Fiber Mass Fraction Research Articles

Effect of Fiber Content on Shape Memory Properties of GO-CF Reinforced SMPC

In this paper, four groups of shape memory composites with carbon fiber mass fraction of 28.09%, 41.87%, 53.20%, and 63.80% were prepared by vacuum infiltration hot-press forming experimental system. The effect of carbon fiber mass fraction on the shape memory properties of shape memory composites was studied. The results showed that the shape fixed rate and the shape recovered speed of composite decreased with the increase of carbon fiber mass fraction. The shape recovered rate and the maximum recovered force first increased and then decreased, and the shape recovered time increased gradually.

МУКА ЗАРОДЫШЕЙ ПШЕНИЦЫ В ТЕХНОЛОГИИ МУЧНЫХ КОНДИТЕРСКИХ ИЗДЕЛИЙ

The article considers the use of wheat germ flour (WGF) to increase the nutritional value and im-prove the quality of butter biscuits. Wheat germ is a by-product of flour milling. Wheat germ flour contains vitamins B, A, E, magnesium, potassium, manganese, phosphorus, phospholipids, phytosterols, polyunsaturated fatty acids, essential amino acids. Studies have been carried out on the effect of various dosages of wheat germ flour on the water absorption capacity of wheat flour, on the rheological properties of shortcrust pastry and finished products, on the organoleptic and physico-chemical parameters of butter biscuits, as well as on the mass fraction of fiber in the fin-ished biscuits. The introduction of wheat germ flour into the biscuit recipe increases the water ab-sorption capacity of wheat flour, and the rheological properties of the dough change towards an increase in elastic properties. A recipe for butter biscuits has been developed with the addition of 9% wheat germ flour to the mass of flour due to the dry matter of all raw materials. This sample has the best commercial and consumer properties. The physicochemical parameters of such a product differ from the control sample by increased by 2.0% mass fraction of total sugar, 1.3% mass fraction of fat, 0.1% mass fraction of total ash, 1.0% mass fraction of fiber and 6.0% wetta-bility. The optimal sample has twice the maximum static and dynamic stresses compared to the control, which leads to less brittleness and brittleness during transportation of products.

Effects of Polyethylene Terephthalate Fibre Reinforcement on Mechanical Properties of Concrete

Cracked concrete is a problem due to several factors such as poor maintenance, insufficient reinforcement, or steel corrosion leading to crack propagation. There is a need to increase the load-bearing capacity of concrete slabs and increase their life span. The use of waste polyethylene terephthalate fibres in concrete can dramatically alleviate the problem of crack propagation and failure sustainably. Furthermore, the utilization of waste plastic in this manner is environmentally friendly. This study presents the experimental investigation into the mechanical strength properties of concrete with respect to the effect of various mass fractions of polyethylene terephthalate fibre. The polyethylene terephthalate fibres were added at mass fraction of 0.5%, 1.0%, 1.5%, and 2.0%. An experimental investigation was carried out to explore the effect of varying fibre mass fractions on the slump value, rebound number, split tensile strength, flexural strength, and compressive strength. An increase in flexural strength, rebound number and compressive strength was noted with an increase in fibre mass fraction. However, a decrease in split tensile strength was noted. The addition of 0.5% fibre gave the highest compressive and flexural strength of 29.32 N/mm2 and 28 N/mm2, respectively. However, the addition of fibre lowered the split tensile strength beyond the control specimen at all fibre mass fractions. The experimental results of this study indicate that the addition of polyethylene terephthalate fibre enhances the mechanical strength of concrete at low fibre mass fraction percentages. The PET fibre reinforced concrete is suitable for use in paving and ceiling slabs at a fibre addition of 0.5% for optimum workability and mechanical strength.

Interfacial and Interlaminar Shear Strength of Unidirectional Viscose Fibre-Reinforced Epoxy Composites—an Overview of the Comparability of Results Obtained by Different Test Methods

In this study, the apparent interfacial and interlaminar shear strength (IFSS and ILSS) of single fibres and unidirectional (UD) viscose fibre-reinforced epoxy composites were characterised using different test methods. Microbond and pull-out tests were used to analyse the IFSS of single fibres embedded in epoxy and the transverse tensile test was applied to measure the IFSS of UD fibre-reinforced composites. The short beam shear test, single edge notched bending test (SENB), double-notched tensile test and double-notched compression test were applied to characterise the ILSS. The composites were produced from continuous tows with fibre mass fractions of 20%, 30% and 40% and fibres of different fineness (1.7, 3.3 and 28.0 dtex). The results showed that the different test procedures led to different trends of ILSS depending on the fibre mass fraction and fibre fineness used. The transverse tensile test revealed that the IFSS decreased with increasing fibre mass fraction and fibre diameter. A different trend was found with the short beam shear test and the SENB test for the ILSS. Here, higher values were detected with increasing fibre mass content, and the influence of the fineness was less noticeable. The double-notched shear tests (tensile and compression) showed a different trend: the ILSS increased with increasing fibre mass fraction from 20% to 30%. With a further increase to 40%, the ILSS tend to decrease slightly. An influence of the fibre fineness on the ILSS could not be statistically proven. The different trends of the test methods are attributed to the constitution of the composite and the different load application caused by the test procedures.

INVESTIGATION OF SOYBEAN PROCESSING BY FORCING – EXTRACTION METHOD

The study of the influence of physicochemical parameters of different sorts of soybean on the extraction of oil in soybean processing, as were as determining the quality of soybean products – petal, meal and oil. Soybean seed samples of three sorts were selected for the study: Mriya, Skelya and Ukrainka, of different humidity and degree of contamination. The Perten DA 7250 infrared analyzer and physicochemical methods in accordance with DSTU were used to determine the quality indicators of soybean seeds. Skelya sort was noted as more oily (20.36%), and Ukrainka sort as more protein (38.49%), the mass fraction of fiber in the samples is from 5.9 to 6.5%. The scheme of soybean processing by the method of forcing – extraction with hexane at the enterprise of «Tavria Agroinvest» was used. Soybean oil is extracted according to the technological regime of the enterprise. After the process of extraction and distillation of the solvent in the evaporator tank, unrefined soybean oil and soybean meal are obtained. According to the scheme of the extraction process, the quality of the final product will depend on the degree of grinding of raw materials and the quality of the petal. Organoleptic and physicochemical parameters of unrefined soybean oil and soybean meal obtained at «Tavria Agroinvest» from three sorts of soybean seeds were determined. It is shown that from moist materials (18.5%) is obtained oil with higher acid and peroxide numbers. The iodine number and cloud point of soybean oil of this sample are also higher than those obtained for dry seeds. The quality indicators of soybean meal for the studied soybean seed sorts were obtained. Mass fraction of crude protein in terms of absolute dry matter is the largest for the Skelya sort and is 46.2%. Soybean meal sort Mriya is less purified from moisture and crude fat, and its high acid number can shorten the shelf life.

Calibration of the PA6 Short-Fiber Reinforced Material Model for 10% to 30% Carbon Mass Fraction Mechanical Characteristic Prediction.

Short-fiber reinforced composites are widely used for the mass production of high-resistance products with complex shapes. Efficient structural design requires consideration of plasticity and anisotropy. This paper presents a method for the calibration of a general material model for stress–strain curve prediction for short-fiber reinforced composites with different fiber mass fractions. A Mori–Tanaka homogenization scheme and the J2 plasticity model with layered defined fiber orientation were used. The hardening laws: power, exponential, and exponential and linear were compared. The models were calibrated using experimental results for melt front, orientation tensor analysis, fiber length, and diameter and tension according to ISO 527-2, for samples of PA6 which were either non-reinforced, or reinforced with 10%, 15%, 20%, and 30% carbon fiber mass fractions. The novelty of this study lies in the transition from the strain–stress space to the strain–stress–fiber fraction space in the approximation of the material model parameters. We found it necessary to significantly reduce the fiber aspect ratio for the correct prediction of the mechanical characteristics of a composite using the Mori–Tanaka scheme. This deviation was caused by the ideal solution of ellipsoidal inclusion in this homogenization scheme. The calculated strength limits using Tsai–Hill failure criteria, based on strain, could be used as a first approximation for failure prediction.

Effect of Fiber Mass Fraction on Microstructure and Properties of 2D CF-GO/EP Composite Prepared by VIHPS.

Graphene is often used to improve interlaminar fracture toughness of carbon fiber/epoxy resin (CF/EP) composites. It is still a challenge to improve the toughness while maintaining the in-layer properties. In this study, 2D graphene oxide carbon fiber reinforced epoxy resin matrix (2D CF-GO/EP) composites were prepared by a vacuum infiltration hot-press forming experimental system (VIHPS), and three-point flexural and end notch flexural (ENF) tests were carried out. With the increase of the fiber mass fraction in the composites, the mode II interlaminar fracture toughness (GIIC) layers decrease gradually, and the bond property between the fiber and matrix interface layer becomes worse, because the accumulation of dense fiber bundles reduces the matrix penetration ability of cracks. However, the flexural properties increased first and then decreased, and reached the best flexural properties at 64.9%. When the fiber mass fraction is too high, the interlamellar bonding properties will decrease, and the fiber bundles will compress and affect each other. The delamination phenomenon will occur between the layers of the composites, which affects the overall bearing strength and stress limit of the composites. The results of the study show that the composites prepared by VIHPS have excellent mechanical properties, and the content of carbon fiber plays an important role in the influencing factors of the interlaminar and in-layer properties of composites.

Effect of Fiber Type and Content on Mechanical Property and Lapping Machinability of Fiber-Reinforced Polyetheretherketone.

Polyetheretherketone (PEEK) is a novel polymer material with excellent material properties. The hardness and strength of PEEK can be further improved by introducing fiber reinforcements to meet the high-performance index of the aerospace industry. The machinability will be influenced when the material properties change. Therefore, it is crucial to investigate the influence of material properties of the fiber-reinforced PEEK on machinability. In this paper, the main materials include pure PEEK, short carbon-fiber-reinforced PEEK (CF/PEEK), and short glass-fiber-reinforced PEEK (GF/PEEK). The effects of the fiber type and mass fraction on the tensile strength, hardness, and elastic modulus of materials were discussed using the tensile test and nanoindentation experiments. Furthermore, the fiber-reinforced PEEK lapping machinability was investigated using lapping experiments with abrasive papers of different mesh sizes. The results showed that the hardness and elastic modulus of PEEK could be improved with fiber mass fraction, and the tensile strength of CF/PEEK can be improved compared with that of GF/PEEK. In terms of lapping ability, the material removal rates of the fiber-reinforced materials were found to be lower than the pure PEEK due to the higher hardness of the fiber. During the lapping process, the material removal methods mainly included the ductile deformation or desquamation of reinforcing fiber and ductile removal of the PEEK matrix. The lapped surface roughness of PEEK material can be improved by fiber reinforcement.

Tensile and water absorption properties of notched glass fiber/polypropylene and glass fiber/polyoxymethylene injection-molded composites

In this work, the tensile properties and hydrothermal aging behavior of notched glass fiber/polypropylene (GF/PP) and glass fiber/polyoxymethylene (GF/POM) prepared by injection molding were investigated. It is shown that the notch strength ratio (NSR) of GF/PP was higher than that of GF/POM with the same fiber mass fraction. With the increase of the fiber mass fraction, the NSR decreased. After 30 times cyclic loading–unloading tensile process, the decrease rate of tensile strength was not evident at 55% level cyclic loading, whereas the decrease rate was over 15% when cyclic loading reached 85% level. The specimens were exposed to 80 °C hot water to investigate the hydrothermal aging behavior. For the water absorption properties, the weight gain and weight loss of GF/PP barely changed after 1600 h. The weight of GF/POM increased within 25 h, and then reached equilibrium. After 1600 h, the weight loss of GF/POM was below 0.4%. The effect of immersion time on the tensile strength of notched GF/POM was noticeable. The decrease rate of tensile strength of GF/POM reached 21% after 1600 h, owing to the hydrolysis of matrix and the weakened interface between matrix and glass fibers.

Enzymatic Treatment of Spent Green Tea Leaves and Their Use in High-Fibre Cookie Production.

By-products of food industry have been studied as sources of high fibre and antioxidant ingredients for healthy food products, because of their economic and environmental benefits. However, the soluble dietary fibre content of these materials is usually lower than the recommended value that is claimed to bring positive health effects. Enzymatic treatment could be an efficient method for modifying insoluble and soluble dietary fibre contents of these materials. The purpose of this study is to investigate the effects of enzymatic treatment conditions on soluble, insoluble and total dietary fibre mass fractions in spent green tea leaves, and evaluate the quality of dough and cookies when different mass fractions of untreated and treated leaves were added to the recipe. The mass fractions of soluble, insoluble and total dietary fibre in spent tea leaf powder was evaluated after the leaves were treated with cellulase amount of 0-25 U/g for 0 to 2 h. Wheat flour was replaced by untreated and treated spent tea leaf powder at 0, 10, 20, 30 and 40% in cookie formulation. Textural properties of dough, proximate composition, physical properties and overall acceptability of cookies were analysed. The appropriate conditions for enzymatic treatment were enzyme loading of 20 U/g and biocatalytic time of 1.5 h, under which the mass fraction of soluble dietary fibre in spent tea leaves increased by 144.5% compared to that of the control sample. The addition of spent tea leaves led to the increase in dough hardness. Increase in the spent tea leaf amount also enhanced fibre mass fraction, antioxidant activity and hardness of cookies but reduced their overall acceptability. Moreover, the enzymatic treatment of spent tea leaves improved the soluble to total dietary fibre ratio of the cookies, which influenced their textural properties and health benefits. The cookies with added 20% untreated or treated spent tea leaves were overall accepted by the panel. For the first time, spent tea leaves have been treated with enzymes to improve their soluble to total dietary fibre ratio. The treated spent tea leaves are a new promising high-fibre antioxidant ingredient for cookie preparation.

Process Improvement to Restrain Emergency Heating Defect of Composite Insulator

The rod in the composite insulator is a load-bearing component, and glass-fiber-reinforced plastic (GRP) has always been regarded as the most suitable material. However, the investigation reveals that the performance shortcomings of GRP rods are the main cause of emergency heating defects of 131 new 500-kV ac composite insulators in South China. The finite-element simulation is conducted to understand the potential mechanism of heating. It is demonstrated that the holes with moisture distort the electric field, increasing heating power. A hole with moisture in the GRP rod longer than 500 mm could lead to emergency heating defects with temperature rise exceeding 5 K. For the holes in the GRP rod are formed by adjacent voids, the emergency heating defect is inevitable unless the porosity decreases. The fiber infiltration process of the GRP rods is analyzed on the basis of Darcy&#x2019;s Law, and an improved process is proposed to reduce porosity. Maintaining the mass fraction of fiber by at least 70&#x0025; and replacing the damp infiltration fluid in time in the production of GRP rods are necessary to restrain porosity. 300-h water diffusion test with a 50-<inline-formula> <tex-math notation="LaTeX">$\mu \text{A}$ </tex-math></inline-formula> threshold is an effective evaluation method of the GRP rod performance. This method should be used before putting composite insulators into operation.

Оценка показателей качества семян зерновых, масличных культур и продуктов их переработки

We analyzed qualitative (biochemical) and safety indicators (toxic elements) in seeds of cereals, oil crops and products of their processing, the comparison of the biochemical traits of the corresponding crops for two years (yields of 2019 and 2020) was conducted. The purpose of the work is a comparative estimation of qualitative and safety indicators (toxic elements) in seeds of cereals, oil crops and products of their processing (for two years). As material of the research there were used seeds of cereals (wheat, corn), seeds of oil crops (sunflower, soybean) and products of their processing (sunflower cake, sunflower meal, mixed feed for pigs). The analysis was carried out by gravimetric, titrimetric and atomic absorption methods. As a result of the study there were noted the high values of the following indicators: the mass fraction of moisture in seeds of cereals and their processed products; the mass fraction of crude protein and crude fiber in seeds of oil crops and their processed products; the mass fraction of crude fat and crude ash in the seeds of oil crops; concentrations of toxic elements (cadmium and mercury) did not exceed the limit of permissible concentrations. There was practically no change in the concentration in the two-year dynamics in the mass fraction: of moisture in seeds of oil crops; of protein in processed products; of crude fat, crude fiber, and crude ash; the contents of cadmium and mercury in all studied objects.

Preparation of MSBF reinforced PP composites & research on their mechanical and sound insulation properties

Nowadays, most researchers at home and abroad are studying the planting of seashore mallow and the efficient extraction of mallow seed oil, while the remaining mallow stems are generally incinerated or discarded. In fact, there are a lot of bundle fibers in mallow stem bark(MSB), and their physical properties such as strength and modulus are close to those of jute and flax. So developing the fiber-reinforced composites of mallow stem bark fiber(MSBF) has high potential application value. Using mallow stem bark as raw material, MSBF was extracted by alkali degumming process, and MSBF reinforced polypropylene(PP) composites with fiber mass fraction of 40%, 30%, 20%, 10% and 0% were prepared by using alkali-treated MSBF as reinforcement and PP fiber as matrix. The effects of fiber mass fraction on tensile, bending and sound insulation properties of MSBF reinforced PP composites were discussed. The results show that when the fiber mass fraction was 30%, the tensile breaking strength, tensile modulus and bending modulus of the composite were the highest, and the bending strength gradually enchanes with the increase of the fiber mass fraction of MSBF. When the fiber mass fraction exceeds 10%, the voltage peak attenuation rate of MSBF reinforced PP composites increases first and then decreases with the increase of sounding frequency. When the sound frequency is the same, the lower the fiber mass fraction, the worse the sound insulation performance of the composite. When the fiber mass fraction exceeds 30%, the voltage peak attenuation rate decreases.

Effect of carbon fiber waste on steel corrosion of reinforced concrete structures exposed to the marine environment

This study experimentally investigates the possibility of using chopped carbon fiber waste for mitigating steel corrosion in reinforced concrete structures. Chopped carbon fiber waste was surface treated with epoxy to address the uniform dispersal of soft chopped carbon fiber into the cement mixture and prevent galvanic coupling between chopped carbon fiber and steel bars. The steel corrosion of reinforced concrete structures with different chopped carbon fiber percentages has been analyzed via electrochemical corrosion measurements, load-displacement curves and microscopy observation analysis. reinforced concrete beams were subjected to sustained point loading, a mass fraction of 3.5% Sodium Chloride marine wet-dry cycle and 50 °C environments for 360 days. A decrease in corrosion rate was observed in the beams with chopped carbon fiber waste compared to the control beams without chopped carbon fiber. The decreased corrosion rates in beams with 2.5% and 5% chopped carbon fiber (mass fraction of cement) were approximately 20% and 10%, respectively, compared to the beams without chopped carbon fiber. The ultimate strength of beams with 2.5% chopped carbon fiber and 5% chopped carbon fiber was increased by 25% and 17% compared to the control beams. Therefore, chopped carbon fiber waste could be used in reinforced concrete structures for reducing corrosion activity.

Effects of Bleeder Schedule to Fiber Mass Fraction and Composites Surface Topography on Wet Lay-up Manufacturing Process

The thermal protector materials of the rocket’s motor are made by a wet lay-up manufacturing process. Since the fiber mass fraction of the product is low, several experiments were conducted to solve this problem including changing the type of the epoxy resin and selecting the most suitable bleeder schedule. Bleeder cloth application results in increasing the fiber mass fraction. The fiber mass fraction of thermal protector material manufactured by hand lay-up can reach a maximum of 56,78%, whereas vacuum bagging can reach a maximum of 66,43%. Peel ply and breather fabric combination are the best bleeder schedule for the hand lay-up method meanwhile perforated release film and breather fabric are the best bleeders for the vacuum bagging method. Composite surface topography obtained from peel ply is visible on the surface. The imprints of the nylon peel ply weave are visible through SEM analysis. Meanwhile, the surface topography obtained from the perforated release film is not visible. The vacuum bagging method helped reduce the number of voids and ductile polymer fractures from the composite surface. This paper recommends peel ply usage in the thermal protector manufacturing process to replace the sanding or filling method that the author use nowadays.

On mean field homogenization schemes for short fiber reinforced composites: Unified formulation, application and benchmark

This paper revisits the topic of mean field homogenization for short fiber reinforced composite materials. A short glass fiber reinforced thermoplastic polyamide 6.6 with a fiber mass fraction of 35 % is used as an example material for which microstructural analyses and experimental tests were performed. We cover a set of common models: the Self-Consistent (SC), Mori–Tanaka (MT), Ponte Castañeda-Willis (PCW), Interaction Direct Derivative (IDD) and Two-Step (TS) schemes. We first recast them into a unified formulation that permits a thorough theoretical comparison, including the topics of loss of major symmetry as well as connections between the models. We are able to show that the MT, PCW and IDD schemes can be expressed in a surprisingly similar form. This extends to the equations for prediction of effective stiffness and compliance tensors as well as the strain and stress localization tensors. Secondly, we address the resolution of the material microstructure within mean field homogenization schemes, comparing classical and more recent and efficient methods. Last, we benchmark the different mean field schemes and modeling approaches, including comparisons to numerical homogenization by Fast Fourier Transformation (FFT) and experimental data from tensile tests. These show that the MT and TS schemes are both capable of accurately modeling the composite material for complex orientations and homogeneous fiber phases. For possibly inhomogeneous fiber phases only the TS scheme yields both accurate and physically reasonable results. Other models such as the IDD or PCW are of great theoretical importance, but cannot be generally applied for the given material class.

Табиғи хош иісті дәмдеуіш қоспалары бар жемісті көкөніс жартылай фабрикаттарының технологиясын жетілдіру

The sharp deterioration of the environmental situation in the Republic of Kazakhstan, associated with human activity and the impact of harmful factors on the environment, affected the quality of food consumed by insufficient consumption of domestic fruit and vegetable products containing vitamins, minerals of an alkaline nature, carbohydrates, vegetable proteins, pectin substances and active fiber. The problem of improving the quality of growing and processing fruits and vegetables is one of the main tasks of the food independence of the Republic of Kazakhstan. Currently, the share of large vegetable farms in the Republic of Kazakhstan is only 10%. The volume of industrial processing of fruit and vegetable crops in Kazakhstan is insignificant. The demand for domestic fruit and vegetable products in the country is met only by 35-40%, most of it is imported from countries such as Russia, Kyrgyzstan, Uzbekistan and China. There is a need for the development of organic vegetable growing in Kazakhstan and the creation of new types of domestic fruit and vegetable products containing a sufficient amount of useful and active substances that can bind and remove toxic substances and radioactive elements from the human body. The purpose of the work is to improve the technology of fruit and vegetable semi-finished products with natural spicy and aromatic additives, to develop a multi-component recipe for vegetable mixtures and a method for producing quick-frozen vegetable mixtures with high quality indicators. These studies were aimed at studying the chemical composition and functional and technological properties of vegetables and spicy - aromatic plants for the content of biogenic compounds: carbohydrates, proteins, vitamins, essential oils, minerals and other substances. The structure of plant tissues was studied and the mass fraction of moisture, dry matter, fiber, mono - and disaccharides, pectin substances, vitamin C was determined, the formulation and production technology of Assorted vegetable mixtures were developed, and quality indicators were determined.

Design of tungsten fiber-reinforced tungsten composites with porous matrix

To overcome the brittleness of tungsten, tungsten fiber-reinforced tungsten composites (Wf/W) have been developed using an extrinsic toughening mechanism. In this work, a novel type of Wf/W with porous matrix produced by field assisted sintering technology (FAST) is studied. The material is optimized regarding mechanical behavior, standing on the adjusting of matrix porosity and fiber mass fraction. Two series of samples with different matrix density and fiber mass fraction are prepared. Based on the mechanical testing, porous matrix Wf/W can represent a promising pseudo ductile behavior. Relatively lower matrix density is helpful to avoid a sudden load-drop during crack opening. The different fracture behavior is attributed to the different fiber/matrix interface bonding condition. By increasing fiber mass fraction from 20% to 50%, porous matrix Wf/W can facilitate improved mechanical properties regarding fracture toughness and strength. However, by further increasing the fiber mass fraction from 50% to 60%, a deterioration of mechanical properties is observed. The high porosity of porous matrix Wf/W causes a degradation of the thermal conductivity compared to conventional bulk tungsten. No significant change regarding thermal expansion coefficient is observed when decreasing the matrix density.

Residual Fiber Length and Fiber Orientation of Anisotropic Injection Molded Glass Fiber Reinforced Polyamide 66 Composites in Experimental and Numerical Study

This paper aims to investigate glass residual fiber length and fiber orientation of anisotropic injection molded glass fiber reinforced polyamide 66 composites (GF/PA66). A combined experimental and numerical study was carried out to investigate the effects of initial glass fiber length and fiber mass fraction on the finished samples. The model was validated with the experimental value. The glass fibers were oriented during the injection molding, and subsequently the composites exhibited anisotropic properties. Additionally, with the increase of fiber mass fraction, more fibers become oriented in the flow direction (Y direction). Moreover, the samples had a skin-core-skin structure and the residual fiber length in the skin layer was shorter than that in the core layer. Furthermore, with the increase of length-diameter ratio of initial fiber ranging from 50 to 90 and the increase of fiber mass fraction, the damage sustained by glass fiber during manufacturing aggravated and subsequently the loss rate of fiber length increased.

Electromagnetic wave absorption of periodic cylindrical structured gypsum composites incorporate with different carbonaceous materials

To improve the impedance matching condition and broaden the effective absorbing bandwidth, a series of cylindrical periodic structured gypsum composites with different kinds of carbonaceous materials as absorbents were fabricated by two-step molding process. The influences of the mass fraction of helical carbon fiber (HCF), carbon nanotube (CNT), and graphene (GE) on the morphology, permittivity, resistivity, and electromagnetic (EM) wave absorbing properties of the proposed gypsum composites were investigated. The experimental results show that the composite with 2 wt% HCF exhibits optimum EM wave absorption performance, its reflection loss is lower than − 10 dB in 2–18 GHz and bandwidth thickness ratio coefficient reaches 0.8 GHz/mm. The EM wave absorption mechanisms were further explained by the simulation of EM field and power loss distribution. The dielectric loss of carbonaceous absorbents, the destructive interference, and the EM wave diffraction and multiple refractions caused by the periodic cylindrical arrays are the main EM wave attenuation mechanisms of the fabricated composites. This study could provide guidance for the design of broadband EM wave absorbing materials.