Type Epoxy Research Articles

Potential applications of basalt fibre composites in thermal shielding

This present study demonstrates the applicability of basalt fibre-reinforced polymer (BFRP) composite materials in thermal shielding. Basalt fibres are produced from natural, sustainable sources and obtain comparable mechanical performance to commercial glass fibres. In addition to their mechanical strength, BFRPs have excellent chemical and heat resistance. Basalt fibres tend to have a higher thermal stability than their competitor glass fibres. The heat resistance of basalt fibres derives from the volcanic origin of the raw material basalt gabbro. These favourable features make BFRP composites an attractive group of materials for application in several industries. To test the fire resistance of the materials, we produced mono and hybrid composite plates from different types of basalt reinforcement structures (milled fibres, chopped fibres and woven fabric) and epoxy resin. Surface treatment with silane coupling agents significantly improved the mechanical and thermomechanical properties of BFRPs by up to 70%. Three-point bending tests were performed to determine the flexural properties of the composite specimens, and their fire behaviour was evaluated with a horizontal burning test, and a novel jet fire test assisted with infrared thermal imaging. Higher fibre content in hybrid laminates decreased the linear burning rate by 8%, and the maximum surface temperature was approximately 80 °C lower after jet fire impingement compared to woven reinforcement structure.

High-performance naphthalene epoxy resins cured by catalyst for packaging materials

Epoxy resins are widely used for electronic packaging materials due to their good performance. A common way to cure epoxy is to add anhydride as a hardener, to this, we added a less used curing method, catalytic curing, to study their effect on the curing system and curd samples. Polymers containing naphthalene rings usually have low moisture absorption, good thermal stability, dimensional stability, and dielectric properties. Here, we used two naphthalene epoxy monomers (1,6- naphthalene diglycidyl ether (1,6-NDE) and 2,7-NDE) and cured them with two methods (anhydride (methyl nadic anhydride, MNA) / accelerator (Tris(dimethylaminomethyl)phenol, DMP-30) curing system and catalyst (DMP-30) curing system). We obtained four types of epoxy resins and compared the differences in their structure and performance. All epoxy resins had excellent tensile properties at around 100 MPa tensile strength. Catalyst cured resins had better thermal stability and higher glass transition temperature that close to 180 ˚C (T g -DMA), compared with anhydride cured resins. Meanwhile, 1,6-naphthalene epoxy resins had better performance than 2,7-naphthalene epoxy resins in high glass transition temperature and high crosslink density. Overall, all naphthalene epoxy resins had good performances, and catalyst-cured resins performed better and provided an additional method. Herein, these types of naphthalene epoxy resins have potential applications in the field of electronic packaging. • Molecular arrangement inferred from mode layer spacing and crosslink density. • Spatial resistance affects the cross-linking density and the performance of the resins. • Better thermal stability and solvent resistance of catalyst cured resins.

Shear strength of steel fiber reinforced lightweight self-consolidating concrete joints under monotonic and cyclic loading

The shear behavior of precast concrete segmental bridges depends on the type of joints between the segments. However, there are few studies evaluating the shear strength of steel fiber reinforced lightweight self-consolidating concrete for application to precast concrete bridges. The purpose of this study is to compare the shear behavior of joints made of general concrete with developed concrete that includes lightweight aggregate and steel fiber under monotonic and cyclic loading. In this study, the push-off shear test was performed in accordance with experimental parameters of different concrete mixtures, key type, confining stress, and application of epoxy between the segments. The tests were carried out to assess the shear strength, shear behavior, crack propagation and failure mode of joints. The test results represented shear capacity of joints decreased 15.2% by replacing normal coarse aggregates with lightweight aggregates but could be enhanced through the incorporation of hooked-end steel fibers. The shear capacities of joints fabricated using developed mixture tended to be underestimated compared to analytically calculated strengths. Furthermore, the normalized stiffness of the joint was decreased with an increased number of load cycles under high-amplitude low-cycle load. The shear resistance through aggregate interlock may gradually decrease with increasing number of cycles resulting in failure at 85% of the failure load of the monotonically tested specimen. An appropriate level of confining stress and application of epoxy shall be considered to prevent sudden failure of joints at high amplitude cyclical loading conditions.

A bio-based intrinsically flame-retardant epoxy vitrimer from furan derivatives and its application in recyclable carbon fiber composites

The recycling of carbon fiber reinforced polymer composites (CFRPCs) is difficult because the thermosetting matrix is insoluble and does not melt. To overcome this problem, a furan-derived epoxy resin (HMF-GAN-EP) was synthesized from 5-hydroxymethylfurfural and cured with a furan-based curing agent (DIFFA). The cured HMF-GAN-EP/DIFFA system showed excellent flame retardancy (UL-94 V-0 and LOI of 40%). The glass transition temperature, tensile strength, and tensile modulus of the cured HMF-GAN-EP/DIFFA system were approximately 234 °C, 67 MPa and 2273 MPa, respectively, all of which were higher than those of the diglycidyl ether of bisphenol A (DGEBA)-type epoxy thermosets cured by 4,4′-diaminodiphenylmethane (DDM) (151 °C, 56 MPa and 1744 MPa). The cured HMF-GAN-EP/DIFFA system could dissolve in a mixed solution of THF:HCl (8:2, v/v), making it possible for the recycling of carbon fibers from CFRPCs.

Relationship between cross-linking network structure and phase change performances toward multifunctional epoxy/bio-based wax form-stable phase change materials

High encapsulation rate resulting from the good compatibility between cross-linking network and encapsulated solid–liquid phase change materials (SLPCMs) cannot necessarily result in high enthalpy value for the polymeric PCMs. However, the inner mechanism considering the above fact is not clear due to the lack of suitable model compound systems. In this work, a type of epoxy resin with crystalline alkyl side chains (named D18) and four types of amine curing agents (with similar structure but different polarity and molecular size) were primarily used as the model compound to achieve the encapsulation of beeswax (Bw, a kind of bio-based wax), and then the influence of the cross-linking network structure (using different curing agents) on the phase change performances of the D18/Bw polymeric form-stable PCMs (FSPCMs) was systematically studied. The results suggest that polarity effect and steric hindrance effect are the two factors that affect the phase change performances of the polymeric FSPCMs. Though the encapsulation rate of Bw is the highest (near 70 wt%) in the EPH-Y systems (using 1,3-Cyclohexanebismethylamine as the curing agent), it is the EPM-60 sample (using M−Xylylenediamine as the curing agent and containing 60 wt% Bw) that exhibited the highest enthalpy value of 146.2 J/g. Subsequently, different amount of multi-walled carbon nanotubes (CNT) was introduced to improve the thermal conductivity (TC) and achieve multifunctionalization of the EPM-60 sample. The TC, electromagnetic interference (EMI) shielding performance, and contact angle of the 30 wt% CNT modified EPM-60 sample can reach 1.37 W/mK, 37.4 dB, and 137°, while the enthalpy value can remain 101.1 J/g. This work is very helpful in clarifying the relationship between cross-linking network structure and phase change performances of polymeric FSPCMs, so as to providing theoretical guidance for the cross-linking network structure optimization in preparing other reliable polymeric FSPCMs with high enthalpy value, high reliability, and multifunctionalization.

CZM-based FE numerical study on pull-out performance of adhesive bonded-in-rod (BiR) joints for timber structures

Bonded-in-Rod (BiR) connections for timber structures are becoming rather popular solution, in place of other traditional fastening techniques. Besides, design rules and recommendations in support of safe and robust verification are still poor in existing standards. As such, the actual mechanical performance and load-bearing capacity – which is severely affected by a multitude of operational parameters – should be possibly addressed with the support of experimental investigations. In this paper, a Cohesive Zone Modelling (CZM) based, Finite Element (FE) numerical investigation is proposed for a total of 144 BiR joints characterized by various geometrical and mechanical properties, including grain orientation (α = 0° or 90°), adhesive type (polyurethane or epoxy glue), diameter (d = 10, 14, 20 mm) and anchorage length of rods (L = 60, 100, 200, 400 mm) is presented. Most importantly, the attention is also focused on the analysis of service class effects / moisture content (9, 18 or 27 %) on the actual residual capacity of the examined joints, which is of paramount importance for safe design applications in timber structures. Based on validation of input model properties to past experimental results, the sensitivity of basic mechanical performance indicators for the examined BiR samples is discussed in the paper.

GFRP composite bars for splicing prestressed precast concrete piles: Design and experimental investigation

Glass Fiber Reinforced Polymer (GFRP) composite bars were investigated in this study as a corrosion-resistant dowel for splicing prestressed precast concrete piles (PPCPs). In addition to their durability and good mechanical performance, GFRP bars show cost advantage when compared to other corrosion-resistant material. Using available design guides for FRP-reinforced concrete sections, a typical epoxy bonded dowel splice using GFRP bars was designed for an 18 × 18 in (457 × 457 mm) PPCP. In order to validate the adopted design procedure and to investigate the effectiveness of GFRP reinforcing bars as bonded dowels for pile splice design, 10 full-scale PPCP specimens of 18 × 18 in (457 × 457 mm) cross-section with a total length of 28 ft (8.5 m) were designed, fabricated, and tested at the Florida Department of Transportation (FDOT) Structures Research Center. In these specimens, three different materials for dowels; GFRP reinforcing bars, Carbon Fiber Reinforced Polymer (CFRP) strand, and traditional carbon-steel reinforcing bars were used in combination with CFRP and steel prestressing strands for PPCPs for both unforeseen and preplanned drivable splicing cases. The focus of this study was on the flexural performance at the splice. The experimental results show that the proposed epoxy GFRP dowel pile splice can match the required design flexural resistance for a preplanned PPCP carbon-steel pile splice. The laboratory tests performed in this research validates the new design procedure for the GFRP dowel splice. The design flexural resistance for the GFRP dowel splice calculated by the new procedure provides 68 % of 245 kip-ft (332.2 kNm), the flexural resistance required by the FDOT design specifications for mechanical preplanned splices. This research will help to improve the standard designs and construction specifications.

Development of Active-Ester Type Epoxy Resin Curing Agents for the Printed Wiring Boards of High-Speed Communication Devices

高速通信機器のプリント配線板用エポキシ材料の開発において低誘電率化，低誘電正接化を，硬化剤側から開発した。1991年に発表された活性エステル型エポキシ樹脂硬化剤の基本技術を発展させ，エレクトロニクス実装材料に対応できる新規の多官能オリゴマー型の活性エステル型エポキシ樹脂硬化剤の開発に成功した。一般的なフェノールノボラック硬化系と比較して，高いガラス転移温度を維持したまま，大幅な低誘電率，低誘電正接化を実現した。中心部に位置するジシクロペンタジエン骨格の剛直性と小さなモル分極率と大きなモル体積，末端封止成分のナフタレン骨格の剛直性や配向性が相まって，耐熱性を維持したまま，優れた低誘電率および誘電正接を示すと考察した。

Tentative identification of BADGE derivatives in epoxy type coatings in a model sample: a beverage can

Tentative identification of BADGE derivatives in epoxy type coatings in a model sample: a beverage can

Enhancing bonding behavior between carbon fiber-reinforced polymer plates and concrete using carbon nanotube reinforced epoxy composites

Externally bonded carbon fiber reinforced polymer (CFRP) composites have been widely used as repairing or strengthening materials for deteriorated reinforced concrete (RC) structures. This study discusses whether carbon nanotube (CNT) can be used as an additive to enhance bonding strength between concrete and CFRP. In this study, two CNT types: single walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), were mixed with two different types of epoxies. CNTs were added at 0.25%, 0.5%, and 1.00% by weight of epoxy to obtain the optimal performance. Single-shear test were conducted to investigate bonding behavior including bond strength, ultimate slip, effective bond length, bond stress-slip relationship, interfacial fracture energy, and crack formation between CFRP plate and concrete. The results showed that epoxy modified by 0.5% SWCNTs and 1.0% MWCNTs by weight of epoxy enhance the ultimate load and slip, bond strength, and interfacial fracture energy when compared to plain epoxy. However, high density epoxy modified with SWCNTs/MWCNTs showed diminished bonding properties.

Molecular mechanics-based design of high-modulus epoxy to enhance composite compressive properties

The performance of carbon fiber reinforced composites has been shown to be constrained by the low compression to tensile strength ratio, which blocks its lightweight application. Designing and preparing high-strength, high-modulus resins has become a popular direction in the field of synthetic materials and increasing resin modulus has become one of the key goals for improving composite compression properties. This study improves the interactions between molecular segments and reduces chain motility by introducing polar groups into resin molecules and increasing the reactive functionality. Four typical polar epoxy resins with high purity were synthesized, with a modulus of 6500 MPa and a tensile strength of 86 MPa when cured. Hydrogen bonds are detected and the complex process of group changes as a function of temperature is investigated using in-situ IR. The compression properties of the composites made with the newly synthesized resins were significantly improved, which suggests the significance of high-performance resin design in lightweight carbon fiber composite materials.

Parameters Influence on the Dynamic Properties of Polymer-Matrix Composites Reinforced by Fibres, Particles, and Hybrids.

In this paper, we present an extensive experimental study on the dynamic mechanical properties of composites with polymer matrices, as well as a quantification of the parameters that influence these properties. Polymer-composite matrices make it possible to form any reinforcement arrangement of fibres, particles, and layers, which makes it possible to form composite materials with certain dominant mechanical properties according to the internal arrangement for the application. In this study, we focused on the dynamic properties (i.e., damping parameters, such as the loss factor (tan d), logarithmic decrement (λ), storage modulus (E′), and loss modulus (E″)) of composites with polymer matrices, including parameters such as the fibre material, fabric weaving, fibre orientation, temperature, frequency, particle size, volume of short fibres, and epoxy resin type. If other articles focus on one type of composite and 1–2 parameters, then the benefit of this article lies in our analysis of 8 mentioned parameters in the experimental analysis of 27 different types of composites with polymer matrices. The tested fibre materials were glass, aramid, and carbon; the tested woven fabrics were twill, plain, unidirectional, and satin; the temperature range was from −50 to +230 °C; the frequency was 1 Hz and 10 Hz; the particle size was 0.1–16 mm; the volume percentages of the short fibres were 3, 6, and 12 vol.% of the hybrid polymer composites and the type of polymer matrix. We used the free-damped-vibration method with vibration dynamic signal analysis and the forced-damped vibration of dynamic mechanical thermal analysis for testing. We ranked the parameters that influence the dynamic vibration properties according to the effects. Among sets of results provided in the paper, considering the storage modulus, loss modulus, and loss factor, the best results of the fibre composites were for aramid-fibre-reinforced polymers, regardless of the weave type, with an advantage for unidirectional fabric. The best results of the particle composites were for those with fine filler sizes that incorporated the short fibres.

Water sorption, thermal, and fire resistance properties of natural shell‐based epoxy composites

AbstractIn this study, walnut shell (WSh), hazelnut shell (HSh), and mussel shell (MSh) waste as inexpensive reinforcements were recycled for the preparation of epoxy composite materials. Subsequent used inexpensive fillers are chars (WShC and HShC), which are the pyrolysis solid products of the natural WSh and HSh wastes. Three types of epoxy resins: bisphenol‐A type (DGEBA), modified with polyurethane (MER with PU), and rubber modified (MER with rubber) epoxy resins were used as the matrix in MSh composites. Thermogravimetric analysis of the composites showed that the thermal strength of the epoxy matrix increased significantly with the MSh and chars. The best water sorption results were obtained with the MSh. The contact angle values of MSh composites prepared with DGEBA epoxy resin were quite high (111°–113.5°) and their water retention values ranged from 0.2% to 0.32%. The composites that were produced using 50 wt% chars and the same epoxy resin showed better flammability stability. The full extinction times were determined as 63 and 58 s for WShC and HShC composites, respectively.

Low-temperature mechanical properties of polyurethane-modified waterborne epoxy resin for pavement coating

ABSTRACT The purpose is to clarify the development law of mechanical properties of waterborne epoxy resin coatings at low temperatures and further promote its application in cold areas. Different types of polyurethane-modified waterborne epoxy resins were prepared. The development law of low-temperature mechanical properties of waterborne epoxy resin at different curing time was studied systematically. The improvement effect of polyurethane on the mechanical properties of waterborne epoxy resin at low temperatures was evaluated. The prediction models of low-temperature mechanical properties of waterborne epoxy resin based on Grey–Markov chain method was established. The results show that the mechanical properties of waterborne epoxy resin decrease after low-temperature treatment for 15 days. Its strength and flexibility are reduced by 3% and 10%. Polyurethane could improve the low-temperature durability of waterborne epoxy resin. The retention rates of the various mechanical properties of modified waterborne epoxy resin increase significantly. Among them, the retention rate of elongation at break increases by more than 50%, and the bending deformation is almost no longer attenuated. The prediction model based on BP–Elman neural network has a higher accuracy, and the relative error is less than 0.04%.

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.

Numerical investigation of the seismic vulnerability of bridge piers strengthened with steel fibre reinforced concrete (SFRC) and carbon fibre composites (CFC)

This research proposes a method aimed at investigating the detection of bridge damage areas using a rigorous method based on mathematical models of dynamic finite elements. Strengthening of the reinforced concrete (RC) is proposed for increasing the strength of RC structures when they present material degradation. It includes reinforcement with carbon reinforcement composites (CFC) and steel fiber reinforced concrete (SFRC), injection with SikaDur 52 Injection type epoxy resin, and the addition of SikaTop 126 type concrete. Establishment of a set of equations and numerical modeling of the specified method are presented in this study for sparse matrices of a large system of equations. A numerical solver with FEM Ansys software was used to avoid the lack of big-data memory storage on the available hardware. RC material properties have been modeled with the composite material mixture laws as a homogeneous material. Several simulations have been achieved. The results obtained allowed location of stress concentration areas and consequently, detection of important von-Mises equivalent stresses of strength bound in severe load cases as well as graphically visualization of the time history of displacements evolution. The study has also revealed that the reliability design of the probabilistic method with the security margin as a stochastic variable is an effective structural health monitoring approach.

Investigating the characteristics of a natural fiber composite fabricated from 9,9′-bis(aryl)fluorene-modified nanocellulose and bamboo fiber

A composite fabricated from 9,9′-bis(aryl)fluorene-modified nanocellulose (FCF) and bamboo fiber was studied to explore its processing conditions and limitations. The FCF acted as a binding agent, and bamboo fibers were used as structural reinforcement. Two types of FCF were fabricated and studied: hydroxy and epoxy functional groups with FCF. The FCF solution was homogenized and coated on bamboo fiber sheets. These sheets were laminated with FCF by hot-pressing at various temperatures, pressures, and weight fractions. Flexural modulus and strength were determined at each processing condition. Epoxy type FCF composites exhibited superior flexural performance compared to the hydroxy type. The epoxy type showed better homogeneous dispersion, which increased interfacial area between fibers. The optimal processing temperature was 230 °C. It was considered that thermal degradation occurred above 250 °C and chemical reaction between binder and bamboo was not enough below 210 °C. Flexural performance in the composites showed that approximately 10 MPa was structurally better due to increase of contact area among fibers, which was crushed flat by pressure.

Double-Decker-Shaped Polyhedral Silsesquioxanes Reinforced Epoxy/Bismaleimide Hybrids Featuring High Thermal Stability.

In this study, we synthesized bismaleimide into a functionalized double-decker silsesquioxane (DDSQ) cage. This was achieved by hydrosilylation of DDSQ with nadic anhydride (ND), reacting it with excess p-phenylenediamine to obtain DDSQ-ND-NH2, and treating with maleic anhydride (MA), which finally created a DDSQ-BMI cage structure. We observed that the thermal decomposition temperature (Td) and char yield were both increased upon increasing the thermal polymerization temperature, and that these two values were both significantly higher than pure BMI without the DDSQ cage structure since the inorganic DDSQ nanoparticle could strongly enhance the thermal stability based on the nano-reinforcement effect. Based on FTIR, TGA, and DMA analyses, it was found that blending epoxy resin with the DDSQ-BMI cage to form epoxy/DDSQ-BMI hybrids could also enhance the thermal and mechanical properties of epoxy resin due to the organic/inorganic network formation created by the ring-opening polymerization of the epoxy group and the addition polymerization of the BMI group due to the combination of the inorganic DDSQ cage structure and hydrogen bonding effect. The epoxy/DDSQ-BMI = 1/1 hybrid system displayed high Tg value (188 °C), Td value (397 °C), and char yield (40.4 wt%), which was much higher than that of the typical DGEBA type epoxy resin with various organic curing agents.

ANALYSIS AND EXPERIMENTAL TESTING OF PHYSICAL AND MECHANICAL PROPERTIES OF FLOORING EPOXY

Epoxy resins are a class of reactive oligomers and polymers with epoxide groups. Depending on the type of epoxy and the hardener used, the curing (hardening) process can be regulated. Consequently, epoxy resins can be characterized by the "working time" or pot-life - the time it provides for certain technological operations to be performed with it. In the hardened state, epoxies are characterized by high strengths and high chemical resistance. Among other applications, they are widely used as materials for industrial floors, and for waterproofing. Laboratory optimization tests have shown that high strengths can be achieved with a lower density, and that the use of quartz filler does not necessarily improve the strength of the epoxy.

Methyl-substitution affects dielectric, thermal, mechanical properties, and shrinkage of fluorinated epoxy

Fluorination reduces dielectric constant and dielectric loss of epoxy resins, expanding their applications in high-speed communication. The methyl group (-CH 3 ) is a non-polar and space-occupying group, and it can reduce dielectric constant ( D k ) in some situations. However, it is not well understood how the methyl groups affect dielectric properties, as well as thermal and mechanical properties of fluorinated epoxy resin. To address this question, we specifically select benzene and m-xylene as the reaction monomer for comparison. We synthesize two fluorinated epoxides, diglycidyl ether of 1,3-bis(1,1,1,3,3,3-hexafluoroisopropyl)-benzene (DGE-bHFIP-B) and diglycidyl ether of 4,6-bis(1,1,1,3,3,3-hexafluoroisopropyl)-m-xylene (DGE-bHFIP-MX). We then thermally cure these two epoxides catalyzed with boron trifluoride ethylamine (BF 3 ·MEA) to obtain EP-bHFIP-B and EP-bHFIP-MX. EP-bHFIP-MX with –CH 3 has D k of 2.49–2.51, slightly lower than EP-bHFIP-B with D k of 2.51–2.54 at a high frequency range of 8.2–12.4 GHz. Their D k is much lower than a commercial bisphenol A type epoxy resin (EP-51) with D k of 2.80–2.83. Additionally, EP-bHFIP-MX shrinks less than EP-bHFIP-B after curing, and exhibits higher glass transition temperature with T g − D M A of 181 °C, higher tensile strength of 39.76 ± 5.51 MPa, compared to 129 °C and 34.73 ± 5.10 MPa for EP-bHFIP-B. EP-bHFIP-B and EP-bHFIP-MX both have very low water absorption of 0.134% w/w and 0.147% w/w after being immersed in water for 24 h at 25 °C. Therefore, incorporating –CH 3 groups into phenylene rings of fluorinated epoxies, we can enhance thermal resistance, increase mechanical strength, and reduce shrinkage without compromising dielectric performance. • Two novel fluorinated epoxides with low dielectric constant are synthesized. • Methyl-substitution slightly decreases D k in fluroinated expoxies. • Methyl-substitution improves thermal, mechanical properties and reduces curing shrinkage.