Epoxy Matrix Phase Research Articles

Water absorption study and characterization of polymer composites developed from discarded nylon carpet

The scientific objective of this work is to reuse the polymer materials generated from carpet waste. The nylon obtained from the discarded carpet was used as reinforcement material into the epoxy matrix phase. A modified approach of Vacuum-assisted resin transfer molding (VARTM) was used to infuse the mixture of epoxy and hardener into the nylon carpet polymer composites. This investigates the water absorption behavior of carpet waste composite. It will justify the application of proposed composites for lightweight structural applications in a moisture environment. The nylon fiber-based-epoxy composite was dipped in water as per ASTM standard for a different duration, namely, 24, 48, 72, 144 hours. The findings demonstrate that it can effectively withstand in moisture environment, and a maximum 4.5% weight of samples increased among all the samples for a different duration. Also, the developed composite showed a lower water diffusion co-efficient than the nail head structure and linden wood. Also, the carpet waste composite samples were investigated for thermal degradation and chemical behavior using X-Ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, respectively. The finding shows that the proposed composite could be used for lightweight components such as dashboard panels, sound absorbers, panel sheets, wall tiles, etc.

Mechanical and thermal behavior of epoxy based halloysite nano clay/PMMA hybrid nanocomposites

In the present study, the influence of Modified Halloysite Nanoclay Tubes (MHNT’s) and Poly-Methyl-Metacrylate (PMMA) on the mechanical and thermal properties of Epoxy/PMMA/MHNT hybrid nanocomposites have been investigated. Different wt% of MHNT’s was dispersed in epoxy resin and then added to dissolved-PMMA to obtain three phase hybrid nanocomposites. The composites were characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform-Infrared Spectrometry (FT–IR), Thermo-gravimetric analysis, tensile test, three point bending test and fracture toughness test. SEM images revealed that PMMA forms an immiscible phase in epoxy matrix. XRD patterns revealed that MHNT’s were in fully exfoliated state in hybrid nanocomposites. The MHNT’s provides good ductility to Epoxy-PMMA blends by forming flexible interface, results in significant improvement in the elongation at break and hence tensile strength. The values of tensile modulus, flexural strength, flexural modulus, fracture toughness and thermal stability showed significant improvement compared to neat epoxy. Hybrid composites exhibited better properties than conventional resin blend and nanocomposites due to positive divergence generated from the combination of two dissimilar toughening mechanisms.

The potential of natural rubber (NR) in controlling morphology in two-matrix epoxy/NR/graphene nano-platelets (GNP) systems

Abstract The potential of natural rubber (NR) in controlling the morphology to promote selective localization of nano-filler in two-matrix epoxy/NR/GNP system was studied. The effect of NR contents (from 5 up to 30 vol%) on mechanical, thermal, and electrical performances of epoxy/NR and epoxy/NR/GNP systems were investigated. It was clearly observed that the mechanical properties of epoxy/NR/GNP system was higher as compared to epoxy/NR system, at 5 vol% of NR content. The incorporation of GNP nano-filler increased viscosity in the epoxy/NR/GNP system, thus, smaller NR phase has formed. The good interfacial adhesion between epoxy matrix and small NR phase promoted effective stress transfer, therefore, increasing the flexural strength, modulus, and toughness properties of the epoxy/NR/GNP system. Moreover, epoxy/NR/GNP system shows higher thermal stability as compared to the epoxy/NR system. Thermal decomposition temperature was delayed in the epoxy/NR/GNP system due to GNP nano-fillers have lower polymer chain mobility. It is interesting to note that electrical bulk conductivity of epoxy/NR/GNP system increases with increasing NR contents from 0 up to 30 vol%. XRD results has proven that NR phase acted as an effective elastomer spacer, which re-aligned the GNP nano-fillers to form more effective conductive pathways for more electrons to travel.

Effect of heat treated HNT on physico-mechanical properties of epoxy nanocomposites

Abstract Halloysite Nano Tubes (HNTs) are naturally occurring Kaolite group minerals having an aluminosilicate-layer in the form of nanotubes which are known to enhance the properties of the polymer matrix composites when effectively dispersed in the epoxy matrix phase. In this regard, the present work is carried out to fabricate the composite specimens by polymer stir casting techniques and evaluate the basic properties viz., density, hardness, tensile strength , flexural strength , impact strength and the microstructure using Transmission electron microscopy (TEM) for better morphological studies of the dispersions in the nanocomposites with a filler content of 0, 5 and 10 wt% of HNT's that are effectively treated at three temperature conditions viz., Room temperature (RT), 50 °C and 70 °C according to specified ASTM test methods selected after thorough investigations and review of literature. As per the experimental investigation, the mechanical properties of the nanocomposite increases by the incorporation of heat treated HNT. Further, the study revealed that the nano composite with a filler content of 10 Wt.% of HNT preheat treated at 50 °C shows superior tensile and flexural strength, However the critical observation of the results reveal that the impact strength is maximum for Nano composites with a filler content of 5 Wt.% HNT pre heat treated at 70 °C. The study of TEM images gives an overview of uniform dispersion of HNTs in the matrix phase owing to varying pre-treatment conditions. It is evident that the properties of the nanocomposite depends on the quantity of functional filler present and temperature of heat treatment.

Facile synthesis of a novel hyperbranched poly(urethane-phosphine oxide) as an effective modifier for epoxy resin

In this work, a novel hyperbranched poly (urethane-phosphine oxide) (HPUPO) was facilely synthesized from 4,4′-diphenylmethane diisocyanate and trihydroxymethylphosphine oxide at room temperature. When HPUPO was incorporated, flame retardancy and toughness of epoxy resin are improved with maintained Tg and increased modulus and strength. The gas and condensed phase flame retardant mechanisms and toughening mechanisms are provided. The poor compatibility of epoxy resin/HPUPO hybrids determines the unchanged Tg of epoxy matrix phase. The tensile modulus and strength and storage modulus of modified epoxy thermosets are raised due to more rigid skeleton of HPUPO and hydrogen bond interaction. Moreover, the reactivity of epoxy resin curing systems containing HPUPO is elevated for the catalytic effect of its hydroxyl. The surface hydrophilicity of epoxy resin composites is decreased resulting from their increased surface roughness and the hydrophobicity of HPUPO. And the thermal decomposition temperature of epoxy resin hybrids is depressed. The epoxy resins modified by HPUPO with simple synthesis and preparation can be used for various high-performance applications in industries.

The effect of Portland cement inclusions in hybrid glass fibre reinforced composites based on a full factorial design

The apparent density, flexural modulus and strength of hybrid laminated composites were investigated through a full-factorial Design of Experiment (DoE) approach. Laminates were manufactured by hand lay-up using nine layers of glass fibre cross-ply fabric with an epoxy matrix phase reinforced with Portland cement microparticles. A first experiment investigated the effect of the inclusion site (particles in upper four layers, lower four layers, all layers or none), curing time (7 and 28 days) and compaction method (vacuum or uniaxial pressure). The fibre–matrix volume fraction and the particle mass fraction were fixed at 48.6/51.4% and 10% respectively. A second experiment investigated two distinct fibre–matrix volume fractions (48.6/51.4 and 29.6/70.4%) and five particle mass fractions (0, 2.5, 5.0, 7.5 and 10 wt%). Particle inclusions were restricted to the upper four layers, with 28 days of curing time and uniaxial compaction. The results were analysed via Analysis of Variance (ANOVA). A significant increase in flexural modulus and strength was observed at 28 days of curing time. Enhanced mechanical properties were obtained for laminates with particle inclusions only in the upper half of the structure, manufactured with 48.6/51.4% fibre-matrix volume fraction and uniaxial pressure. Higher flexural strength was achieved for composites manufactured with 51/49% fibre–matrix volume fraction and 2.5% of particle mass fraction. These fibrous-particulate hybrid composite laminates can be considered for future secondary structural parts in lightweight engineering applications.

Thermoset Polymer Reinforced With Silica Micro and Nanoparticles

Abstract Fiber-reinforced composites (FRCs) have been used to replace conventional materials in a wide range of applications in transportation and civil engineering. The dispersion of nanoparticles and microparticles into epoxy matrix phase has been widely investigated to enhance the mechanical properties of hybrid FRCs. The nanoparticles generate large attractive forces among themselves, providing a significant tendency to agglomerate. A chemical treatment based on diallyldimethylammonium chloride (PDDA) was evaluated to disperse the silica nanoparticles within the epoxy polymer. A microstructural analysis was conducted to better assess the results. Experimental analysis was carried out based on the analysis of variance (ANOVA) and Tuckey test in order to verify the effect of PDDA treatment, silica particle size (micro and nano), and silica particle inclusion (1, 2, and 3.5 wt.%) on the mechanical properties of epoxy polymer commonly used as matrix phase in FRCs. The PDDA treatment was able to disperse the silica nanoparticles. The incorporation of 1 wt. % of silica micro or 1 and 2 wt. % of nanoparticles slightly improved the tensile strength and modulus of the epoxy polymer.

Influence of Portland Cement Addition in the Physical and Mechanical Properties of Epoxy Resin

This research evaluated, with the of the analyses of variance (ANOVA), a composite material based on epoxy matrix phase reinforced with Portland cement (CP-II) particles (0%wt [100%wt of resin], 20%wt, 40%wt, 60%wt). The response-variable investigated were modulus of elasticity (E) and compressive strength (S), bulk density (ρB), apparent density (ρA) and porosity (P). The highest values of the modulus of elasticity were provided from the composites manufactured with 40wt% of cement addition. The inclusion of 60% of cement implies in a reduction in the mechanical properties when compared with the results of the composite manufactured with 40% of cement. For the physical properties, the gradually inclusion of cement provides increasing in the density of the composites, and reduce the porosity of the materials manufactured.

Mechanical properties of mendable composites containing self-healing thermoplastic agents

The tensile and compressive properties of mendable composites containing thermoplastic particles as self-healing agents are assessed in this paper. The effects of the type and concentration of thermoplastic healing agent on the mechanical properties of carbon fibre–epoxy composites were determined experimentally by mechanical testing and computationally using finite element analysis. The elastic modulus and failure stress of the mendable composites decreased at a linear rate with increasing weight fraction of thermoplastic agent in the epoxy matrix phase. Microstructural analysis revealed the thermoplastic agents thickened the polymer-rich layers between the plies, and this reduced the average fibre volume content of the mendable composite thereby lowering its mechanical properties. Restoration of the in-plane properties of mendable composites following healing of delamination damage using thermoplastic particles was also assessed. Healing partially restored the compressive modulus of the mendable composites, but had no healing effect on their compressive strength or tensile properties.

Epoxy composites containing CFRP powder wastes

The increasing utilisation of carbon materials increases the waste generation. Therefore, it is necessary to analyse recycling alternatives. In this research, carbon powder wastes obtained from the cutting process of laminate composites have been incorporated into epoxy matrix phase in order to improve the mechanical characteristics. Physical and mechanical properties, hardness, abrasion, erosion and thermal behaviour have been analysed. Results show that carbon powder wastes incorporated to new epoxy matrix phases act basically as reinforcement. This allows for the recycling of the residues as well as improves some properties of the composites.

The effect of silica microparticles and maleic anhydride on the physic-mechanical properties of epoxy matrix phase

AbstractThermoset polymers, especially epoxy resin, have been applied in several industrial applications in which high stiffness and adhesive strength are demanded. On the other hand, epoxy resin is rather brittle and has poor fracture toughness. For this reason, the addition of fibres/particles into thermoset polymer can be used to enhance strength and toughness for several structural applications. This work investigated the addition of silica microparticles and maleic anhydride (as a coupling agent between the phases) into epoxy resin, which will be used as the matrix phase of hybrid biocomposites. A full factorial design was conducted to evaluate the effect of silica microparticles and chemical additive into the epoxy matrix under compressive loadings. Apparent density was also evaluated. Experimental factors such as weight fraction of silica microparticles (0, 20, and 33.3 wt%) and weight fraction of maleic anhydride (0 and 2 wt%) were investigated. The statistical analysis revealed that the main factors ‘chemical additive’ and ‘silica addition’ significantly affected the compressive modulus of the composites.

Investigation on Bio-waste Reinforced Epoxy Composites

In this paper, the alkali treated keratin present in natural fibers like chicken feathers are used as reinforcing phase in epoxy matrix to form composites. Mechanical properties of these composites such as tensile strength, flexural strength, etc. are evaluated and possible chemical reactions taking place during composite making are identified. The present communication also throws light on the structural features engraved on alkali treated keratin and the functional groups involved in the composition of the resulting composite material by Fourier transform infrared (FTIR) spectroscopic analysis.

Mode II Mesoscopic Fracture Toughness of CFRP by Raman Coating Method

Mesoscopic fracture toughness of epoxy matrix phase in unidirectional Carbon Fiber Reinforced Plastics (CFRP) in Mode II loading was investigated using End Notched Flexure (ENF) specimens and Raman spectroscopy. The distribution of shear strain near the crack tip in the epoxy matrix phase was measured experimentally. A lead oxide (PbO) thin film was deposited on the measured surface of the ENF specimen by Physical Vapor Deposition (PVD) as the pretreatment for Raman spectroscopy. The Mesoscopic fracture toughness of the epoxy matrix phase in CFRP in Mode II was determined using the measured results. It was also investigated using the Finite Element Method (FEM). The macroscopic fracture toughness measured by conventional ENF testing was four times as great as the mesoscopic fracture toughness of the epoxy matrix phase.

Mode I mesoscopic fracture toughness of CFRP by Raman coating method

Mesoscopic fracture toughness of epoxy matrix phase in unidirectional Carbon Fiber Reinforced Plastics (CFRP) in Mode I loading was investigated using Double Cantilever Beam (DCB) specimens and Raman spectroscopy. Strain distribution near the crack tip in the matrix phase was experimentally measured. A PbO thin film was deposited on the measured surface of the specimen by physical vapor deposition (PVD) as the pretreatment to measure the strain by Raman spectroscopy. The mesoscopic fracture toughness of the epoxy matrix phase in CFRP was determined using the measured results. The fracture toughness of the matrix phase was also investigated using the Finite Element Method (FEM). These results coincided well with the fracture toughness of neat resin measured by Single Edge Notched Bend (SENB) testing. Macroscopic fracture toughness measured by modified compliance calibration (MCC) was twice as great as the mesoscopic fracture toughness of the epoxy matrix phase.

Evaluation of Mesoscopic Fracture Toughness based on Strain Measurement in Epoxy Resin Phase near Crack Tip of CFRP using Raman Spectroscopy.

Mesoscopic fracture toughness of epoxy matrix phase in unidirectional Carbon Fiber Reinforced Plastics (CFRP) in Mode I and Mode II loading was investigated using Double Cantilever Beam (DCB) specimens, End Notched Flexure (ENF) specimens and Raman spectroscopy. The strain distribution near the crack tip in the epoxy matrix phase was measured experimentally. A lead oxide (PbO) thin film was deposited on the measured surface of the DCB and the ENF specimen by physical vapor deposition (PVD) as the pretreatment for Raman spectroscopy. The Mesoscopic fracture toughness of the epoxy matrix phase in CFRP was determined using the measured results. It was also investigated using the Finite Element Method (FEM). These results coincided with macroscopic fracture toughness.

Hydrothermal Aging of Composite Materials Part 2: Matrix Aspects

Abstract The effects of hydrothermal (100°C in H2O) aging on the epoxy matrix phase of a graphite-epoxy composite is examined in terms of chemical structure and Theological response. Infrared spectra indicate the resin system is a dicyandiamide (DICY) cured diglycyl ether of Bisphenol-A (DGEBA). Hydrothermal aging is shown to modify the resin network structure and increase the magnitude of the low-temperature β transition in short range molecular motion where T β ≃ 45±15°C at frequencies of 3.5 to 110 Hz. In addition to network structure changes the absorbed moisture temporarily lowers the resin glass temperature so that at 100°C in water the resin exhibits a rubbery response state. Evaluation of fracture properties of aged resin shows a loss in fracture toughness and development of internal microcracks in the bulk resin during hydrothermal aging.

Hydrothermal Aging of Composite Materials Part 1 : Interfacial Aspects

Abstract A surface energetics theory of bonded interfaces is applied to design graphite-epoxy composites with controlled moisture sensitivity at the fiber-matrix interface. Hydrothermal (100°C in H2O), aging of the composite materials shows an equilibrium degree of degradation in interlaminar shear strength λb which is in reasonable agreement with theoretical expectation. Hydrothermal aging produces changes in composite acoustic response, both sound velocity C2 and attenuation α2, which correlate with changes in λb or reduced aging time t/τ where τ is the relaxation time for hydrothermal degradation. The temperature dependence of λb is also shown to be modified by hydrothermal aging indicating possible changes in the chemical structure and rheology of the cured epoxy matrix phase.