Mechanical Properties Of Epoxy Composites Research Articles

High mechanical performance of 3-aminopropyl triethoxy silane/epoxy cured in a sandwich construction of 3D carbon felts foam and woven basalt fibers

Abstract Epoxy-based sandwich composites with improved economic efficiency were developed to better utilize composite components with functions such as high mechanical performance and light weight, which influenced quality for load-bearing applications. Herein, an epoxy-based sandwich composite was made by laminating woven basalt fibers (WBFs) as a face sheet on 3D carbon felt foam (3D CFs) as a core material. The cast-in-place process was used to infuse the epoxy solution within the sandwich, resulting in bicontinuous composites with outstanding mechanical characteristics and high performance. In addition, the epoxy solution was combined with a silane coupling agent to boost the composite’s toughness by enhancing the adhesion between the fibers and the epoxy. The mechanical properties of epoxy composites were also found to be much improved when WBFs were used as a face on 3D CF foam. Compared to the epoxy/3DCFs/WBFs composite sandwich to pure epoxy, the flexural and tensile strengths improved by 298.1 and 353.8%, respectively, while the impact strength rose to 135 kJ/m2. This research shows a new way to make a new process for making sandwich composites with epoxy that is cheap and strong.

Electrical and Mechanical Properties of Epoxy Composites Reinforced with Kaolin-Coated Basalt Fibers

Electrical and Mechanical Properties of Epoxy Composites Reinforced with Kaolin-Coated Basalt Fibers

Dynamic Mechanical Properties of Epoxy Composites Modified with Polysulphide Rubber

Harbin Institute of Technology, 92 Xidazhi street, Nangang District, Harbin, Heilongjiang Province, People's Republic of China

The Synergistic Effects of Hybrid Micro and Nano Silica in Influencing the Mechanical Properties of Epoxy Composites-A New Model.

HighlightsMicro silica and nano silica are found to yield similar effects in influencing the values of Young’s modulus.The values of Young’s modulus of hybrid silica particle are higher than single filler, at the same weight loading.The highest improvement in Young’s Modulus was recorded 25 wt.% hybrid loading (12.5 wt.% micro silica + 12.5 wt.% nano silica).1.1 weight percentage is applied for the hybrid composite, which makes equal distribution of weight for nano and micro.Epoxy nano composites containing micro and nano silica were prepared by varying the filler’s weight loading as an attempt to investigate the effects of incorporating these fillers in influencing its mechanical properties. Mechanical properties characterizations include the evaluation of tensile. The mechanical properties of the epoxy composites were found to tremendously increase as both micro and nano silica were added together at a 1:1 wt.% ratio. For example, the highest values of Young’s modulus were recorded to be 5.39 GPa for 25 wt.% loading (12.5 wt.% Micro + 12.5 wt.% nano), while Young’s modulus values of 5.22 MPa and 5.32 MPa were recorded for micro and nano silica, respectively, at the same weight loading. The most outstanding results were observed at 25 wt.% hybrids (12.5 wt.% micro silica + 12.5 wt.% nano silica), where the values of Young’s modulus were increased by 228% compared to the neat epoxy. This study successfully demonstrated synergistic effects demonstrated by combining micro and nano silica fillers, which created an interaction that significantly enhanced the Young’s modulus of epoxy composites.

Graphene oxide/epoxy composites with enhanced fracture toughness for liquid hydrogen storage

AbstractGraphene oxide (GO)/epoxy composites cured by aliphatic dibasic acids have been prepared. The influences of structure of aliphatic dibasic acid and loading of GO on curing process and mechanical properties of epoxy composites were studied. The results show that the reaction activities, gel time of corresponding epoxy‐acid system and tensile strength of the formed epoxy resins decrease with the increase of the chain length of aliphatic dibasic acids. Both fracture toughness (>1.96 MPa⋅m1/2) and elongations at break (>6%) increase with the increase of the chain length of aliphatic dibasic acids. The introduction of GO is helpful to increase the mechanical properties and the gas transmission coefficient of GO/epoxy composites. A maximum of tensile strength and elongations at break were obtained when the loading of GO is 0.6 wt%. The gas transmission coefficient of GO/epoxy composite increases with the increase of GO loading. The excellent mechanical properties and gas leakage resistance coefficient of the formed epoxy composites provides potential application in many fields where conventional brittle epoxy resins are inapplicable.

Comparison of the Influence of Two Types of Plasma Treatment of Short Carbon Fibers on Mechanical Properties of Epoxy Composites Filled with These Treated Fibers.

The interfacial interface between fibers and matrix plays a key role for epoxy matrix composites and short recycled randomly arranged fibers. This study used short recycled carbon fiber (RCF) as a filler. Plasma treatment was used for carbon fiber surface treatment. This treatment was performed using radio (RF) and microwave (MW) frequencies at the same pressure and atmosphere. Appropriate chemical modification of the fiber surfaces helps to improve the wettability of the carbon fibers and, at the same time, allows the necessary covalent bonds to form between fibers and the epoxy matrix. The effect of the plasma treatment was analyzed and confirmed by X-ray photoelectron spectroscopy, Raman microscopy, scanning electron microscopy, transmission electron microscopy and wettability measurements. Composite samples filled with recycled carbon fibers with low concentrations (1 wt%, 2.5 wt% and 5 wt%) and high concentrations (20 wt% and 30 wt%) were made from selected treated fibers. The mechanical properties (impact toughness, 3PB) were analyzed on these samples. It was found that the modulus of elasticity and bending stress increase with the increasing content of recycled carbon fibers. A more significant change in impact strength occurred in samples with low concentration.

Constructing a Superior Interfacial Microstructure on Carbon Fiber for High Interfacial and Mechanical Properties of Epoxy Composites.

The interface quality is crucial for the properties of carbon fiber-reinforced polymer- matrix composites (CFRPs). In order to improve the interfacial and mechanical properties of CFRPs, a superior gradient modulus interfacial microstructure is constructed on the carbon fiber (CF) surface by chemically grafting a self-assembly carboxyl-terminated hyperbranched polymer (HP-COOH). A monofilament debonding test, a short beam shear test, an impact test and a dynamic mechanical thermal analysis (DMTA) were conducted to investigate the properties of the modified composite. Prominent improvements of 79.6% for the interfacial shear strength, 51.5% for the interlaminar shear strength, and 49.2% for the impact strength, as well as superior heat-resistance properties are achieved for composites with the gradient modulus interface over those of the untreated CF composites. The mechanism for performance improvement is mainly attributed to the enhanced CF surface energy, mechanical interlocking, and chemical bonding interactions. In particular, an atomic force microscopy (AFM) test proved that the gradient modulus interfacial microstructure formed by HP–COOH could widen the interface layer thickness and buffer the sharp variations in the modulus from CF to resin, thereby transmitting an external force and reducing the stress concentration. This work provides a facile and efficient strategy for constructing a superior and versatile interface for high- performance composites.

Improvement of structural, thermal and mechanical properties of epoxy composites and bonded joints exposed to water environment by incorporating boron nanoparticles

This research aims to investigate the effects of hexagonal boron nitride (h-BN) and hexagonal boron carbide (h-B 4 C) nanoparticles on the epoxy composites and single lap joints against hydrothermal ageing and resultant degradations of mechanical, thermal and structural properties. The undoped, h-BN and h-B 4 C nanoparticles doped epoxy composites and single lap joints were fabricated and then exposed to distilled water for 20, 40, and 60 days. Water absorption, FT-IR, SEM, DSC, DMA and tensile tests were performed to characterize the epoxy composites after hydrothermal ageing. In addition, a tensile test was performed to determine the failure load of the single-lap joints bonded with undoped, h-BN and h-B 4 C doped epoxies. It was seen from the experimental results that the ageing time and the doping of boron nanoparticles into the epoxy resin changed the rates of degradation. The degradation in the mechanical and thermal properties of h-BN and h-B 4 C nanoparticles doped epoxy composites occurred to a lower extent than undoped epoxy. After 60 days of the hydrothermal ageing, the storage modulus and the tensile strength of undoped epoxy composites decreased by approximately 30% and 29%, while these degradation rates were determined as 16% and 18% in the h-BN doped epoxy composites, respectively. Similarly, the degradation of thermal and mechanical properties of h-B 4 C nanoparticle doped composites is lower than that of undoped composites. Additionally, it was observed that the joints bonded with h-BN and h-B 4 C doped epoxies exhibited better mechanical performance after the hydrothermal ageing. The failure load of the undoped, h-BN and h-B 4 C doped epoxy joints was decreased by 34%, 19% and 20% at the end of 60 days of ageing, respectively. The results of this research work are thought to benefit the wide and safe application of epoxy resin systems in engineering applications.

Study of Polymeric Composite Reinforced with Natural Particles: Measurement and Evaluation

Natural particles and their composites are important in materials science, where a significant attentiveness is being displayed in the usage of natural particles as reinforcement in polymer composites. The purpose of this research is to investigate the effect of the walnut shell particles as reinforcing fillers in a matrix composite. So, the amount composite examples were advanced through varying the percentage by weight of filler (3, 5, 7, and 9%) in an epoxy and unsaturated polyester polymer. Composite samples were mechanically characterized by tensile tests, flexural tests, hardness tests, and the Izod impact test. The tensile strength and impact strength of epoxy resin were increased after adding organic waste filler. The highest values of tensile strength and impact strength happened at 7% wt. The flexural strength and hardness of shore D increased with the percentage of walnut shell particles. The highest values of flexural strength and hardness were found at 9% wt. The results show that the mechanical properties of epoxy composite are better than the mechanical properties of unsaturated polyester composite when walnut shell particles are added.

The effect of adding natural materials waste on the mechanical properties and water absorption of epoxy composite using grey relations analysis

Recently, there has been a tendency for scientific studies to deal with natural materials as fillers and reinforcement for polymer composites, which are used in many different applications due to their environmentally friendly properties when compared to synthetic materials. The current study aims to preserve the environment by dealing with natural materials and their influence on the mechanical properties and water absorption property of the polymer composites. In this study, epoxy composites were produced from local natural sourced non-hazardous raw natural materials using grey relational analysis (GRG). The materials used for fabrication include micro-filler of pollen palm 50 μm, seashell 75 μm and epoxy resin. Nine different composites were prepared using pollen palm and seashell as reinforcement material by varying the wt % of the micro-filler. Rule of the mixture was used for formulation and wt % of (0.5, 1 and 1.5) % reinforcement and 99.5, 99 and 98.5 % epoxy (binder) were used for composites. Grey relational analysis was conducted in order to scale the multi-response performance to a single response. The results indicate that optimum performance can be achieved with the addition of 1.5 wt % micro-filler of seashell, which achieved the first rank, while the second rank achieved by 0.5 wt % micro-filler of palm pollen and seashell when compared to other composites. The addition of micro-fillers has improved greatly the mechanical properties of epoxy composites. The loading of micro-fillers has influenced the water absorption property of composites based epoxy in ascending order

Physical Characteristics and Mechanical Properties of Epoxy Composites Reinforced With Double-Walled Carbon Nanotubes

Physical Characteristics and Mechanical Properties of Epoxy Composites Reinforced With Double-Walled Carbon Nanotubes

Manganese dioxide nanostructures reinforced epoxy nanocomposites: a study of mechanical properties

ABSTRACT Manganese dioxide nanoflowers (MnO2-F) and nanowires (MnO2-W) are synthesized and MnO2 nanostructures reinforced (0.1 wt.%) epoxy composites are fabricated. The reinforcing effects are studied through tensile, flexural, and impact tests. SEM, TEM, EDAX, XRD, and FTIR characterization techniques are used to understand the interaction between epoxy and the MnO2 nanofiller. It is observed that MnO2 nanostructures have greatly enhanced the mechanical properties of epoxy composites. The tensile strength of EP/MnO2-F composites has improved by 73%, percentage elongation increased for EP/MnO2-F composites by 173%, and flexural strength of EP/MnO2-W has improved by 15%, respectively. Impact strength increased by 35% for EP/MnO2-F nanocomposites.

MECHANICAL PROPERTIES AND WEAR BEHAVIOUR OF KAOLINITE CLAY PARTICLES REINFORCED EPOXY MATRIX COMPOSITES

Epoxy matrix composites reinforced with clay particles were developed by hand lay-up open mould casting technique. The clay used in this study was pulverized and processed into ultrafine particles through the sedimentation process. The composites were developed by blending the epoxy matrix and hardener with various weight fractions of the ultrafine clay particles (2, 4, 6, 8 and 10 wt%) in open test moulds. In order to accomplish a homogeneous blend of the constituents; manual mixing of the blend was carried out for 3 min. The test specimens were left to cure for 24 hours in the moulds and for additional 27 days at room temperature of 27 ± 2 °C and were thereafter detached from the moulds. The developed composites test specimens were subjected to mechanical tests (flexural, tensile and impact) in accordance with ASTM standards and performed at room temperature. Structural characteristics of the clay particles were determined with the aid of an X-ray diffractometer (XRD). The morphologies of the composites were determined using a scanning electron microscope (SEM). There was a progressive enhancement in the mechanical properties of epoxy composites containing 2-6 wt.% ultrafine clay particles while a drastic decrease in the mechanical properties was noticed in the epoxy/clay composites reinforced with 8-10 wt.% ultrafine clay particles. The SEM images revealed homogeneous particles distributions within the epoxy matrix at lower ultrafine clay particles weight fractions (2 wt. % and 6 wt.%).

Tensile properties of Graphene Epoxy Nanocomposite

In this research, tensile test was conducted to reveal the notable enhancement of Young Modulus and tensile stress composites. Epoxy resin is a cross-linked polymer, thus it has major influence on the properties of polymers generally in hardness, strength, stiffness, brittleness, and better dimensional stability. Epoxy resin plays many roles in industry especially in adhesion process in automotive and aerospace composites. Discovered in 2004, graphene has revealed that it has tremendous mechanical properties and thermal properties. On top of that, addition of graphene to epoxy can lead to innovate in various adhesion industry and structural materials. In this project, an experiment was conducted in various phases which varying with graphene loading ratio, stirring speed, and stirring time. Outcome from this experiment showed that 1.0% of graphene loading with 500 rpm stirring speed and 30 minutes stirring time shows the optimum condition to enhance the measured properties. The enhancement showed are 53.03 % of Young Modulus and 51.19 % for tensile test result compared to the preliminary result. This study clearly stated the enhancement of mechanical properties of epoxy composites by merely adding 1 wt.% graphene.

Improving the flame retardancy and mechanical properties of epoxy composites significantly with a low-loading CNT-based hierarchical hybrid decorated with reactive hyperbranched polyphosphoramide

A reactive hyperbranched polyphosphoramide (HBPPA) was in situ polymerized on CNT surface to generate a novel CNT hybrid (HBPPA@CNT) with abundant terminal amine groups which can induce epoxy (EP) curing network around CNT hybrid and gain an excellent cure system. Benefited from the good dispersion state and the improved interfacial bonding, EP/HBPPA@CNT composite exhibited good flame-retarding performance (LOI of 28.5 %, UL94 V-1 rating, and flame retardancy index of 1.26) and outstanding mechanical performance simultaneously at a low loading of 2 wt%. Its tensile strength and impact strength increased by 67.9 % and 71.8 % respectively. Moreover, the peak heat release rate (PHRR), total heat release (THR) decreased by 17.0% and 15.6% respectively. After being decorated by HBPPA, the CNT hybrid was not only well dispersed in the EP matrix to achieve the superior reinforcing properties, but also linked together by the reactive P-rich compounds deriving from HBPPA to form a continuous char layer shielding the heat and mass transfer effectively. The synergistic effect between HBPPA and CNT resulted in good mechanical performance and fire safety of EP composites, which may provide a novel and facile approach to functionalize carbon materials for expanding its application value in polymer-matrix composites.

Prediction of Mechanical properties of Epoxy composites containing mono and hybrids particulate fillers.

This paper reports the mechanical properties such as tensile strength and tensile modulus of epoxy composite systems containing micro particulates of Cu, Al and hybrid (Al-Cu) which are randomly distributed. The experimental results are compared with strength prediction equations of Biggs, Ross Murphy &Todd, Langley& Green and Wong. Experimentally determined tensile modulus was compared with Reuss, and Counto equations. The values obtained from above equations was not in line with experiment. Hence in view of the above, a new strength predictive equation is developed which is empirical in nature and exhibits good correlation with experimental data.

The Effect of Hybridisation on Mechanical Properties and Water Absorption Behaviour of Woven Jute/Ramie Reinforced Epoxy Composites.

Recently, the most critical issue related to the use of natural fibre-reinforced polymer composites (NFRPC) is the degradation properties of composites exposed to the environment. NFRPC’s moisture absorption behaviour has adverse effects on the composite’s mechanical properties and dimensional stability. The purpose of this study is to analyse the mechanical properties of epoxy composites reinforced by jute–ramie hybridisation. This study also analysed the effect of stacking sequence hybridisation of the jute–ramie composite on water absorption behaviour. A five-layer different type of stacking sequence of single and hybrid jute–ramie is produced with the hand lay-up method. The results obtained from this study found that the mechanical properties and water absorption behaviour of a single jute fibre are lower compared to a single ramie fibre. The hybrid of jute–ramie has been able to increase the performance of composite compared to pure jute composites. The mechanical properties of the hybrid jute–ramie composite show a reduction effect after exposure to an aqueous environment due to the breakdown of fibre matrix interfacial bonding. However, after 28 days of immersion, all types of the stacking sequence’s mechanical properties are still higher than that of pure epoxy resin. In conclusion, the appropriate sequence of stacking and selecting the material used are two factors that predominantly affect the mechanical properties and water absorption behaviour. The hybrid composites with the desired and preferable properties can be manufactured using a hand-lay-up technique and used in the various industrial applications.

Combination of cardanol-derived flame retardant with SiO2@MOF particles for simultaneously enhancing the toughness, anti-flammability and smoke suppression of epoxy thermosets

In this work, an organic-inorganic flame retardant composite system was utilized by combining the renewable cardanol-based flame-retardant toughening agent (CF-PO(OPh)2) and the core-shell SiO2@MOF particles, then a series of high-performance epoxy composites with simultaneously enhanced mechanical properties, fire safety as well as smoke suppression effect were prepared with incorporating different ratio of the organic and inorganic flame retardant components. The epoxy composite containing 3% CF-PO(OPh)2 and 2% SiO2@UiO-66 (EP3) showed the most striking enhancements in the mechanical and flame retardant performances. The tensile strength and impact strength of EP3 was 48.8% and 25.3% higher than those of EP0, respectively. In view of flame retardant properties, EP3 showed maximum reductions in PHRR, SPR, CO, and CO2 productions which were 30.5%, 25.8%, 51.4%, and 43.7% lower than those of EP0, respectively. The excellent flame retardant and mechanical properties of epoxy composites resulted from the synergetic effect of cardanol-based phosphorus-containing CF-PO(OPh)2 and inorganic core-shell SiO2@UiO-66 particles.

Preparation and Properties of Epoxy Resin Based Conductive Composites

The epoxy resin-based conductive composite was prepared by filling the epoxy resin with carbon fiber powder and graphene. The influence of the additive quantity on the conductive properties and mechanical properties were investigated, and the influence of carbon fiber powder surface treatment on the conductive properties and mechanical properties were investigated. The results show that the addition of carbon fiber powder and graphene can improve the conductivity and mechanical properties of epoxy composites.

Mechanical Properties of Bio-Composites Based on Epoxy Resin and Nanocellulose Fibres.

The aim of our research was to investigate the effect of a small nanocellulose (NC) addition on an improvement of the mechanical properties of epoxy composites. A procedure of chemical extraction from pressed lignin was used to obtain nanocellulose fibers. The presence of nanoparticles in the cellulose pulp was confirmed by FTIR/ATR spectra as well as measurement of nanocellulose particle size using a Zetasizer analyzer. Epoxy composites with NC contents from 0.5% to 1.5% w/w were prepared. The obtained composites were subjected to strength tests, such as impact strength (IS) and resistance to three-point bending with a determination of critical stress intensity factor (Kc). The impact strength of nanocellulose composites doubled in comparison to the unmodified epoxy resin (EP 0). Moreover, Kc was increased by approximately 50% and 70% for the 1.5 and 0.5% w/w NC, respectively. The maximum value of stress at break was achieved at 1% NC concentration in EP and it was 15% higher than that for unmodified epoxy resin. The highest value of destruction energy was characterized by the composition with 0.5% NC and corresponds to the increase of 102% in comparison with EP 0. Based on the analysis of the results it was noted that satisfactory improvement of the mechanical properties of the composite was achieved with a very small addition of nanofiller while other research indicates the need to add much more nanocellulose. It is also expected that this kind of use of raw materials will allow increasing the economic efficiency of the nanocomposite preparation process. Moreover, nanocomposites obtained in this way can be applied as elements of machines or as a modified epoxy matrix for sandwich composites, enabling production of the structure material with reduced weight but improved mechanical properties.