Reinforced Epoxy Resin Research Articles

Enhancing Structural Integrity of Composite Sandwich Beams Using Viscoelastic Bonding with Tapered Epoxy Reinforcement

Enhancing Structural Integrity of Composite Sandwich Beams Using Viscoelastic Bonding with Tapered Epoxy Reinforcement

Optimizing Biomedical Facilities Performance with Dombeya Fiber-Paper Particle Hybrid Reinforced Epoxy Composites

Since the last two decades, the use of natural fiber reinforced polymer composites has garnered significant application considerations over the synthetic fiber reinforced composites due to their numerous advantages and unique properties. Likewise, epoxy resin has attracted the interest of many researchers for composite synthesis, basically because of its chemical stability, thermal and mechanical characteristics. Hence, the primary aim of this study was to investigate the influence of dombeya fiber and paper particulate on the physical and mechanical properties of dombeya fiber and paper particulate-reinforced polymer composites for structural applications. Dombeya fiber and paper particles are renewable and biodegradable materials, thereby making them environmentally friendly materials to replace synthetic materials. Hand lay-up technique was utilized to fabricate the hybrid-reinforced biocomposites after which they were subjected to mechanical, wear, density, and moisture absorption properties. The surface morphology of the fractured surface was also analyzed to investigate its microstructural features. It was discovered from the results that hybrid biocomposites demonstrated improved properties over the unreinforced composite, with composites from 9-wt% dombeya fiber-paper particles reinforced biocomposite exhibiting the most suitable properties with commensurate density with the unreinforced epoxy matrix. These obtained characteristics support the material as a suitable material for biomedical apparatus application such as orthopedic implants, surgical instruments, and bone fixation devices.

Post-creep residual tensile properties of multi-walled carbon nanotube/epoxy nanocomposites

Epoxy resin as a thermoset polymer is vulnerable to creep loading even at room temperature due to its viscoelastic nature. This study investigated the effect of reinforcing epoxy resin with different functionalized multi-walled carbon nanotubes (MWCNT) contents on the creep response and post-creep residual tensile properties of nanocomposites. The creep tests were performed on the nanocomposite specimens containing different filler contents and the neat epoxy specimen at 40°C under a constant load level of 200 N. It was found that the nanocomposites containing 0.3 wt% MWCNTs experienced 29.6%, 69.1%, and 74.1% decreases in the elastic strain, creep strain, and steady-state creep strain rate, respectively, compared to the neat epoxy. Furthermore, the tensile strength and stiffness of the neat epoxy and nanocomposite specimens were evaluated before and after a partial creep test (at a load level of 200 N for 150 min) by conducting tensile tests. The nanocomposites containing 0.3 wt% MWCNTs demonstrated considerable improvements of 35.9%, 41.2%, 27.9%, and 28.1% in strength, residual strength, stiffness, and residual stiffness, respectively, compared to the neat epoxy. Furthermore, scanning electron microscopy assessment was utilized to investigate the fracture surfaces of the nanocomposite specimens.

Constructing coral-like PDA layer on glass fiber to enhance the erosion resistance of epoxy coating

Glass fiber (GF) reinforced epoxy resin composite materials are widely used in wind power, automobiles, and ships, etc. The failure of glass fiber reinforced epoxy resin composites (GF/EP) is mainly attributed to the smooth surface and chemical inertness of GF. Dopamine, extracted from the adhesive protein secreted by mussels, exhibits excellent adhesion performance especially in wet environments. Thence, we constructed a coral-like layer of dopamine nanoparticles on the surface of glass fiber (PDA@GF) by self-surface polymerization deposition, which could simultaneously improve the chemical activity and roughness of the fiber surface, and form mechanical meshing and chemical bonding with the epoxy resin, thereby enhancing the interfacial adhesion strength between GF and EP. PDA layer with different surface morphologies were constructed on the GF surface by finely adjusting the reaction parameters, and the influences of surface morphologies on the mechanical performance of GF/EP coatings were explored. Based on the results obtained from tensile test, friction test, and erosion test, it was evident that the PDA@GF/EP composite material exhibited superior mechanical properties when the PDA layer exhibited a coral-like morphology, in comparison to the other two kinds of surface morphologies. Meanwhile, the dispersion of the fiber within the epoxy resin was examined using X-ray computed tomography (X-ray CT). On this basis, we investigated the anti-wear performance and erosion resistance of composite coatings with different fiber contents, furthermore, we revealed the anti-wear and anti-erosion mechanism.

Effect of carbon nanotubes on thermoset curing and mechanical properties of carbon fiber reinforced epoxy resin laminates fabricated by self‐resistance electric heating

AbstractSelf‐resistance electric (SRE) heating for the curing of carbon fiber reinforced plastic (CFRP) offers the benefits of saving energy consumption and reducing investment in equipment. In this work, the investigation was carried out to illustrate the effect of carbon nanotubes (CNTs) addition (0.5, 1.0, and 1.5 wt%) on the thermoset curing and mechanical properties of carbon fiber‐reinforced epoxy laminates fabricated by SRE heating method. The results show that adding CNTs can improve the temperature uniformity and interlayer‐resin flow during the SRE heating process and have a limited influence on the curing degree of CFRP composites. The tensile strength in the longitudinal direction of the composites increased with the increase of CNT addition. Meanwhile, the flexural strength and interlaminar shear strength had the maximum value with the CNTs content of 0.5 wt% and decreased significantly at the CNTs content of 1.5 wt%. It concludes that the appropriate content of CNTs addition has the potential to improve the thermoset curing performance and mechanical properties of the CFRP laminate composites fabricated by SRE heating.Highlights This study focuses on the effect of CNT addition on SRE heating for CFRP. The addition of CNTs improved the temperature uniformity during SRE heating. The addition of CNTs can reduce the voids of SRE‐cured CFRP composites. Threshold value of CNTs affected the mechanical performance of SRE‐cured CFRP.

Design and study of biomimetic resin matrix composites based on shellfish structure

Differences in microstructure can often lead to large differences in mechanical properties. Here, the composition, microstructure, and mechanical properties of mussel, scallop, and ostreidae were researched. And subsequently, three bionic models were designed based on the microstructures of the three shellfish. Three models were prepared by printing the substrate with light-cured resin and filling with carbon fiber reinforced epoxy resin. The mechanical properties and reinforcement mechanisms of the three models were also investigated. The bending fracture force, compression fracture, and the impact fracture energy of mussels was best of three shellfish. The bionic model 1 with mimic mussel structure has good mechanical properties. Bending strength of model 1 is 42.80 ± 7.00 MPa which was 5.42% higher than bionic model 2 and bionic model 3, and 33.75% higher than that of the pure epoxy resin (32.00 MPa). The absorbed energy of the model 1 is 63.53 ± 2.56%, which is 3.82% and 7.89% higher than model 2 and model 3, respectively. The fracture showed obvious toughness fracture. The unique crack deflection induced by the structure also leads to enhanced mechanical properties. This study provides new design ideas and references for the structural design of high-strength composites.

Mechanical properties of a carbon fiber reinforced epoxy resin composite improved by integrating multi-walled carbon nanotubes and graphene nanoplatelets

The pairs of nanofillers prepared by graphene nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs) were added to the epoxy matrix in various ratios to produce hybrid epoxy nanocomposites. The effects of the presence of these nanofillers at 0.1–0.4 wt.% on the mechanical and thermal properties were tested. Likewise, carbon fiber reinforced MWCNT/GNP modified epoxy nanocomposite laminates were also manufactured and tested. The dispersion of nanofiller in the polymer matrix was evaluated by Scanning Electron Microscopy (SEM). It was determined that the hybrid composite consisting of a MWCNT:GNP ratio of 1:3 and a nanofiller ratio of 0.3 wt.% showed the best mechanical properties with a tensile strength of 75.1 MPa. The presence of GNPs and MWCNT nanofillers in epoxy/carbon fiber laminates influenced positively the tensile strength and strain but negatively the elastic modulus. Glass transition temperature of epoxy increased from 87.25°C to 114.67°C for MWCNT:GNP ratio of 1:1 (0.3 wt.%).

Investigation failure behaviours of notched composite plates repaired with using adhesive and patch

In this study, the damage behaviors of different type-notched composite plates repaired with composite patches were investigated experimentally and numerically. Eight-layer woven glass fiber reinforced epoxy resin matrix composite plates and epoxy-based adhesive were used as materials. Notch type’s variations, adhesive thickness, patch length; double-side repair and single-side repair were used as parameter. Although the same size patch was used, the load values varied due to the different positions of the notches. Notched composite samples with the same area dimensions but different locations have different tensile strength values. Patching and bonding processes have different effects on notched samples with different tensile strength values. A feature of this study is that many parameters were compared for many samples under the same experimental conditions in order to improve repair quality and durability in an understandable way. As a result of the repair process, the failure loads were increased from 47% to 307% ratios according to parameters.

Investigation of patch application failure behaviors according to fiber orientation difference at notched composite plates

In this study, the damage behaviors of different type notched composite plates bonded with external composite patches were investigated experimentally under static tensile test. Eight-layer woven glass fiber reinforced epoxy resin matrix composite plates and epoxy based adhesive were used as materials. Notch type, fiber orientation angle, double side repair and single side repair were used as parameter. Effects of fiber orientation angle was investigated for 0 ° , 15 ° , 30 ° and 45 ° . Radial notch in the center (Type I), semicircular notch on the plate edge (Type II), a circular hole in the plate center (Type III) and U notch at the edges (Type IV) have been examined for 4 different notch types. The outstanding feature of this study is that many parameters were compared for many samples under the same experimental conditions. The composite plates and patches were used from same materials. Reducing of the damage loads has been observed for all notch types depending upon the increasing of fiber orientation angle significantly. In addition, that patch application to different fiber orientation plates is quite effective on damage loads. The extension was changed depending on the notch geometry at unrepaired composite. The load increasing rate is between + % 24 and + % 189 for one-sided bonded repair; + % 60 and + % 349 for two-sided bonded repair compared to the unrepaired samples. The results of this work can serve as a guide for workers to improve repair quality and durability in an understandable way.

Efficient degradation of amine cured epoxy resin via the cleavage of C-N bond by amphiphilic dodecylbenzenesulfonic acid

Amine-cured epoxy resin (EP) is often compounded with carbon fiber (CF) used for wind power blades due to its excellent performance. However, the insolubility and infusibility of service-life-expired carbon fiber reinforced epoxy resin (CFREP) hinder its sustainable recycling. We reported a new strategy for efficient degradation of EP and CFREP with 0.5 mol% amphiphilic dodecylbenzenesulfonic acid (DBSA) in aqueous system. It was found that the strong lipophilicity of DBSA accelerated its enrichment on EP surface, and further promoted the diffusion of DBSA and H2O to the resin bulk phase. As a result, the degradation ratio of the EP powder reached 100 % at 190 °C only in 10 h. The characterization of FT-IR and NMR proved that the degradation mechanism of EP was the selective cleavage of C-N bond catalyzed by H+. The resin degradation products (RDP) containing active hydrogen were used to prepare polyurethane (PU) with good mechanical properties. This method achieves complete recycling of waste CFREP in aqueous systems.

Preparation and mechanical properties of Ni/RGO reinforced epoxy resin composites

The graphene/nanonickel composites(Ni/RGO) were prepared by liquid phase reduction method, and the graphene/nanonickel epoxy composites(Ni/RGO/EP) were prepared by in-situ polymerization method. The glass transition temperature (Tg) of the modified epoxy resin was increased by 19°C compared to EP with 2.1 wt% Ni/RGO loading. The tensile strength and hardness increased by 65% and 18%, the impact strength is increased by 10.053 KJ·m−2 compared to EP, and the shear strength reaches 34.78 MPa for the Ni/RGO/EP with 1.7 wt% Ni/RGO loading. It can be seen, that the addition of Ni/RGO greatly improves the heat resistance and mechanical properties of epoxy resin when the Ni/RGO are evenly dispersed into the epoxy resin by emulsion dispersion method.

IMPROVING THE PERFORMANCE OF HYBRID BIOCOMPOSITE MATERIALS USING EPOXY, VINYL ESTER AND POLYIMIDE POLYMER MATRIX: COMPARATIVE STUDY

The present study aims to assess the impact of alfa and date palm natural fibers as reinforcement for epoxy, vinyl ester, and polyimide polymer (Alfa-Date palm/epoxy, Alfa-Date palm/vinyl ester, and Alfa-date palm/polyimide) through a genetic approach. The study employs a genetic simulation rooted in the Weibull formalism, employing genetic operators such as selection, crossing, and mutation for a nuanced evaluation of the damage at the fiber-matrix interface across the studied materials. The genetic algorithm results authentically capture the intrinsic behaviour of these materials, emphasising key mechanical properties like Young’s Modulus, deformation, and stress at break. The obtained results highlight that the matrix showing the highest Young’s modulus value at its fiber- matrix interface exhibits superior strength. These conclusions align with contemporary advancements in natural fiber-reinforced composite materials tailored for diverse industries and eco-friendly applications.

Interlaminar shear strength and self-healing of spread carbon fiber/woven carbon fiber hybrid reinforced epoxy resin laminates containing microcapsules

Interlaminar shear strength and self-healing of spread carbon fiber/woven carbon fiber hybrid reinforced epoxy resin laminates containing microcapsules

Mechanical and Tribological Behavior of Graphene Oxide Supported Aramid Fiber Reinforced Epoxy Resin

Mechanical and Tribological Behavior of Graphene Oxide Supported Aramid Fiber Reinforced Epoxy Resin

Армированные композитные материалы на основе фосфорсодержащих связующих с перспективными физико-механическими и пожаробезопасными свойствами

In this work, a comparative analysis of the properties of glass fiber-reinforced epoxy resin (ED-20) composites and composites based on glass fiber-reinforced phosphorus-containing ester methacrylate oligomers (PEAO) was carried out. Reinforced fiberglass plastics made on the basis of PEAO have demonstrated promising fireproof characteristics, especially in limited oxygen index and smoke emission tests. It is also worth noting that the mechanical properties of materials based on phosphorus-containing ester-acrylate resins are outstanding. The samples of a widely used glass fiber reinforced epoxy resin ED-20 with 9,10-dihydro-9-hydroxy-10-phosphaphenanthrene-10-oxide-4,4`-diaminodiphenylmethane (DDM-DOPO) additive demonstrated lower flammability compared to the samples without fire retardant additives. A mixture of DDM-DOPO and graphene added to the samples led to a low smoke generation rate of the samples; however, the rate was 1.5-2 times higher than that of the samples based on phosphorus-containing ester methacrylate resins. The addition of fire retardants has reduced the mechanical properties of fiberglass plastics based on epoxy resin, which can be a problem for the use of these materials in the aviation industry. These results clearly show better prospects of using fiberglass-reinforced plastics based on phosphorus-containing ester methacrylate oligomers in comparison with modified plastics based on the widely used epoxy resin.

Analysis and Development of Military Helmet Using Date Palm Fibre Reinforced Epoxy Composite

The study discusses on analysis, fabrication and characterization of military helmet using date palm fibre reinforced with epoxy. The study is aimed at identifying the possibility of using the locally available material such as date palm fibre for the production of military protective helmet. Composite plates were prepared using Date palm fibre (DFE) reinforced with epoxy with varying composition. Six samples were produced and cut into the required size and shape for testing mechanical properties (impact strength ASTM D-156, Hardness ASTM D-2240, tensile strength ASTM D-638 and flexural strength ASTM D-790) of the material. Based on the result obtained, sample label S3 has 20% DFE and 80% epoxy has the highest impact strength of 0.225 J/mm2, hardness 70 Hv, tensile strength 25.87 N/mm2 and flexural strength. The scan electron microscopy (SEM) was carried on the selected sample in which voids were observed in the image which could be instrumental to air trapped in the composite during mixing which might have escaped during curing at high temperature living the void in the sample. The helmet was produced using the selected sample with a thickness of 8mm while that of Daungkumsawat, et al (2020) has a thickness of 6.94mm

A facile and efficient solvothermal degradation route for carbon fiber reinforced epoxy resin composite waste

Carbon fiber reinforced epoxy resin composite (CF/EP) is widely used in aerospace applications, automotive industry, construction engineering and many other important sectors, for it has excellent mechanical properties and corrosion resistance. However, the three-dimensional cross-linked structure of the cured epoxy resin determines its insolubility and non-melting characteristics, which makes it challenging to efficiently degrade CF/EP waste and recycle the high-value carbon fibers. In this study we propose a strategy that degrades the CF/EP waste via a facile and efficient solvothermal degradation route. The results showed that the degradation ratio of the resin increased significantly with the rise in reaction temperature. When the reaction temperature reached 180 °C there were no obvious resin residues on the surface of the recycled carbon fibers. It was found that the recycled carbon fibers were not obviously damaged during the solvothermal degradation process, as shown by the scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman analyses.

Experimental and simulation study on surface material stripping of glass fiber reinforced composites by baking soda abrasive jetting technology

Glass fiber reinforced composites (GFRP) working in a specific environment require regular inspection and maintenance. It is necessary to remove the surface material of fiber reinforced composites to check the fracture of fibers and the damage to matrix that binds fibers in this process. In this paper, the baking soda abrasive jetting was utilized to strip the surface material of glass fiber reinforced epoxy resin (GFREP). The stripping effects of baking soda abrasive jetting technology under different jetting parameters (fiber orientation, jet angle, jet pressure) were explored, and the optimum stripping conditions were determined as parallel to the fiber, 30°, 0.4 MPa. Compared with the chemical stripping method (phenol-dichloromethane), baking soda abrasive jetting can better retain epoxy resin between glass fibers. The LS-DYNA was applied to simulate the erosion process of a single abrasive particle under the optimum stripping condition. The plastic deformation of the matrix and the slight bending deformation of the glass fiber under abrasive impact were observed.

Degradation behavior and ageing mechanism of E-glass fiber reinforced epoxy resin composite pipes under accelerated thermal ageing conditions

In this work, accelerated ageing experiments with circulating air and simulated oilfield water were carried out at 95 °C on aromatic amine-cured GFRP pipes used in oilfield environments, with effective ageing times of 5000 h and 3000 h respectively. The differences in ageing behavior and ageing mechanisms of the GFRP tubes at different times under the two conditions were then analyzed and discussed. The changes in the apparent morphology and microstructure of the samples after thermal ageing were first observed using optical microscopy and scanning electron microscopy, and the results demonstrated that the thermal oxygen environment triggered more drastic color changes and obvious oxidation layers. The resin matrix manifests a large number of nano-scale micropores and modest matrix shrinkage pores in the micron size range, this is accompanied by damage to the fiber cross-section. Hydrothermal ageing causes further dissolution of the surface resin and dissolution of the exposed fibers. ATR-FTIR analysis verifies the increase in CO bonding of the ester group during thermal oxidation and the decreasing strength of the C–O–C and C–H bonds, while the behavior of ageing water absorption and glass fiber hydrolysis is illustrated by changes in the intensity of the –OH and Si–O characteristic bands. NMR hydrogen spectroscopy verified the formation of amides, methyl ethers and carboxylic acids in the thermal oxidation products of epoxy resins. Furthermore, the decay pattern of the circumferential tensile strength indicates that the hydrothermal environment has a more significant effect on the mechanical properties of GFRP pipes, which is attributed to the physical dissolution of the surface resin, significant hydrolytic damage to the surface exposed fibers, and the combined damage to the resin-fiber interfacial bonding by chloride ions in simulated oilfield water.

Cut/puncture resistance and mechanisms of protective composite textiles reinforced with inorganic powder

This study presents a soft-rigid unified structure (SRUS) textile composed of an inorganic powder (IP) reinforced epoxy resin block (EIPB) array and a soft textile substrate via a pattern-controllable integrated molding method. The influence of IP content and alumina particle size on the cut and puncture resistance of the resulting SRUS textile was systematically investigated. Furthermore, the anti-puncture and anti-cutting mechanisms of the SRUS textile were comprehensively evaluated based on the analysis of damage morphology and process. The experimental results demonstrated a significant enhancement in the puncture and cut resistance of the SRUS textile upon the incorporation of IP. Moreover, the cut/puncture resistance of the SRUS textile increased with an increase in IP content and the size of Al2O3, and the optimal cut/puncture resistance was observed at 60 mesh-50 wt.%. Additionally, the anti-puncture mechanism of the SRUS textile was attributed to the presence of hard passivation at the EIPB, as well as friction self-locking at the gaps. The anti-cutting mechanism was ascribed to the reverse cutting action exerted by the hard particles on the blade, preventing further penetration. Overall, these findings provide valuable insights into the underlying mechanisms that contribute to its enhanced protective performance.