Modified Epoxy Resin Research Articles

High mechanical strength aluminum foam epoxy resin composite material with superhydrophobic, anticorrosive and wear-resistant surface

By combining organic materials with metal materials, it is easy to obtain new composite materials with excellent properties. Here, an excellent performance aluminum foam epoxy resin composite material (AFE) was prepared by heat-assisted vacuum infusion technology. Owing to the unique foam structure of aluminum foam (AF) and excellent physical and chemical properties of modified epoxy resin, the AFE with an interpenetrating network structure shows excellent wear resistance, bending resistance and corrosion resistance. The SEM images show that the filling efficiency of epoxy resin to AF is over 99%, and the epoxy resin was tightly combined with the metal foam. The surface and mechanical properties test results show that AFE has excellent mechanical properties and high wear resistance, the maximum bending σb and tensile strength σt can reach 74.33 MPa and 42.09 MPa, respectively, and the minimum wear rate Ws is 8.231 × 10−4 mm3/Nm. Tafel polarization curve and electrochemical impedance spectroscopy (EIS) results show that the AFE has excellent corrosion resistance, with corrosion current icorr as low as 1.399 × 10−9 A•cm−2 and Z0.01 Hz as high as 7.74 × 107 Ω•cm2 after superhydrophobic treatment process.

Synthesis, characterization, and properties of silicone grafted epoxy/acrylonitrile butadiene styrene/graphene oxide nanocomposite with high adhesion strength and thermal stability

AbstractTo improve thermal, mechanical and adhesion properties, epoxy resin was modified with methyl phenyl silicone (MPS), acrylonitrile butadiene styrene (ABS) and graphene oxide (GO). In order to increase compatibility and stability, MPS intermediate was grafted on epoxy resin through condensation reaction. Transmission electron microscopy images showed well dispersion of GO particles in the system proving successfully preparation of the MPS grafted epoxy/ABS/GO nanocomposite. Single lap shear strength for steel‐epoxy/carbon fiber composite joint in sample containing 15% MPS and 2% ABS improved up to 108% compared to neat epoxy. Such an improvement occurred when only 5% MPS, 2% ABS and 0.1% GO were used showing GO could decrease required content of modifiers in this case. Tensile strength of sample containing 5% MPS and 2% ABS was 49.89 MPa and it reached 55.23 MPa by adding 0.1% GO while it was 37.12 MPa in pure epoxy. Nanocomposite modified sample had a residual char of 20 wt%. at 600°C and increment of 30°C in initial degradation temperature and 7°C in maximum degradation temperature compared to pure epoxy. These finding beside 23% increasing in calculated activation energy using Kessinger's and FWO method's proved significantly improved thermal stability of modified epoxy resin. Scanning electron microscope images of fractured surface of specimens showed micro size domains obtained by phase separation cause toughness improvement and crack energy absorption.

Curing process optimization and mechanical properties improvement of epoxy resin copolymer modified by epoxy-terminated hyperbranched polyether sulfone

A new epoxy-terminated hyperbranched polyether sulfone (EHPES) has been synthesized by a facile one-step method using 4,4′-dihydroxydiphenylsulfone (monomer A2) and trimethylolpropane triglycidyl ether (monomer B3). The diglycidyl ether of bisphenol-A (DGEBA) was modified by EHPES through the optimal curing process. Compared with the unmodified DGEBA, the copolymer containing 7% EHPES showed the best comprehensive performance. The maximum tensile, flexural, and impact strengths were increased by 9.24%, 10.70%, and 19.38%, respectively. The tensile and flexural moduli were enhanced by 40.74% and 16.20%, respectively. The excellent performances were attributed to the good compatibility of EHPES, increased rigidity, more free volumes, and more “flexible” crosslinking points. Meanwhile, the outstanding tensile property led to the narrow strain concentration region of DGEBA/7% EHPES copolymer through the observation of digital image correlation (DIC) system. The EHPES modified epoxy resin can also be potentially used for carbon fiber reinforced composites in some advanced applications.

Experimental study of the influence of the epoxy resin modification with additives on the contact angle

Influence of concentration of introduction the different industrial organic additives into the epoxy resin on wetting contact angle is studied experimentally. Epoxy resin ED-20 is modified with small concentrations of polydimethyl siloxane, OH-polymer silicone rubber, monoglycidyl ether of butyl cellosolve (Laproxide 301B), tris(2-chloroethyl) phosphate. The importance of these studies is related to the need to improve the adhesive properties of repair compounds based on epoxy resin, which are associated with the value of the contact angle. The contact angle of the resin drop is measured for glass, metal, asbestos cement, and concrete surfaces. The effect of the mass fraction of additives on the contact angle is more pronounced on smooth surfaces of dense materials, and less pronounced on rough surfaces of porous materials. It is observed that all dependences of contact angle on the mass fraction of additives in the range of 0.5–2% wt are linear. The linear equation describing the contact angle θ dependence on the mass fraction c of additives, which sufficiently fitting the experimental data with calculated coefficients s and θ 0, is found.

Preparation and research of epoxy modified by carboxyl-terminated polybutylene adipate at room temperature.

In this study, carboxyl-terminated polybutylene adipate (CTPBA) was used to modify epoxy resin, and the modified epoxy resin was cured by a room temperature rapid curing agent (T-31). The effects of CTPBA modification on bonding properties and mechanical properties of epoxy resin adhesive at room temperature were carefully studied. Epoxy-terminated prepolymer was synthesized by pre-polymerization and its structure was characterized. Compared with the addition method of direct blending, the bonding properties and mechanical properties of pre-polymerized epoxy resin adhesive were significantly better. Compared with unmodified epoxy resin, CTPBA modification significantly improved the bonding strength. Furthermore, with the increase of CTPBA content, the shear strength of the material increased first and then decreased, and reached the maximum when the addition amount was 40 phr. This shows that the tensile strength of the material decreased with the increase of CTPBA content, and the elongation at break increased with the increase of CTPBA content. Dynamic mechanical analyzer (DMA) test results showed that the addition of CTPBA reduced the glass transition temperature, but broadened the damping temperature range. TG analysis showed that the thermal stability of the modified epoxy resin was good, and compared with pure epoxy resin, the initial temperature of thermal weight loss and the maximum thermal decomposition rate decreased, but the overall thermal stability was not significantly different. In summary, CTPBA modification of epoxy resin is expected to improve the comprehensive mechanical properties at room temperature.

Dynamic Mechanical and Chemorheology Analysis for the Blended Epoxy System with Polyurethane Modified Resin

As the important matrix material, epoxy resin has been widely used in the composites for various fields. On account of the poor toughness of epoxy resin limiting their suitability for advanced applications, considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements. In this study, the bio-based polyurethane (PU) modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions. Aiming to illuminate the curing behavior, mechanical and thermal properties, the blended epoxy systems were characterized by viscosity-time analysis, dynamic mechanical analysis (DMA) at different frequencies and temperatures, mechanical tensile test, thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the introduction of PU modified epoxy was found to significantly inhibit the viscosity growth rates especially when the content of PU modified epoxy resin is higher than 60%. Notwithstanding the dynamic modulus and Tg reduced with the increment of PU modified epoxy, remarkable increment on the elongation at break was found and the flexibility was greatly promoted with the introduction of PU modified epoxy. The proportion of PU modified epoxy in the blends should be put balance considerations to obtain optimal mechanical properties. TGA results and FTIR spectrum demonstrated that the addition of PU modified epoxy did not change the thermal decomposition mechanism and chemical reaction mechanism, but the addition of PU modified epoxy inhibits the curing reaction of epoxy resin by measured and calculated the damping temperature domain ΔT from 35.7°C to 48.9°C.

Study on preparation and performance of additive flame retardant DOPO-HQ modified epoxy composite

An additive flame retardant was prepared from DOPO-HQ. Fourier transform infrared spectroscopy (FT-IR) was used to analyze its chemical structure. It was added to the experimental formula to prepare EP composite material, and the limiting oxygen index experiment and thermogravimetric analysis experiment were carried out on the material, and the scanning electron microscope experiment was carried out on the residual carbon after combustion. The results show that the modified epoxy resin has a limiting oxygen index of 29.5%, and there is no droplet during combustion; thermogravimetric analysis experiments show that the temperature at which the thermal weight loss is 5%wt decreases, but the residual carbon rate increases. Scanning electron microscopy (SEM) test results show that carbon layer formed by the combustion products of epoxy resin is denser..

Investigation of kinetics and mechanism of secondary structures' formation of modified epoxy resin

Investigation of kinetics and mechanism of secondary structures' formation of modified epoxy resin

Improving mechanical, thermal, and erosive wear performance of natural bamboo fibers modified epoxy resin matrix composites

Natural bamboo fibers (BFs), which were treated by silane coupling agents, reinforced epoxy resin (EP)–based composite were synthesized. Effects of the coupling agents on the chemical structures of the BFs were characterized by Fourier Transform Infrared Spectroscopy. The mechanical properties, such as tensile strength, flexural strength, impact strength, and hardness of the BFs/EP-based composites were improved significantly, which could be attributed to the excellent strengthening effect of the BFs. Simultaneously, experimental investigations on the thermal behaviors of the BFs/epoxy composites were also presented, indicating that the thermal decomposition temperature of the polymer materials was lowered but the flame retardancy was improved. The bamboo fiber breakage and fiber split were also observed on the impact fracture surface of the composites, which indicate energy dissipation during fiber debonding and pullout process. Moreover, the erosive wear tests have also been carried out to analyze the erosive wear properties of the natural bamboo fibers which modified the epoxy matrix composites. The results indicate that the erosive wear resistance of the EP-based composite was improved greatly when the natural bamboo fibers content was 15 wt.%.

Supervised classification model for estimation of wear in sisal fibre-epoxy composites

The paper models the high stress abrasive wear behaviour of unidirectional epoxy composite reinforced with sisal fibre through supervised classification model. Rigorous experimentation initially involved the making of composites using polysulphide modified epoxy resin with varied sisal fibre concentrations and orientation (longitudinal, traverse, and normal). Later the abrasive wear behaviour of the composite fibre under various functional parameters was studied and recorded. A supervised classification model was then built to describe the effect of the various functional parameters on the abrasive wear behaviour of sisal fibre reinforced epoxy composite. The paper employs classification through decision tree and sequential covering rule induction. The results successfully show that decision tree classification has high ability to model the nonlinear dependence of the wear behaviour on the parameters describing the characteristics of the materials and conditions during the experimental work (like sliding distance, fibre weight, grit size and applied load). Once in operation the model can then be used for prediction of the wear behaviour in place of analytical investigations, thus reducing complexity and effort. Predicted values obtained through model testing were in good agreement with the experimental data.

Preparation and Properties of a Novel Waterborne Epoxy Resin Modified Emulsified Asphalt

Preparation and Properties of a Novel Waterborne Epoxy Resin Modified Emulsified Asphalt

Preparation of YAG Transparent Ceramics by Epoxy Resin Modified Spontaneous Coagulation Casting

Preparation of YAG Transparent Ceramics by Epoxy Resin Modified Spontaneous Coagulation Casting

Experimental Investigation into Mechanical Properties of Coconut Shell Powder Modified Epoxy/ 3d E-Glass Composites

Experimental Investigation into Mechanical Properties of Coconut Shell Powder Modified Epoxy/ 3d E-Glass Composites

Improvement in Thermal Conductivity of Through-Plane Aligned Graphite Flake/Silicone Modified Epoxy Resin Composites

We describe, here, our study of the thermal conductivity (TC) properties of silicone modified epoxy resin (SEP) films which were prepared by blending low molecular weight SH-023-7 silicone resin with Dow 332 epoxy resin as the matrix of composites using graphite flakes (GF) as a thermally conductive filler. The SEP/GF composites with different filler contents and SEP/vertically aligned GF (AGF) composites utilizing various magnetic field intensities were fabricated, and the TC, and thermal stability (TS) were characterized by thermal gravimetric analysis, and the morphology was observed by scanning electron microscopy (SEM). According to the experimental results, both the TC and TS increased with the increasing addition of filler. When the weight fraction of M (M = ) was 60 wt%, the TC of the composites was 1.38 W/mk, which was 5.52 times higher than that of pure SEP (0.25 W/mK). In addition, the addition of graphite also increased the decomposition temperature of the composites. The vertically aligned GFs resulted in effective, vertical, thermally conductive pathways in the SEP matrix, and the SEP/AGF composites exhibited much higher through-plane TC compared to the non-orientated SEP/GF composites. The SEP/AGF reached 5.66 W/mK, which was approximately 4.1 and approximately 23 times higher than 60 wt% SEP/GF and pure SEP, when the nano-Fe3O4 content was 0.4 g, the strength of magnetic field was 0.65 T and the added amount of M was 60 wt%. In addition, by SEM observation, when the flake graphite was found in the direction of the magnetic field orientation, the graphite formed heat conduction channels touching each other in the magnetic field direction, improving the TC. Using XRD analyses the orientation degree of the graphite in the composite showed that the graphite obviously changed its internal orientation in the composite material when subjected to the magnetic field in the SEP melt.

Hyperbranched epoxy resin-grafted graphene oxide for efficient and all-purpose epoxy resin modification

Despite great efforts have been made on epoxy resins modification, development of additives that can be used to efficiently and universally modify epoxy composites remains a challenging task. Herein, graphene oxide (GO) sheets were covalently linked with hyperbranched epoxy resin (HBPEE-epoxy) to form HBPEE-epoxy functionalized GO (HPE-GO), which was then incorporated into epoxy resin (EP) matrix to achieve efficient and all-purpose enhancement of the properties of EPs. Compared with unmodified GO sheets, the functionalized HPE-GO sheets were better dispersed and exhibited better interfacial compatibility with the epoxy matrix, and consequently, the mechanical and thermal properties of HPE-GO/EP composites improved significantly compared to unmodified GO/EP composites. The tensile strength, flexural strength, impact strength, and fracture toughness (KIC) of EP composites containing 0.5 wt% HPE-GO increased by 65.0%, 36.2%, 259.1%, and 178.9%, respectively, compared with those for the neat EP. The storage modulus (E'), glass transition temperature (Tg), and thermal stability (T5%) also showed modest improvements. Furthermore, the HPE-GO/EP composites exhibited optimal thermal conductivities and thermal expansion properties, while maintaining higher volume resistivities compared with GO/EP composites. The results of this study support that HPE-GO is a promising, all-purpose modifier for EPs.

Modified epoxy resin with SEBS-g-MAH to fabricate crack-free and robust hydrophobic coatings on the surface of PP/SEBS matrix

Epoxy resin (EP) has been widely used in superhydrophobic coating areas for excellent adhesion and robustness. However, large amounts of hydrophobic particles addition are required to make the polar EP coating presents hydrophobicity, which will simultaneously cause the epoxy resin to crack. In this work, suitable SiO2 content was analyzed to pursuit the superhydrophobicity of epoxy resin coatings. Then, functionalized polyolefin elastomer maleic anhydride grafted styrene-ethylene/butylene-styrene (SEBS-g-MAH) was adopted to modify the cracking properties of the epoxy coatings. Results indicate that the coating with 50 wt% SiO2 content can present Cassie's superhydrophobic state and the water contact angle reached 155o, while the coating exists cracking performance significantly. Effects of SEBS-g-MAH on the surface performance of EP coatings were then investigated. EP/SEBS-g-MAH (5/5) coating can hardly find the cracks and the water contact angle still possesses 143o, which means that SEBS-g-MAH can improve the interface interaction between EP and SiO2 particles and modify the cracking behavior. Hence, the robust superhydrophobic coating by combining EP, SEBS-g-MAH and superhydrophobic SiO2 particles was successfully fabricated on the surface of polypropylene (PP) / styrene-ethylene-butylene-styrene copolymer (SEBS) matrix.

Synthesis of waterborne epoxy resin with diethanolamine-assisted succinimide for improving the strand integrity of polyimide filament

A water-soluble epoxy resin emulsion was synthesized by diethanolamine-assisted succinimide modified epoxy resin (DSEP) and used to reinforce the strand integrity of polyimide filament (PI). FTIR, XPS, and 1H NMR provide an evidence for the succinimide (SI) and diethanolamine (DEA) bonded onto the epoxy resin (EP) structure in the form of C-N-C. The DSEP emulsion shows high storage and dilution stability, with its particle size distribution and PDI of 118∼232 nm and 0.106∼0.638, respectively. Compared with DEA modified EP, DSEP exhibits better strand integrity for PI filament. The breaking strength of PI filament infiltrated by DSEP can reach 2.59 GPa, which is increased by 47.04% than that of PI filament, and is close to that of commercially available water-soluble polyimide resin (2.63 GPa). In addition, the fracture microstructure of PI filament further confirms that DSEP significantly reinforces the aggregation of PI filament. Importantly, there is no wire splitting phenomenon of DSEP reinforced PI filament after more than 200 times of friction. These benefit from the similar material groups of imide ring and benzene ring between DSEP and PI filament structure, as well as the strong hydrogen bonding interaction between them, as further confirmed by FTIR and SEM analysis.

A novel nitrogen-containing DPO derivative as flame retardant and co-curing agent for epoxy resin

A phosphorous-nitrogen flame retardant 1-N,4-N-bis(diphenylphosphorylmethyl)benzene-1,4-diamine (DPO-N) was synthesized by the reaction of p-phenylenediamine, formaldehyde and diphenylphosphine oxide (DPO). The modified epoxy resin (EP) was prepared using DPO-N as a flame retardant and co-curing agent in the presence of 4,4’-diaminodiphenylsulfone to cure bisphenol A diglycidyl ether (DGEBA). The flame retardancy of the DPO-N-modified EP was evaluated by the limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test. The results showed that the EP/DPO-N-0.7 (DPO-N-modified EP at a phosphorus content of 0.7 wt.%) passed the UL-94 V-0 rating test, and the LOI value of the sample increased to 30.4%. The peak of the heat release rate (pk-HRR), average of the heat release rate (av-HRR) and average of the effective heat of combustion (av-EHC) of the modified EPs were reduced by 32.4, 27.4 and 28.4%, respectively. The flame retardant mechanism was investigated by scanning electron microscopy, pyrolysis/gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy analyses. The results demonstrated that DPO-N exerted its flame-retardant effect through the barrier effect of the condensed phase and the quenching effect of the gas phase. Furthermore, the water resistance of the EP was enhanced with the incorporation of DPO-N.

Enhanced Anticorrosion Properties through Structured Particle Design of Waterborne Epoxy-Styrene-Acrylate Composite Emulsion

In order to develop a waterborne epoxy-styrene–acrylate composite latex with a better stability and anticorrosion resistance, a novel synthetic approach has been proposed. First, modified by methyl acrylic, epoxy resin containing terminal C=C double bonds was successfully synthesized, where epoxide groups were partially retained. Then, by structural design and multi-stage seed emulsion copolymerization, a stable waterborne epoxy-styrene-acrylate composite latex composed of a modified epoxy resin acrylate polymer as the core, inert polystyrene ester as the intermediate layer, and carboxyl acrylate polymer as the shell was successfully fabricated. The structure of the obtained latex was characterized by fourier transform infrared (FTIR) and transmission electron microscopy (TEM). The stability of the composite latex was tested based on the wet gel weight, Zeta potential, and storage stability, and the corrosion resistance of the composite latex films was analyzed by electrochemical measurements and salt spray tests. The thickness of each layer of the composite latex was calculated by the temperature random multi-frequency modulation DSC (TOPEM-DSC) technique. In addition to the successful emulsion copolymerization that occurred between the modified epoxy resin and acrylate monomer, the presence of carboxyl groups in the obtained latex was evidenced, while the epoxide groups were partially retained. The anticorrosion resistance and stability of the multilayer composite latex with the intermediate layer are better than that of the conventional core-shell latex. The outstanding stability and corrosion resistance is attributed to the multilayer core-shell structure. The TOPEM-DSC approach can accurately determine the thickness of the intermediate layer in the multilayer core-shell particles and is a new strategy for characterizing the core-shell structure of polymer particles with a similar monomer composition.

Effect of a Dwell Stage in the Cure Cycle on the Interphase Formation in a Poly(ether imide)/High Tg Epoxy System

Epoxies are inherently brittle materials and to overcome this brittleness, a second microphase (i.e., thermoplastic) is typically added. This modification of epoxy resin using thermoplastics results in reaction-induced phase separating morphologies in the micrometer range. In this study, the influence of the curing history, beyond phase separation, on the interphase formation and final morphology of PEI and the high Tg epoxy system is investigated. Several cure cycles were examined, each with a first dwell temperature ranging from 120 to 180 °C for a given time up to the onset of phase separation (OPS) or up to the 80% degree of cure (80% DOC) and then with a second dwell at 200 °C for 20 min to complete the cure cycle. Hot-stage microscopy experiments were carried out at several first dwell temperatures before final conversion at the second dwell. The morphologies and resulting droplet size distribution at the interphase, after the final cure, were analyzed through scanning electron microscopy. Results showed that the diffusion distance was significantly higher in the case of OPS as compared to the 80% DOC case, particularly at lower first dwell temperatures. This behavior was attributed to the fact that, in the case of OPS, polymeric chains were still in a mobile state and diffused further during the second dwell curing stage, while at 80% DOC, polymeric chains were completely bound but still diffuse due to non-stoichiometric curing. This restricted mobility of polymeric chains after phase separation (80% DOC) resulted in a larger number of smaller droplets as compared to the OPS case.