Fiber thickness

We control fiber properties by changing the relative speeds of different stages of the process. Orientation is increased and fiber thickness decreased by increasing the final take-up speed relative to the rate at which the molten polymer strands leave the spinneret. To produce high modulus fibers we generally adopt conditions that maximize orientation. Fiber diameters... 

While carbon fiber (thickness on the order of 1000 nm) composites offer very strong materials, carbon nanotubes make even stronger composites. These carbon nanotubes have aspect ratios of over 1000 (ratio of length to diameter). Further, because some carbon nanotubes are electrically conductive, composites containing them can be made to be conductive. A number of carbon nanotube matrixes have been made including using a number of engineering resins, such as polyesters, nylons, polycarbonates, and PPE. 

Figure 6.1 Schematic of laminate lay-up. Insert shows serpentine path that matrix resin and voids might take through connected pores formed by the graphite fibers. Each ply is actually many more fibers thick than is shown...

The largest temperature difference occurs at the center of the tissue (z = 1), and for typical tissue fiber conditions, the maximum temperature difference is w/2 = 1.7 X 10 5oC at the tissue core. A similar increase with the effect of the chemical-binding reaction between myoglobin and oxygen is approximately 1.1 X 10-5oC. Equation (2) shows that the temperature difference increases with the square of the fiber thickness. Since the radii of skeletal muscle fibers are approximately 20 p.m. the temperature difference is not considerable. However, some experiments suggest that there is a temperature effect on the rate of facilitated transport (Dowd et al., 1991). 

FIGURE 13-29 The tensile strength of glass fibers versus fiber thickness [redrawn from a figure in J. E. Gordon, The New Science of Strong Materials, Penguin Books (1991)). 

Metal fibers can be produced by metal-cutting processes, by foil cutting processes, powder metallurgically by the sintering of metal powders which can be extruded with the help of organic binders to fibers, by metallization of non-metalic fibers and also by the controlled chemical dissolution of wires to the required fiber thickness. Thin metal wires and thick metal fibers can in principle be produced by the same methods. 

Boron fibers have at their core a tungsten (ca. 12 to 15 pm in diameter) or carbon fiber, which serves as a substrate during manufacture. Due to the high density of tungsten (19.3 Mg/m- ), a fiber thickness of 100 to 200 pm is necessary to achieve a low overall density for the fiber (ca. 2.6 Mg/m ). Therefore, latterly deposition on carbon fibers (density 1.8 Mg/m, diameter 8 to 10 pm) has been favored. This development has been driven by their commercial availability of carbon fibers. In addition to their low density (ca. 2.0 to 2.3 Mg/m- ) these fibers exhibit a low surface roughness and low internal stress. 

Glass fibers, 69, 80, 82, 85, 86, 129-133, 147 Aspect ratio, 147 Chemical composition, 147 Density, 147 Fiber length, 147 Fiber thickness, 147 Mohs hardness, 147 Moisture content, 147 Specific gravity, 147 Water absorption, 147 Glass floats, 220... 

Figure 5-10 (A) The fiber is composed of peptides arrayed in a parallel /3-sheet with residues in register. (B) Up to six )3-sheets can be laminated together to define the fiber thickness with the peptides oriented perpendicular to the direction of growth of the fiber. Side chain-side chain interactions stabilize the lamination.

The anagen period not only controls hair fiber thickness but it also controls the maximum length that hair can grow. Therefore, one can expect a... 

Although human hair fibers vary in cross-sectional shape, from nearly circular to elliptical, normalizing most elastic and other properties to fiber thickness can significantly reduce experimental scatter. Thickness is usually characterized as fiber diameter or cross-sectional area. Corrections to diameter for ellipticity are generally not employed. Hair fiber dimensions are also necessary to calculate fundamental elastic properties, and dimensional changes are often employed to follow the course of chemical reactions with hair. 

The linear density method is the method of choice, in my opinion, for determining hair fiber thickness (diameter). A fiber is cut to a given length (10cm is convenient), conditioned at 55 to 65% RH, and weighed on a microbalance sensitive to 2pg or better. This gives the fiber weight in g/cm, which is divided by the fiber density, 1.32 g/cm, to obtain the cross-sectional area in cm (A). 

When sufficient fiber thickness has been developed, the form is removed from the slurry, the excess liquid is vacuumed off, and the part separated from the form. 

The data corresponding to concentrations between 0.8-0.9 wt96 were not obtained due to frequent fracturing at these conditions. The effect of increasing fiber thickness followed by an increase of fiber tendon cancels out each other, giving rise to this unstable condition. 

PVA could penetrate into the BC structure and enwrapped the BC fibrils. From the SEM images, it could be observed that the diameter of the composite fibrils was larger than that of unmodified BC [84]. However, the overall structure of BC and BC-PVA composite, fiber thickness, fiber distribution and three-dimensional orientations were quite similar [85]. The SEM examination of BC and BC-PVA revealed that interpenetrated networks could be formed by integrating PVA fiber into the original BC pellicle [85]. The drying method and conditions also have significant effects on the composite structure. The BC-PVA composites dehydrated by freeze-drying process [84] had a structure that was different from those dried in an incubator oven [85]. When PVA fibers are heated, they contract [86]. 

Effective Length Inner Diameter of Fiber, Thickness of Membrane,... 

Glass Fiber (%) Thickness (mm) Tensile Strength (MPa) Young s Modulus (MPa) Break Elongation (%) Hermans Orientation Function... 

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