Sizing of the fiber

The as-spun acrylic fibers must be thermally stabilized in order to preserve the molecular structure generated as the fibers are drawn. This is typically performed in air at temperatures between 200 and 400°C [8]. Control of the heating rate is essential, since the stabilization reactions are highly exothermic. Therefore, the time required to adequately stabilize PAN fibers can be several hours, but will depend on the size of the fibers, as well as on the composition of the oxidizing atmosphere. Their are numerous reactions that occur during this stabilization process, including oxidation, nitrile cyclization, and saturated carbon bond dehydration [7]. A summary of several fimctional groups which appear in stabilized PAN fiber can be seen in Fig. 3. 

Capability of remote measurements. The small size of the fiber and its electrical, chemical, and thermal inertness allow long-term location of the sensor deep inside complex equipment and thereby provide access to difficult locations where temperature may be of interest. Beyond this, however, certain of the optical techniques allow noncontact or remote sensing of temperature. 

With the appropriate fiber-optic probe and data processing techniques, UV-vis spectroscopy may be used to determine the optical thickness of a transparent thin film. It is possible to simultaneously measure thickness of different layers in a multilayer structure as long as each layer falls within the analysis range of the instrument. Typically, this means layers in the 0.5-150/rm range. A further constraint on this technique is that the layer structure of the film must be smooth on the scale of the spot size of the fiber-optic probe. Neighboring layers must have different indices of refraction in order for them to appear as distinct layers to the analyzer. 

Fiber A fiber is a solid particle, and normally its length is at least three times its width hazard of a particle depends on the size of the fiber. 

Electrospun polymer nanofibers with the smallest fiber diameter were obtained with the highest electrical conductivity. This interprets that the drop in the size of the fibers was due to the increased electrical conductivity [50]. 

Perform the applicable solubility tests. Use acetone first. Time, temperature, and reagent concentration are important, as well as the size of the fiber bunch, yam, or fabric piece. Use the smallest sample possible in order to speed up the test results. 

Fiber-optic sensors may also be combined to form a bundle of fiber applicable to the simultaneous sensing of, eg, physiological pH, oxygen, electrolytes, anesthetics, glucose, creatinine, temperature, and flow rate. This is possible because of the minute size of the fibers. There is considerable industrial activity in this direction. 

The other problem that arises during MO observation is that the SNOM resolution operating in transmission mode is limited not only by the size of the fiber-tip aperture but also by the thickness of the magnetic film [93-96]. 

For the large size of the fibers, the Kc/ARe data varied with sin (0/2) or the square of the scattering wave vector q non-linearly despite the low angles used. We fitted the data using... 

Most of the embedded fiber devices (Table 1) contain small diameter (50-100 pm) multimode fibers. Many researchers further reduce the size of the fiber by acid etching to remove much of the cladding. For example, when starting with... 

Electrospinning [29] is a facUe method to make almost any polymer into nano- and micro-fibers if the polymer can be solution-processed or melt-processed (Figure 7.4). However, due to the low solubility of polyaniline, it is very difficult to make polyaniline fibers thinner than 100 nm. To solve this problem, polyaniline is usually blended with a more soluble polymer to increase the weight percentage of polymer in solution. As a result, the obtained nanofibers are a polymer blend [29—33] this significantly reduces the conductivity of the polymer. Additionally, when the size of the fiber decreases, phase separation may occur, yielding a mixture of nanofibers of polyaniline and other polymers [33]. 

Alumina based fibers are subject to creep, even at low temperatures, This phenomenon is exacerbated by the fine grain size of the fibers [20] [54] [67] [70] [73] [79-80]. At 1200°C and with an applied stress of 70 MPa, the strain rate for the fine-grained Nextel 610 a-alumina fiber is higher than that of Fiber FP with a coarser microstructure. Both strain rates are about one order of magnitude higher than that for a bulk alumina ceramic with a grain size of 1.2 jm. The aeep of Nextel 610 is already measurable at a temperature as low as 900 C under an applied stress of 200-500 MPa [70]. 

Ablation of the surface will remove the surface and reduce the diameter of the fibers. This will weaken the individual fiber but it may increase the net strength of the composite because the plasma will preferentially remove small defects in the surface of the fibers. This will increase the critical flaw size of the fibers. 

An increase in sheath or core polymer concentration led to an increase in the size of the sheath or the core component and, consequently, to an increase in the size of the fiber (Fig. 2.26). 

In the case where one performs time-resolved experiments on real fibers, be they natural or synthetic, the use of SR has some distinct advantages. Because of the nature of a fiber, the interaction section between the x-ray beam and the fiber, which determines to a great extent the quality of the diffraction pattern, is limited by the size of the fiber. It is clear that, for a fixed number of photons in the x-ray beam, the smaller the beam the better the experimental situation is. 

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