Papers by Keyword: Epoxy

Abstract: This research investigated the effect of the thickness of adhesive to the stiffness (Young’s modulus) of adhesive butt joint at high strain rate loading. A split Hopkinson pressure bar (SHPB) test is used to obtain the stress-strain response of join specimen at strain rate of 530±10 s^-1. The joint is composed of aluminum adherend bonded by epoxy adhesive with 0.5, 1, 2, and 3 millimeter of thickness variation. The results show that the joint deformed elastically and the stiffness increases with the increase of adhesive thickness. However, the rate at which the stiffness increases with thickness decreases at thick adhesive layer. The facts of this research are important for the improvement of the crashworthiness of structure such as automobile structures.

Abstract: In the past few decades, concrete has been the most widely used material for structural applications in the world and uses steel reinforcement as aide to meet the flexural, tensile and ductility demands required of concrete structures. Manufacturing of concrete and steel reinforced concrete structures is associated with millions of tons of carbon dioxide emissions and mineral waste. This activity is also responsible for the depletion of a large number of non-renewable resources. Reinforcing steel is also a high cost material, consumes a lot of energy in its production. Consequently, the use of natural fibres as an alternative for steel reinforcement is widely investigated, to promote the use of sustainable concrete structures. This study aims to investigate the effect on durability, flexural, compressive, tensile properties and workability of concrete by incorporating coir fibre at varying fibre content to find the fibre content which gives optimum results. The fibre contents used were 0%, 0.5%, 1.0%, 1.5% and 2.0% by weight of cement. Furthermore, the effect of modifying the surface of the coir fibres by alkali treatment (i.e. 5 wt.% NaOH solution) and coating the fibres with epoxy paint and polyurethane varnish on coir fibre reinforced concrete (CFRC) were also investigated. Tests conducted on the CFRC specimens included slump test and flexural, compressive and tensile strength tests. Water absorption and sorptivity tests were also conducted to investigate the durability. Slump (workability) and unit weight reduced with an increase in fibre content. The surface modification methods used, had resulted in an increased workability and a reduced unit-weight. A coconut fibre content of 1% produced the best combination of flexural, tensile and compressive properties. Water absorption and sorption rate per unit time, increased with an increase of coir fibre content. It is also found that epoxy paint and alkali treatment of the fibres has a positive effect on the mechanical strength properties and also the durability and workability of the CFRC specimens. However, polyurethane varnish coating had a detrimental effect on the mechanical strength properties of the CFRC specimens.

Abstract: Carbon nanotubes (CNTs) have a great potential to be used as filler to enhance the mechanical properties of polymer composites due to excellent properties. However, CNTs have limitation of difficult to disperse in polymer matrix. The hybridization of CNTs and inorganic fillers can improve the dispersion and combine their properties in polymer composites. In the present work, the properties of the epoxy composites filled with carbon nanotube-calcium carbonate (CNTs-CaCO₃) hybrid, at various filler loading (i.e., 1-5 wt.%) were studied. The CNTs-CaCO₃ hybrid fillers were prepared by physically mixing (PHY) method and chemical vapor deposition (CVD) method. The tensile properties and hardness of both composites were investigated at different weight percentages of filler loading. The CNTs-CaCO₃ CVD hybrid composites showed higher tensile strength and hardness than the CNTs-CaCO₃ PHY hybrid composites. This increase was associated with the homogenous dispersion of CNT–CaCO₃ particle filler. The morphological studies of fracture surfaces after tensile test by means of SEM showed homogenous dispersion of CNTs-calcium carbonate CVD hybrid in epoxy matrix. The result shows that the CNTs-calcium carbonate CVD hybrid composites are capable in increasing tensile strength by up to 116.4%, giving a tensile modulus of 40.3%, and hardness value of 39.2% as compared to a pure epoxy.

Abstract: The property of superabsorbent polymer (SAP) was investigated as component of composite material for corrosion control application. The composite material is a multilayer coating consisting of SAP particles, epoxy and hardener. The absorption property of SAP at different concentrations of sodium chloride was measured. It included 3% NaCl concentration, which represent the concentration of salt in sea water, an environment which is corrosive to carbon steel. Results showed decreasing absorbency of SAP at increasing concentration of sodium chloride. Predetermined amount of SAP and epoxy were mixed to obtain a homogenous mixture after which the hardener was added and mixed homogenously to form the composite material’s main component. The composite material was studied for absorption properties in an HDPLE substrate and then later applied onto a carbon steel specimen of size 40 mm x 100 cm and thickness of 0.70 mm using paint brush forming a film on the carbon steel surface. After curing, the film was scratched with a definite length using a sharp knife. Immediately, the samples were exposed to cyclic immersion in 3% sodium chloride solution and subsequent drying to run the corrosion test. Results showed that the composite material was able to control corrosion on the surface of the carbon steel which could be attributed to its self-healing property.

Abstract: The polymer-cement composites have special specifications, high strength compared to their low density, satisfactory deformability, deterioration resistance, tailored design. This enables the construction of new elements and the structural recovery of the existing parts made of traditional materials. two sets of mixtures were prepared that consist of mortar and polymer to produce the polymer-mortar composites were cured at room temperature and post-cure at 50 ͦ C. The set includes mortar (cement-sand) without water. The polymer was epoxy which is added to the mortar after mixing the hardener with resin. Set consists of the proportion of polymer (15, 20 and 30%).The effect of the polymer was studied on both sets by computing the density also measuring the hardness, compressive strength and flexural strength of specimens. The addition of polymer showed an improvement in these properties and post-cure have improvement properties .the lowest percent of the polymer showed The highest results were density 1133.3 kg/m3, the hardness of composites was 97.28 shore D. the compressive strength was about 100.816 MPa and the value of flexural strength was about 29.418 MPa.

Abstract: Surface treatment is one of the method used to enhance the mechanical performance of natural fiber composite by improving the compatibility of fiber and matrix. Nevertheless, no proof can be shown on which surface treatment is the absolute solution in improving the mechanical properties of natural fiber composite. Different surface treatments might have needed for different kinds of natural fiber composites. In this research work, water, alkaline, permanganate, bleaching and acetylation treatment on bagasse fiber are evaluated and the effect of soaking temperature as well as the effect of fiber loading are investigated. The mechanical performance of bagasse fiber-epoxy composite was studied by carrying out three-point bending test and optical microscopy test. Among 0w/w% and 5w/w% fiber loading, composite with 1w/w% and 2w/w% fiber loading possessed the highest flexural strength and modulus respectively. However, poor wettability between fiber and matrix was observed at higher fiber loading. Water, bleaching, permanganate and acetylation treatment have minor positive effect on the mechanical performance of the composite, yet a great increment in flexural properties of alkali treated fiber composite was noticed such that 21.48% and 23.95% of improvement was made on flexural strength and flexural modulus respectively. Optical microscopy test indicated that alkali treatment is responsible for roughening the fiber surface, and improving the fiber wettability and dispersion. Depend on the surface treatment, effect of soaking temperature may vary. In some treatments, hotter soaking temperature led to faster rate of reaction, which resulted in greater surface roughening and greater cleansing effect. Despite of that, over reaction can be happened in some cases, which will result in lower flexural properties due to over damaged fiber. Hence, it was concluded that the alkaline treatment at room temperature could be the most effective surface treatment to enhance the mechanical performance of bagasse fiber-epoxy composite.

Abstract: New technologies are using natural fibres in composites materials in the industry. It is still often natural fibres in modern buildings, chemists, airports, sport and automotive. Using for construction pieces and their better properties than steel or traditional materials. New forward science and technic are recycled or decrease waste. The problem for central Europe is a waste of agricultural, invention relates to an epoxy resin filled with an organo-inorganic filler of natural origin, production especially plants and sheep wool as well as other usable wastes such as old textiles. New applications are in new construction types and industries finding cheaper materials. There is available modern technology for injection moulding granulate polypropylene with filler from sheep wool and plant fibres. For example, to make furniture or building cladding. This could reduce waste production, pollution of nature and emissions in the production of these products from new raw materials. The work presents the possibilities of using new polymer-based materials contain sheep wool as filler. The paper deals with the evaluation of the mechanical properties of the effect of the addition of sheep wool in a concentration of 3% to selected types of thermosetting matrices. In the experiments, the modulus of elasticity, tensile strength, ductility and deformation work were built on the sample set. The results are statistically processed and document the possibilities of adjusting the mechanical properties of composites with sheep wool.

Abstract: Over the past fifteen years, Russian and foreign scientists have conducted a large amount of research in the development and use of composite materials based on epoxy resins, including the ways to restore structural integrity. In the oil and gas industry, composite materials are used for repair works.

Abstract: The current paper was aimed to investigate the effect of addition of MWCNTs on mechanical properties of epoxy. Tensile, fracture and impact tests were carried out for mechanical characterization while the weight concentration of the MWCNTs was 0.5 wt.%. Results showed that addition of MWCNTs resulted in decreasing tensile strength of the nanocomposites, whereas an improvement appeared for fracture and impact tests. In fact, fracture toughness and impact strength of the MWCNTs/epoxy increased by 65 and 117 percentage, respectively, compared with the pristine epoxy.

Abstract: . Natural fibers have been found to be an alternative resource for synthetic materials. Natural composites are found to be a one hundred percent bio degradable product. Natural composites are also found to be having a great strength to weight ratio. In this process, hybrid sisal and polylactic bio composites are reinforced together by using the hand layup method. The ratio of sisal and polylactic element is in the ratio of 1:1 that are subjected to a compressive force with simultaneous heating process. Tensile strength and Flexural strength are evaluated as per the ASTM standards. Results shown that the there is good improvement in polylactic acid based biocomposite due to good interfacial between fiber and matrix.