Fiber-based hybrid structures

Fiber-based hybrid structures as scaffolds and implants for regenerative medicine... 

Keywords pitch-based high performance-type carbon continuous fiber reinforced plasUc, chemically resolvable resin, environment-conscious materials (ecomaterials) design, deformed rebar, hybrid structure, lighweight precast concrete, recycle, service life,... 

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. 

Modem dashboard constmctions are based on a supporting structure made of sheet metal, a plastic-metal hybrid, fiber-reinforced thermoplastics (GMT [PP]) or dur-oplastics (SMC [UP], SRIM [PUR]). 

Fig. 1 Supramolecular systems described in this chapter. Top-. The extracellular matrix inspires most of the work and consists of fibers to resist tensile stresses such as collagens, fibers to resist compressive stresses such as the glycosaminoglycans, and soluble factors for cell signalling. Bottom Natural systems such as collagen, coiled-coil structures, p-sheet peptides such as peptide amphiphiles and multidomain peptides, hybrid systems such as streptavadin-biotin cross-linked microparticles, and synthetic systems such as the UPy-based hydrogelators...

Carbon nanofibers or vapor-grown carbon nanofibers are sp hybridized one-dimensional carbon nanostructures. Three types of carbon nanofiber structures classified based on the angle of graphene sheets are stacked, cup-stacked, and nanotubular [10]. The diameter of carbon nanofibers lies in between carbon nanotubes (100 nm) and carbon fibers (1000 nm). The synthesis procedures used for carbon nanofibers include chemical vapor deposition (CVD). 

Sp and Sp Bonding. Another important structural characteristic of PAN-based fibers is the probable existence of sp hybrid bonding as indicated by Raman spectroscopy and shown in Fig. 8.10. In this figure, the pitch-based graphitized fiber (PI 00) is the only one to exhibit a strong sp line. All others show structural disorders which may be caused by some sp bonding.t l The fibers listed in Fig. 8.10 are identified in Secs. 6.3 and 6.4 below. 

To summeirize, small ciystallite size, high interlayer spacing, and general structural disorder are the factors that contribute to the unique and stable turbostratic structure of PAN-based carbon fibers (which is likely to include both sp and sp hybrid bonds), and explain their inability to form a graphitic structure even after high-temperature heat-treatment (i.e., 3000°C). 

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