Papers by Keyword: Hybridisation

Abstract: The hybridisation of fibre-reinforced plastics is one of the perspective technological methods that make it possible to reduce the sensitivity of polymer composites to stress concentration and increase their damage tolerance. In this case, hybridisation means a combination of different types of reinforcing fibres in one yarn, one layer or one package. In most published papers, the authors investigated the mechanical behaviour of hybrid fibre-reinforced plastic under static loading or low-velocity impact conditions only. At the same time, statically preloaded structures made of composite materials can also be subjected to high-velocity impact. Tensile or compressive preloading affects not only the amount of energy absorbed by the composite but also changes the deformation and fracture pattern. This paper presents the results of the experimental study of the mechanical behaviour of a woven carbon/aramid hybrid composite under tensile preloading and high-velocity impact. Pre-tensioned specimens of homogeneous and hybrid composites were subjected to a high-velocity impact by a steel spherical projectile with the velocities up to 900 m/s. The experimental results showed that the hybrid composite had the lowest sensitivity of the ballistic limit to the tensile preloading.

Abstract: One of the urgent tasks of the development of new protective structures is to improve the ballistic performance of thermoplastic composites reinforced with synthetic high-strength fibres. Hybrid composites based on various types of fibres or fabrics with different weaving could be a possible solution to this problem. This paper presents the results of computational and experimental studies of hybrid composites based on aramid fabrics with satin and plain weave structures. Numerical modelling based on the reduced ply-level approach was used for the design of hybrid composites. The results obtained during calculations were in good agreement with validation experiments.

Abstract: We review electron spin resonance (ESR) experiments in several concentrated Yb-, Ce-, and Eu-based intermetallic systems. Recent theoretical studies attribute well resolved ESR signals with hybridization effects between 4f and conduction electrons (CE) in the presence of ferromagnetic (FM) fluctuations. We believe that the ESR absorption is caused here by a novel type of ESR excitations – hybridized electronic states, which are created in some strongly correlated electronic systems due to hybridization between the 4f-orbitals and the wavefunctions of the CE of the outer d, s, and p shells in conjunction with FM RKKY interaction.

Abstract: This study develops a nanocomposite structure with magnetism and biocompatibility. Composite structures with magnetism can be applied for biomarkers, specific tissue cell detection and targeted drug therapy. This study adopts a chemical disposition method to prepare Fe3O4 magnetic nanoparticles with the average size of 20-25nm. The complex biocompatible chitosan-alginate membrane covers Fe3O4 magnetic nanoparticles and the thickness of the complex membrane is controlled at 50-80nm. The efficiency of the oligonucleotide (ODN) combination is increased through the high biocompatibility of this composite film. Two groups of different sequences of ODNs and a bridge ODN undergo hybridization. The results show that the intensity at which the Fe3O4 is covered by chitosan-alginate composite film conjugated with ODNs is 2300nN. Furthermore, Fe3O4 covered by complex membrane of chitosan-alginate hybridized with 30 μM ODNs to yield the optimum hybridization intensity of 4528 nN, and the average hybridization intensity of ODNs with different concentration is 3971 nN.

Abstract: Natural fibre-based thermoset composites are generally lower in strength performance compared to synthetic thermoset composites. Hybridization with some amount of synthetic fibre enhanced the mechanical properties of the composites. This study focused on the performance of mechanical properties of hybrid banana/glass fibre reinforced polyester composites. Hybrid composites with different volume ratios of banana to glass fibre were prepared. The reinforcing effect of both fibres in polyester is also evaluated in various fibre loadings. Results showed that both flexural and tensile properties have been improved with the increasing level of overall fibre content loading. Tensile and flexural strength shows great enhancement by the introduction of a slight amount of glass fibre to the banana fibre polyester matrix.

Abstract: Hybridization, especially where only variant natural lignocelluloses are combined, is fast receiving encouraging attention because it offers range of properties that are quite difficult to obtain with a single kind of reinforcement. In this work, tensile strength and modulus of hybridized kenaf/PALF reinforced HDPE composite was examined. Pellets were produced form the mixture of the composite in an internal mixer at 190oC, 40rpm and 25minutes for processing temperature, speed and duration of mixing respectively. The composite sheets with thickness of 1mm produced from pellets were prepared using compression moulding. Then the tensile specimen were prepared and tested using an INSTRON bluehill universal testing machine according to ASTM D638 requirements. All samples were prepared at 1:1 kenaf:PALF ratio; ≤0.25mm and ≤0.5mm fibre length; fiber loading of 10 to 40% were utilized. Linear relationship of tensile modulus was observed with about 26% reduction in tensile strength at 10% fibre loading that subsequently reduced but with a reversal increase at 40% fibre loading. This was attributed to a better supportive load at that fibre content and a better interaction between fibre and matrix. Furthermore, the result also corroborates with the one obtained for the tensile modulus at same fibre loading. The best tensile strength and tensile modulus obtained was 32.43MPa;642.61MPa and 30.01MPa;636.73MPa for 0.25mm and 0.5mm fibre length respectively. Increase in fibre length did not show any significant improvement in tensile strength which may have been coursed by fibre attrition. It is possible to achieve improved mechanical properties if the fibres are given some kind of treatment.

Abstract: We have been interested in the soluble interpolyelectrolyte complexes (IPEC) between DNA and the cationic comb-type copolymers, poly(L-lysine)-graft-dextran (PLL-g-Dex), consisting of a polylysine backbone and abundant hydrophilic graft chains of dextran as a model of nucleic acid-binding proteins. In this paper, we described the kinetic effect of the copolymers on the DNA hybridization. We found that the cationic copolymer at nano molar concentrations in cationic groups accelerated DNA duplex formation by two orders under physiologically relevant conditions.

Abstract: Hybridization is a promising method for core/shell particles by a mechanical shock process involving dry blending and dry impact blending. In this paper, hybridization was used to prepare TiB2/Ni ceramics/metal and TiB2/Al2O3 ceramics/ceramics core/shell particles. The mechanism of the formation and the features of the core/shell particles were analyzed. The nano- Al2O3 particles can be coated on the surface of micron TiB2 particles directly by hybridization, The sub-micron Al2O3 particles can be coated on the surface of micron TiB2 particles, only with the introducing of PE-wax as transition layer. The mechanical properties of cermet sintered from TiB2/Ni core/shell ceramics/metal particles were compared with that from TiB2/Ni blended particles.

Abstract: A novel approach was developed to prepare Ni-coated TiB2 cermet. Fine Ni particles with mean particle size of about 80 nm were impacted onto coarse TiB2 particles having a mean size of about 5 μm to form Ni-coated TiB2 powder by Hybridization. The conventional blended TiB2-Ni powder, as well as Ni-coated TiB2 powder, was sintered by hot pressing (HP) method and Spark Plasma Sintering (SPS) method. Compared with the conventional blended TiB2-Ni cermet, particle features and mechanical properties of the Ni-coated TiB2 cermet were investigated. The microstructure analysis reveals that the thickness of Ni film is around 4 nm. It is concluded that the mechanical properties of Ni-coated TiB2 cermet are superior to the blended TiB2-Ni cermet.

Abstract: Carbon, aramid and glass fibers are inherently superior to conventional textile fibers in terms of mechanical properties as well as other chemical characteristics. Because of inherent advantages and disadvantages associated with each material, it is generally better to hybridize them to fully benefit of their high performance in many practical applications. In this paper, the possibility of hybridizing Carbon/Aramid-, Carbon/Glass- and Aramid/Glass- matrices has been investigated through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of experiments, it was concluded that the hybridized materials has shown better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the Carbon/Glass/matrix combination turned out to be good enough for general purpose applications. However, for high tensile applications, Carbon/Aramid or Aramid/Glass with matrix combinations was better than the other material combinations. The hybridization process was also investigated under an air pressure of 5 bar, a yarn oversupply-rate of 1.5% for reinforced filaments, and 3.5% to 6% for matrix materials, respectively. It was also shown from the experimental results that Carbon/Glass/matrix combination may be desirable for small tensile force applications and Carbon/Aramid/matrix and Glass/Aramid/matrix combinations most suitable for heavy tensile force applications, respectively. As a matrix material, polypropylene and polyester have shown better performance than polyether-ether-keeton in terms of tensile property.