cement slurry was cured up to 30 days. At the end of the curing period, the pressure and temperature were reduced to ambient conditions and the test specimens were removed from the curing chamber to be tested for mechanical properties.

Activation of inert triethylene tetramine-cured epoxy by sub-critical water decomposition

Cured epoxy is stable and difficult to be recycled. To make the inert cured epoxy and its derivatives or composites reactive is still a challenge. In this study, sub-critical water was used to decompose the solid diglycidyl ether-based epoxy resin (bisphenol A and bisphenol F) cured with triethylene tetramine (TETA) to reactive species. First of all, the thermally most unstable bonds in the epoxy resin underwent homogeneous cleavage reaction. Next, the generated free radicals were saturated by extracting hydrogen from the sub-critical water. The decomposition rate was improved with increasing the temperature and reaction time. During the reaction, breakage occurs preferentially in the epoxy resin main chain because of the existence of ether groups. The compounds evolved and the decomposition was analyzed. The experimental outcomes revealed that the decomposition mechanism of diglycidylether of bisphenol A (DGEBA)/TETA and diglycidylether of bisphenol F (DGEBF)/TETA resin regimes in sub-critical water may include side group elimination, random fracture and unzipping. Moreover, a segmented second-order kinetic analysis of the decomposition process was performed. The decomposition processes of two resins in sub-critical water were divided into two stages. Both stages were second-order reaction, the activation energy of DGEBA/TETA was 175 kJ/mol (Ea1(15-45min)), and 612 kJ/mol (Ea2(52.5-75min)). The activation energy of DGEBF/TETA was 258 kJ/mol (Ea1(15-45min)), and 686 kJ/mol (Ea2(52.5-75min)), respectively. This study provides a way for recycling inert epoxy wastes from different industrial fields and generating reactive and functional polymers.

Addressing diffusion behavior and impact in an epoxy–amine cure system using molecular dynamics simulations

To deepen understanding of diffusion-controlled crosslinking, molecular dynamics (MD) simulations are carried out by taking the diffusion image of 3,3′-diamino diphenyl sulfone (3,3′-DDS) and polyethersulfone (PES) with epoxy resin varying temperatures from 393.15 to 473.15 K over crosslinking conversion of 0–85%. The diffusion of PES and 3,3′-DDS into the bulk increased with increasing the temperature as a result of enhanced mobility of the molecules when the difference between the glass-transition temperature (Tg) and the curing temperature. Beyond the onset points of the converged crosslinking conversion ratio of 3,3′-DDS and PES, their diffusion properties are obviously restricted with crosslinking conversion ratio. At low crosslinking conversion ratios (> 10%), the diffusion coefficients of triglycidyl p-aminophenol (TGAP) were 1.1 times higher than those of diglycidyl ether of bisphenol F (DGEBF) because of the lower molecular weight of TGAP. On the other hand, the diffusion coefficients of TGAP decreased when the crosslinking ratio was up to ~ 60% because, compared with DGEBF, it had more functional groups available to react with the curing agent. At higher crosslinking ratios, the diffusion coefficients of both resins converged to zero as a result of their highly crosslinked structures.

Molecular-level investigation on the effect of surface moisture on the bonding behavior of cement-epoxy interface

Epoxy resins are widely used as construction and repair materials. However, their bond with the concrete substrate under wet conditions is of concern as the loss of compatibility will lead to the failure of the bonded system. The reported study investigated the effect of surface moisture at the epoxy/cement interface using molecular dynamics (MD) simulation. The model of the interface was built using calcium silicate hydrate (C–S–H), as a hydrated cement substrate and diglycidyl ether of bisphenol-F (DGEBF) as an epoxy resin. Subsequently, different layers of water molecules were inserted into the model to represent varying moisture concentrations at the interface. The interfacial properties of the dry and wet models were evaluated in terms of adhesion, debonding, and energy ratios. In addition, the radial distribution function (RDF) was employed to deeply investigate the atomic interaction between the cement surface and epoxy. The results of the model indicated that the adhesion properties were adversely affected by the presence of moisture at the epoxy/cement interface. The degradation in the adhesion at moisture contents of 3% and 6% was 37.49% and 72.02%, respectively. Additionally, it was found that the detachment increased, as evident from the values of debonding, at higher moisture contents due to an increase in the adhesion between the C–S–H and water molecules where the latter form hydrogen bonds with the substrate. This work provides valuable molecular-level insights into the epoxy/cement bond that can be used to design new epoxy resins suited for cement and concrete applications.

Research on the relationship between time-dependent strains and delamination of plastic packaged devices at polymer/copper interface under thermal-hygro environments

Delamination of polymer/metal interfaces has a destructive effect on plastic packaged devices containing thin layered structures. The physics mechanisms of the delamination inside the microstructure devices are not well understood and difficult to reveal. In order to get a deeper understanding of strain variations at the interface between the viscoelastic polymer and other elastic metal bases under a thermal-hygro environment, the following researches are conducted. Firstly, by combining the generalized Maxwell model and the hygro-mechanical strain equation of bi-layer plate, the equation set for hygro-mechanical strain at the interface of bi-layer plate is established considering the viscoelasticity of epoxy resins. Secondly, two bi-layer plate test pieces are made using elastic copper plates and two different types of viscoelastic epoxy resins (diglycidyl ether of bisphenol F (DGEBF) and Cycloaliphatic epoxy resins), and the normal strains at the interface of the two bi-layer plates under a thermal-hygro environment are measured by strain gauges sealed between the epoxy resin layer and the copper plate. Thirdly, by substituting the thermal strain results into the polynomial equations for thermo-mechanical strain at the bi-layer plate interface, the coefficients of thermal expansion of the two epoxy resins at different temperatures are obtained. Finally, multi-parameter fitting of the interface hygro-mechanical strain curves are drawn through programming in MATLAB software based on the genetic algorithm, and the shear modulus and relaxation time of the two viscoelastic epoxy resins are obtained. This paper’s experiment and calculation results reveal the relationship between time-dependent strain and delamination of plastic packaged devices at polymer/copper interface under a thermal-hygro environment, and provide a valuable reference to improve the reliability of plastic packaged devices.

Phosphazene as an effective flame retardant for rapid curing epoxy resins

A rapid curing, low viscosity epoxy amine resin developed for high pressure resin transfer moulding composite fabrication possessing good thermal and mechanical properties and excellent flame retardancy after cure is presented here. The resin system consists of diglycidyl ether of bisphenol F (DGEBF), an epoxy phenolic novolac resin and diethyl toluene diamine (DETDA), while rapid cure is enabled by 2-ethyl-4-methylimidazole (2E4MI) catalysis. The fire-retardant additive, a crystalline powder, hexaphenoxy cyclotriphosphazene (HPCTP) produces only a small increase in viscosity and regardless of additive concentration, the formulations are less than 200 mPas at processing temperatures of between 80 and 125 °C. Using the UL-94 vertical burn test, a V0 rating and a limiting oxygen index (LOI) of 36.2% were achieved using only 10 phr HPCTP. Indeed at 20 phr of HPCTP an LOI of 43.6% was achieved. The HPCTP additive remains miscible in the network after cure which reduces reactivity modestly and the glass transition temperature (Tg), but the flexural properties, including modulus, strength and strain to failure, either increase modestly or were unaffected.

Thermochemical Mechanism of the Epoxy-Glutamic Acid Reaction with Sn-3.0 Ag-0.5 Cu Solder Powder for Electrical Joining.

An epoxy-based solder paste (ESP) is a promising alternative to conventional solder pastes to improve the reliability of fine-pitch electrical joining because the epoxy encapsulates the solder joint. However, development of an appropriate epoxy formulation and investigation of its reaction mechanism with solder powder is challenging. In this study, we demonstrate a newly designed ESP consisting of diglycidyl ether of bisphenol F (DGEBF) resin, Sn-3.0 Ag-0.5 Cu (SAC305) solder powder, and L-glutamic acid (Glu), which is a proteinogenic amino acid for biosynthesis of proteins in living systems. The mechanism of the thermochemical reaction was explored and tentatively proposed, which reveals that the products of the reaction between SAC305 and Glu function as catalysts for the etherification of epoxides and alcohols produced by chemical bonding between DGEBF and Glu, consequently leading to highly crosslinked polymeric networks and an enhancement of impact resistance. Our findings provide further insight into the mechanism of the reaction between various formulations comprising an epoxy, amino acid, and solder powder, and their potential use as ESPs for electrical joining.

Comparative Study on Toughening Effect of PTS and PTK in Various Epoxy Resins.

This study investigated the toughening effect of in situ polytriazoleketone (PTK) and polytriazolesulfone (PTS) toughening agent when applied to various epoxy resins, such as diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F (DGEBF), and triglycidyl p-aminophenol (TGAP) with 3,3′-diaminodiphenylsulfone as a curing agent. The fracture toughness, tensile properties, and thermal properties of the prepared epoxy samples were evaluated and compared. When PTK was mixed with DGEBF, the fracture toughness was improved by 27% with 8.6% increased tensile strength compared to the untoughened DGEBF. When PTS was mixed with TGAP, the fracture toughness was improved by 51% without decreasing tensile properties compared to the untoughened TGAP. However, when PTK or PTS was mixed with other epoxy resins, the fracture toughness decreased or improved with decreasing tensile properties. This is attributed to the poor miscibility between the solid-state monomer of PTK (4,4′-bis(propynyloxy)benzophenone (PBP)) or PTS (4,4′-sulfonylbis(propynyloxy)benzene (SPB)) and the epoxy resin, resulting in the polymerization of low molecular weight PTK or PTS in epoxy resin. Therefore, the toughening effect of PTK or PTS can be maximized by the appropriate selection of epoxy resin based on the miscibility between PBP or SPB and the resin.

A Triple Crosslinking Design toward Epoxy Vitrimers and Carbon Fiber Composites of High Performance and Multi-shape Memory

It remains a challenge to use a simple approach to fabricate a multi-shape memory material with high mechanical performances. Here, we report a triple crosslinking design to construct a multi-shape memory epoxy vitrimer (MSMEV), which exhibits high mechanical properties, multi-shape memory property and malleability. The triple crosslinking network is formed by reacting diglycidyl ether of bisphenol F (DGEBF) with 4-aminophenyl disulfide, γ-aminopropyltriethoxysilane (APTS) and poly(propylene glycol) bis(2-aminopropyl ether) (D2000). The triple crosslinking manifests triple functions: the disulfide bonds and the silyl ether linkages enable malleability of the epoxy network; the silyl ether linkages impart the network with high heterogeneity and broaden the glass transition region, leading to multi-shape memory property; a small amount of D2000 increases the modulus difference between the glassy and rubbery states, thereby improving the shape fixity ratio. Meanwhile, the high crosslinking density and rigid structure provide the MSMEV with high tensile strength and Young’s modulus. Moreover, integrating carbon fibers and MSMEV results in shape memory composites. The superior mechanical properties of the composites and the recyclability of carbon fiber derived from the dissolvability of MSMEV make the composites hold great promise as structural materials in varied applications.

Lignocellulosic Natural Fiber Reinforced Bisphenol F Epoxy Based Bio-composites: Characterization of Mechanical Electrical Performance

ABSTRACT The current research deals with bio-composites developed by using four different types of lignocellulosic natural fibers, e.g., jute, sisal, coconut/coir, and sugarcane (bagasse) for reinforcement. A multifunctional resin derived from phosphoric acid modified Diglycidylether of bisphenol-F (DGEBF) was used as a matrix. Mechanical properties, e.g., impact strength, flexural strength, tensile strength, and modulus etc. were evaluated and analyzed. Among all the different types of samples developed, sisal and jute fiber-based composites exhibit superior tensile, impact, and flexural properties as compared to other fiber types investigated. Bagasse composites exhibit the highest specific bending performance due to lowest density. Coir and bagasse-reinforced composites show higher electrical resistivity due to lower fiber density and lower crystallinity of fibers. Relatively higher resistivity suggests application in small switches, insulation rods, mobile/laptop, and computer covers etc. The results from the developed samples demonstrate that lignocellulosic fiber-reinforced epoxy composites could open new opportunities for their applications in different electrical goods and as an environmentally friendly alternative.

Well-Defined Networks from DGEBF-The Importance of Regioisomerism in Epoxy Resin Networks.

The previously ignored or unreported impact of regiosomerism within diglycidyl ether of bisphenol F (DGEBF) on its network properties is presented. Routes to the isomers of DGEBF were explored: high-performance liquid chromatography showed good separation of the three isomers [para–para-DGEBF (ppDGEBF), para–ortho-DGEBF (poDGEBF), and ortho–ortho-DGEBF (ooDGEBF)] with small yields; column chromatography gave good separation of pp- + po- from oo-DGEBF but pp-/po- separation was not achieved. Synthesis was optimized to crude yields of 76% for pp-; 87% for po-, and 86% for oo-. Subsequently, crosslinked networks were prepared with meta-xylylenediamine. With increasing ortho content, degradation of chemical resistance and an inherent weakening of the network was observed, that is, glass transition temperature (Tg), beta transition temperature (Tβ), density, crosslink density, and the desorption diffusion coefficient decreased, whereas sorption diffusion coefficient and ultimate solvent uptake increased. This clearly shows that a subtle chemical structure change can significantly impact network performance.

Mechanical and Thermodynamic Properties of Unidirectional Flax Fiber Reinforced CNT Modified Epoxy Composites

In this paper, the mechanical and thermodynamic properties of diglycidyl ether of bisphenol-F (DGEBF) epoxy resin and flax fiber FRP composites, which was modified with multi-walled carbon nanotubes (MWCNTs) were studied. The mechanical property tests show significant improvements in the tensile strength (48.7 %), tensile modulus (25.2 %) at 1.0 wt.% of MWCNTs. DMTA test reveals that mixture of 1.0 wt.% MWCNTs into the epoxy resin increases 10.68 K of Tg, which is in accordance to the simulated results from molecular dynamics. These improvements in mechanical and thermodynamic properties are attributed to the balanced effect of stress concentration and radiation. The mechanical and thermodynamic properties of flax fiber FRP composites are improved with the addition of MWCNTs. This study is expected to provide an opportunity to develop high performance of natural fiber FRP composites.

Weldable, malleable and programmable epoxy vitrimers with high mechanical properties and water insensitivity

Vitrimers with covalent adaptable networks usually show low mechanical properties and water resistivity. Here, we report an epoxy vitrimer which possesses not only high weldability, malleability and programmability, but also outstanding mechanical properties and water insensitivity. Such epoxy vitrimer is fabricated by crosslinking diglycidyl ether of bisphenol F (DGEBF) with a novel curing agent bearing imine backbones and amino terminals. The curing agent is synthesized by a one-pot reaction between 3-aminobenzylamine and terephthalaldehyde by taking advantage of the different reactivity of the aromatic amine and aliphatic amine. The dynamic imine bonds of the curing agent enable malleability, shape reconfiguration and programming of the epoxy vitrimer, while the aromatic structure of the curing agent imparts the epoxy vitrimer with high tensile strength, Young modulus and thermal stability. Moreover, the epoxy vitrimer is highly water-resistant due to the hydrophobicity and high crosslinking density of the network. Such a combination of comprehensive properties and convenient fabrication approach makes the epoxy vitrimer hold great promise to serve as structural materials in diverse applications.

Novel self-healing CFRP composites with high glass transition temperatures

Carbon fiber reinforced polymer (CFRP) composites were fabricated using a novel intrinsically healable isocyanurate-oxazolidone (ISOX) thermosetting matrix. After multiple delamination events, repeatable strength recovery of the composites has been demonstrated with a first healing efficiency up to 85% after thermal treatment. The healing mechanism results from transformation of the isocyanurate with epoxide groups to yield new oxazolidone rings at the fracture surface. This novel ISOX polymer utilizes commercial diglycidyl ether of bisphenol F (DGEBF) and toluene diisocyanate to produce a high cross-link density thermoset with a glass transition temperature (Tg) up to 285 °C, and 99.5% of the composite weight remains at 300 °C. The strength and stiffness of the composites are comparable with an engineering grade polymer matrix composite typically used in aerospace applications and the thermal stability places the materials in the polybismaleimide performance region although with greater toughness. This polymer exhibits the highest Tg of any self-healing material reported and is composed of low cost reactants, which gives the polymer great potential to function as a major component of an advanced structural composite for extreme environments.

Issue of Epoxy-Based Coatings System Crystallization and Effect of Partial Crystallinity on Mechanical Parameters

Crystallization of bisphenol A-based and bisphenol F-based epoxy resins is the common property of the oligomers. However, producers of paints, coatings and other systems based on these epoxy resins are making efforts to slow down the crystallization process as much as possible. Thereby the shelf life is prolonged, while improving the competitiveness of their products. The main topic is the generalization of factors influencing the crystallization process of bisphenol A-based and bisphenol F-based epoxy resins, the validation of new approaches to possibility of influencing their crystallization process, and the determination of possibility of using a certain degree of crystallinity of bisphenol A-based and bisphenol F-based epoxy resins when preparing and producing paint and coating systems. Two types of the epoxy resins in formulations of paint and coating and other systems, namely: diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) were used. The tendency to crystallize not only for the pure epoxy resins, but also various mixtures with reactive diluents, fillers, etc. was determined according to the standard ISO 4895 Plastics – Liquid epoxy resins – Determination of tendency to crystallize. Furthermore, the crystallinity of individual samples was determined. The effectiveness of potentially active nucleating agents such as precipitated calcium carbonate, DGEBA, and DGEBF crystals, etc. was selected and tested according to the ISO 4895 standard. The effectiveness of potentially active admixtures with crystallization retardation effect was selected and tested according to the ISO 4895 standard. Selected samples of the epoxy resins with a specified degree of crystallinity were cured with 3-aminomethyl-3,5,5-trimethylcyclohexylamine (IPD) based crosslinking agent. Mechanical parameters such as compressive strength and flexural strength were determined. The influence of crystallinity on selected mechanical parameters was also observed.

Characterization of Interfacial Properties of Graphene-Reinforced Polymer Nanocomposites by Molecular Dynamics-Shear Deformation Model

In this paper, we present an approach for characterizing the interfacial region using the molecular dynamics (MD) simulations and the shear deformation model (SDM). The bulk-level mechanical properties of graphene-reinforced nanocomposites strongly depend on the interfacial region between the graphene and epoxy matrix, whose thickness is about 6.8–10.0 Å. Because it is a challenge to experimentally investigate mechanical properties of this thin region, computational MD simulations have been widely employed. By pulling out graphene from the graphene/epoxy system, pull-out force and atomic displacement of the interfacial region are calculated to characterize the interfacial shear modulus. The same processes are applied to 3% grafted hydroxyl and carboxyl functionalized graphene (OH-FG and COOH-FG)/epoxy (diglycidyl ether of bisphenol F (DGEBF)/triethylenetetramine (TETA)) systems, and influences of the functionalization on the mechanical properties of the interfacial region are studied. Our key finding is that, by functionalizing graphene, the pull-out force moderately increases and the interfacial shear modulus considerably decreases. We demonstrate our results by comparing them with literature values and findings from experimental papers.

A UV-curable epoxy with “soft” segments for 3D-printable shape-memory materials

Three-dimensional (3D)-printable shape-memory polymers (SMPs) are of great interest for making advanced shape-memory materials. However, it has been challenging to combine 3D-printable capability with shape-memory function into one material. Here, we report a UV-curable epoxy with excellent shape-memory performance and improved toughness as compared with traditional epoxy counterpart. The epoxy system is realized by cross-linking epoxy resin diglycidyl ether of bisphenol F (DGEBF) (“hard” segments) with toughening agent 3-ethyl-3-oxetanemethanol (TMPO) (“soft” segments), which finally creates a three-dimensional network with TMPO-co-DGEBF block structures. The fold-deploy tests show that the shape fixity ratio (Rf) and the shape recovery ratio (Rr) of the epoxy with 50 wt% TMPO soft segment are above 97 and 99% even after 20 cycles of testing, respectively. In addition to bringing shape-memory performance, the toughness of the epoxy system is notably improved by the TMPO soft segments. This study provides a very promising epoxy system for 3D-printable shape-memory materials.

Investigation on fracture behavior and mechanisms of DGEBF toughened by CTBN

Carboxyl-terminated butadiene-co-acrylonitrile (CTBN) was used as the toughener to improve the mechanical performance and fracture toughness of diglycidyl ether of bisphenol F (DGEBF) by prereacted approach. The results show that the chemical bonding interface was formed between DGEBF and CTBN particles in the prepolymerization reaction process, which remarkably enhances the fracture toughness of the composites. Based on the qualitative and quantitative analyses, it shows the main toughening mechanisms are the plastic shear banding effect resulted from the plastic deformation of the EP matrix and the plastic void expansion because of the debonding of CTBN particles from the EP matrix.

Effect of excess silane on the viscoelastic behavior of epoxy under hygrothermal conditions

This study investigates the effects of excess organofunctional silane on the elastic and viscoelastic properties of an epoxy resin. Samples were prepared by adding 3–glycidoxypropyl trimethoxysilane (GPTMS) in varying amounts ranging from 0.5 to 8.0 wt% to diglycidyl ether of bisphenol–F (DGEBF) epoxy cured using an amine-based hardener. Prepared samples were subjected to hygrothermal conditioning by immersion in water at 21 °C and 50 °C. Subsequently, instrumented nanoindentation was used to determine the elastic modulus and creep compliance. A Fickian model fitted to moisture absorption data indicates that after 48 h specimens were fully saturated to a depth of approximately 150 µm, which is significantly higher than the maximum indentation depth of 1 µm. This implies that the indentation material response was determined from a fully saturated region. It was found that the addition of silane leads to a reduction in the elastic modulus. In the presence of hygrothermal degradation, this reduction still occurs but is less than the non-conditioned case, especially for exposure at 50 °C. For example, the addition of 8.0 wt% silane reduces the elastic modulus by an average of 70% as compared to the pristine sample, and conditioning at 21 °C and 50 °C results in reductions of elastic modulus by 73% and 52%, respectively. The overall reduction in the elastic modulus value is due to the inclusion of flexible silane into the epoxy resin. Under hygrothermal conditions, however, the hydrolysis of silane mitigates the reduction in elastic modulus, especially at higher temperature conditioning. The viscous response of the material is sensitive to the inclusion of silane and hygrothermal conditioning. However, at very low wt% of silane (less than 2%), the material becomes creep resistant and at higher wt%, the behavior is similar to the elastic modulus. Fourier transform infrared (FTIR) spectra indicates that Si–Si interaction becomes predominant at higher wt. fractions leading to softening of the material. Inclusion of silane also reduces the glass transition temperature, which supports the increase in flexibility of the polymer chain.

Electrical performance of TGPAP and DGEBF-based epoxy resin insulation materials for superconducting magnets

For the insulation materials of the superconducting magnet, the mechanical and electrical properties should be guaranteed under stresses of cryogenic temperature and intense radiation. In this study, two types of epoxy resins were prepared, which consist of diglycidyl ether of bisphenol-F (DGEBF) and triglycidyl-p-aminophenol (TGPAP) as matrixes respectively, and diethyl toluene diamine (DETD), isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether] (IPBE) and boron-free glass fibre were used as curing, toughing and reinforcing agents for each resin. The direct-current (dc) electric breakdown strength and flashover voltage, dielectric properties and space charge characteristics of both epoxy composites were investigated. According to the results, DGEBF composite shown a higher dielectric strength, lower permittivity and dielectric loss at cryogenic temperature and smaller shallow trap density, which makes it more potential to be used for the cryogenic insulation.