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This paper presents the results of an investigation of the influence of the aluminum-powder concentration on the thermomechanical characteristics of the composites based on the high-density polyethylene. We show that use of a compatibilizer—maleic anhydride–polyethylene graft copolymer—in a mixture with high-density polyethylene has an influence on the regularity of variation of the thermomechanical curves. We study the influence of various cross-linking agents (dicumyl peroxide and sulfur) on the thermomechanical properties of composites. At a particular dicumyl peroxide and sulfur concentration, the composites might reside in three physical states: solid, highly elastic, and viscous flow.

A rigid-and-flexible interphase was established by a starlike copolymer (Pc-PGMA/Pc) consisting of one tetraaminophthalocyanine (TAPc) core with four TAPc-difunctionalized poly(glycidyl methacrylate) (PGMA) arms through the surface modification of carbon fibers (CFs) and compared with various interphases constructed by TAPc and TAPc-connected PGMA (Pc-PGMA). The increase in the content of N-C═O showed that PGMA/Pc branches were successfully attached onto the CF-(Pc-PGMA/Pc) surface, exhibiting concavo-convex microstructures with the highest roughness. Through adhesive force spectroscopy by atomic force microscopy (AFM) with peak force quantitative nanomechanical mapping (PF-QNM) mode and visualization of the relative distribution of TAPc/PGMA via a Raman spectrometer, a rigid interphase with highly cross-linked TAPc and a flexible layer from PGMA arms as the soft segment were separately detected in CF-TAPc/EP and CF-(Pc-PGMA)/EP composites. The rigid-and-flexible interphase in the CF-(Pc-PGMA/Pc)/EP composite provided excellent stress-transfer capability by the rigid inner modulus intermediate layer and energy absorption efficiency from the flexible outer layer, which contributed to 64.6 and 61.8% increment of transverse fiber bundle test (TFBT) strength, and 33.8 and 40.6% enhancement in interfacial shear strength (IFSS) in comparison with those of CF-TAPc/EP and CF-(Pc-PGMA)/EP composites. Accordingly, schematic models of the interphase reinforcing mechanism were proposed. The interfacial failures in CF-TAPc/EP and CF-(Pc-PGMA)/EP composites were derived from the rigid interphase without effective relaxation of interfacial stress and soft interphase with excessive fiber-matrix interface slippage, respectively. The cohesive failure in the CF-(Pc-PGMA/Pc)/EP composite was attributed to the crack deflection through the balance of the modulus and deformability from the twin-stage gradient intermediate layer.

Polymer and composite materials (PCMs) are widely used in various industries for production of small but complex parts and large-sized body parts subjected to significant loads. The production of more critical parts from PCM has led to the need to develop new compositions, structures and technologies for molding composites. The manufacturing technology of PCMs with a hybrid matrix is presented, one of the components of which retains its "liquid" state after the molding of the products, and the second is completely solid. In the resulting composite, the “liquid” components form an independent phase and together with the main binder material, the PCMs represent a hybrid matrix. The results of dynamic mechanical analysis (DMA) of basalt plastics with hybrid matrices, in which the composition of the “liquid” component are anaerobic technical wax and organosilicon polymer materials, are presented. DMA is performed on samples of two types: № 1 - samples with a low content of "liquid" components in the matrix and № 2 - samples with a high content of "liquid" components in the matrix. According to the results of the tests carried out, the best characteristics among PCMs with various types of hybrid matrices are possessed by samples with an organosilicon polymer material in the matrix

We have obtained polymer composites based on low-pressure polyethylene and carbon-containing fillers: carbon black, carbon nanotubes. The electrical properties of the obtained polymer composites have been investigated. Obtained polymer composites have electrically conductive properties. This article shows that the electrical properties significantly depend on the concentration, type of carbon-containing filler, as well as on temperature and voltage. It was found that containment of a certain amount of carbon-containing fillers leads to a formation of conductive paths composites, leading to the manifestation of a positive temperature coefficient in electrical resistance by the material.

In this paper we present some researches about the static mechanical properties for some composites made in this way: the reinforcement is made from two types of felt and the matrix is from epoxy resin Resoltech 1050 with its hardener Resoltech 1055. There are built some plates from felt/epoxy resin and from these plates there are cut some samples. The samples are tensile loaded on an universal testing machine Instron 1000 HDX which is assisted by a BlueHill software. There are determined the next mechanical properties: Young modulus, yield strength, elongation at break and breaking strength. By using an optical microscope, there are presented some images with the breaking sections.

The morphological and thermal properties of composites containing a bioplastic blend and micro/nano-sized biochar from pyrolyzed jatropha seeds from microwave pyrolyzed jatropha seeds were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The biocomposite samples exhibited a brittle structure with a slightly ductile chip-like appearance. The Fourier transform infrared spectroscopy results for the PLA/PEMA/BC bio-composites were comparable to the PLA/BC biocomposites. A lower bio-filler content had more pronounced peak intensities than the higher bio-filler content biocomposites. The added PEMA compatibilizer in the PLA/PEMA/BC biocomposite showed more pronounced peaks, which indicated slightly improved bonding/interaction between the bio-filler and the matrix. Overall, increasing bio-filler content did not drastically affect the functional groups of the biocomposites. Thermogravimetric and differential scanning calorimetry analysis showed the developed biocomposites had a slight improvement in thermal stability, in comparison to the PLA sample. Improvements in the thermal stability of the PLA/PEMA/BC biocomposite could be attributed to the additional hydroxyl group, which was due to the added PEMA in the PLA and PLA/BC. According to the results of the analysis of the developed biocomposites, the biocomposites were more brittle and had reasonable thermal stability.

Given the inherent manufacturing variabilities and potential for in-service damage of composite parts, the identification of the elastic properties of composites is important to ensuring the safety and the proper performance of the part. The primary objective of this manuscript is to determine, nondestructively, the elastic properties of composite parts, whether as in-situ components that are part of a larger system, or as laboratory coupons. The proposed technique is based on multimode and dispersive ultrasonic guided waves propagating along a single direction, and the inversion of their phase velocity dispersion curves. The inversion procedure utilizes an efficient Semi-Analytical Finite Element method to solve the forward problem, and a Simulated Annealing algorithm as the optimization tool. The method is particularly well-suited for the characterization of composite laminates. In particular, the manuscript presents experimental evidence of the effectiveness of this technique, that was suggested earlier in a solely numerical work previously conducted by the authors. The test results show that reasonable accuracy can be obtained in the identification of four in-plane and three out-of-plane engineering constants of a quasi-isotropic laminate and a highly anisotropic laminate utilizing the single wave propagation direction. Non-obvious sensitivities of certain wave modes to particular constants are explained on the basis of stress coupling phenomena that are revealed by the SAFE wave propagation models. The study gives experimental evidence of the suitability of ultrasonic guided wave inversion schemes to identify the engineering constants of laminated composites, with the potential to properly characterize parts in-situ, because of the insensitivity of guided waves to boundary conditions located outside of the transmitter–receiver path.

This paper reports on studies of tribotechnical behavior under conditions of friction without lubrication and the mechanical properties of fluoroplastic composites with discrete carbon fibers obtained from different grades of fluoroplastic-4 (F-4, PTFE). The particle size of PTFE powder and its mechanical properties influence the tribotechnical properties of composites with carbon fibers. The wear resistance and PV factor are higher and the friction coefficient is lower for the composite based on F-4 grade PN 90, whose powder particles are larger than the PTFE particles of the other studied grades. Composite made of modified fine-particle PTFE (grade TFM 1705) showed the highest modulus of elasticity and strength. It is assumed that large PTFE particles, which affect the mechanical properties of the composite negatively, contribute to a more intense formation of a transfer film during friction, and also reduce the contact area, which reduces the friction coefficient with increasing pressure in the friction zone.

The paper presents the results of a study of the effect of aluminum content on the physicomechanical properties of composites based on high-density polyethylene and low-density polyethylene. The properties of metal-filled composites, such as ultimate tensile stress, elongation at break, elastic modulus, melt flow rate, and heat resistance, were studied. According to the data obtained, the loading of aluminum into the composition of low density polyethylene contributes to a monotonic increase in the ultimate tensile stress and the elastic modulus. When aluminum is loaded into the composition of high density polyethylene, on the contrary, a natural decrease in the ultimate tensile stress and elongation at break of the composites is observed. It is shown that, when using a compatibilizer, which is polyethylene modified with maleic anhydride, a significant increase in the ultimate tensile stress of high-density polyethylene composites is observed. A schematic representation of the structure of composites with an interpretation of the probable mechanism of hardening of the material in the presence of a compatibilizer is given. It is shown that the crystallinity of the initial polyethylene has a significant effect on the hardening effect of composites. Electron microscopic micrographs of the structure of a filled composite without and with compatibilizer are given. A comparative assessment shows that, in the presence of a compatibilizer, aluminum particles are in the bulk of the polymer matrix, i.e., are not in an isolated state. It is assumed that HDPE macrochains free of maleic anhydride (MA) are involved in the formation of crystalline formations, and small sections of macrosegments containing polar groups of MA are concentrated mainly in amorphous regions and in defects in crystalline structures in the form of passage chains. The concentration of PEMA macrosegments containing MA in the narrow amorphous space of HDPE favorably affects the increase in the adhesive forces of interaction on the surface of aluminum particles, which affects the preservation of the ultimate tensile stress at a relatively high level over a wide range of aluminum concentrations.

The article is devoted to research in the development of composite materials based on polyvinyl chloride and industrial waste from the metallurgical, energy and mining industries. The properties of dispersed waste have been studied, which make it possible to speak of the possibility of their use as fillers for polymer compositions. A comparative analysis of the tested physical and mechanical properties is carried out, depending on the characteristics of the particle size of the fillers. It was revealed that from the point of view of construction materials, all the wastes under study can be used as fillers. The development will make it possible to dispose of industrial waste to obtain useful products and save natural non-metallic materials used in the creation of composites.

Alkali treated (5 wt. % alkali was used on the total weight of the alkali solution and the treatment time was 2 h) discontinuous cellulosic fiber (jute and sisal were used as cellulosic fibers and 35 wt. % filler content was incorporated) reinforced chemically modified ZrO2 (ZrO2 was used as 10 wt. % of total filler content. In this context, it is worthwhile to mention that when both fillers were used, the fiber content was taken in the weight ratio of 1:1.) dispersed hybrid unsaturated polyester composites were fabricated by a compression molding technique. The mechanical behavior of the fabricated composites was evaluated at the sub-micron scale by nanoindentation (indentation with an applied load on the composites surface at the nano-metric range) or depth-sensing instrumented indentation technique. The significant effect of incorporation of the dispersing phases within the unsaturated polyester matrix with respect to mechanical properties at microstructural length scale was observed. A marked improvement in the nanoindentation-derived parameters viz. , nanohardness, reduced modulus, elastic recovery, and indentation creep was observed which may be attributed due to the influence of fillers inclusion within the unsaturated polyester matrix. An extensive effort was laid to analyze the dynamic mechanical properties using the sinus indentation mode associated with nanoindentation measurements to further correlate the influence of fillers addition with the indentation-derived parameters.

Made available in DSpace on 2022-04-28T19:40:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Thermoplastic starch (TPS) is a widely studied biopolymer as an alternative to the use of conventional polymers. In this sense, the incorporation of fillers or reinforcements coming preferably from other substances of natural origin, can be an alternative to try to improve some mechanical and thermal properties of starch polymers. Thus, Kraft Lignin (KL), can be an excellent filler to be incorporated, since it presents mechanical and thermal properties and reduces the cost and weight of the final compounds. TPS films were prepared by casting using dimethyl sulfoxide (DMSO) as solvent and additives with 2, 4 and 8% KL. Characterization of TPS films and compositions with KL were carried out by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), Dynamic Thermomechanical Analysis (DMTA), tensile testing and contact angle. Samples were also analyzed for biodegradation and for the ability to remove contaminants in water, Metil Orange (MO), by Ultraviolet-Visible Spectroscopy (UV–Vis). The FT-IR spectra of the films showed bands typical of functional groups derived from starch and lignin, with the intensity of these bands varying among the samples studied. Micrographs revealed slightly different morphologies among the films, but all showed irregular shapes with structures that appeared as plots. Increasing the percentage of KL led to an increase in contact angle values, showing a more hydrophobic behavior. In the TGA analysis, it was possible to observe a change in the main degradation event of the films for lower temperatures, especially of TPS – 4 and 8% KL compared to the TPS film. Films with KL had the peak of maximum degradation shifted to temperatures below the starch film, where the decrease in intensity of the main peak in the TPS - 4% KL and TPS - 8% KL samples demonstrates that there was less mass loss in the event. There was also in the percentage of residue as the addition of KL was increased The DMTA analyses allowed for the conclusion that presence of KL in TPS film allowed for an increase in its energy storage property, and that the loss modulus followed a decreasing order of storage modulus values to TPS - 8% KL from TPS. For the tensile strength property only TPS - 4% KL has significant improvement, and the elongation at break showed an increase for TPS – 4 and 8% KL compared to TPS. Samples showed a continuous and progressive biodegradation process, being completely biodegraded within 10 days. The monitoring of the ability to remove contaminants from water by UV–Vis, also showed promising results of compounds for this application. The best results were obtained, in most tests, for the TPS- 4% KL films. Polymers and Biopolymers Technology Laboratory (TecPBio) Institute of Science and Technology (ICT) Federal University of São Paulo (UNIFESP) Lignocellulosic Materials Laboratory Science and Technology Center for Sustainability (CCTS) Federal University of São Carlos (UFSCar), João Leme dos Santos, km 110 Science and Technology Institute of Sorocaba (ICTS) São Paulo State University (UNESP), Av. Três de Março, 511 Science and Technology Institute of Sorocaba (ICTS) São Paulo State University (UNESP), Av. Três de Março, 511 CAPES: 001 FAPESP: 2019/15976-0 FAPESP: 2019/19401-1 CNPq: 313989/2018-4

Polymeric construction materials based on epoxy resin, carbon fillers, such as graphene nanoplates (GNP), carbon nanotubes (CNT) and fillers of inorganic nature – perlite, vermiculite, sand with improved electrophysical characteristics have been developed. The electrophysical propertieгs of composites obtained in various ways which differ according to the principle of injecting components have been investigated. GNP were obtained in two ways. Size distribution of GNP obtained by electrochemical method is 50 to 150 nm. The average particle size is up to 100 nm. It occurs that these particles tend to aggregate as it is shown by the method of dynamic light scattering. The GNP obtained by dispersing thermally expanded graphite in water in a rotary homogenizer have a particle size distribution of 400 to 800 nm if very small particles and large aggregates are absent. The second method of obtaining GNP is less energy consuming and requires fewer manufacturing cycles, so it is more cost-effective. Obtaining composites using aqueous suspensions of GNP is environmentally friendly. Due to the hydrophobic properties of its surface the electrical conductivity of the system which uses vermiculite is higher than one of that which uses perlite for composites with CNT and GNP. It has been found that the difference of electrophysical characteristics between two systems which contain the same amount of carbon filler is caused by the nature of the surface of dielectric components – sand. By changing the content of dielectric ingredients can expand the functionality of composites if use them for shielding from electromagnetic fields.

The main purpose of the article is to present the new possibilities of producing composite reinforcement with the use of a computer embroidery machine. This kind of production is in line with the principles of sustainable development. The study below presents the results of strength tests of composites containing sevenfold embroidery systems. Each variant included different directions of arrangement of individual layers as a reinforcement. Flax roving was used to strengthen the composite. Flax fibers are characterized by the highest strength among all-natural fibers, at the level of 50–80 cN/tex. The composite was made using the vacuum bag method, using epoxy resin. The embroidery was made on a ZSK embroidery machine, type JCZA 0109-550. The test material was subjected to strength tests—tensile strength, tensile elongation, and bending strength, on the INSTRON machine. Based on the research, it can be concluded that the arrangement of the roving in the direction of the tensile force allowed to obtain the best mechanical properties.

The dielectric properties of chicken feather fibre-natural rubber (CF-NR) composites have been studied at varying frequencies. The effects of alkali treatment, thermal treatment and a three-component dry bonding agent consisting of hexamethylenetetramine, resorcinol and nano silica (HRS) on these properties were studied. Dicumyl peroxide (DCP) and sulphur were used as curing systems in the preparation of the composites. Fibre filled composite systems have higher values of dielectric constant than the gum (unfilled) sample. This is due to the polarization exerted by the addition of fibres into the matrix. The dielectric constant decreases with frequency due to the dropping out of dipolar and interfacial polarization at higher frequency. The dielectric constant values of composites containing alkali treated chicken feather fibres (ACF) were higher because of the increase in number of polar groups after the treatment. The carbonized chicken feather fibre (CCF) incorporated NR composites have highest dielectric constant values because they consist of conducting material in an insulating matrix which leads to interfacial polarization. The dielectric constants of sulphur cured composite samples are higher than the corresponding DCP cured ones. The addition of fibres and with the incorporation of the bonding agents causes an increase in the dielectric constant and decreases the volume resistivity of the composites.

In this study, we have synthesized the composites of polythiophene and titanium dioxide nanoparticles with different TiO2 percentage (3, 5, 7, and 10%) by chemical oxidative polymerization method. The composite materials were characterized by various techniques including Fourier transform infrared spectro-scopy, X-ray diffraction, ultraviolet-visible spectroscopy and electrical conductivity. The results of the photocatalytic evaluation carried out on the synthesized composites show a continuous decrease in the relative concentration of methyl orange with the increase in the concentration of TiO2 in the composite. Whereas, the results of the photocatalytic evaluation carried out on direct mixtures of polythiophene and TiO2 show a considerable increase in the decolorization of methyl orange. The results of the adsorption study of methyl orange on the catalyst materials show an improvement in the maximum capacity adsorption of methyl orange on polythiophene and 40% TiO2 mixture relative to that of pure TiO2 (in 2.3 times) and to that of pure polythiophene (in 1.3 times).

The carbon fiber/epoxy matrix interface plays an important role in the behavior and damage onset of unidirectional fiber reinforced epoxy matrix composites and accurate modeling techniques are needed to study the effects of this complex region on the composite response. In this work, a microscopic cohesive zone model (MCZM) based on atomic potential energy is established for the interface. A multiscale analysis method is proposed for predicting the transverse mechanical properties of unidirectional fiber composites: (1) At the microscale, MCZM is established for the interface; (2) At the mesoscale, a unit cell model is established for the fiber, matrix and interface; and (3) At the macroscale, the homogenization method, failure criteria and damage degradation models are used for predicting the transverse mechanical properties. Subsequently, the transverse mechanical properties and the damage evolution process are simulated with the multiscale analysis method. A comparison between the simulations and experiments shows that: (1) The maximum errors of the predicted transverse modulus and transverse strength are −4.45 % and −1.28 %, respectively; and (2) MCZM can reflect the nonlinearity of epoxy matrix composite materials. Moreover, the effects of the interfacial strength on the macroscopic transverse mechanical properties and the damage onset are analysed. The simulation results show that: (1) The interfacial strength has a more significant effect on the transverse strength and ultimate strain than on the transverse modulus; (2) Decreasing the interfacial strength has a greater effect on the transverse modulus, strength and ultimate strain than increasing the interfacial strength; and (3) The interfacial strength can change the damage onset.

The aim of this research is to develop environmentally friendly, lightweight composites using egg shell, as filler in some thermoplastic polymer matrices Polypropylene (PP), High Density Polyethylene (HDPE), Acrylonitrile-Butadiene-Styrene (ABS) and Polystyrene (PS) polymer; to determine the physico-mechanical properties of the egg shell agro-residue polymer composite, to find if there is any new improvement over the properties of the starting thermoplastic polymer composites.This research work studied the reinforcement potential of egg shell in thermoplastic polymers (HDPE, PS, PP and ABS). Egg shell was collected from the surroundings of Ekwulumili in Nnewi-South L.G.A of Anambra State, Eastern Nigeria where they have been dumped after usage. The research was carried-out at JUNENG NIG LIMITED Enugu, Civil Engineering Department Laboratory University of Nigeria and Chemical Engineering Department Laboratory Ahmadu Bello University (ABU), Nigeria; between May 2016 and August 2018. The agro-wastes were grand into power and incorporated into the virgin thermoplastic polymers as filler at varied levels of 3%, 6%, 9%, 12% and 15%. The virgin thermoplastic polymers were used as the Control in the study. The mechanical properties of the composites produced were determined using American standard for Testing and Materials (ASTM), Standard Testing Methods. The results generally showed significant improvements in the physico-mechanical properties of the egg shell filler composites which were largely influence by the amount of filler in the composites. However, the water absorption capacities of the composites were found to be higher than those of the virgin thermoplastic polymers; an indication that egg shell reinforced at different percentage values are not compactable with polymer matrices due to the hydrophilic nature of natural fibers. HDPE at 15% (8.95%), 3% (4.28%), 9% (3.11%), 12% (0.88%) and 6% (0.85%) and Control (0.00%). PS, at 3% (8.24%), 6% (7.49%), 12% (2.18%), 9% (1.13%), 15% (0.49%) and Control (0.12%). PP, 9% (5.02%), 12% (3.99%), 3% (3.06%), 6% (0.78%) and 15% (0.67%) and Control (0.13%). ABS at 6% (5.52%), 12% (5.03%), 15% (1.50%), 3% (1.02%) and 9% (0.83%) respectively also had very high-water absorption than the Control (0.11%). Brinell hardness property of egg shell/polymer matrix composites had better values than the virgin polymer; HDPE value at 6% (39.48 N/mm2) > 3% (39.46 N/mm2) > 9% = 12% (39.40 N/mm2) > 15% (39.39 N/mm2) and Control (36.44 N/mm2). PS at 3% (39.60 N/mm2) > 6% (39.56 N/mm2) > 9% (39.54 N/mm2) > 12% (39.12 N/mm2) > 15% (38.85 N/mm2) respectively had higher brinell hardness above the Control (37.04 N/mm2). PP had value only at 3% (29.28 N/mm2) that showed lower brinell hardness; 6% (39.35 N/mm2) > 15% (37.55 N/mm2) > 9% (37.36 N/mm2) and > 12% (36.93 N/mm2) respectively showed higher brinell hardness than the Control (36.32N/mm2). ABS; 12% (39.54 N/mm2) > 6% (39.40 Nmm2) > 3% equal to 9% (39.39 N/mm2) and > 15% (39.35 N/mm2) respectively had better brinell hardness than the pure polymer. Abrasion results of all egg shell/polymer matrix composites used (exception of PS) showed poor abrasion values than the Control; For HDPE the value at 3% (29.47 g/s), 9% (25.03 g/s), 12% (23.54 g/s), 15% (23.13 g/s) and 6% (22.36 g/s) and Control (14.57 g/s). PS, at 12% (12.16 g/s), 3% (10.79 g/s), 6% (8.35 g/s),15% (6.69 g/s) and 9% (5.59 g/s) and Control (16.20 g/s). PP had at 12% (55.47 g/s), 6% (47.90 g/s), 3% (40.16 g/s), 9% (32.80 g/s) and 15% (22.11 g/s) and Control (18.02 g/s). ABS at 3% (15.05 g/s), 15% (87.52 g/s), 6% (24.10 g/s), 12% (22.08 g/s), 9% (21.07 g/s) and Control (17.39 g/s). The impact strengths absorbed higher amount of energy than the Control in PP, HDPE, ABS, 3%, 6%, 9% of PS, 3%, and 6% of PP in egg shell composites. HDPE at 12% (3.12 J/mm2) > 3% (2.95 J/mm2) > 6% (2.88 J/mm2) > 9% (2.35 J/mm2) > 15% (1.63 J/mm2) and Control (1.84 J/mm2). In PS, 3% (4.03 J/mm2) > 6% (2.86 J/mm2) > 9% (2.67 J/mm2) >12% (1.48 J/mm2) > 15% (1.25 J/mm2) and Control (1.98 J/mm2). PP at 6% (2.16 J/mm2) and 3% (1.63 J/mm2) showed higher impact strength while 15% (1.23 J/mm2) > 9% (1.08 J/mm2) > 12% (0.91 J/mm2) respectively showed lower impact strength than the Control. In ABS 15% (1.14 J/mm2) absorb lower energy while 9% (1.17 J/mm2) had equal value with control (1.17 J/mm2); at 12% (3.18 J/mm2), 6% (2.16 J/mm2), and 3% (1.38 J/mm2) respectively absorb higher energy than the Control. This study has provided different combinations of agro-waste/agro-residue thermoplastic polymer composites which has potential application in the automobile and building construction industry.

Chemical polymerization of o-phenylenediamine (OPD) in the presence of poly(ethylene oxide), double-wall carbon nanotubes (DWNTs) and ferric chloride is carried out in order to obtain composites based on the poly(o-phenylenediamine)-poly(ethylene oxide) (POPD-PEO) fibres covered and interconnected with DWNTs. Vibrational and photoluminescence properties of these composite materials as well as their morphologies are shown by infrared (IR) spectroscopy, Raman scattering, photoluminescence (PL) and scanning electron microscopy (SEM). An adsorption of DWNTs onto the POPD rods surface in the absence and in the presence of PEO is highlighted by SEM. The vibrational changes reported by Raman scattering and IR spectroscopy prove a covalent functionalization of DWNTs with the macromolecular compound POPD which is doped with FeCl−4 ions. New hydrogen bonds are generated between POPD covalently functionalized DWNTs and hydroxyl groups of PEO according to IR spectroscopic studies. The two macromolecular compounds, POPD and POPD-PEO, show a complex emission band with maxima at 572 and 566 nm, having a shoulder at 667 nm. A significant change in the profile of the PL bands of POPD and POPD-PEO is induced in the DWNTs presence. We show that DWNTs induce (i) a diminution in the POPD PL band intensity peaked between 525–600 nm simultaneous with the increase in the intensity of the PL band situated in the 600–800 nm spectral range and (ii) an enhancement process of the emission band localized in the 475–800 nm spectral range in the case of POPD-PEO.

The present research aimed to investigate the effect of stitching angle and stacking sequence of stitched layers on high velocity impact behavior of composites reinforced by glass woven fabrics. To study the effect of stitching angle on ballistic impact behavior, six different angles of (0°), (90°), (45°), (0°,90°), (±45°) and (0°,90°,±45°) were chosen as stitching angles. These stitching angles were applied on eight layers of glass woven fabric. To study the effect of stacking sequence of stitched layers, a different number of layers were stitched together with the angle of 0°. Unstitched and stitched composites were exposed to high velocity impact with 180 m/s using a spherical projectile. The residual velocity of projectile and dimensions of damage area on the composites’ front and back sides were measured. It was found that the sample with the 45° stitching angle had the best behavior against ballistic impact and its energy absorption was significantly higher than the other samples. Stitching also reduces damage area in front and back sides of the composites and inhibits delamination.

Environmentally friendly commercial applications spurred us to screen a suitable ablative throat material for the hybrid rocket, while preserving its cost-effective advantages as a special chemical motor. In this research, two types of carbon fiber reinforced composites, i.e. carbon/carbon (C/C) composite and Cf/C–SiC–ZrC composite utilized in high temperature environment, were employed to make the hybrid rocket nozzle. By comparison with the high-density graphite, the anti-ablation properties under the firing environment of Ф100mm H2O2-polyethylene hybrid rocket motor were characterized. We used whole felt preform to make C/C composite, whose matrix carbon was coming from chemical vapor infiltration of propylene; and the Cf/C–SiC–ZrC composite, which employs the same whole felt preform to make the low-density C/C billet, by infiltrated with Si and Zr organic precursors and pyrolysis at elevated temperatures repeatedly to make the advanced ceramic matrix composite. The firing test lasted 40s for all the candidate materials and the result indicated that the Cf/C–SiC–ZrC composite, whose average linear ablation rate was only 0.003 mm/s, was the most stable one in the firing environment. The SEM images gave detailed morphologies of those nozzle throat materials and proved that the fiber architecture, together with the glassy ceramic oxide, helped the nozzle to withstand the hybrid motor firing environment.

We investigated the photoconducting and photovoltaic properties of thin film composites derived from poly-N-epoxypropylcarbazole doped with molecules of two organic conductors, namely, tetrathiafulvalene and nickel dithiolene derivatives. These compounds were found to possess hole photoconductivity. The internal photoeffect is a function of the photogeneration of the charge carriers from the additive molecules and charge transport through the donor fragments of the polymer matrix.

In this work, composites based on yttria-stabilized zirconia (3Y-TZP) with additives of 1.5 and 10 wt % multi-walled carbon nanotubes (MWCNTs) were studied. Samples were obtained by spark plasma sintering (SPS) at a temperature of 1500°C. It was found that, after high-temperature sintering, MWCNTs retain their structure and are located along the ZrO2 grain boundaries forming a network structure. It was found that the addition of 1 wt % MWCNTs increases the relative composite density from 98.3 to 99.0%. It was noted that nanotubes can significantly affect the phase composition of composites. The addition of 5 wt % MWCNT partially limits the monoclinic–tetragonal phase transition of ZrO2, and the addition of 10 wt % MWCNTs leads to the formation of a cubic phase of zirconium carbide. It was found that fracture toughness of the composite with 10 wt % MWCNTs increases from 4.0 to 5.7 MPa m1/2.

The paper presents a modification of the asymptotic averaging method for solving the homogenization problem of elastic properties for composite materials. The elasticity of the phase interface is taken into account. The conditions of a soft imperfect interface are considered, which account for a displacement jump on the phase boundary. A review of the interface-modeling methods in composite materials is presented. The finite element method is used for the numerical implementation of the averaging method. A model of a interface finite element is proposed. Elastic properties averaging is adapted to the presence of a discontinuity in the displacement field. Application limits of the soft imperfect interface are estimated in terms of interphase layer properties. The identification of the interface parameters using experimental data is considered. Computational experiments are conducted for dispersed-reinforced and unidirectional composite with isotropic inclusion.

The use of cellulosic fibers from different natural sources as fillers in polymer matrices to improve their properties has been extensively studied in the last years. It is mainly due to the vast availability of natural fibers as well as their biodegradability. The purpose of this present work was to extract cellulose, silica, and cellulose-silica fillers – these last called “hybrids” – from rice husk through delignification and subsequent oxidation and, then, prepare composites with polyamide 6 and improve mainly its thermal-mechanical properties. The content of 10 wt.% of fillers was inserted in PA 6 matrix. Infrared spectroscopy pointed the main characteristic peaks of cellulose and silica of hybrids, as thermogravimetric analysis showed high thermal stability of fillers, allowing their incorporation in PA-6 matrix by extrusion method. Thermo dynamic-mechanical analysis showed, in a general overview, a significant improvement of mechanical properties of composites, as elastic modulus, compared with neat polyamide-6, mainly the one with 2.5 wt% of silica and 7.5% of cellulose. This last also showed increasing of degree of crystallinity, measured by differential scanning calorimetry, showing the extraction efficiency of fillers from rice husk as well as the potential application of composites as structural components in automotive parts.

A study is made of the effect the nature of a heterogeneous highly dispersed additive has on the electrical properties of composites based on an oxygen-ion conductor (calcium tungstate). Heterogeneous doping of CaWO4 is found to sharply increase ionic conductivity, regardless of the physicochemical properties of the dispersed additive. New data on the electrical properties and morphology of CaWO4–SiO2 composites are obtained. It is shown that a composite with 6 mol % nanosized silica has ionic conductivity an order of magnitude stronger than that of CaWO4. The composite effect of increasing ionic conductivity is discussed using the model for the formation of a coherent dispersed system in which a highly conductive film that forms at an interphase boundary acts as a bonding matrix.

The aim of the work is to analyse the effective elastic properties of composites with randomly distributed thin rigid fibres. The matrix is linear-elastic, homogenous and isotropic, and the fibres are perfectly connected to the matrix. Two-dimensional models of composites are analysed using the boundary element method (BEM). The method requires division of fibres and external boundaries of the plate into boundary elements. The boundary quantities are interpolated using quadratic shape functions. The direct solutions are: displacements and tractions along the external boundaries, displacements of fibres and interaction forces between the fibres and the matrix. Three numerical examples are presented in the paper: a single fibre in a circular disc, uniformly distributed parallel fibres and randomly distributed and oriented fibres in a square plate. The influence of distribution and orientation of fibres on effective Young’s moduli, Poisson’s ratios and Kirchhoff’s moduli is analysed. The examples demonstrate the accuracy and efficiency of the method.

In this work, the effect of the methods of synthesis on the phase composition and photocatalytic properties of composites formed in the section of (SrO)0.2(Bi2O3)0.8–BiFeO3 is studied on the examples of the decomposition reactions of methylene orange (MO). The studied compositions have the MO degradation degree ranging from 30 to 62% (C0 = 20 mg/L, catalyst loading of 30 mmol/L) under irradiation for 3 h with a fluorescent mercury lamp. The band gap estimated by the Kubelka–Munk function is lower than 2.6 eV for the studied compositions. This indicates the possibility of their application as photocatalysts of the visible range.

The properties of fiber–matrix interfaces are one of the most important factors that influence the performance of carbon fiber-reinforced polymer (CFRP) composites. Therefore, it is necessary to strengthen the interfacial adhesion between carbon fibers (CFs) and the matrix to obtain composites with excellent properties and meet the future demand for advanced composites. Inspired by Humulus scandens, graphene oxide (GO) was introduced on the surface of CFs to build a barb structure. The structure could achieve a mechanical interlock between CFs and the matrix to obtain good interfacial properties. Most remarkably, the bionic structure could not only effectively enhance the interfacial properties, but also deflect the direction of interfacial crack propagation as supported by detailed micro- and macro-characterizations. Compared with the original CFs, both the interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of treated CFs increased by 49.20% and 54.93%, respectively. Above all, this work verified that the bionic structure has a good effect on the interface, and paves a new path to explore the enhancement methods of the interface.

Polymer composite materials (PCMs) with a hybrid matrix, which increases the deformation properties of structures in specified local zones, are described. The technology of manufacturing PCMs based on basalt and carbon-filled plastic with various modifiers of a hybrid matrix is ​​described. The structure of PCMs with various hybrid matrix modifiers is ​​estimated. The results of determining the deformation properties of PCMs with various hybrid matrix modifiers using dynamic mechanical analysis are presented. The effect of hybrid matrix modifiers on the glass transition temperature of PCM is revealed. The hybrid matrix modifier having the best characteristics is found.

Composite materials are increasingly been used in a variety of fields such as transportation, civil engineering, etc. However, despite their unique characteristics, composite materials have been known to be highly susceptible to fire. To effectively access such risks, the current research studies the intumescent surface coating thickness effect on carbon, glass fiber reinforced epoxy and sandwich composites. These specimens were subjected to 30 kW/m2 flame for 150, and 300 s using butane burner as the fire source. The results showed that tensile, flexure, impact and compression properties decreased rapidly as the heat-exposure time increased. There was a significant improvement in the post-fire mechanical properties in thermally-protected carbon and glass/epoxy laminates and sandwich structures compared to specimens without intumescent protection. This result is due to the intumescent protection and ability of the charred layer to effectively reduce the transferring of heat to the substrate.

Composites with high content of rice husk (80% based on the solids weight) without and with PLA (5%) and PBAT (2.5%) coating were produced and characterized. Thickness, morphology, thermal and mechanical properties, water absorption capacity and hydrophilicity were evaluated. The optical microscopy indicated a more uniform surface after double coating with PLA that was confirmed by the iodine test. The modulus of elasticity and deflection were not influenced by the thin layer of PLA. On the other hand, water absorption capacity decreased with both polymers used as coating, but lower values were reached with PLA. All materials presented hydrophobic character (contact angle higher than 90°) when measured instantly, with a small decreased after 5 min. The samples coated only once with PLA or PBAT showed analogous thermograms to the uncoated composite.

Film samples of composite material based on polylactide (PLA) and a manganese(III) complex with tetraphenylporphyrin containing 0.1–2 wt % are obtained. It is shown by spectrophotometry that this complex is distributed in the PLA matrix in the form of microinclusions. It is determined that the introduction of the porphyrin metal complex changes the glass transition and melting temperatures of polylactide by 1–2°C and increases the degree of crystallinity by 4–5%. It is found that the temperature corresponding to the maximum of the degradation peak of composites is 2–7°C lower compared to pure PLA. The antibacterial effect of the obtained composites against bacteria Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli is shown.

In the present work, two types of composites were produced, both reinforced with 30 vol% of curaua fibers (CF). In the first type, only the fiber was functionalized with graphene oxide (GO), producing the GOCF/EM composite. While in the second, only the epoxy matrix (EM) was functionalized, producing the CF/GOEM composite. The objective of the work was to investigate the influence of functionalization with GO on the tensile properties of these produced composites. In comparison with the non GO-functionalized composite, as control CF/EM, the results revealed an increase in yield strength (64%), tensile strength (40%), Young's modulus (60%) and toughness (28%) of the CF/GOEM composite. The GOCF/EM composites for which the fibers were functionalized with GO also performed better than the CF/EM composite. The ANOVA and Tukey tests confirm this increase. As for ductility, within the standard deviation, no change was observed between samples functionalized by GO and those from the control. For the first time, comparing the results of the composites, it was demonstrated that a polymer matrix functionalized by GO offers superior tensile performance compared to the other types, keeping the same GO concentration in the composite. This fact is corroborated by the analysis of the corresponding fracture mechanisms. Preliminary results of composite with simultaneous functionalization of both fiber and epoxy matrix failed to present superior properties. This might be attributed to high amount of GO, which is apparently not a good reinforcement as the curaua fiber.

The objective of designing a biocompatible and mechanically stable scaffold for hard tissue regeneration was achieved by fabricating diopside/forsterite composites. Superior mechanical strength, slow degradation, excellent antibacterial activity and good cell viability were attained with the increase in forsterite ratio in the composites whereas apatite deposition ability got enhanced as the diopside content was increased. The variation in the rate of apatite deposition on the surface of composites exhibited different surface topography such as nano-structured interconnected fibrous network and globular morphology. The scaffolds after one-month immersion in a physiological environment exhibited good Young’s modulus and compressive strength. Clear and distinguishable prevention of bacterial growth confirms that composites have the potential to inhibit microbial colony formation of nine different clinical pathogens. The composite containing major diopside content was more effective toward S. aureus while the growth of E. coli was inhibited more by the composite containing a higher ratio of forsterite. The interaction of composites with MG-63 cells showed an enhancement in cell viability as the content of forsterite was increased. MTS assay confirmed the cytocompatibility of samples with negligible toxicity effects.

Context: Tetra Pak® is a common material used for the production of food containers. Currently, those containers are recycled by physical separation of the cellulose fibers through a hydro pulped process, but sometimes separating the individual components is not economically viable. This work evaluates an alternative process to obtain composites from recycled Tetra Pak®. Methodology: Tetra Pak® used containers were collected and cut into small pieces at the laboratory. Then, the containers were hot-pressed to obtain sheets in a manual hydraulic press by using different configurations. Samples were cut, and their tensile strength was evaluated (ASTM D3039). Failure analysis of samples was carried out by FE-SEM to identify issues related to processing and to understand the differences in mechanical properties. Results: The results showed that the lowest tensile strength was 9.5 MPa (type I sample) and the highest tensile strength was 37.4 MPa (type III sample). Conclusions: The results of mechanical tests show that this material can be used for non-structural purposes in the building industry. Failure analysis shows that fiber pull-out and delamination are the most important failure mechanisms in type I samples. For type III sample, failure was produced by a sequence of intralaminar fractures. Financing: Instituto Tecnológico Metropolitano de Medellín Resumen Contexto: Tetra Pak® es un material común que se utiliza para recipientes de alimentos. Actualmente, esos contenedores se reciclan mediante la separación física de las fibras de celulosa a través de un proceso de hidropulpeado, pero a veces no es económicamente viable separar los componentes individuales. En este trabajo, se evaluó un proceso alternativo para obtener materiales compuestos de Tetra Pak® reciclado. Metodología: Inicialmente, los contenedores de Tetra Pak® usados se recolectaron y cortaron en trozos pequeños en el laboratorio. Después, los contenedores se prensaron en caliente para obtener laminados en una prensa hidráulica manual utilizando diferentes configuraciones. Después de obtener los materiales compuestos, se cortaron las muestras y se evaluó su resistencia a la tracción (ASTM D3039). El análisis de fallas de las muestras fue realizado por FE-SEM para identificar problemas relacionados con el procesamiento y para comprender las diferencias en las propiedades mecánicas. Resultados: Los resultados mostraron que la menor resistencia a la tracción era de 9,5 MPa (muestras de tipo I). La mayor resistencia a la tracción fue de 37,4 MPa para muestras de tipo III. Conclusiones: Los resultados de las pruebas mecánicas permitieron concluir que el material se puede utilizar para fines no estructurales en la industria de la construcción. El análisis de fallas mostró que el desprendimiento de la fibra es el mecanismo más importante en las muestras de tipo I. Para las muestras de tipo III, la fractura se produjo por una secuencia de fallas interlaminares. Financiamiento: Instituto Tecnológico Metropolitano de Medellín

In this work, the morphological and electrical properties of the composite nanoporous carbon material/thermally expanded graphite or acetylene black have been investigated. Nanoporous carbon material was obtained from plant materials by its thermochemical activation based on potassium hydroxide. The dependence of the specific capacity of the nanoporous carbon/electrolyte electrochemical system on the applied potential was determined by the impedance spectroscopy method. Furthermore, the concentration of charge transfer and the density of states, as well as the flat-band potential of the system under research, were determined based on the Mott-Schottky model.

The compatibility of polypropylene with chemical hydrocarbon structures formed on the surface of basalt fibers is predicted using a nonstandard method of their processing. CCl4 steaming is performed in a flow reactor to replace oxygen atoms with chlorine atoms, after which the chlorinated surface is treated in a stream of CH4 to replace chlorine with hydrocarbon groups. The chemical structure of hydrocarbon groups most compatible with polypropylene is determined by calculations using the Cascade computer program. IR spectroscopy and microanalysis confirm the presence of groups and on the surface of basalt fibers, which are chemically bonded to silicon atoms. The resulting composites based on secondary polypropylene reinforced with processed basalt fibers show a significant increase in the relaxing stress and modulus at all observation times.

Poor dispersion of nanoparticles in polymer matrix would limit the development and application of particulate-filled polymer composites. Therefore, the Sb2O3 nanoparticles were functionalized by a ...

Dependences of the wear resistance of ultra-high molecular weight polyethylene and composites based on it with carbon fibers on contact pressure have been obtained, which make it possible to determine their load capacity in the regime of dry and boundary friction in the environment of various lubricating oils at a sliding speed of a steel counterbody of 0.5 m/s. It has been established that the life of UHMWPE and composites based on it during dry friction with increasing contact pressure is determined mainly not by the wear of the working surface, but by the plastic deformation of the surface layers of the composites due to an increase in temperature in the frictional contact zone. It has been found that the use of gear oil as a lubricant during friction of PCM contributes to the formation of a more durable boundary layer which protects the material from wear

The physic-mechanical properties of filled composites based on secondary polypropylene are investigated. As fillers the dispersed wastes of processing of agricultural plants - buckwheat and oat husk, as well as needles flour and wood flour were used. Water absorption, abrasion, impact strength and bending strength of composites were investigated. It has been proven that oat and buckwheat husks can be effectively used in composites based on secondary polypropylene and replace traditional wood fillers. It has been shown that the physic-chemical properties of the filled composites depend on the structure and physicochemical interactions on the phase separation surface, as well as on the surface properties of the filler particles. It is established that for the production of filled composites with improved physic-mechanical characteristics it is necessary to use fillers with small specific surface and concentration of surface functional groups, and the acid-base characteristic of the surface should be closer to neutral. It is shown that these conditions provide for the formation of a uniform structure of the filled composite with less internal stresses.

LiF–NixMn1−xO composites are prepared by the mechanical milling of LiF and NixMn1−xO (x ≤ 1) solid solution for 72 h. The obtained composites are examined by XRD, charge–discharge measurements, CV, and XPS. X-ray diffraction peaks of LiF–NixMn1−xO are broadened by milling. The diffraction peaks of NixMn1−xO in x

The needs of environmental protection led to the introduction of composites based on the use of plastics reinforced with biodegradable materials or other easily accessible materials. The overall purpose of the research was to experimentally investigate the possibilities of using some accessible reinforcement materials. Textile based on plants fibers and glass fibers were used as reinforcement materials, while the matrix was a polymer type material. An empirical mathematical model was proposed to highlight the effect of the number of glass fiber reinforcements on the tensile strength. The determined mathematical empirical model and graphical representations highlight how the number of glass fiber reinforcements affects the modulus of elasticity of the composite materials.

Сatalyst precursors, substituted by rare-earth and transition metals, promoted with Ru nanoparticles using the modified Pechinimethod (Organic polymeric precursor) have been synthesized. To transform biofuel (ethanol) into hydrogen from the obtained active phases, three different methods were used to synthesize composites with the general formula [LaMn1-xBxO3 + δ / Ln1-yZryO2] (1: 1 by mass), B = Ni, Ru, Ln = Pr, Sm , Ce. Structural and surface properties of the obtained samples of complex oxides and composites were studied using the BET and XPA methods. The textural and structural characteristics of composites differing in the methods of their preparationare presented. Key words: perovskite, fluorite, composites, biomass, hydrogen.