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Epoxy Nanocomposites Containing Hybrid Montmorillonite/Geopolymer Filler for Piping Application
Published in Ahalapitiya H. Jayatissa, Applications of Nanocomposites, 2022
Mat Daud, Azlin Fazlina Osman, Mohammad Firdaus Abu Hashim
Epoxy is a commonly used polymer to replace heavier non-polymeric materials for structural applications such as ceramic and metal. However, the mechanical and physical properties of epoxy can be severely reduced when exposed to harsh and corrosive environments such as in the oil and gas pipeline. The structure of epoxy can chemically degrade and leads to deterioration in its mechanical and physical properties. These may hamper the long-term use of epoxy in piping applications, where mechanical and physical integrity are required to allow stability in various environmental conditions. In that case, epoxy has been restored by adding the nanofiller such as organo-montmorillonite (organo-MMT). Organo-MMT is a promising reinforcing nanofiller for epoxy matrix due to its high aspect ratio, hydrophobicity and capability to enhance the mechanical properties of the matrix when added in small quantities. However, the morphology and structure properties found in the nanoclay type filler affect the stability of the mechanical properties of the composite. Therefore, due to this limitation of single nanofiller, researchers have initiated the idea of using hybrid filler in the epoxy matrix to obtain composite with greater combination properties. However, only a small number of published researches focused on the use of two physically/ chemically different silicate/clay materials as hybrid fillers in the epoxy matrix (Wang et al. 2011, Osman et al. 2016b).
Manufacturing Techniques
Published in Sumit Sharma, Composite Materials, 2021
In the resin film infusion (RFI) process, a precatalyzed resin film placed under the dry fiber preform provides the liquid resin that flows through the preform and on curing, becomes the matrix. The process starts by covering the mold surface with the resin film and then placing the dry fiber preform on top of the resin film (Figure 3.29). The thickness of the resin film depends on the quantity of resin needed to completely infiltrate the preform. RFI can be carried out using the bag-molding technique described earlier. In that case, the assembly of resin film and dry fiber preform is covered with a vacuum bag and placed inside an autoclave. The full vacuum is applied at the beginning to remove the trapped air from the preform. As the temperature is increased in the autoclave, the resin viscosity decreases and the resin starts to flow through the dry fiber preform. Pressure is applied to force the liquid resin to infiltrate the preform and wet out the fibers. With the temperature now raised to the prescribed curing temperature, the curing reaction begins and the liquid resin starts to gel. If an epoxy film is used, the curing cycle may take several minutes to several hours depending on the resin type and the curing conditions used.
Braiding and Recent Developments
Published in Asis Patnaik, Sweta Patnaik, Fibres to Smart Textiles, 2019
In 2D/3D braiding and braided preforms, thermoset or thermoplastic matrices were employed by making the prepreg and rigid structure for various applications. Thermosets are polyester, vinyl ester, epoxy, phenolic, etc. Thermoplastic includes polyethylene, polypropylene, acrylic polymer, polyamides and polyurethanes. Thermosets are used to make the braided composite to enhance thermo-mechanical properties. Contrarily, thermoplastic contributes to the fracture toughness of the resulting material. Epoxy has outstanding mechanical, thermal and fracture toughness properties and is moisture resistant. However, it is expensive and requires high processing temperatures during curing (Babcock and Rose 2001). Rubber can be used to coat the braided fabric surface to suppress crack propagation in the case of loads as well as protect the braided structure from critical environmental conditions such as UV light, seawater and sunlight. Examples of some of the coating materials were natural rubber, polybutadiene, polyisoprene, ethylene–propylene copolymers, polyurethane elastomers, silicone elastomers, and thermoplastic elastomers (Harpell et al. 1988). Another thermoplastic polymer is polycarbonate that is made by the reaction of the precursor monomer bisphenol A and phosgene (COCl2). It is very tough and has high impact resistance as well as being optically transparent (Bilisik 2018).
Thermal conductivity and shear strength characterisation of hybrid GNPs and silane functionalised BN as thermal conductive adhesive
Published in The Journal of Adhesion, 2023
S. Jasmee, M Ramli, S.S. Othaman, G. Omar
Epoxy has long been used in the production of TCAs. Being inexpensive and light in weight, it offers adhesion to various substrates,[24] low shrinkage upon curing,[25] resistance to thermal and mechanical shock,[26] excellent adhesion and mechanical properties,[27] chemical resistance,[28] and anti-corrosion.[29] However, despite its many advantages, epoxy has several limitations, including low heat conductivity, toughness, and poor resistance to crack growth.[30,31] Such limitations make it inadequate to dissipate the heat produced in electronic components and limit its application in structures. Thus, numerous efforts have been made to improve the thermal conductivity and shear strength of epoxy by adding conductive fillers from ceramic, metal, or carbon-based fillers.[32,33] Conductive fillers are known to have improved intrinsic thermal (thermal conductivity, glass transition) and mechanical properties (shear strength, fracture strength, and Young’s modulus), which can remarkably improve the properties of composite adhesives.[34]
Non-linear finite element analysis of prestressed T-beams strengthened with FRP laminates and patch anchors
Published in Structure and Infrastructure Engineering, 2023
Reem Jumaah, Robin Kalfat, Riadh Al-Mahaidi
Prior to application of the FRP, both faces of the webs were sandblasted to remove laitance and achieve a surface roughness equivalent to 60 grit sandpaper. Preparation of the anchored specimens involved initially applying the first layer of ±45° bidirectional fabric sheet on the webs of the specimens. The FRP laminates were applied directly on top of the first layer of bidirectional fabric sheet over which the second layer of bidirectional fabric was applied, effectively sandwiching the laminate. Figure 2 presents the application process of the anchored specimen. The epoxy was allowed to cure for 7 days at a temperature of 40 °C which was induced by use of a series of heat lamps. Generally, curing of epoxy at 25 °C for 7 days is sufficient as per the manufacturers datasheet. However, curing at 40 °C would result in full curing of the epoxy in 48 hrs as per manufacturers recommendations.
Low-temperature mechanical properties of polyurethane-modified waterborne epoxy resin for pavement coating
Published in International Journal of Pavement Engineering, 2022
Qian Chen, Chaohui Wang, Sixin Yu, Zhi Song, Hao Fu, Tao An
Epoxy resin has high hardness, brittle quality, poor impact resistance and insufficient durability. It is necessary to add polyurethane to improve flexibility and impact resistance of epoxy resin. After literature investigation and preliminary test analysis (Chen et al. 2022), polyether-based and polyester-based polyurethane prepolymers are selected as modified materials. Among them, polyether-based polyurethane is used to modify E–51 waterborne epoxy resin, and polyester-based polyurethane is used to modify E–44 waterborne epoxy resin. They are supported by Nan Ya Plastics Corp (NPC), and their technical indexes are shown in Table 3. In addition, a catalyst (dibutyltin dilaurate) needs to be added. And a certain amount of defoamer (polydimethylsiloxane) needs to be added to reduce bubbles. They are supported by Xi'an Xinhui Experimental Instrument Co., Ltd.