Papers by Keyword: Epoxy

Abstract: This study analyzes the wear mechanisms of a Kevlar-Zirconia-Epoxy composite casing coating under varying drillpipe joint speeds and side loads, using both dry and water-based mud lubrications. Employing Scanning Electron Microscopy, the research highlights the influence of ceramic microfillers on the wear characteristics. Findings indicate that abrasive wear dominates at low speeds, while higher speeds increase adhesive wear. Side load changes had minimal impact on wear mechanisms. Additionally, specimen temperature significantly affects composite behavior, underscoring the importance of lubrication for maintaining composite integrity. The results suggest this composite is well-suited for applications requiring high durability and wear resistance.

Abstract: To improve the toughness of epoxy resins, we add N, N-dimethylformamide (DMF) to epoxy resin as it is curing, and the flexible epoxy resin is prepared. According to the results of Fourier Transform Infrared Spectroscopy (FT-IR), DMF is able to effectively graft onto the epoxy resin. The glass transition temperature (Tg) of the epoxy resin drops from 99.9°C to 19.4°C, indicating a reduction in the thermodynamic stability of DMF/epoxy, according to the results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). According to tensile studies, DMF/epoxy's mechanical strength is decreased, but its elongation is significantly longer and enhanced by three orders of magnitude. Impact testing reveals a significant improvement in the material's hardness (from 1.67 to 15 J·cm^-2). Furthermore, DMF/epoxy is flexibly bendable. Finally, the DMA test shows that DMF/epoxy can achieve good shape memory at low temperatures to room temperature.

Abstract: The sepiolite and Al₂O₃-doped sepiolite contents in the as-received sepiolite/epoxy systems were maintained at 2 and 4wt %, respectively. The flame-retardant capabilities and combustion behavior of Al₂O₃-doped sepiolite in epoxy resin were meticulously evaluated through a series of tests including cone calorimetry (CC), limiting oxygen index (LOI), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). Several features, including degradation kinetics, combustion characteristics, thermomechanical properties, flame retardancy, and thermal degradation were evaluated with the intention of drawing comparisons to standard sepiolite. The findings from the studies were positive. In contrast, Al₂O₃-doped sepiolite not only further improved the LOI values and char formation post-cone testing but also decreased the previously mentioned combustion-related parameters in the composites. A potential synergistic interaction between sepiolite and Al₂O₃ in augmenting the flame retardancy of the composite was suggested. The thermal degradation of composites was only little affected by addition of sepiolite, although Al₂O₃-doped sepiolite addition seemed to speed up the deterioration process. The epoxy composite’s glass transition temperature (Tg) was shown to increase when sepiolite or Al₂O₃-doped sepiolite was added, as determined by DMA. The findings presented in this research provided a practical approach to improving the fireproofing of polymers. Keywords: Al2O3-doped sepiolite; TGA, flame retardancy; DSC, epoxy; thermal properties.

Abstract: This study explores the use of sodium bicarbonate-treated Nito core fiber as a natural and eco-friendly alternative for fiber-reinforced composites to address the challenge of enhancing the mechanical properties of composite materials while also prioritizing environmental sustainability. Nito core fibers were treated with different concentrations of sodium bicarbonate, an economical and eco-friendly alternative to alkali treatment, to enhance its compatibility with various matrices. FTIR results showed that NaHCO3 treatment effectively removed and reduced some non-cellulosic components present in the Nito fiber such as hemicellulose and lignin. This resulted in the NaHCO3-treated fiber-epoxy composite showing better tensile strength and modulus of elasticity than the epoxy composite reinforced with untreated Nito fiber. The use of treated fiber, however, did not have a noticeable effect on the flexural strength and flexural modulus of the epoxy composite. The SEM images of the nito fiber-epoxy composites showed better fiber-matrix adhesion between the treated nito fiber and epoxy matrix. Thermogravimetric analysis (TGA) of nito fiber-epoxy composites shows that the thermal stability of the composite is mainly due to the presence of cellulose, which can also be enhanced by some lignin. This study, therefore demonstrates the potential of Nito ‘core’ fibers as a viable substitute for synthetic reinforcements that can contribute to the advancement of composite material technology that aligns with the global shift towards environmentally responsible manufacturing practices.

Abstract: This research investigates the effect of different particle sizes of recovered carbon black (rCB) on the electrical conductivity, flexural and fractured toughness properties and morphology of epoxy/rCB conductive composites. The rCB powder was a product from the pyrolysis process of waste rubber tires. This research aims for the application of tray production in semiconductor packaging. In this study, the composite was prepared by using a simple mechanical stirring method. The testing and characterizations carried out included electrical conductivity test, flexural test, fracture toughness test, Scanning Electron Microscopy (SEM) and viscosity. The epoxy/rCB conductive composite shows significant differences in electrical conductivity and mechanical properties when incorporated with different particle sizes of rCB. The conductivity percolation threshold was found at 1000 mesh with enhanced mechanical and electrical conductivity properties simultaneously.

Abstract: Composites of natural fiber-reinforced thermoplastic and thermoset polymers have been studied for developing prosthetic socket materials. This study investigated the abaca fiber (AF)/carbon fiber (CF)/epoxy (EP) hybrid composite properties: i.e., tensile, flexural, impact, thermal, and water absorption, by varying AF and CF ratios of 1: 0, 0: 1, 2: 1, 3: 1, and 4: 1 with 80 vol% epoxy resin. The cracks formed in bending test specimens were characterized with an optical microscope, whereas the tensile fracture surface was characterized by scanning electron microscopy (SEM). The results confirmed that the mechanical properties of the CF/EP composite are the highest. The higher the AF/CF ratio, the lower the hybrid composite's mechanical properties and the higher the water absorption. The hybrid composite with a 2:1 AF/CF ratio achieved the highest tensile and flexural strengths of 70 MPa and 103 MPa, respectively, and the lowest water absorption of 7.89%. Based on the experimental results, a simulation of the prosthetic socket was performed using Autodesk Inventor 2019 integrated with ANSYS Workbench 2019 R1, resulting in von Mises stress of 2.14 MPa and deformation of 0.015 mm. Besides, its thermal gravimetric analysis (TGA) resulted in good thermal stability.

Abstract: Mechanical characteristics, dimensional stability, and bonding strength are all impacted by water sorption in polymer filler materials. The diffusion coefficient (D) of water through polymer composite, should be determined to understand the impact of the deterioration on service life and micro-leakage. In this study, the kinetics and properties of water absorption by short-term immersion in room-temperature plantain fibre reinforced epoxy bio-composites (PFRC), were studied. 5, 10, 20, and 30 percent, plantain fiber (PF) volume fractions of bio-composite specimens were made. Due to the high cellulose content of natural fibers (NF), the percentage of moisture absorption grew as the PF volume fraction increased. The mechanism and kinetics of PFRC's water absorption were found to follow the Fickian diffusion mode and had the propensity to behave in the Fickian mode.

Abstract: Non-isothermal DSC has been used to investigate the curing kinetics of epoxy adhesives (DGEBA-cycloaliphatic amine). The epoxy samples were scanned on DSC with five heating rates (5°C/min, 7.5°C/min, 10°C/min, 12.5°C/min, and 15°C/min). The curing kinetics were obtained through ASTM standards E2890 and E698 (the Ozawa and Kissinger methods). The kinetic parameters obtained include Ea (activation energy), A (pre-exponential factor), and n (reaction order). The activation energy calculated from the Kissinger and Ozawa method was slightly different but insignificant. The reaction rate (dα/dt) and degree of curing/conversion (α) relationship towards temperature (T), and time (t) was also investigated. The curing process's reaction rate (dα/dt) has maximum value; it can no longer increase after a specific conversion rate (α).

Abstract: The rapid development of the timber industry has caused the total capacity of the Indonesian timber industry to exceed the ability of production forests to provide raw materials sustainably. One of the industries that require a supply of wood as its main raw material is the furniture industry. The raw materials for furniture that are commonly used are logs and planks. In recent years, there has been the development of new materials that use natural fibers as polymer reinforcement, which can be used to replace wood materials. The material is a natural fiber composite. Composite materials reinforced with natural fibers are widely used in aerospace, automotive, circuit boards and other applications. One of the natural fibers that can be used as a composite is straw fiber. This high proportion of cellulose in straw fiber can be used for several things, one of which is composite materials. The utilization of rice straw fiber and epoxy as raw materials for making composites is an alternative to overcoming the increasing demand for wood. The purpose of this study was to determine and analyze the effect of volume fraction and alkalization treatment on the physical and mechanical characteristics of straw fiber composites, also to determine and analyze the effect of adding a coating of PE/SiO₂ on the hydrophobic characteristics of straw fiber composites. The physical and mechanical properties of the composites were evaluated based on the SNI 03-2059-2006 and SNI-01-4449-2006 standard. The volume fractions used are 40%, 50%, and 60%. The length of the fiber used is 5 mm. And the alkalization variables used were 5% and 10% NaOH with 4 and 8 hours of immersion. The compressive strength decreased by adding fiber volume fraction and increased by higher treatment alkalization. The coating method can produce composite with the contact angle value of more than 90^o.

Abstract: The effects of nanocellulose extracted from pineapple leaf fiber on the physico-chemical and thermal properties of epoxy nanocomposite are reported. Nanocellulose was added to the epoxy in different amounts of loadings (0.5, 1.0, 1.5, and 2.0 wt.%) to prepare nanocomposites. The physico-chemical and thermal properties of the nanocellulose reinforced epoxy nanocomposites were investigated. Surface characterization of the nanocomposite was done using scanning electron microscopy (SEM). Functional groups of the nanocomposites were evaluated using fourier transform infrared (FTIR) spectroscopy. Thermal properties of the nanocomposites were investigated using thermogravimetric analyzer (TGA) and differential thermal analyzer (DTA). Experimental results revealed that the 0.5, 1.0, and 1.5 wt.% nanocellulose loadings were homogeneously distributed and well-dispersed in the composite matrix as indicated in the SEM images. However, aggregation was observed in the matrix with 2.0 wt.% nanocellulose loading. Moreover, FTIR spectra revealed that the absorbance of the vibrational mode corresponding to the interaction of nanocellulose and epoxy matrices significantly increases as the nanocellulose loading ratio increased. Furthermore, thermal analysis (TGA/DTA) showed that the incorporation of nanocellulose improved significantly the thermal properties of epoxy nanocomposites.