Material resistence and damage formation analysis of charcoal-filled composite materials: case study on pyrolysis product

Effects of the processing methods on the mechanical properties of treated bagasse fibre reinforced epoxy composite were evaluated. The composite materials were processed by employing hand lay-up and compression moulding methods and fibres were treated with NaOH solution. The composite samples were subjected to tensile, flexural and impact tests. Based on the findings, compression moulding method produced better mechanical properties compared to the composites manufactured by hand lay-up method. The results showed that the tensile strength and Young’s modulus of the samples produced by compression moulding method increased by 77 percent and 47 percent respectively (at optimal fibre loading) compared to those produced by the hand lay-up method. The results also showed noticeable improvements in the impact strength of the material produced by compression moulding method, with impact strength of 11.5 kJ/m2 against the samples produced by hand lay-up method, with impact strength of 7 kJ/m2.

Quasi-static and intermediate rate axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). The quasi-static tests were conducted at 10 mm/min (1.67 × 10—4 m/s); five different crush initiators were used. Tests at intermediate rates were performed at speeds of 0.25, 0.5, 0.75, 1, 2, and 4m/s. Modes of failure and specific energy absorption (SEA) values were studied. The highest SEA measured was 86 kJ/kg. This value was observed using Carbon/Epoxy samples at quasi static rates with a 45° chamfer initiator. The highest energy absorption for Twintex tubes was observed to be 57.56kJ/kg during 45° chamfer initiated tests at 0.25m/s. Compared with steel and aluminium, SEA values of 15 and 30 kJ/kg, respectively, the benefits of using composite materials in crash structures become apparent.

Formation, characterization and suitability analysis of polymer matrix composite materials for automotive bumper

Basin‐type insulators are made by epoxy resin composite materials. Curing defects are easily formed in basin‐type insulators, and degrade their insulating performances. High curing exothermic rates of epoxy resin composite materials have deemed as the main cause of curing defects formation. In this study, methyl tetrahydrophthalic anhydride (Me‐THPA) was used to extend the molecular chain of liquid epoxy resin to prepare epoxy resin composite materials with low curing exothermic rates. Curing exothermic properties, molecular weight distribution, curing stress, microstructures, and surface flashover characteristics of the composite materials were investigated. The results showed that chain‐extended epoxy resin had low curing exothermic rates. The curing stress of the chain‐extended epoxy resin composite materials was small. The curing defects forming in the composite materials were inhibited. Negative DC surface flashover characteristics of these composite materials were improved. Furthermore, variation of functional groups of the composite materials was studied before and after surface flashover tests. Results showed that the content of carbon–oxygen single bonds (–C–O) in the chain‐extended epoxy resin composite materials was observed to decrease. The –C–O bonds also affect the voltage withstand capability of the epoxy resin composite materials.

Macroscopic structures consisting of two or more materials are called composites. The decreasing reserves of the world’s oil reserve and the environmental pollution of existing energy and production resources made the use of recycling methods inevitable. There are mechanical, thermal, and chemical recycling methods for the recycling of thermosets among composite materials. The recycling of thermoset composite materials economically saves resources and energy in the production of reinforcement and matrix materials. Due to the superior properties such as hardness, strength, lightness, corrosion resistance, design width, and the flexibility of epoxy/vinylester/polyester fibre formation composite materials combined with thermoset resin at the macro level, environmentally friendly sustainable development is happening with the increasing use of composite materials in many fields such as the maritime sector, space technology, wind energy, the manufacturing of medical devices, robot technology, the chemical industry, electrical electronic technology, the construction and building sector, the automotive sector, the defence industry, the aviation sector, the food and agriculture sector, and sports equipment manufacturing. Bonded joint studies in composite materials have generally been investigated at the level of a single composite material and single joint. The uncertainty of the long-term effects of different composite materials and environmental factors in single-lap bonded joints is an important obstacle in applications. The aim of this study is to investigate the effects of single-lap bonded GFRP (glass fibre-reinforced polymer) and CFRP (carbon fibre-reinforced polymer) specimens on the material at the end of seawater exposure. In this study, 0/90 orientation twill weave seven-ply GFRP and eight-ply CFRP composite materials were used in dry conditions (without seawater soaking) and the hand lay-up method. Seawater was taken from the Aegean Sea, İzmir province (Selçuk/Pamucak), in September at 23.5 °C. This seawater was kept in different containers in seawater for 1 month (30 days), 2 months (60 days), and 3 months (90 days) separately for GFRP and CFRP composite samples. They were cut according to ASTM D5868-01 for single-lap joint connections. Moisture retention percentages and axial impact tests were performed. Three-point bending tests were then performed according to ASTM D790. Damage to the material was examined with a ZEISS GEMINESEM 560 scanning electron microscope (SEM). The SEM was used to observe the interface properties and microstructure of the fracture surfaces of the composite samples by scanning images with a focused electron beam. Damage analysis imaging was performed on CFRP and GFRP specimens after sputtering with a gold compound. Moisture retention rates (%), axial impact tests, and three-point bending test specimens were kept in seawater with a seawater salinity of 3.3–3.7% and a seawater temperature of 23.5 °C for 1, 2, and 3 months. Moisture retention rates (%) are 0.66%, 3.43%, and 4.16% for GFRP single-lap bonded joints in a dry environment and joints kept for 1, 2, and 3 months, respectively. In CFRP single-lap bonded joints, it is 0.57%, 0.86%, and 0.87%, respectively. As a result of axial impact tests, under a 30 J impact energy level, the fracture toughness of GFRP single-lap bonded joints kept in a dry environment and seawater for 1, 2, and 3 months are 4.6%, 9.1%, 14.7%, and 11.23%, respectively. At the 30 J impact energy level, the fracture toughness values of CFRP single-lap bonded joints in a dry environment and in seawater for 1, 2, and 3 months were 4.2%, 5.3%, 6.4%, and 6.1%, respectively. As a result of three-point bending tests, GFRP single-lap joints showed a 5.94%, 8.90%, and 12.98% decrease in Young’s modulus compared to dry joints kept in seawater for 1, 2, and 3 months, respectively. CFRP single-lap joints showed that Young’s modulus decreased by 1.28%, 3.39%, and 3.74% compared to dry joints kept in seawater for 1, 2, and 3 months, respectively. Comparing the GFRP and CFRP specimens formed by a single-lap bonded connection, the moisture retention percentages of GFRP specimens and the amount of energy absorbed in axial impact tests increased with the soaking time in seawater, while Young’s modulus was less in three-point bending tests, indicating that CFRP specimens have better mechanical properties.

Core-shell Zinc Oxide/Layered Double Hydroxide (ZnO@LDH) composite nanomaterials have been produced by a one-step continuous hydrothermal synthesis process, in an attempt to further enhance the application potential of layered double hydroxide (LDH) nanomaterials. The synthesis involves two hydrothermal reactors in series with the first producing a ZnO core and the second producing the Mg2Al-CO3 shell. Crystal domain length of single phase ZnO and composite ZnO was 25 nm and 42 nm, respectively. The ZnO@LDH composite had a specific surface area of 76 m2 g−1, which was larger than ZnO or Mg2Al-CO3 when produced separately (53 m2 g−1 and 58 m2 g−1, respectively). The increased specific surface area is attributed to the structural arrangement of the Mg2Al-CO3 in the composite. Platelets are envisaged to nucleate on the core and grow outwards, thus reducing the face–face stacking that occurs in conventional Mg2Al-CO3 synthesis. The Mg/Al ratio in the single phase LDH was close to the theoretical ratio of 2, but the Mg/Al ratio in the composite was 1.27 due to the formation of Zn2Al-CO3 LDH from residual Zn2+ ions. NaOH concentration was also found to influence Mg/Al ratio, with lower NaOH resulting in a lower Mg/Al ratio. NaOH concentration also affected morphology and specific surface area, with reduced NaOH content in the second reaction stage causing a dramatic increase in specific surface area (> 250 m2 g−1). The formation of a core-shell composite material was achieved through continuous synthesis; however, the final product was not entirely ZnO@Mg2Al-CO3. The product contained a mixture of ZnO, Mg2Al-CO3, Zn2Al-CO3, and the composite material. Whilst further optimisation is required in order to remove other crystalline impurities from the synthesis, this research acts as a stepping stone towards the formation of composite materials via a one-step continuous synthesis.

An investigation and comparison of tensile strength in Fiber Sandwiched Wood Composite (FSWC) materials subjected to axial loading

RETRACTED: Experimental investigation of parameters affected on behavior of composite tubes under quasi static and dynamic axial loading

reduction obtained from short-term creep experiments so that the results obtained by the two methods can be compared. The idea to use quasistatic tests for the accelerated evaluation of the long-term creep stress is well known [2, 3], but no work has been carried out to analyze in detail and compare both methods on the basis of experimental investigations carried out on composite materials. The experiments with short-term loading were conducted on a microplastic (Vniilvlon filaments impregnated in the EDT-10 binder and hardened in the temperature conditions corresponding to those of manufacturing technology of the organic plastic) and on specimens cut in the reinforcement direction from sheets of the organic plastic with a volume fraction of the reinforcement of ~ = 0.64.

Nonlinear damage in the composite materials is developed with the growth of damages in the material under fatigue loading. Nonlinear ultrasonic techniques are sensitive to early stage damages such as, fiber breakages, matrix micro-cracking, and deboning etc. Here, in this work, early stage damages are detected in Unidirectional (UD) carbon fiber composite under fatigue loading. Specimens are prepared according to American Society for Testing and Materials (ASTM) standard. Specimens are subjected to low cycle high load (LCHL) fatigue loading until 150,000 cycles. Sensors are mounted on the specimen used for actuation and sensing. A five count tone burst with low frequency (fc =375 kHz) followed by high frequency (fc =770 kHz) signal, was used as actuation signal. Pitch-catch experiments are collected at the interval of 5,000 cycles. Sensor signals are collected for various excitation voltage (from 5V to 20V, with 5V interval). First Fourier Transform (FFT) of the sensor signals are performed and side band frequencies are observed at around 770 kHz. Severity of damages in the material is quantified from the ratio of amplitude of side band frequencies with the central frequency. Nonlinearity in the material due to damage development is also investigated from the damage growth curve obtained at various excitation amplitude. Optical Microcopy imaging were also performed at the interval of 5,000 to examine developments of damages inside the material. This study has a good potential in detection of early stage damages in composite materials.

This research Investigates the new composite materials are fabricated of two or more materials raised. The fibers material from the sources of natural recycled materials provides certain benefits above synthetic strengthening material given that very less cost, equivalent strength, less density, and the slightest discarded difficulties. In the current experiments, silk and fiber-reinforced epoxy composite material is fabricated and the mechanical properties for the composite materials are assessed. New composite materials samples with the dissimilar fiber weight ratio were made utilizing the compression Molding processes with the pressure of 150 pa at a temperature of 80 °C. All samples were exposed to the mechanical test like a tensile test, impact loading, flexural hardness, and microscopy. The performing results are the maximum stress is 33.4MPa, elastic modulus for the new composite material is 1380 MPa, and hardness value is 20.64 Hv for the material resistance to scratch, SEM analysis of the microstructure of new composite materials with different angles of layers that are more strength use in industrial applications.

One of the important properties of reinforced composite polymer materials is their physico-chemical properties. Their structure plays an important role in assessing the physico-chemical properties of composite materials. Research objectives - to study the physico-chemical properties of high-strength polymer composite materials. Experiments were carried out at 100 and 400-fold magnification in an optical microscope to study the morphology and structural changes of various parts of high-strength polymer composite materials with a polymer binder - ED-20 and nitrone fibers. IR spectroscopic studies were also carried out to study the interaction of nitron fibers with an epoxy binder - ED-20 during the formation of high-strength polymer composite materials. The data obtained in the study of various sections of polymer composites revealed a linear structure characteristic of nitron fibers coated on all sides with a polymer binder - ED-20, and structural changes in morphology at 100 and 400-fold magnification. Infrared spectral studies showed that the intermolecular interaction between hydroxyl and amide groups was established as a result of the interaction of the nitrile groups of the nitrone fiber and ED-20 with PEPA. Based on the analysis of the results obtained, it can be concluded that the developed composite materials based on epoxy binders with nitrone fibers can be considered as a new class of composite materials designed to operate under high stress conditions.

Link for citation: Kopanitsa N.O., Demyanenko O.V., Kulikova A.A., Tkach E.V., Shestakov N.I., Stepina I.V. Secondary resources in production of composite building materials based on cement. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 49-60. In Rus. The relevance of the research is caused by the importance of the problem of rational use of natural resources in production of composite building materials. The possibility of partial replacement of natural non-renewable raw materials used in the production of multi-ton concrete and mortar mixtures based on cement with secondary products from the production of various industries will solve the problems of: resource saving, energy consumption and ecology. The construction industry is the largest consumer of by-products of mining enterprises: overburden and waste from mining and processing enterprises, which is hundreds of millions of tons per year. The most studied are the issues related to their use as fine and coarse aggregates in concrete and mortar mixtures for various purposes. The expansion of the possibility of using secondary products of mining enterprises in the production of composite building materials is associated with the production of active mineral additives, fillers in concrete and mortar mixtures, as well as energetically active nanomodifiers. The use of by-products of different chemical composition and dispersion makes it possible to control the processes of structure formation and hardening of composite materials based on cement and to obtain composite materials with the required performance properties. The main goal of the research is to scientifically substantiate and investigate the possibility of using waste from mining enterprises as components in concrete and mortar mixtures based on cement. Objects: modifying additives based on secondary products; composite materials with enhanced performance properties. Methods: determination of the mobility of mixtures, normal density, hardening time, flexural and compressive strength according to SS; thermal analysis; electron microscopy, x-ray phase analysis, colorimetry. Results. The paper introduces the results of studies necessary for the scientific substantiation, development and implementation in the construction industry of the technology for production of building mortar mixtures obtained using secondary products of mining enterprises as well as the comparative results of studies on the effect of a complex additive of microcalcite and nano-SiO2 on the properties of cement systems. It is shown that the introduction of a complex additive increases the compressive strength of cement stone, reduces the consumption of cement without reducing its standard characteristics and improves the performance properties of concrete.

Regarding the current need for high capacity anode materials in order to further increase the specific energy (Wh kg-1) and energy density (Wh L-1) of LIBs, silicon is one of the most promising candidates. Among different alloying elements, such as tin or aluminum, silicon displays the highest theoretical capacity of 4,200 mAh g-1 (practical: ca. 3,500 mAh g-1) and a relatively low lithiation potential of 0.2 V vs. Li/Li+, compared to the conventional carbonaceous anode materials, displaying a relatively low specific capacity (372 mAh g-1), which cannot meet the growing demand for the next-generation high performance lithium-ion batteries. However, there are some critical drawbacks arising with the use of silicon, which are mainly related to the severe volume changes (up to 300%) during the lithium insertion/extraction process and the low intrinsic electronic conductivity.[1,2] The large stress and strain during lithiation/de-lithiation may lead to particle cracking and even particle pulverization. The volume changes of alloying materials in general also lead to a contact loss between the active material particles and the conductive carbon and/or current collector as well as to an ongoing formation of the solid electrolyte interphase (SEI; dynamic process of breaking off and reforming) and an increase in the overall resistance, thus resulting in an enhanced capacity fading during charge/discharge cycling.[3,4] Several strategies have been developed in order to reduce the detrimental effects of the large volume changes of silicon and to suppress the side reactions with the electrolyte and thus to improve the long-term cycling stability.[3] One main approach is to reduce the silicon particle size to the nanometer range, while several material structures, including e.g. nanowires[5], nanospheres[6] and nanotubes[7], have been proposed. In addition, another strategy is to design porous structures, e.g. macroporous (pore width ˃ 50 nm) or mesoporous materials (pore width of 2 to 50 nm), that can offer sufficient local void space to absorb the volume expansion of silicon and thus to enhance the cycling stability. A further main strategy to improve the electrochemical performance of silicon is the formation of multiphase composite materials, i.e. by introducing a second or more components, which display no or only less volume changes as well as preferentially a high electronic conductivity. The idea of this approach is to use the host matrix to buffer the volume changes of silicon and thus to maintain the electrode integrity and electronic network. Examples are silicon-carbon composite materials, e.g. silicon particles dispersed in a carbon composite matrix[8], and silicon-based alloys or composite heterostructures, such as Si/SiOx/carbon composites[9], or intermetallic compounds like Si/TiSi2[10] or NiSi alloys[11]. In this work, we report a facile synthesis route for a porous core-shell NiSi2/Si/carbon composite material and its electrochemical characterization as anode material for lithium-ion batteries. The as-prepared composite material consists of NiSi2, silicon and carbon phases, in which the NiSi2 phase is embedded in a silicon matrix having homogeneously distributed pores, while the surface of this composite is coated with a carbon layer (Figure 1). The electrochemical characterization shows that the porous and core-shell structure of the composite anode material can effectively absorb and buffer the immense volume changes of silicon during the lithiation/de-lithiation process. The obtained NiSi2/Si/carbon composite anode material displays an outstanding electrochemical performance, which gives a stable capacity of 1,272 mAh g-1for 200 cycles at a charge/discharge rate of 1C. The simple and high-yield synthesis process, using cheap and abundant raw materials, makes it more competitive for industrial applications.

Many types of polymer materials used in engineering are exposed to ultraviolet (UV) light, including automotive components (car bodies, bumpers, dashboards, etc.) which will cause degradation. Some polymers are used in the form of pure polymers and some in the form of composite materials. This study aims to determine the occurrence of degradation in composite materials. This study used polypropylene as a matrix in the composite material sample, while oil palm fiber was used as a reinforcement. This research investigates the degradation of composite materials due to exposure to ultraviolet light. In this research, the degradation of the specimen samples was measured based on changes in Break Strain (BS) and Strain at the Ultimate Tensile Strength (SUTS), related to the length of UV exposure based on 6 different levels of UV exposure, i.e.: 0 hours (UV unexposed), 96 hours, 336 hours, 504 hours, 1008 hours, and 1512 hours. Then the test resulted data was used to generate a strain regression model of BS and SUTS it was obtain from this reaserch that regression model of SUTS is : Y1 = -3.10-9x3 + 7.10-6x2 - 0.0067x + 14.706 with R² = 0.9894 and regression model of BS is : Y2 = 10-8x3 + 2.10-5x2 - 0.0161x + 50.287 with R² = 0.9961. Furthermore, these regression models can be used to predict the maximum strain, of composite materials exposed to UV light for some many time length, which can later be used, to determine the lifetime of the material.