Composite systems hybrid

A more recent trend in polymer materials research is the hybridization of cellulosic polysaccharides with inorganic compounds natural and synthetic layered clays, silica, zeolites, metal oxides, and apatites are employable as nanoscale components. In addition, if mesoscopic assemblies such as liquid-crystalline ordering are used in the construction of new compositional systems, the variety of functionalized cellulosic materials will be further expanded. 

The parametric curves in Figures 6.8 to 6.11 can be used individually to select hybridization ratios to satisfy a particular design requirement or they may be used jointly to satisfy two or more design requirements simultaneously, for example, frequency and impact resistance. Comparable plots can be generated for other structural components, such as plates or shells. Also plots can be developed for other behavior variables (local deformation, stress concentration, and stress intensity factors) and/or other design variables, (different composite systems).This procedure can be formalized and embedded within a structural synthesis capability to permit optimum designs of intrapiy hybrid composites based on constituent fibers and matrices. 

J.T. Blackham, K.S. Vanderwalle, W. Lein, Properties of hybrid resin composite systems containing prepolymerized filler particles, Oper. Dent. 34 (2009) 697-702. 

For the N22 CMC system, remaining open porosity in the CVI SiC matrix was filled by room-temperature infiltration of SiC particulate or slurry casting, followed by the melt-infiltration (MI) of silicon metal near 1400°C. This yielded a final composite with 2% closed porosity within the fiber tows and 0% porosity between the tows. The final composite system (often referred to as a slurry-cast MI composite) typically displayed a thermal conductivity about double that of a full CVI SiC composite system in which the CVI matrix process was carried to completion. Also the composite did not require an oxidation-protective over-coating to seal open porosity. Decreasing the porosity of the hybrid matrix also increased the N22 CMC elastic modulus, which in turn contributed to a high proportional limit stress. However, since the filler contained some low-modulus silicon, the modulus increase was not as great as if the filler were completely dense SiC. 

TABLE 1. Selected mechanical properties and area of application of some glass-containing composite systems with interpenetrating, graded or layered microstructure and hybrid composites. (The fracture strength values quoted are flexural strength data unless otherwise stated). 

The design of particular microstmctures in different glass-containing composite systems, as discussed in this Chapter, leads to composites with specific properties targeted for selected applications in a variety of fields. The variety of processing techniques developed to produce composites with interpenetrating, graded and layered microstmctures as well as hybrid composites was reviewed. A number of specific composite systems was described and their typical properties were presented. 

The main interest in developing composite systems with interpenetrating, graded and layered microstmctures as well as hybrid composites is the improvement of thermomechanical properties. However the composites are usually designed for specific applications where functional properties are also required, i.e. electric, magnetic, dielectric, etc., or a combination of them. 

In the last decade, considerable progress was observed in the field of PO/compatibil-izer (predominantly on the base of PO-g-MA)/organo-surface-modified clay nanocomposites. Polyethylene (PE), polypropylene (PP), and ethylene-propylene (EP) rubber are one of the most widely used POs as matrix polymers in the preparation of nanocomposites [3,4,6,30-52]. The PO silicate/silica (other clay minerals, metal oxides, carbon nanotubes, or other nanoparticles) nanocomposite and nanohybrid materials, prepared using intercalation/exfoliation of functionalized polymers in situ processing and reactive extrusion systems, have attracted the interest of many academic and industrial researchers because they frequently exhibit unexpected hybrid properties synergisti-cally derived from the two components [9,12,38-43]. One of most promising composite systems are nanocomposites based on organic polymers (thermoplastics and thermosets). 

It should be noted that there is not simply an addition of thermotropic LCPs into fiber-reinforced plastics to get in situ hybrid composites. Bafna et al. used glass fibers to decrease the anisotropy of LCP fibril-reinforced polyetherimide [136]. He et al. improved the processability and mechanical performances of glass fiber-reinforced polypropylene by the addition of LCPs [159]. However, these two works did not actively and purposely generate a reinforced composite with the reinforcements having their diameters at two orders of magnitude. The key point for in situ hybrid composites is the formation of LCP fibrils in the material system. As a combination of in situ composite and hybrid fiber reinforcing, the fabrication of in situ hybrid composites utilizes fabrication... 

Nugay, N. Erman, B., Property Optimization in Nitrile Rubber Composites via Hybrid Filler Systems. J.Appl. Polym. Sci. 2001, 79, 366-374. 

Hybrid composite materials (HCM) represent the newest group of various composites where more than one type of fibre is used to increase cost-performance effectiveness, i.e., in a composite system reinforced with carbon fibres the cost can be minimised by reducing its content while maximising the performance by optimal partial replacement with an another fibre or by changing the orientations. HCM include nanocomposites [31], functionally gradient materials [32], Hymats (hybrid materials) [33], interpenetrating polymer networks (IPN) [34], and liquid crystal polymers [35]. 

In civil infrastructure, filament winding is traditionally used to produce pipes, power poles and pressure vessels. Recent years, however, have seen an increase in the use of filament-wound composites in innovative structural systems. The most intuitive of these systems is the combination of filament-wound tubes with concrete to produce hybrid stractural components suitable for civil infrastructure. The FRP tube not only serves as a permanent formwork for the concrete but also provides it with hoop and longitudinal reinforcement. The concrete in return provides the composite system with overall stability and stiffness. 

The type of chemical system that templates can be used for is virtually limitless. Templates have been used for the preparation of pnrely organic materials, ceramic materials, and all other kinds of hybrid and composite systems in between from metallo-organic and coordination systems to polymers. In addition, the phase in which the templates act is extremely varied, from the solntion-state syntheses of molecnles to the growth of layers on crystals and the nse of soft materials for the formation of porons... 

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