Type Epoxy Research Articles

Self-assembled complexes of graphene oxide and oxidized vapor-grown carbon fibers for simultaneously enhancing the strength and toughness of epoxy and multi-scale carbon fiber/epoxy composites

Reinforcement of polymers with small addition of nanofillers has been intensively investigated. It has been suggested that combination of few-layer graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) is more effective than single nanofillers for polymer reinforcement. Herein, we report that the complexes of single-layer graphene oxide (GO) and oxidized vapor-grown carbon fibers (OVGCFs), with dimensionalities of 2 and 1, respectively, simultaneously improve the strength and toughness of epoxy and multi-scale carbon fiber reinforced composites at an extremely low content (∼0.2 wt%). The GO-OVGCF complexes are formed in water by the π-π stacking-induced self-assembly of OVGCFs and GO, and then rapidly transferred to a tertiary amine type epoxy oligomer for the preparation of epoxy and multi-scale composites. OVGCFs were observed to be wrapped by small GO sheets, which greatly improve the dispersion uniformity of OVGCFs in epoxy matrix and the filler-matrix interfacial interactions. The influences of the complexes with various GO-to-OVGCF ratios on the mechanical properties of epoxy and multi-scale composites were investigated systematically. At the optimized GO-to-OVGCF ratio, the complexes increase the mechanical properties of epoxy and multi-scale composites more significantly than previously reported individual nanofillers and the CNT-GNP hybrids.

An investigation into 3D printing of fibre reinforced thermoplastic composites

Fused filament fabrication (FFF) is a 3D printing technique which allows layer-by-layer build-up of a part by the deposition of thermoplastic material through a nozzle. The technique allows for complex shapes to be made with a degree of design freedom unachievable with traditional manufacturing methods. However, the mechanical properties of the thermoplastic materials used are low compared to common engineering materials. In this work, composite 3D printing feedstocks for FFF are investigated, wherein carbon fibres are embedded into a thermoplastic matrix to increase strength and stiffness. First, the key processing parameters for FFF are reviewed, showing how fibres alter the printing dynamics by changing the viscosity and the thermal profile of the printed material. The state-of-the-art in composite 3D printing is presented, showing a distinction between short fibre feedstocks versus continuous fibre feedstocks. An experimental study was performed to benchmark these two methods. It is found that printing of continuous carbon fibres using the MarkOne printer gives significant increases in performance over unreinforced thermoplastics, with mechanical properties in the same order of magnitude of typical unidirectional epoxy matrix composites. The method, however, is limited in design freedom as the brittle continuous carbon fibres cannot be deposited freely through small steering radii and sharp angles. Filaments with embedded short carbon microfibres (∼100 μm) show better print capabilities and are suitable for use with standard printing methods, but only offer a slight increase in mechanical properties over the pure thermoplastic properties. It is hypothesized that increasing the fibre length in short fibre filament is expected to lead to increased mechanical properties, potentially approaching those of continuous fibre composites, whilst keeping the high degree of design freedom of the FFF process.

Poly-DCPD형 복합에폭시수지의 무기물 충전재별 특성에 관한 연구

Poly-DCPD type epoxy resin and composite materials were prepared reaction injection molding(RIM) polymerization from polyamide based curing agents(G-5022:G-0930) with inorganic filler(SiO₂, Cu₂O, CuO and CaO). and the effects of composite on the impact strength, flexural strength and surface hardness of the reinforced poly-DCPD type epoxy resin were experimentally examined.<BR> Impact strength and flexural strength increased as the amount of SiO₂ added increased. but decreased at more than 0.6wt%. also surface hardness showed a constant value regardless of the addition amount. and impact strength and flexural strength increased as the size of SiO₂ particles was smaller. it was found that the surface hardness had little effect.<BR> The impact strength, flexural strength and surface hardness were highest when Cu₂O was used as a filler. SiO₂ and CuO were similar to each other. and the curing temperature was increased, impact strength, flexural strength and surface hardness did not changed.

A composite of epoxy resin/copper(II) acetylacetonae as catalyst of copper addition on insulated substrate

A novel type of Epoxy Resin (EP)/Copper(II) acetylacetonate (Cu(acac)2) composites is developed and applied to improve electroless plating. This efficient and palladium-free process is based on the EP filled with various mass fractions of Cu(acac)2 via ball milling. The thermal stability of the composite of EP/Cu(acac)2 was performed with corresponding instruments. Moreover, the results of the viscosity and adhesion strength show that the viscosity of sample is positively correlated with the mass fraction of Cu(acac)2 in the composite. On the contrary, the shear strength of sample coated on FR-4 diminishes with the increasing fraction of Cu(acac)2. Results of parametrical optimizing reach the conclusion that under the condition of 50 °C for 15 min by electroless deposition (ELD) of copper, EP containing 40% Cu(acac)2 composites yields the best result.

Synergetically Improving the Strength and the Toughness of Epoxy Based Composites with Multiscale Reinforcements for Direct Extrusion Fabrication

In this paper, a new type of epoxy based composites, which is modified by multiscale reinforcements, for Direct Extrusion Fabrication (DEF) is developed. In the composites, micron-sized fillers-Carbon Fibers (CFs) were treated by ball milling and liquid-phase-oxidation/sonication methods in order to enhance the surface roughness and improve the interfacial interactions. In this way, both the tensile strength and Young’s modulus were increased. A modified Halpin-Tsai model was presented to predict the Young’s modulus of multiscale reinforced composites with both micron-sized and nano-sized reinforcements. However, the improvement of toughness was limited. In order to increase the toughness without sacrificing other properties, nano-sized fillers—rubber nano-particles (RNPs) and carbon nano-tubes (CNTs) were added. Mechanical experiments and scanning electron microscopy (SEM) observations were used to study the effects of the micron-sized, nano-sized reinforcements and their combination on tensile and toughness properties of the composites. The results showed that the combined use of multiscale reinforcements had synergetic effects on both the strength and the toughness of the composites.

Erosion wear response of epoxy composites filled with steel industry slag and sludge particles: A comparative study

In the field of composite research, use of industrial wastes such as slag and sludge particles as filler in wear resistant polymer composites has not been very common. Owing to the very high cost of conventional filler materials in polymer composites, exploring the possibility of using low cost minerals and industrial wastes for this purpose has become the need of the hour. In this context this work explores the possibility of such polymer composites filled with low cost industrial wastes and presents a comparison of mechanical characteristics among three types of epoxy based composites filled with Linz - Donawitz sludge (LD sludge), blast furnace slag (BF slag) and Linz - Donawitz slag (LD slag) respectively. A comparative study in regard to their solid particle erosion wear characteristics under similar test conditions is also included. Composites with different weight proportions (0, 5, 10, 15 and 20 wt. %) of LD sludge are fabricated by solution casting technique. Mechanical properties such as micro- hardness, tensile strength and flexural strength of three types of composites have been evaluated as per ASTM test standards and solid particle erosion wear test is performed following a design of experiment approach based on Taguchi’s orthogonal array. Five control factors (impact velocity, erodent size, filler content, impingement angle and erodent temperature) each at five levels are considered to conduct erosion wear tests. The test results for epoxy-LD sludge composites are compared with those of epoxy-BF slag and epoxy-LD slag composites reported by previous investigators. The comparison reveals that epoxy filled with LD sludge exhibits superior mechanical and erosion wear characteristics among the three types of composites considered in this study. This work also opens up a new avenue for value added utilization of an abundant industrial waste in the making of epoxy based functional composites.

An Experimental Study Regarding the Vibratory Behaviour for Some Textile Composites

The paper presents the results of our research in the elaboration and characterization of composites type epoxy - textile fiber and vibration behaviour. These were made by pressing, and the textile fibers we tested were cotton, flax, hemp and wool. Starting from the dynamic response of composite beam with damping (which is in free vibration), there is established a way to determine the damping factor. There has been experimentally determined the damping factors for some samples: sample 1 – built from cotton; sample 2 – built from hemp; sample 3 – built from flax; sample 4 – built from whool.

Fatigue retrofitting of cracked steel beams with CFRP laminates

In recent years, carbon fiber-reinforced polymer (CFRP) externally bonded to steel members has been considered an effective technique for fatigue crack repair of steel components. This paper investigated the fatigue behavior of six cracked steel beams strengthened using CFRP laminates via two approaches, i.e., sole adhesive bonding and adhesive bonding together with mechanical anchorage. Two types of epoxies were selected to compare the effectiveness. The tensile flange of the steel beam was artificially cut to simulate an initial crack. A digital image correlation (DIC) system was adopted to detect strain distribution along the retrofitting patches. Different failure modes were observed for specimens with different retrofitting schemes. Test results showed that, in comparison with control specimens with sole adhesive bonding, application of mechanical anchorage significantly retarded crack propagation and extended fatigue life of the steel beams attributed to the pronounced frictional bond. The crack mouth opening displacement (CMOD) was also considerably reduced. The displacement fields obtained from the DIC recorded at specific crack lengths were analyzed to provide information on strain distribution along the CFRP laminates and corresponding bond-slip relationship. This study extends the understanding of fatigue repair for steel beams and provides useful suggestions for the strengthening method.

Study on the effect of waterborne epoxy resins on the performance and microstructure of cement paste

Concrete repairing, rehabilitation and prolonging the effective service-life of structures plays an important role in building field worldwide. The polymer-modified cementitious material dominated by different resins has been widely applied in repairing and reinforcing, wherein the epoxy resin is a material with excellent comprehensive properties. The waterborne resin gets a better compatibility and coupling effects with the cement hydration. In this paper, the effect of two waterborne epoxy resins on the hydration of cement and the microstructure of paste have been studied. The mechanical properties, mesoscopic morphologies after mixing and curing, the hydration products, chemical bonds and three-dimensional structures of the cement paste with emulsion type epoxy resin (EEP) and non-emulsion type epoxy resin (NEP) (with content of 5%–80% wt.) are studied by optical microscopy, field emission scanning electron microscopy, X-ray diffractometer, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray computed tomography. The results show that EEP and NEP have a significant effect on the formation of portlandite crystals at an early stage. NEP is more effective than EEP on the toughening effect with the content of 40% wt. The stress–strain curve of non-emulsion epoxy cement paste (NEPC) manifests an obvious secondary step, and the fracture strain value rises from 0.6% to 1.2–1.3% which proves the NEP enhances the resistance to cracking. The resin in NEPC mainly consists of a layered network structure with the continuous phase in the transverse direction.

Improvement of mechanical properties and anticorrosion performance of epoxy coatings by the introduction of polyaniline/graphene composite

We reported the preparation of epoxy coatings incorporated with a composite filler of poly(styrenesulfonate)-polyaniline/reduced graphene oxide (PSS-PANI/rGO) and their performance on the mechanical and anticorrosion properties. The rGO platelets were first dispersed in the PSS solution, followed by in situ oxidative polymerization of aniline. The resulting PSS-PANI/rGO composite was then blended with a bisphenol-A type epoxy at different loadings by tri-roller mill, and was subsequently cured with a curing agent. The ultimate tensile strength and tensile toughness of the epoxy composite at a loading of only 0.5 wt% PSS-PANI/rGO were improved by 39% and 127%, respectively, when compared to the respective values of the pristine epoxy. This was ascribed to their strong interfacial bonding upon curing by the reaction between the PANI and epoxy. Furthermore, the potentiodynamic polarization of the carbon steels coated with the epoxy/PSS-PANI/rGO composite revealed that the anticorrosion performance was greatly improved when compared to those with the neat epoxy and epoxy/rGO coatings. The superior anticorrosion effect was attributed to its larger tortuosity of diffusion pathways, improved interfacial strength between the epoxy and filler, and the passivation layer formed by the presence of polyaniline which was confirmed by X-ray photoelectron spectroscopy. The improved anticorrosion and toughness would allow the coatings to withstand externally mechanical impact and prevent corrosion effectively.

Fabrication of nanocomposites with silica nanoparticles

Functionalization of silica nanoparticles is needed as to improve the mechanical performance of epoxy nanocomposites. Previous experience showed that direct dispersion of commercially available silica nanofillers does not improve significantly the mechanical properties of resulting nanocomposites. Different methods of fabrication are presented along with comments on the possibilities to improve the quality of obtained specimens. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%. The obtained nanocomposites were subjected to monotonic uniaxial loading at room temperature. The static mechanical properties were not significantly changed regardless the filler type or percentage and type of epoxy resin.

The Effect of the Kenaf Natural Fiber on Enhancing the Mechanical Properties of Bio-Composites Materials Used in Civil Engineering

AbstractIn this work, we have investigated the effect of the natural Kenaf reinforcement on the improvement of the interfacile bond between two types of epoxy and Polypropylene (PP) matrix. Our genetic model is based on Weibull's probabilistic models and on Cox's interface model. The moisture content for each material is determined by Fick's law. Our simulation results show that the most resistant interface is that of Kenaf-Polypropylene compared to the other interfaces. This result coincides perfectly with the experimental data found by Paul Wambua et al. Which have shown that Kenaf is a promoter fiber for the improvement of the mechanical properties of biocomposite used in the field of civil engineering.

Analysis of linear dimensional change of different materials used for casting dental models: plaster type 4, nanocomposites carbon nanostructures, polyurethane resin and epoxy resin

This study evaluated the linear dimensional change of two dental plasters plaster type Elite rock and plaster modified with carbon nanotubes a PU resin Novox and an epoxy resin Sikadur An aluminum matrix was made to create specimens for each material analyzed The measurements were performed using SEM with differences expressed in terms of linear dimensional change Tukey test showed that polyurethane resin had significantly greater shrinkage than plaster type and nanoparticulate plaster Polyurethane resin shrinkage was also significantly higher than that measured for the epoxy resin though both were poor at reproducing the original cone measurements In relation to plaster type nanoparticulate plaster and epoxy resin polyurethane resin shrinkage was and higher respectively No significant difference was observed between the tested plasters and epoxy resin regarding dimensional changes

多官能メソゲン骨格エポキシ樹脂による高Tg・高熱伝導化

多官能メソゲン骨格エポキシ樹脂による高Tg・高熱伝導化

Thermal and mechanical properties of tetra‐functional mesogenic type epoxy resin cured with aromatic amine

ABSTRACTA novel tetra‐functional epoxy monomer with mesogenic groups was synthesized and characterized by 1H‐NMR and FTIR. The synthesized epoxy monomer was cured with aromatic amine to improve the thermal property of epoxy/amine cured system. The glass transition temperature (Tg) and coefficient of thermal expansion (CTE) of the cured system were investigated by dynamic mechanical analysis and thermal mechanical analysis. The properties of the cured system were compared with the conventional bisphenol‐A type epoxy and mesogenic type epoxy system. The storage modulus of the tetra‐functional mesogenic epoxy cured systems showed the value of 0.96 GPa at 250 °C, and Tg‐less behavior was clearly observed. The cured system also showed a low CTE at temperatures above 150 °C without incorporation of inorganic components. These phenomena were achieved by suppression of the thermal motion of network chains by introduction of both mesogenic groups and branched structure to increase the cross linking density. The temperature dependency of the tensile property and thermal conductivity of the cured system was also investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46181.

Behaviour of Epoxy Silica Nanocomposites Under Static and Creep Loading

Abstract Specific manufacturing technologies were applied for the fabrication of epoxy-based nanocomposites with silica nanoparticles. For dispersing the fillers in the epoxy resin special equipment such as a shear mixer and a high energy sonicator with temperature control were used. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%.. The obtained nanocomposites were subjected to monotonic uniaxial and creep loading at room temperature. The static mechanical properties were not significantly improved regardless the filler percentage and type of epoxy resin. Under creep loading, by increasing the stress level, the nanocomposite with 0.1 wt% silica creeps less than all other materials. Also the creep rate is reduced by adding silica nanofillers.

One-component epoxy adhesive for repair of cell phone board

The development of a one-component epoxy adhesive for cell phone board repair was described. The most important goal of this study is to obtain long storage stability in conjunction with the curing reaction process at a relatively low temperature of 95 °C. Bisphenol-A type, bisphenol-F type, and NBR-based epoxy resins were used as the basic resins. Dicyandiamide (DICY) was used as a curing agent, and 2-methylimidazole (2MI) was used as an accelerator. 2MI was encapsulated using a copolymer of methacrylic acid and dodecyl methacrylate to achieve latent curing performance. After mixing the epoxy resin with DICY and encapsulated 2MI, this curing system showed excellent storage stability with almost no viscosity increase for 2 months at 20 °C, and full curing was achieved at 95 °C for 50 min. We determined the optimum formulation of the epoxy adhesive for adhesion of a cell phone board after the measurement of physical properties.

Curing kinetics and characterization of dual-curable thiol-acrylate-epoxy thermosets with latent reactivity

A new dual-curing scheme was developed for thiol-acrylate-epoxy mixtures. A photo-initiated latent catalytic system was used to carry out thiol-acrylate Michael addition at 35°C (Stage 1) followed by thiol-epoxy click reaction (Stage 2) at 80–110°C. The intermediate materials were shown to have several days of storage stability. The use of a radical inhibitor has suppressed radical mediated acrylate homopolymerization which would otherwise lead to unreacted thiols remaining. Kinetics of Stage 2 was analyzed mathematically using isoconversional differential method and Kamal model regression. Glass transition temperatures (Tg) of samples with varying contents of epoxy and different types of acrylates were measured. Epoxy-rich formulations gave the highest final Tg. Although not as influential as the epoxy content, using higher functional and more rigid acrylate monomers resulted in higher intermediate and final Tg. The proposed curing scheme and the resulting materials could be useful in applications such as adhesives, industrial coatings with high chemical resistance, optical and electronic materials.

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.

Comparative Adsorption of Different Dyes from Aqueous Solutions onto Polymer Prepared by ROP: Kinetic, Equilibrium and Thermodynamic Studies

Poly(1,2-epoxy-3-phenoxy)propane was synthesized by ring-opening polymerization using $$\hbox {Sn}(\hbox {Oct})_{2}$$ as a catalyst and benzyl alcohol as an initiator. Homopolymer’s epoxy type was acylated with chloroacetyl chloride firstly and then modified with the diethanol amine. The polymers were characterized by FT-IR and $${}^{1}\hbox {H}{-}\hbox {NMR}$$ . Dye adsorption properties of poly(2-phenoxy ethyl [bis(2-hydroxy ethyl)amino]acetate) were investigated by using bromocresol green (BCG), alizarin yellow (AY) and methylene blue (MB). Amounts of dye holding polymers at different times were calculated and plotted as a function of time. According to the removal results, all of the dyes reach its highest efficiency at 90 min. The effect of pH on adsorption of dyes was studied in the pH range of 2–11. Kinetic models known as pseudo-first order and pseudo-second order were used to analyze the mechanism of adsorption, and the results indicated an adsorption kinetic compatible with the pseudo-second order. The Langmuir and Freundlich isotherms were utilized to explain the adsorption equilibrium, and when it was compared with each other, it was revealed that the Langmuir isotherm model was better than Freundlich isotherm. The maximum adsorption capacities of BCG, AY and MB were 52.63, 15.87 and 31.25 mg/g, respectively. Furthermore, thermodynamic properties ( $$\Delta {H}^{{\circ }}$$ , $$\Delta {S}^{{\circ }}$$ , $$\Delta {G}^{{\circ }})$$ of modified polymer were investigated for the three dyes. According to the thermodynamic parameters, the adsorption of the dyes occurred spontaneously and was endothermic. The results of this study support that novel polymer, an inexpensive and effective adsorbent, could be used for dye removal from aqueous solutions.