Physical, mechanical, and thermal properties of epoxy composites with woven kenaf and kenaf/cotton fabrics

Investigation of Mechanical and Thermal Properties of Silica-Reinforced Epoxy Composites by Using Experiment and Empirical Model

In this study, we report a simple and efficient method to prepare three-dimensional graphene oxide (3DGO) network by freeze drying and investigate the effect of 3DGO network on thermal properties of epoxy composites. It was found that the 3DGO network not only improved thermal conductivity, thermal stability, glass transition temperature and storage modulus of epoxy composites, but also reduced the thermal expansion properties of epoxy composites. For instance, the thermal conductivity value of epoxy composite with only 1.3 wt% 3DGO is 0.62 Wm-1K-1, increased by 148 % in comparison with that of the neat epoxy (0.25 Wm-1K-1).

The increasing demand for the development of environmentally friendly alternatives to petroleum-derived materials has increased research efforts on sustainable polymer composites. This study systematically examined the effect of nano-biochar derived from agricultural wastes such as olive pulp on the mechanical and thermal properties of epoxy-resin-based composites. First, the biochar from olive pulp was produced by pyrolysis at 450 °C and turned to nano-biochar using ball milling. Composite samples containing nano-biochar at different rates between 0 and 10% were prepared. The nano-biochar and composite samples were characterized by using different techniques such as SEM-EDS, BET, FTIR, XRD, Raman, TGA, and DMA analyses. Also, the tensile strength, elastic modulus, Shore D hardness, thermal stability, and static toughness of the composite samples were evaluated. The best performance was observed in the sample containing 6% nano-biochar; the ultimate tensile strength increased from 17.37 MPa to 23.46 MPa compared to pure epoxy, and the elastic modulus and hardness increased. However, a decrease in brittleness and toughness was observed at higher additive rates. FTIR and DMA analyses indicated that the nano-biochar interacted strongly with the epoxy matrix and increased its thermal stability. The results showed that the olive-pulp-derived nano-biochar could be used to improve the structural and thermal properties of the epoxy composites as an inexpensive and environmentally friendly filler. As a result, this study contributes to the production of new polymer-based materials that will encourage the production of environmentally friendly composites with nano-scale biochar obtained from olive waste, which is an easily accessible, renewable by-product.

Liquid epoxy resins have received much attention from both academia and the chemical industry as eco-friendly volatile organic compound (VOC)-free alternatives for applications in coatings and adhesives, especially in those used in households. Epoxy resins show high chemical resistance and high creep resistance. However, due to their brittleness and lack of thermal stability, additional fillers are needed for improving the mechanical and thermal properties. Halloysite nanotubes (HNTs) are naturally abundant, inexpensive, and eco-friendly clay minerals that are known to improve the mechanical and thermal properties of epoxy composites after suitable surface modification. Zirconium is well known for its high resistance to heat and wear. In this work, zirconium oxide-impregnated HNTs (Zr/HNTs) were added to epoxy resins to obtain epoxy composites with improved mechanical and thermal properties. Zr/HNTs were characterized by field-emission transmission electron microscopy, transmission electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Changes in the thermal properties of the epoxy composites were characterized by thermo mechanical analysis and differential scanning calorimetry. Furthermore, flexural properties of the composites were analyzed using a universal testing machine.

Background: The technological developments for nanocellulose production from cheaper plant materials compared to wood, in particular, agricultural waste is an urgent task of nanobiophysics. The discovery of possibility of expanding the functional characteristics of materials in compositions with modified cellulose particles essentially stimulated the interest of researchers in cellulose composites. Surface modification of cellulose particles by functional materials, such as dyes, metal oxides, silicon, allows applying composites with modified cellulose in various areas of modern industry. A significant improvement in the operational performances of functionalized cellulose particles can be achieved by using them as filler in polymers. Epoxy resin compositions with modified and unmodified cellulose particles, studied in present work, are an example of hybrid biosystem. The interfacial interaction of filler particles with the epoxy matrix, their concentration and dispersion can change the physical and chemical properties of the biopolymer and the functional parameters of biocomposites. Studying the influence of external fields on the physical and chemical properties of epoxy resin-based biosystems and their influence on operational parameters seems to be an urgent problem of advanced and sustained materials science. Objectives: The purpose of this work was to develop an effective nanocellulose synthesis from plant materials and surface functionalization of micro- and nanocellulose particles with clathrochelate iron (ΙΙ) dye as well obtaining biocompositions of epoxy resin with functionalized and non-functionalized micro- and nanocellulose, and to explore of the morphology, chemical resistance, mechanical and thermal properties of epoxy composites with cellulose micro and nanoparticles. Materials and methods: The studying objects were the composites of epoxy resin Eposir-7120 with a polyethylene polyamine “PEPA” hardener in a ratio of 6.2:1 and 10% cellulose micro and nanoparticles. The microcellulose obtained from wood has been a commercial product. Nanocellulose has been synthesized from organosolv cellulose obtained from Miscanthus x giganteus stalks. Surface modification of micro- and nanocellulose was performed using the clathrochelate iron (ΙΙ) dye. The specific surface area of cellulose particles was determined using low-temperature nitrogen adsorption-desorption according to the Brunauer-Emmett-Teller method. Mechanical parameters were determined using universal Shopper and UMM-10 machines. Thermal analysis was performed using Q1500 analyzer. Swelling was determined by the gravimetric method. Results: Elastic modulus E, compressive strength σ and thermogravimetric parameters were determined. It was shown that in composites with micro and nanocellulose the E rises in 7.0–12.2% while the σ increases in 9.1% for composites with cellulose micro particles. The loading resin with nanocellulose and modified cellulose microparticles no affects the σ value of composites. The thermal stability of epoxy polymer (310°C) reduces after loading with micro and nanocellulose to 290 and 300°C, respectively. Chemical resistance of composites with both celluloses to 20% nitric acid reduces. In neutral medium swelling characterizes by rapid sorption to saturation of 15–20% acetone in 36 hours. Conclusions: Thus, the synthesis method of nanocellulose from plant materials and functionalization of its surface with clathrochelate iron (ΙΙ) were developed. Light response of dye was detected in visible spectral range. Epoxy resin composites with 10% micro and nanocellulose were obtained. The filling effect with micro- and nanocellulose at elastic modulus, compressive strength, and thermal stability of epoxycomposites was studied. The swelling processes run similarly in composites with cellulose micro and nanoparticles.

Epoxy composites were fabricated with a filler of silicon carbide (SiC) and/or graphite to improve the thermal conductivity and thereby enhance the transfer of the heat from the light-emitting diode (LED) to the heat sink. The two fillers (SiC and graphite) were each added either separately, within a content range of 10 − 50 wt.%, or together to give a combined total content of 40 − 60 wt.%. The effect of the filler addition on the thermal and the mechanical properties of the epoxy composites was examined. The filler-induced change on the structural properties was investigated by using a morphological analysis of the epoxy composites, and the thermal conductivity was analyzed by measuring the thermal diffusivity, heat specific, and density. To confirm the adhesive property with aluminum, which is mostly used as the heat sink material were tested, the mechanical properties by using a bonding test with a modified tensile test. The thermal and the mechanical properties were improved with increasing filler content in the epoxy composites. In the case of combined filler addition, graphite was more effective than SiC in increasing the thermal properties. However, excessive filler addition reduced the epoxy’s natural adhesive property and hence degraded the mechanical properties.

This study aims to investigate the synergistic effects of graphene, aluminum oxide (Al2O3), and silicon oxide (SiO2) nanofillers on the mechanical and thermal properties of epoxy composites. The objectives were to enhance the performance of epoxy resins by incorporating these nanofillers at varying weight fractions (0.5 %, 1 %, and 1.5 %) using ultrasonication for uniform dispersion. Standard ASTM tests, including tensile, flexural, and impact strength tests, along with thermal conductivity measurements, were conducted to evaluate the properties of the nanocomposites. The results revealed that graphene-reinforced composites exhibited the most significant improvements, with tensile strength increasing by 32 %, flexural strength by 21 %, and thermal conductivity by over 300 % compared to neat epoxy. Alumina and silica also enhanced the composite properties but to a lesser extent. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses showed key differences in the dispersion of nanoparticles and the interactions between the nanofillers and the epoxy matrix, with graphene demonstrating superior interfacial bonding. These findings highlight graphene’s exceptional potential for enhancing the mechanical and thermal properties of epoxy composites, making them suitable for applications in thermal management and structural components in advanced engineering fields. The study provides valuable insights into optimizing nanocomposite formulations to achieve multifunctional performance.

Investigation of thermal properties of epoxy composites embedded with Aluminum Nitride (AlN) micro-fillers is estimated in the present thesis with help of the experimental and ANSYS results. Thermal conductivity of AlN powder filled epoxy composite is calculated by measuring temperature difference at two surfaces by using instruments thermal heater and thermal laser gun. The samples of composites prepared with AIN for three different sizes of AIN powder particles [AIN particles size 1)70µm 2)80µm 3)90µm]. For each size three samples are prepared with different concentration of AIN powder [AIN concentration by wt. 1)10 gm 2)20 gm 3)30 gm].The numerical results obtained by using the ANSYS software. The effective thermal conductivity values obtained from experimentally validate with ANSYS results. It is observed that The conductivity values measured experimentally are compared with the ANSYS results. These Epoxy composites with AlN and glass fiber have been fabricated and thermal conductivities of the samples are calculated by using experimentally obtained temperature values. Observations can be made that with At highest testing temp. 80oC for size 70µm of AIN particles we get thermal conductivity of epoxy composites for sample 20weight %(30gm AIN powder out of total weight of sample) has increased by 30 times than epoxy. Epoxy composites with 80µm size of AIN particles the sample with 20 % of AIN gives thermal conductivity at heater temp.80oC has increased by about 32 times than epoxy. For 90 µm size AIN particles samples at heater temp.80oC we found better thermal conductivity for sample with 20% AIN particles out of the nine samples the thermal conductivity of epoxy has increased by 34 times as compare to epoxy. A conclusion to draw from the measured values we got better thermal conductivity of epoxy composites with 20% of AIN with size of 90µm.Increase of thermal conductivity of epoxy composites with increase of size and percentage of AIN powder.

Polymer matrix wave transparent composites are used in a variety of high-speed communication applications. One of the applications of these involves making protective enclosures for antennas of microwave towers, air vehicles, weather radars, and underwater communication devices. Material performance, structural, thermal, and mechanical degradation are matters of concern as advanced wireless communication needs robust materials for radomes that can withstand mechanical and thermal stresses. These polymer composite radomes are installed externally on antennas and are exposed directly to ambient as well as severe conditions. In this research, epoxy resin was reinforced with a small amount of quartz fibers to yield an improved composite radome material compared to a pure epoxy composite with better thermal and mechanical properties. FTIR spectra, SEM morphology, dielectric constant (Ɛr) and dielectric loss (δ), thermal degradation (weight loss), and mechanical properties were determined. Compared to pure epoxy, the lowest values of Ɛr and δ were 3.26 and 0.021 with 30 wt.% quartz fibers in the composite, while 40% less weight loss was observed which shows its better thermal stability. The mechanical characteristics encompassing tensile and bending strength were improved by 42.8% and 48.3%. In high-speed communication applications, compared to a pure epoxy composite, adding only a small quantity of quartz fiber can improve the composite material's dielectric performance, durability, and thermal and mechanical strength.

To enhance the thermal properties of epoxy composites, expanded graphite (EG) was oxyfluorinated and embedded into epoxy resin as a reinforcement. The maximum thermal conductivity was obtained for epoxy composites with oxyfluorinated EG, representing a 62% increase compared to that of neat epoxy. Additionally, the glass transition temperature (Tg) and integral procedural decomposition temperature of epoxy composites with oxyfluorinated EG show the increase of 6% (4.4 °C) and 106% (264 °C), respectively, which indicated the improvement in thermal stability. These results can be attributed to the interfacial interaction between epoxy and oxyfluorinated EG, which formed strong interfacial interactions between the epoxy resin and EG due to the presence of oxygen- and fluorine-containing functional groups in oxyfluorinated EG.

The thermal properties of epoxy composites filled with boric acid fine powder at different percentage were studied. Epoxy composites were prepared using epoxy resin ED-20, boric acid as flame-retardant filler, hexamethylenediamine as a curing agent. The prepared samples and starting materials were examined using methods of thermal analysis, scanning electron microscopy and infrared spectroscopy. It was found that the incorporation of boric acid fine powder enhances the thermal stability of epoxy composites.

The aim of this study was to examine the properties of epoxy composites that have sisal fiber (SF) and pineapple leaf (PF) reinforcements. Using dielectric barrier discharge (DBD) plasma for different periods ranging from 3 to 15 minutes, both fibers were treated. A combination of epoxy resin (EP), SF, or PF was prepared with or without plasma treatment. Fibers treated with plasma had a higher peak intensity of carboxyl groups in their Fourier-transform infrared spectra. A maximum tensile strength (TS) (up to 62.26 MPa) was observed in EP/SF treated for 15 minutes, but a more notable increase in elongation break (EB) (6.89 %) was observed in EP/PF treated for the same amount of time. In comparison to the sisal composites, the flexural strength (FS) of the pineapple leaf composites was found to be up to 63.2 MPa after plasma treatment. Both composites’ interfacial bonding and fiber surface roughness were enhanced by the plasma treatment. Following treatment with DBD plasma, both the wettability and thermal stability were enhanced. Composites’ mechanical, thermal, and wettability properties were improved by DBD of plasma treated surfaces, which increased interfacial bonding among the fibers and the epoxy.

ABSTRACTIn this paper, the ammonium polyphosphate (APP) is mixed with epoxy to fabricate APP/epoxy goat horn composites. The composites were obtained by casting method with different weight ratios of APP of 0%, 10%, 15%, and 20% for improving the mechanical and thermal properties. This is the first paper to discuss about both mechanical and thermal properties of APP/epoxy goat horn composites. The mechanical properties were evaluated by tensile test and wear test. For the goat horn composites with a content of 20 wt% of APP, the tensile strength was 30 MPa, shows that adding APP led to composites having a better tensile strength. From limiting oxygen index test results, it is clear that goat horn composite is fire retardant, and that the fire‐retardant value improves with the addition of APP up to a weight ratio of 15% APP. The thermogravimetric analysis (TGA) reveals that the degradation of composites in relation to temperature. From the TGA analysis, the bio composites without APP gives the better results comparing with incorporation of APP in composites up to 40% of weight loss. At the same time, the 50% of weight loss occur at the degradation temperature of around 380°C for 20 wt% of APP composites. It shows the addition of APP improves the thermal stability of the composites. The ignition time from the horizontal flammability test of the composites of 0, 10, 15, and 20 wt% APP were 20, 22, 24, and 25 (in s) respectively. It shows that the addition of filler material into the composites, the ignition time also increases. The water absorption percentage was peak at 15% of APP and lower at 10% of APP. All the samples were saturated after 80 h. The lower percentage of water absorption in composites can be attributed to the improved interfacial bonding between the fibers and matrix. From scanning electron microscopy (SEM) analysis the morphological structure and dispersion of ammonium polyphosphate and goat horn particles in epoxy bio composites were studied.

A novel Fe2O3@APFS/epoxy composite with enhanced mechanical and thermal properties

Bio-filled polymer composites are gradually replacing plastics to achieve the aim of environmental sustainability. Present study has been carried out to prepare the composites made by reinforcing waste peanut shell powder (PSP) as a natural filler into epoxy resin matrix. The natural filler extracted by manual process was subjected to alkali treatment with the concentrations of 2, 5 and 7 w/v%. The composites fabricated by varying the weight fractions of filler in the range of 5 to 15 wt%. The effects of bio-filler content of the composites on tensile and thermal properties were evaluated by Fourier transmission infrared spectroscopy (FTIR), universal testing machine, scanning electron microscope (SEM) and thermal gravimetric analysis (TGA). The studies reveal that the tensile strength and tensile modulus increased with the increasing of bio-filler content. The highest mechanical properties of 7 % alkali treated PSP loaded Epoxy composite were achieved at biofiller mass content of 15 wt.%. The morphology of the composites shows better bonding between the filler and resin, thus leading to improvement of the mechanical properties. The TGA results revealed that the polymer composites showed thermal resistance on increasing NaOH concentration and filler content.