Particulate Epoxy Research Articles

Damping Behavior of Alumina Epoxy Nano-Composites

Polymer nano composites, consisting of a polymer matrix with nanoparticle filler, have been predicted to be one of the most beneficial applications of nanotechnology. Addition of nano particulates to a polymer matrix enhances its performance by capitalizing on the nature and properties of the nano-scale fillers. The damping behavior of composites with nano structured phases is significantly different from that of micro structured materials. Viscoelastic homopolymer exhibit a high material damping response over a relatively narrow range of temperature and frequencies. In many practical situations, a polymeric structure is required to possess better strength and stiffness properties together with a reasonable damping behavior. Viscoelastic polymers show higher loss factor beyond the glassy region which comes with a significant drop in the specific modulus. Addition of nano alumina particles to epoxy leads to improved strength and stiffness properties with an increase in glass transition temperature while retaining its damping capability. Experimental investigations are carried out on composite beam specimen fabricated with different compositions of alumina nano particles in epoxy to evaluate loss factor, tan δ. Impact damping method is used for time response analysis. A single point Laser is used to record the transverse displacement of a point on the composite beam specimen. The experimental results are compared with theoretical estimation of loss factor using Voigt estimation. The effect of inter phase is included in theoretical estimation of loss factor. The result reveals that the study of interface properties is very important in deriving the overall loss factor of the composite since interface occupies a significant volume fraction in the composite.

Epoxy-acrylic core-shell particles by seeded emulsion polymerization

We developed a novel method for synthesizing epoxy-acrylic hybrid latexes. We first prepared an aqueous dispersion of high molecular weight solid epoxy prepolymers using a mechanical dispersion process at elevated temperatures, and we subsequently used the epoxy dispersion as a seed in the emulsion polymerization of acrylic monomers comprising methyl methacrylate (MMA) and methacrylic acid (MAA). Advanced analytical techniques, such as scanning transmission X-ray microscopy (STXM) and peak force tapping atomic force microscopy (PFT-AFM), have elucidated a unique core-shell morphology of the epoxy-acrylic hybrid particles. Moreover, the formation of the core-shell morphology in the seeded emulsion polymerization process is primarily attributed to kinetic trapping of the acrylic phase at the exterior of the epoxy particles. By this new method, we are able to design the epoxy and acrylic polymers in two separate steps, and we can potentially synthesize epoxy-acrylic hybrid latexes with a broad range of compositions.

Experimental Determination of Mechanical and Physical Properties of Almond Shell Particles Filled Biocomposite in Modified Epoxy Resin

Rapid Advancement in the field of advance Biocomposite has attracted large number of researchers to diagnose and expand the use of light weighted and environment friendly materials for various applications. In this work, depolymerized natural rubber (DNR) was prepared and used as toughening agents for epoxy resin and almond shell particles are filled in modified epoxy resin as reinforcing material. Further, different tests including Tensile Test, Compression Test, Hardness Test, Impact Test etc. were performed to diagnose the effect of various weight percentage (wt%) of composition of blended DNR for achieving maximum toughness and then its effect on treatment with different weight percentage of Almond Shell Particle. Results were analyzed and finally the conclusion is made based on the experiments.

Preparation of silicon nitride foam with three-dimensional interconnected pore structure

Silicon nitride (Si3N4) foams with three dimensional (3D) interconnected pore structure were prepared by a combination of protein foaming method and sacrificial template method. Hydrophobic epoxy resin (EP) particles were used as the sacrificial template. The hydrophobic character of EP particles enabled them to absorb on to the air–water interface in the foamed slurry, resulting in the formation of windows on the cell walls after the burn out of EP particles. Pore structures and properties of the Si3N4 foams fabricated with adding different amount of EP powder and different sintering temperature were investigated. It was indicated that the Si3N4 foam fabricated without EP powder exhibited catastrophic failure during the compression test, whereas the Si3N4 foams fabricated with EP powder did not. Moreover, the Si3N4 foams with large numbers of windows on the cell walls exhibited higher compressive strength than the Si3N4 foam without window on its cell walls, even though the open porosities of the former were similar to the latter or even higher than the latter.

Organosilanes Surface Modification of Zirconium Diboride Composite Engineering Ceramics and Its Effect on the Tribological Performance of Epoxy Composites

Zirconium diboride/alumina composite particles are modified by three kinds of organosilanes. The modified particles are characterized by Fourier transform infrared spectrometer, X‐ray photoelectron spectra, and transmission electron microscope. The results show that the organosilanes are successfully grafted onto the surfaces of composite particles by Al–O–Si bonds from the chemical reaction between particles and organosilanes, which makes contribution to reducing the agglomeration of particles in epoxy. The epoxy composites containing modified particles present higher tribological performances and more even distribution of the thermal flux which restrains the deterioration of the tribological properties caused by the concentration of friction heat.

Fracture resistance, thermal and electrical properties of epoxy composites containing aligned carbon nanotubes by low magnetic field

Abstract The alignment of carbon nanotubes (CNTs) with residual catalyst Ni particles in epoxy resin (EP) was achieved under a low magnetic field of 0.4 T. EP composites containing different loading of CNTs were prepared at 60 °C based on the rheology results of CNT/EP suspensions. The effects of CNT loading and magnetic field on the fracture toughness (KIC), glass transition temperature (Tg) and electrical properties of the composites were studied. The obtained results showed significant enhancements in KIC, independent of the orientation of the CNTs, compared to neat epoxy. The maximum increase (∼51%) was achieved by composites with 3 wt.% aligned CNTs transverse to crack growth. Additionally, composites with magnetically aligned CNTs displayed anisotropy in KIC. Compared to CNT/EP composites with no applied magnetic field, the KIC increase was less effective at high CNT loading. Finally, toughening mechanisms, Tg and electrical conductivity results were discussed.

Epoxy/BN micro- and submicro-composites: dielectric and thermal properties of enhanced materials for high voltage insulation systems

Hexagonal boron nitride (h-BN) is a very promising material for application in high voltage insulation engineering due to its high thermal conductivity and good electrical insulating properties. In order to study the effect of incorporating BN particles in epoxy resin, composites with different filler sizes and several BN loadings have been fabricated. Two different filler sizes, one micrometric with an average grain size of 9 μm and a submicrometric one with 0.5 μm, have been used to form composites. The amount of either type of BN in the matrix has been varied from 1 to 5 wt%. Dielectric and thermal performances of the test specimens have been assessed by means of Dielectric Spectroscopy, Differential Scanning Calorimetry, surface erosion, AC breakdown tests and thermal conductivity measurements. It has been found that incorporation of BN particles in the epoxy resin resulted in significant improvements of parameters such as resistance to electrical discharge, as well as diminished dielectric losses for the composites at higher temperatures. Furthermore, BN composites with 5 wt% filler loadings have shown a noteworthy enhancement of thermal conductivities, which was more distinct for the submicrometric BN composite.

Nano-Composite manufacturing using the Electro-Orientation method of Micro/Nano-Particles in a liquid polymer with mechanical characteristics analysis

A new technology for manufacturing micro/nano composites by utilizing an electric field to fabricate particle orientations in a polymer liquid state is developed and its thermo-mechanical properties are tested. This method allows the manipulation of the local orientation of the submerged micro/nano size particles in a liquid matrix. The study demonstrates that the technology is able to locally manipulate the particle orientation and applicable diverse metal/non-metal inclusions in a polymer matrix. The theoretical background of this process includes the dielectrophoresis, diploe moment, and electrophoresis of particles in a polymer matrix. Electrophoresis is an important phenomenon in the orientation of non-spherical particles in a continuous phase. Attempts were made to distribute several types of metal and non-metal particles in a liquid epoxy, in order to test the effects of electrophoresis under an electric field; the rotation and alignment of the particles were clearly observed and pictures were taken. The mathematical models of the kinetic movements caused by the electrophoretic force are also presented here. The results obtained from the experiment indicate the effectiveness of the proposed method and validate the suggested mathematical models, including all of the expanded manipulation.

Synthesis of Dispersed and Self-Assembled Metal Particles in Epoxy via Aqueous to Organic Phase Transfer Technique

A convenient and effective method of dispersing gold (Au), silver (Ag) and copper (Cu) particles in epoxy is described. Particles were synthesized in aqueous phase and subsequently dispersed in toluene-epoxy with or without the presence of curing agent. Sodium borohydride and 2-propanol were used as reducing and phase transfer agents respectively. The surface plasmon resonance (SPR) at ~ 540-620 nm, ~ 525 nm and ~450 nm confirms the presence of Cu, Au and Ag nanoparticles in the composites. No chemical interaction occurred between the metal particles and the epoxy or cured epoxy. Increase in epoxy content caused the size of the particles to decrease for all metals. The average particle size for Au, Ag and Cu in 1% and 10% epoxy are 3.9 nm and 2.5 nm, 10.1 nm and 3.2 nm as well as 8.1 nm and 5.9 nm respectively. Similar decreasing trend was also observed upon addition of curing agent. In all cases, metal nanoparticles exhibit self-assembly with inter-particle spacing of <10 nm. The absence of any curing peak in the DSC thermograms suggests that the composites are well cured before any of the DSC analyses were performed. The Tg of the metal-cured epoxy is higher than neat epoxy, that is 71.3 °C, 69.8 °C and 62.0 °C for Cu, Au and Ag respectively.

Production of epoxy spherical mesoporous as a spherical membrane separator

Epoxy spherical membrane (ESM) is a porous epoxy material, a combination of micro-spherical particles. The spherical membrane, built from the space formed among the particles is applied for filtering and separation purposes. ESM was obtained after curing the emulsion of the epoxy mixture (epoxy, polyamide and calcium carbonate (CaCO3)) and water, which was prepared based on the water in oil in water (W/O/W) technique by using a high speed homogenizer. It was found that an increase in CaCO3 content produced smaller spherical epoxy particles and a higher porosity ESM. Therefore, a reduction in compression strength was induced; however, the compression modulus was increased. An ESM column with polypropylene (PP) tubes was applied as the separator column. Using the ESM column, carbon black N330 was successfully separated from the water. They were located at the top of the ESM column and trapped among the epoxy micron particles. ESM-25 possessed the highest flow rate of the water medium, while ESM-50 exhibited the highest weight of carbon black at the top of the membrane and the lowest weight of carbon trapped in the column. The oil–water separation function of ESM was observed using crude oil–water and palm oil–water solutions. Oils travelled slower through the ESM column in comparison to water, so the separation occurred; hence pure water was obtained first followed by the oils. It was found that ESM-25 exhibited the best oil flow rate for palm oil separation, while ESM-50 exhibited the best crude oil separation.

Improved thermal properties of epoxy composites filled with thermotropic liquid crystalline epoxy grafted aluminum nitride

A liquid crystalline epoxy (LCE) grafted AlN particles (LCE-g-AlN) were fabricated and then incorporated these into epoxy matrix to obtain the composites. The structure of LCE-g-AlN was characterized by Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR), thermal gravimetric analyses (TGA), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). The morphology and thermal properties of composites were systematically investigated. The morphology of the epoxy/LCE-g-AlN composites performed by scanning electron microscopy (SEM) indicated a homogeneous distribution of the LCE-g-AlN particles in epoxy. Moreover, the glass transition temperature (T-g), thermal stability, thermal conductivity and dynamic mechanical properties of composites showed a significant improvement due to the good miscibility and improvement of the interfacial interaction between LCE-g-AlN particles and epoxy matrix.

Characterization of Nanoclay-Modified Epoxy Polymers Using X-Ray Diffraction Analysis

Clay-nanoplatelets have emerged among the other nanomaterials for over the past few years due to their good thermal stability and mechanical properties. This paper presents the X-ray diffraction (XRD) analysis of nanoclay filled epoxy nanocomposites. In this study XRD was used to measure the dispersion state of clay particles in epoxy. A series of nanocomposites with 1 wt%, 3 wt% and 5 wt% nanoclay was fabricated using mechanical stirring and three roll mill methods. The overlaid of XRD patterns of pure Epikote 828 polymer, Cycom 977-20 polymer and polymer-nanoclay nanocomposites were produced. It was found that, there were no peak of diffraction pattern appeared for pure Epikote 828 and Cycom 977-20. Based on XRD results, the polymer is able to intercalate between the clay layers because the interlayer spacing between the clay platelets increased significantly. In addition, the results showed that the dispersion of clay in epoxy was more uniform using three-roll mill method compared to mechanical stirring method.

Wear and friction performance of PTFE filled epoxy composites with a high concentration of SiO2 particles

In this work, the tribological performance of PTFE filled SiO2 particles–epoxy composites is investigated. Under a load of 60N (~140MPa contact pressure), the optimum content of PTFE lies between 10 and 15wt%, which yields an ultralow coefficient of friction (CoF) in conjunction with a low wear rate of the composite when dry sliding against bearing steel balls within 1000m. With 12.5wt% PTFE in the composite, a CoF around 0.095 and a wear rate as low as 8.4×10−7mm3/Nm were measured up to a sliding distance of around 2000m. After 2000m, eventually the gradual accumulation of the fractured SiO2 particles and back-transferred steel on the worn composite surface leads to a significant increase of CoF. In the steady-state of sliding, smearing of the PTFE particles along the worn surface was observed together with fracturing of the SiO2 particles and cracking of the epoxy matrix. Successive EDS mapping shows the formation and evolution of a PTFE-containing third-body tribolayer on the worn surface of the composite. The thickness of the tribolayer was measured about 20–30nm on the surface of SiO2 particles after sliding for more than 700m.

Synthesis and characterization of titanium oxide nanotubes and its performance in epoxy nanocomposite coating

Abstract Titanium oxide nanotubes (TiO 2 nanotube, TNT) were prepared from hydrothermal treatment of TiO 2 particles in NaOH at 140 °C, followed by neutralization with HCl. The structure of the nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). TNT synthesized under the optimal conditions with approximately 10–20 nm wide, and several (100–200) of nanometers long. TNT is used as white pigment for two component epoxy-based coating. Ultrasonication followed by mechanical stirring has been applied for dispersion of TNT powder in an epoxy matrix. The resulting perfect dispersion of TNT particles in epoxy coating revealed by scanning electron microscopy (SEM) ensured white particles embedded in the epoxy matrix. The effects of TNT particle concentrations on thermal, mechanical and corrosion resistance of epoxy coatings composite were studied and compared to that of submicron particles. It was found that the TNT significantly enhances the heat resistance, the thermal stability and the glass transition temperature of epoxy resin. Epoxy/TNT nanocomposite with 5.0 wt.% TNT shows the highest thermal stability, the temperature of 50% weight loss increased from 365 to 378 °C, the amount of char yields or residues at 600 °C increased from 7.13 to 13.50 wt.%, respectively to 1.0 and 5.0 wt.% TNT. The glass transition temperature (Tg) increased from 182 to 220 °C too. The mechanical properties and corrosion resistance of epoxy resin greatly improved by using reinforcing TNT and this improvement increases with increase TNT wt.%.

The Stiffness and Thermal Expansion Coefficient of Iron Particulate Epoxy Composites Defined by Considering the Particle Contiguity

A theoretical model for the determination of the stiffness and the thermal expansion coefficient of particulate composites is presented in this work. This model takes into consideration the influence of neighboring spherical particles on the thermo mechanical constants of the composite material consisting of matrix and filler. A microstructural composite model which represents the basic cell of the composite at a microscopic scale was transformed to a tetraphase spherical representative volume element, (R. V. E.), in order that classical theory of linear elasticity is applied. This work constitutes a modified consideration of body – centered tetrahedral models that appeared in the literature. The obtained theoretical results using this model were compared with experimental results carried out on iron particles reinforced epoxy resin composites as well as with other theoretical values derived from well known expressions given in the literature and derived by other scientists. Finally an observation of the fracture surface of the specimens was performed through S. E. Microscopy.

Effect of external loads on damage detection of rubber‐toughened nanocomposites using carbon nanotubes sensory network

Multiwalled carbon nanotubes of 0.2% weight fraction are used as a sensory network for detecting and characterizing the damage of particulate epoxy composites under shear loading conditions. Three different weight fractions of carboxyl‐terminated butadiene acrylonitrile copolymer rubber [10 parts per hundred of epoxy resin (phr), 20 phr, and 30 phr] are used for toughening a thermoset epoxy composite. The electrical response of the specimens is measured, nearest the central shearing plane, using a four‐circumferential ring probe technique in conjunction with a high‐resolution data acquisition system. A collection of the electromechanical response results are reported with respect to the shear strain. The resistance changes observed under shear loading are related to nonlinear deformation mechanisms, void initiation, and growth around rubber particulate. With increasing rubber content, the strength of the material decreases and a greater drop in resistance is recorded as a result of decreased distance between neighboring carbon nanotubes (CNTs) due to declustering and straightening of molecular chains of host matrix. In the end, a comparison for 30 phr composites under shear loading with that of tensile and compression loading conditions is presented. For initial deformation, there is no change in resistance under shear loading condition; however, the significant resistance change can be noticed under both tension and compression. The specimen under shear loading conditions experiences smaller decrease in resistance when compared with both tension and compression. However, the decrease in resistance is higher for compression due to higher decrease in distance between neighboring CNTs. POLYM. COMPOS., 37:360–369, 2016. © 2014 Society of Plastics Engineers

Toughening of dicyandiamide-cured DGEBA-based epoxy resin using MBS core-shell rubber particles

A diglycidyl ether bisphenol-A-based epoxy resin, cured using a dicyandiamide hardener, has been toughened by the addition of core-shell rubber particles, methyl methacrylate-butadiene styrene. Different amounts of core-shell particles (2.5, 3.75, and 5 wt%) were added to the epoxy resin and their effect on the fracture, mechanical-physical, and thermal properties of the epoxy resin was investigated. The fracture surfaces of the samples were studied using a scanning electron microscope. The results showed that increasing methyl methacrylate-butadiene-styrene particles in epoxy resin increased the fracture toughness (KIC) and fracture energy (GIC) of the modified epoxy resin compared with the unmodified epoxy resin. The tensile strength and Young’s modulus of the modified epoxy resin decreased slightly and the glass transition temperature, cure onset, peak and end temperatures remained approximately constant. Scanning electron microscope revealed that the unmodified epoxy resin fracture surface was smooth and brittle, but the modified epoxy resin showed significant plastic deformation.

Strain Rate Effect on the Mechanical Properties of Recycled Wood Particles/ Epoxy Composites

The objective of this research is to study the mechanical properties of recycled wood particles epoxy matrix composites through the manipulation of composites wood particles size and weight fraction for tensile tests with different strain rate. Wood saw dust has been collected from a saw mill, dried and sieved into 300 and 600 μm. Unsieved wood particles were also used in this study. Each of the categories of wood particles was mixed into Epoxy resin with weight percentage of 20% and 40% of total composites to produce dumbbell-shaped tensile test specimens. Result shows that there is an optimum wood particles size where the tensile properties are at the highest before the properties start to decrease with increasing particles size, except for 20% wt. wood particles whereby the Young’s modulus is the highest with mix (largest) wood particles. With increasing wood particles weight percentage, tensile strength decreased while young’s modulus increased. A wood plastic composite (WEC) was shown to be strain rate sensitive whereby tensile properties increased with increasing strain rate. Our study proves that WPC can be very advantageous due to its higher average tensile strength and also high young’s modulus compared to commonly used materials in the industries.

Mechanical Properties of Highly Flexible Epoxy Systems Containing Nano-Sized Polymeric and Inorganic Particles

Epoxy systems containing flexible epoxy and nano-sized particles were prepared and mechanical properties, such as lap-shear and impact-peel strengths were measured. Core-shell rubber (CSR), CaCO3, and SiO2 particles were used as nano sized particles. Polyurethane- and polyamide-modified epoxies were used to form flexible epoxy matrix. As curing agents, DDS (4,4-diaminodiphenyl sulfone) and DICY (dicyandiamide) were used, and 2E4MZ-CNS(1-cyanoethyl-2-4-metylimidazole) was used as catalyst. As an adhesion promoter, zirconate coupling agent was used. CSR has significantly improved impact-peel strengths especially at low temperature, −40°C, due to the presence of highly flexible segments in epoxy backbones. Furthermore, nano-sized inorganic particles, CaCO3, and SiO2, have improved the impact-peel strengths of the epoxy systems. However, the lap-shear strength was decreased as the content of flexible epoxy was increased in epoxy systems.

Influence of surface charge on DC flashover characteristics of epoxy/BN nanocomposites

Epoxy is widely used in electronic and electrical devices because of its excellent insulation properties. The addition of nanoparticles to epoxy could change the material structure and then charge behaviors are altered as a consequence. The accumulation of surface charge may cause electric field distortion, which would lead to surface flashover. In this paper, the samples were made by dispersing nano-scale boron nitride (BN) particles in Epoxy with the weight ratios of 5, 10, 20, 30, 40 wt%. The samples were charged by a dc corona triode system using needle-plate electrodes. The distribution of charges was measured with an electrostatic voltmeter and the effect of nanoparticles on charge accumulation and decay behavior was studied. A flashover test was carried out under a dc stress between two finger-type electrodes. The effect of nanoparticles on flashover characteristics and the relation between surface charging and surface flashover were also investigated. The results showed that the traps between nanoparticles and the polymer, which were introduced by the added nanoparticles, could cause surface charge accumulation. In addition, the flashover occurred at a lower voltage because of the accumulated charge on the sample surface.