Properties Of Composite Samples Research Articles

Study on the Influence of SiO2 on Silicone Rubber Material Used in Cable Accessories

Silicone rubber is an insulating material widely used in DC cable accessories. Its interface is a weak area of insulation. Hydrated silica (SiO2·H2O) is a reinforcing agent commonly used in SR, and its main component is SiO2. Based on the theory of nano-composite dielectric, four kinds of composite silicone rubber samples with different filler contents were prepared by taking silica as the filler and liquid silicone rubber as the matrix. The properties of composite samples were tested. It is found that nano-modification can optimize the surface morphology distribution characteristics of silicone rubber, reduce the roughness, improve the tensile strength, and deepen the trap energy distribution of silicone rubber. The results of the research provide help for the design of DC cable accessories.

COMPARATIVE EVALUATION OF BND 50/70 ROAD BITUMEN MODIFIED WITH SKEPT-60 AND SKN-26 ELASTOMERS

The article provides information on the physical and mechanical properties of polymer-bitumen compositions obtained by modifying road bitumen BND 50/70 with elastomers SKEPT-60 and SKN-26 and determination of the obtained polymer-bitumen composites. The properties of composite samples of various concentrations (2.5, 3.0, 5.0%, 6.5 and 7.0%) were determined: needle depth, softening, brittleness and flash point, stretching and adhesion. It was determined that the physical and mechanical characteristics of polymer-bitumen composite materials obtained at high concentrations (6.5, 7.0%) are improved

Bacterial nanocellulose and softwood pulp for composite paper

Abstract: Scaling biosynthesis of bacterial nanocellulose (BNC) allowed samples of composite paper with an increased proportion of BNC to be obtained. This work aims to study BNC samples and bleached soft wood kraft pulp (BSKP) composite paper with a ratio of components varying across a wide range: 10:90, 30:70, 50:50, 60:40, 70:30, 90:10. The method of paper manufacturing was chosen based on the determinations of strength and deformation properties of composite samples with the BNC:BSKP ratio of 20:80. Surface application of BNT on BSKP handsheet provided for an increase in the strength values (tear resistance – by 37%, burst index – by 17%) and deformation characteristics (tension stiffness – by 66%, fracture work – by 8%, breaking length – by 4%) compared to a reference sample. The formation of composites is confirmed in all samples. Scanning electron spectroscopy revealed that paper composites comprise interlaced micro BSKP and nano BNC fibres. As the proportion of BNC in composites elevated, densification of the structure was observed due to an increased fraction of cross-linked nanosized elements. IR spectroscopy indicated the resemblance of cellulose structure in all samples. It was found that an increase in the degree of polymerisation of composite paper is directly proportional to an increase in the BNC amount in the samples. The filtering ability of composite paper samples against microorganisms in the culture liquid of the Medusomyces gisevii Sa-12 producer was studied. It should be noted that yeast retention is achieved with 70% BNC in the paper composite. The presented properties of the new material determine prospects for its use in filtering microorganisms.

Investigation of Effective Mechanical Characteristics of Nanomodified Carbon-Epoxide Composite by Numerical and Analytical Methods

In this work, the mechanical properties of composite samples prepared using a conventional and nanomodified matrix were studied. The thickness of the monolayers in the samples was 0,2 μm. It was found in experiments, that the addition of fullerene soot as a nanomodifierled to an increase in the mechanical properties of the samples along the direction of reinforcement. At the same time, an improvement in the quality of the contact of the matrix with the fibers in the samples with the nanomodifier was observed: on the fracture surface, the nanomodified matrix envelops the fibers, while the usual matrix completely exfoliates. The obtained effects of changing the strength of composites can be associated, among other things, with a change in the level of residual stresses arising in composites during nanomodification. Analytical and numerical modeling methods are used to explain these effects.

Preparation and Characterization of Calcium Carbonate Reinforced Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) Biocomposites

Background: The objective of this work was to develop biopolymer/calcium carbonate biocomposites with enhanced properties, relative to the neat polymer, by using low-cost filler calcium carbonate (CaCO3). To this end, we selected as matrices Poly (3-hydroxybutyrate-co-3- hydroxyvalerate, PHBV), which has attracted the most considerable interest among the biopolymers in industry. Methods: Novel biodegradable PHBV/CaCO3 composites with 0.1-1 wt% of CaCO3 content were manufactured by melt extrusion. The effect of the CaCO3 on the thermal, barrier and dynamic mechanical properties of the PHBV was comprehensively investigated by SEM, XRD, FTIR, TGA, DSC, and DMA. The water and oxygen barrier properties of the biocomposites were also measured. Results: DSC and XRD analysis showed that CaCO3 served as a nucleating agent, promoting crystallinity and crystal size. The addition of CaCO3 particles has a small effect on lamellae thickness and distribution. DMA measurements showed considerable improvements in storage modulus and viscose damping by incorporating CaCO3 particles. The storage modulus of the PHBV at 20°C in the DMA was increased up to 76% and loss modulus was increased up to 175% when composite was prepared with 0.1wt% coated CaCO3 particle. Water vapor and oxygen permeability were measured to study the effect of particles on the barrier properties of composite samples. Biocomposites exhibited smaller oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) due to the increase in crystallinity and tortuosity of the composite samples. Conclusion: The results of this study have demonstrated that properties of biocomposites prepared by using low-cost commercially available filler are greatly improved to obtain the high-performance composites.

Mn Clusters in Nanoporous Carbon: Magnetic Properties

A method is described for introducing Mn clusters into nanoporous carbon. The resulting magnetic properties of composite samples of this kind are demonstrated in the dynamics of their development in the course of time.

Dielectric Properties of 0–3BCTZO/High Calcium Fly Ash Geopolymer Composites

0–3 Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZO)/geopolymer composites were fabricated by normal mixing of geopolymer paste and BCTZO ceramic particles. Four composites were prepared with BCTZO concentrations of 0, 30, 50 and 70% wt. of total solid (BCTZO+FA). Phase and morphology of composite samples were characterized. The effect of addition of BCTZO ceramic particles on the dielectric properties of composite samples was also investigated. The results showed that high dielectric constant values in the order of ∼105 at frequency of 103 Hz for all composites were obtained. This was due to space charge polarization mechanism.

Cross-property connections for copper–graphite composites

Copper–graphite composite materials in the range of 0–10 vol% of carbon phase were prepared from the mixture of copper and graphite powders by hot isostatic pressing. The microstructure, mechanical (tensile strength, elongation to fracture) and physical (electrical and thermal conductivity) properties of composite samples were investigated, and the cross-property connections were calculated. It was shown that electrical and thermal conductivity cross-property (Lorenz number) is almost constant and increases only slightly (no more than 10 % increase was observed). This implies that in the investigated composition range the Lorenz number of a copper–graphite composite system behaves according to Franz–Wiedemann law for pure metals at constant temperature. On the contrary, the conductivity to tensile strength cross-property connections showed significant linear increase (over 200 % in the investigated composition range) for both electrical conductivity and thermal conductivity of composite materials. The cross-property connections of conductivity to the elongation to fracture exhibit a nonlinear dependence on the volume fraction of graphite.

Multiferroic Properties Of 0.05 NZF - 0.95 Ba0.9-3x/2Sr0.1LaxTiO3 Magnetoelectric Composites

For the present work, the magnetoelectric (ME) composites with composition 0.05 Ni0.8Zn0.2Fe2O4 - 0.95 Ba0.9-3x/2Sr0.1LaxTiO3(NZF-BSLT) with x = 0, 0.01and 0.02 were synthesized by conventional solid state reaction route. The existence of both phases was confirmed by the X-Ray diffraction (XRD) technique. The dielectric properties such as dielectric constant and dielectric loss were measured as a function of temperature at different frequencies. P-E hysteresis loops and M-H hysteresis loops confirm the ferroelectric and ferromagnetic nature of the composite samples.La substitution in ferroelectric phase results in significant improvement in properties of composite samples. The investigated composites seem to be very attractive for multiple state memory devices where data can be stored both as polarization (P) and magnetization (M).

Effects of hexamethylenediisocyanate coupling agent on physical, mechanical, and thermal properties of wood plastic composites

In this study, we investigated the physical, mechanical, and thermal properties of polypropylene/old corrugated container fibers and polypropylene/poplar fiber composites, which were treated with 1, 2, 3, and 4 wt% of hexamethylenediisocyanate coupling agent. Compounding was conducted by a counter-rotating twin-screw extruder, and samples for measurements of tensile, flexural, and impact properties were prepared by an injection molding machine. Thermal properties of composite samples were studied by thermogravimetric analysis and differential scanning calorimetry techniques. Thermal stability and crystallinity content of the prepared composites were determined, as well. The obtained results showed that the addition of coupling agent increased the thermal properties of the composites. Mechanical resulting indicated that by the addition of coupling agent, there was improvement in the tensile and flexural properties but there was declination in impact properties. Scanning electron micrographs taken from failed surfaces of the composite samples showed that the addition of coupling agents resulted in the improvement of bonding between wood fibers and polymer matrix at their interface.

Tensile Properties on Single-Bar Modified Tricot Fabric Reinforced Composites

Four kinds of single-bar modified tricot fabrics are knitted on a Raschel latch needle warp knitting machine with glass continuous-filament yarns. The glass warp knitted fabric/ unsaturated polyester resin composites are produced by manual molding technology. The tensile properties of composite samples are tested on the universal material testing machine. The stress-strain curves, elastic modulus, fracture strengths of composites are analyzed in the course, wale and diagonal directions. The results show that the tensile stress/strain curves of single-bar modified tricot warp knitted fabric reinforced composites were nonlinear. The tensile properties of composites possess obvious anisotropic characteristics. The values of elastic modulus and tensile strength were in relation to the yarn numbers bearing tensile load in tensile directions

The Theoretical Prediction and Experimental Verification of Modal Parameters for Carbon Fiber Reinforced Composites with Sandwich Structure

A innovative structure of sandwich composite rectangular plate with dimensions of 350 ×83.5×9.5mm was designed, it was made of unidirectional prepreg of carbon fibre and woven fabric prepreg of carbon fiber as face materials and paulownia as core material by hand lay-up performing and press molding technology for investigating the dynamic performance such as natural frequency and modal shapes. Based on testing the in-plane and out-plane mechanical properties of composite samples reinforced by unidirectional carbon fibre and carbon fiber woven fabric, a ANSYS FEA dynamic modeling was developed. According to the impulse response modal test method, a modal test system was established. The natural frequency test results showed that the minimum natural frequency of sandwich composite rectangular plate is about 616.45Hz which is higher about 27.5% than that of aluminum rectangular plate reinforced by carbon. The modal experiment indicated that the 1st modal shape, 2nd modal shape, 3rd modal shape and 4th modal shape of the sandwich composite rectangular plate were torsional vibration, flexural vibration shape, torsional flexural vibration and double-flexural vibration separately. It was found the calculating precision of FEA dynamic predication was very high, the dynamic predicating results by FEA could provide fundamental data to the optimal design high speed reciprocating sandwich composite rectangular parts.

Fabrication of 0-3 Non-Lead Based Piezoceramic/Polymer Composites Using Suction Technique

In this research, 0-3 composites between non-lead based piezoceramic and polymer were fabricated using the suction technique. Bismuth sodium titanate (Bi0.5Na0.5TiO3:BNT) which prepared from conventional mixed oxide method was used as active phase whereas epoxy resin was used as matrix phase. The 50% volumetric fraction of BNT/epoxy resin can obtain from suction technique. The physical and piezoelectric properties of composites samples were examined. It can be found that density of composite samples were about 1.78 g/cm3. Moreover, the piezoelectric coefficient (d33) of sample was 13 pC/N. Furthermore, the microstructure of composites was determined using SEM technique.