Thermal Properties Of Epoxy Resin Research Articles

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.

Thermal degradation and flame retardance of epoxy resins containing a microencapsulated flame retardant

AbstractTwo steps were used in the synthesis of a microencapsulated intumescent flame retardant (MIFR). First bis (1‐oxo‐2,6,7‐trioxa‐l‐phosphabicyclo[2.2.2]octane‐4‐methylol) phosphate melaminium salt (Melabis) was synthesized. Then the Melabis was encapsulated with melamine resin to obtain the MIFR. Its structure was characterized by XPS, SEM, and elemental analysis, and the factors affecting microencapsulation were identified and discussed. Epoxy resins (EP) were modified with the MIFR to prepare flame‐retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI) tests. The microcapsules (20% by weight) were added to EP in order to achieve an LOI of 29.5% and a UL 94 rating of V‐0. The thermal properties of epoxy resins containing the MIFR were investigated by thermogravimetry (TG) and differential thermogravimetry (DTG). The FR decreased by weight loss, Rmax (the maximum weight loss rate), and the thermal stability of EP while promoting the formation of an effective charring layer. The char structures were studied by SEM. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers

Epoxy resin/polymer blends: Improvement of thermal and mechanical properties

AbstractFatty acid waste was recycled as raw material and utilized to synthesize epoxy (HP) or unsaturated ester group (OEE) containing polymers. The radicalic polymerization between the styrene and itaconic acid was carried out, too. Glycidyl ester of styrene‐itaconic acid copolymer was obtained by esterification reaction with epichlorohydrin. The polymers were characterized by means of Fourier transform infrared spectroscopy and chemical analysis. The polymers were incorporated into diglycidyl ether of bisphenol A type commercial epoxy resin to prepare composites. The effects of polymer structure and amount on the physico‐mechanical and thermal properties of epoxy were investigated. Surface hardness, tensile strength, percentage elongation and stress at maximum load of the composites were obtained higher than pure epoxy resin. The composites reinforced with bio‐based polymers showed about 74.55–243% increase in elastic modulus over the pure epoxy matrix. Obtained Young's modulus values were higher for composites with styrene‐based polymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Preparation and characterization of epoxy resin modified with alkoxysilane- functionalized poly(urethane-imide) by the sol-gel process

The sol–gel process has been frequently employed for preparation of high performance silica/polymer composites. In this paper, novel sol–gel precursor triethoxysilane-terminated poly(urethane-imide) (PUI-Si), combining the advantages of polyurethane (PU) and polyimide, was synthesized and characterized. Then PUI-Si was incorporated into the epoxy resin matrix to prepare a series of EP/PUI-Si organic-inorganic hybrids through an in situ sol–gel process and crosslinking reactions. The thermal stability of EP/PUI-Si hybrids was evaluated by thermogravimetric analysis and the results show that the PUI-Si could significantly improve the thermal properties of epoxy resin. The initial decomposition temperature of composites with 50 wt% PUI-Si reached 347.1 °C, 157.3 °C higher than that of neat epoxy resin. Furthermore, the tensile strength and breaking elongation can also be clearly improved by adding a suitable amount of PUI-Si. Similarly, the water contact angle increased to 97.4° with 70 wt% PUI-Si, showing a hydrophobic surface. The morphology was investigated by transmission electron microscopy and the results reveal that the silica particles are smaller than 20 nm and have a strong interaction with the epoxy resin matrix, resulting in the above-mentioned high performance properties. Copyright © 2011 Society of Chemical Industry

Morphologies and Mechanical and Thermal Properties of Epoxy Resins Modified by a Novel Polysiloxane Capped with Silane Coupling Agent, Epoxide, and Imino Groups

A novel polysiloxane capped with silane coupling agent, epoxide, and imino groups (AGPMS) was synthesized to modify the diglycidyl ether of bisphenol-A (DGEBA). The chemical structure of AGPMS was confirmed using Fourier transform infrared (FT-IR), 29Si NMR, and 13C NMR. The toughness of the epoxy resin, in terms of impact strength and fracture toughness, was improved by introducing AGPMS, while the tensile strength decreases a little at relatively low addition levels. The glass transition temperature from differential scanning calorimetry (DSC), the initial degradation temperature for 5% weight loss (Td 5%) and the residual weight percent at 800°C (R800) from thermogravimetric analysis (TGA), all increased. The morphologies of the fracture surfaces, examined by environmental scanning electron microscopy (ESEM), show that the miscibility of polysiloxane with epoxy resin increased after being capped with γ-aminopropyl triethoxysilane (APTES) and the size of the silicone phase increased with the increase of the AGPMS content. The silane coupling agent structure, and the epoxide and imino groups in AGPMS can react during the curing process, and chemically incorporate into the crosslinking network. AGPMS is thus expected to significantly improve the toughness of epoxy resin, and also increase the thermal stability.

Comparative study of different polymerically-modified clays on curing reaction and thermal properties of epoxy resin

polymerically-modified clays including polystyrene-co-methyl acrylate modified clay (PSMA-clay) and polystyrene-co-acrylic acid modified clay (PSAA-clay), which contain either ester groups or carboxylic acid groups, were prepared by cation exchange and used to prepare diglycidyl ether of bisphenol A (DGEBA)/clay composites. The curing reaction of DGEBA/clay composites was investigated using DSC and FT-IR. The morphology and thermal properties of DGEBA/clay composites were characterized using XRD, TEM, TGA and DSC. DSC and FT-IR analyses demonstrated that there is a reaction between epoxy groups and carboxylic acid groups besides the curing reactions between epoxy groups and the curing agent, 4,4′-diaminodiphenylmethane (DDM) for DGEBA/PSAA-clay composites. XRD and TEM results indicated that the reaction between epoxy groups and carboxylic acid groups in the inter-gallery of PSAA-clay facilitated the clay dispersion in the epoxy matrix. Improved thermal properties due to the addition of reactive clay were also achieved for DGEBA/PSAA-clay composites.

Thermal Properties of Epoxy Based Expanded Graphite Composite for Bipolar Plate of Polymer Electrolyte Fuel Cells

The application of polymer electrolyte fuel cell (PEMFC) to the electrical vehicles is restricted by high material cost and complicated manufacturing process. The epoxy based graphite composite has been prepared with various additives. The possibility for bipolar plate material at PEMFC was investigated by electrical and thermal properties. Density of bipolar plate with graphite composite was decreased from 5.40 to 2.57 as 80 w/o of graphite content were changed to 50 w/o of graphite content and 30 w/o of expanded graphite. The percolation thresholds showed around 75 w/o of graphite content was varied by molding pressure. From the TGA analysis, the glass transition temperatures were shown around 250 degrees and less that 3% of weight loss was found at 150 degree. The surface conductivity of epoxy/graphite bipolar plate showed from 4.5 S/cm to 87 S/cm and the highest value of conductivity was obtained using expanded graphite powder only. The improvement of thermal stability and electrical properties was accomplished by addition of expanded graphite powder.

Simultaneously Increasing Impact Resistance and Thermal Properties of Epoxy Resins Modified by Polyether-Grafted-Epoxide Polysiloxane

In this paper, polyether-grafted-epoxide polysiloxane (FEPMS) was synthesized via hydrosilylation among poly(methylhydrosiloxane) (PMHS), allyl polyoxyethylene polyoxypropylene ether (F6) and allyl glycidyl ether to modify Diglycidyl Ether of Bisphenol A (DGEBA). The morphology, thermal properties, and toughness of all cured samples were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and impact testing. Results indicated that grafted polysiloxane can be well dispersed in epoxy matrix, and the epoxy resin modified with FEPMS at relatively low addition levels exhibited higher thermal properties and improved toughness than the neat epoxy resin.

Studies on the Thermal Properties of Epoxy Resins Modified with Two Kinds of Silanes

Dimethyldiethoxysilane (DMDES) and diphenyldimethoxysilane (DPDMS)-containing epoxy resins were synthesized by dehydration polycondensation. The chemical structures were determined by FT-IR, 1H NMR, and 13C NMR. The cured samples, with 4, 4′-diaminodiphenylmethane (DDM) as curing agent, were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile and impact testing. Results showed that DMDES and DPDMS-modified epoxy resins possess higher glass transition temperatures, better thermal stability, and better fracture toughness than the neat epoxy resin.

The preparation of inorganic/organic hybrid nanomaterials containing silsesquioxane and its reinforcement for an epoxy resin network

A series of new inorganic/organic hybrid nanomaterials were prepared through the reaction of cage octa(γ-aminopropylsilsesquioxane) with n-butyl glycidyl ether. The structures and properties of these hybrid materials were characterized by Fourier transform infrared spectroscopy, 29Si nuclear magnetic resonance (NMR), 1H-NMR, and mass spectrometry spectra. The hybrid materials were used for improving mechanical and thermal properties of epoxy resin E-51. The results showed that appropriate amount of addition of the hybrids could enhance the fracture elongation ratio and impact strength. The tensile strength decreased with the addition of the hybrids. The thermal properties such as glass transition temperature, antioxidant index, decomposition temperature, and Vicat softening temperature were obviously improved. Scanning electron microscope observation displayed a rough structure inside the cured epoxy resin by the addition of the hybrids. Kinetic study indicated that the curing process was continuous with average activation energy of 48.06 kJ/mol which was based on Kissinger and Flynn–Wall–Ozawa models.

Thermal Properties of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides

Thermal Properties of Epoxy Resins from Ester-Carboxylic Acid Derivatives of Mono- and Disaccharides

Preparation and Mechanical Properties of Epoxy Resin Reinforced with Jeffamines-Grafted Carbon Nanotubes

The increasing proliferation and application of advanced polymer composites requires higher and broader performance resin matrices. Poly(oxypropylene) with –NH2 end-groups has been widely used to toughen epoxy resins, but the strength of resin matrix may be reduced due to the addition of flexible segments in the crosslinking network. Carbon nanotubes (CNTs) have been paid more and more attention in recent years because of their superior thermal and mechanical properties. In this paper, CNTs grafted with Jeffamines T403 were used to simultaneously improve the reinforcement and toughening of an epoxy resin. The untreated multi-walled carbon nanotubes (u-MWNTs) were functionalized with amine groups according to three steps: carboxylation, acylation, and amidation. The f-MWNTs were characterized by Fourier transform infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS). The experimental results indicated that the T403 was grafted to the surface of MWCNTs. The mechanical and thermal properties of epoxy with f-MWNTs were investigated. The tensile and flexural strength increased by 7.77 % and 7.03 % after adding 0.5wt% f-MWCNTs without sacrificing the impact toughness. At the same time, dynamic mechanical thermal analysis (DMTA) showed that the glass transition temperature (Tg) of epoxy with f-MWNTs were increased. The fracture surface of epoxy with f-MWNTs was observed by scanning electron microscopy (SEM) to understand the dispersion of f-MWNTs in epoxy matrix and interfacial adhesion between f-MWNTs and epoxy matrix, which can be attributed to the strong interfacial bonding between f-MWNTs and epoxy resin.

New Bismaleimide-Epoxy Resin System

New functional epoxy resins were prepared by the reaction of dialyldiglycicylbisphenol A (DADGBPA) with diaminodiphenylmethane. DADGBPA was prepared by reaction of o,o′-diallylbisphenol A with epichlorhydrine. By reaction of functional epoxy resins with bismaleimides, new epoxy-bismaleimide resins with good thermostability were obtained. The thermal properties of epoxy resins and epoxy-bismaleimide resins were determined by DSC and TGA measurements.

Kinetics and thermal properties of epoxy resins based on bisphenol fluorene structure

The fluorene-containing epoxy, diglycidyl ether of 9,9-bis(4-hydroxyphenyl) fluorene (DGEBF) was synthesized by a two-step reaction procedure. In order to investigate the relationship between fluorene structure and material properties, DGEBF and a commonly used diglycidyl ether of bisphenol A (DGEBA) were cured with 4,4-diaminodiphenyl methane (DDM) and 4,4-(9-fluorenylidene)-dianiline (FDA). The curing kinetics, thermal properties and decomposition kinetics of these four systems (DGEBA/DDM, DGEBF/DDM, DGEBA/FDA, and DGEBF/FDA) were studied in detail. The curing reactivity of fluorene epoxy resins was lower, but the thermal stability was higher than bisphenol A resins. The onset decomposition temperature of cured epoxy resins was not significantly affected by fluorene structure, but the char yield and T g value were increased with that of fluorene content. Our results indicated that the addition of fluorene structure to epoxy resin is an effective method to improve the thermal properties of resins, but excess fluorene ring in the chain backbone can depress the curing efficiency of the resin.

Thermal degradation and flame retardancy of epoxy resins containing intumescent flame retardant

Abstract Pentaerythritol diphosphonate melamine-urea-formaldehyde resin salt, a novel cheap macromolecular intumescent flame retardants (IFR), was synthesized, and its structure was a caged bicyclic macromolecule containing phosphorus characterized by IR. Epoxy resins (EP) were modified with IFR to get the flame retardant EP, whose flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI). 25 mass% of IFR were doped into EP to get 27.2 of LOI and UL 94 V-0. The thermal properties of epoxy resins containing IFR were investigated with thermogravimetry (TG) and differential thermogravimetry (DTG). Activation energy for the decomposition of samples was obtained using Kissinger equation. The resultant data show that for EP containing IFR, compared with EP, IFR decreased mass loss, thermal stability and R max, increased the char yield. The activation energy for the decomposition of EP is 230.4 kJ mol−1 while it becomes 193.8 kJ mol−1 for EP containing IFR, decreased by 36.6 ...

Thermo-Viscoelastic Analysis of Warp for Laminated Body Consisting of Epoxy Resin and Steel with Thermal Deterioration by Thermal Load

The mechanical and thermal properties of epoxy resin used for electronic parts are changed by thermal load in manufacturing processes and prolonged use, and these properties make defective of electronic devices. In this report, warp behavior of a two-layer-laminated body consisting of epoxy resin and steel caused by thermal load were examined from both sides of experiment and theory. As a result, it was clarified that viscoelastic properties of epoxy resin, such as storage modulus, loss modulus, loss tangent and glass transition temperature were changed by thermal load, and that warp behavior could be predicted by thermo-viscoelastic analysis based on linear thermo-viscoelastic theory by using these viscoelastic properties.

Mechanical and Thermal Properties of Epoxy Resin Modified with Polyurethane

Epoxy resin was modified with polyurethane having different isocyanate index. Impact strength, tensile strength, elongation at break and flexural strength were estimated as functions of polyurethane content and isocyanate index. Hardness, linear expansion coefficient and the deflection temperature under load were estimated for selected compositions. Infrared spectroscopy was carried out for unmodified epoxy resin and compositions with improved mechanical properties. Maximum improvement in the fracture toughness was reached with polyurethane with highest content of isocyanate. Hardness was not affected but elastic modulus decreased, implying a softening of epoxy-based compositions. The infrared spectra indicated that an excess of isocyanate groups leads to a grafting process between the modifier and the matrix, explaining the toughening of the latter.

Effects of EPON on Mechanical and Thermal Properties of Epoxy Resins

Low cost composite materials are widely used in civil and structural engineering applications. This project uses EPON to plasticize a commonly used resin, epoxy resin to lower the cost of the composite and to find out the mechanical and thermal properties of the plasticized epoxy resin to see if it is suitable for the said applications. Three point bending tests were carried out to evaluate the flexural properties of the plasticized resins. Differential scanning calorimetry and dynamic mechanical thermal analysis are used to evaluate the thermal properties of the plasticized epoxy resin. The study with epoxy and EPON showed that the mechanical properties of the epoxy composite were lowered but its ability to dissipate energy increased because of its improved thermal properties. As EPON is much cheaper that epoxy resin, the composite produced is therefore cheaper and provided the service requirements were not so demanding, it can be used in the said applications.

Nanoclay and long‐fiber‐reinforced composites based on epoxy and phenolic resins

AbstractIn this study, high‐performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long‐fiber‐reinforced composites and polymer‐ layered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of curing agent on the properties of mineral silica filled epoxy composites

AbstractPolymer materials have been used extensively as the organic substrate materials in electronic packaging industry. The mechanical, thermal, and morphology properties of the alternative low cost composites have been investigated in this article. One of the materials is epoxy resin cured by aliphatic amine, and the other is cured by aromatic amine. It was found that the physical, mechanical, and thermal properties of epoxy resins are strongly depended on the curing agents. Morphology changed differently in these two epoxy‐curing systems. Crosslink density obtained from rubbery modulus in dynamic flexural storage modulus showed aromatic amine functionality group that gives higher crosslink density and increased in physical, mechanical, and thermal properties. POLYM. COMPOS., 29:27–36, 2008. © 2007 Society of Plastics Engineers