Fiber changes

Dimensional Stability. Dimensional stabiHty refers to how a fiber changes length under the influence of load or heat. Conventionally described in terms of fiber shrinkage (ASTM D885-64) at a defined temperature, the term has also come to mean time dependent length change or creep. 

Biochemical reconstitution of the 30 nm fiber has recently been succeeded by using a salt-dialysis procedure with a long DNA template (>100 kb) (Hizume et al, 2005). AFM imaging of the reconstituted chromatin has shown that the beads-on-a-string structure of the nucleosomes ( 400 nucleosomes on 100 kb DNA) are converted to a thicker fiber in the presence of histone HI. The thickness of the fiber changes reversibly between 20 nm and 30 nm, depending on the salt environment (in 50 mM and 100 mM NaCl, respectively) (Fig. 4) namely, the linker histone directly promotes a thicker fiber formation in a salt-dependent manner. 

On this level, the collagen fibers change their orientation and lose the uniformity of size and interspace that are specific to the stroma. The cellularity increases (fibroblast, macrophages, lymphocytes, plasmocytes, melanocytes, Langerhans cells). The Descemet s membrane disappears. 

This method utihzes a fused silica rod coated with a thin layer of stationary phase mounted in a holder. During extraction, the fiber is exposed to the sample, and analytes are adsorbed onto the stationary phase and concentrated. After a defined extraction time, the fiber is withdrawn in the holder and then analytes are thermally desorbed in the GC injector. Several types of coatings are commercially available, such as PDMS, polyamide, Carbowax-DVB, Carboxen-PDMS, and PDMS-DVB. Coatings prepared with three kinds of materials are also available (e.g., DVB-Carboxen-PDMS) [71]. Selection of the fiber is mainly based on the principle like dissolves like. For example, PDMS sorbent is suitable for the extraction of hydrocarbons, and the sorbent should be polar for the extraction of alcohols or ketones. The thickness of the coating film determines the sorption capacity of the fiber. Changing the temperature, pH, or ionic strength of the hquid... 

Figure 19.16 shows how nickel fiber changes EMI shielding effectiveness in polycarbonate. Less than 10 wt% fiber is needed to reach the target value." Figure... 

Measuring U-v - spectrum displayed, that modifier concentration of 2% to the mass of a fiber change spectrum considerably. It is necessary to note, that after irradiation the spectrum looks differently absorption bands change to reduction. Possibly, these changes are caused by absorption of CDA decomposition products CDA, which, in its turn, decelerates further polymer decomposition. 

Blending with corn zein protein can strengthen soy protein fibers. Soy—zein blends exhibited increased tenacity and more flexibility. As with soy protein fibers, properties of blended fibers changed with water activity, but the properties were always better with blended fiber systems (Zhang et al., 1997). 

Not only do complex lipids form vesicles, but lecithin-type bilayer crystallites also swell in water to form helical multilayers (Fig. 2.5.16a). The resulting fibers change their shapes continuously and are also of fluid character. 

Scanning electron microgrEQihs were taken for the fibers changing the polymer concentration (Figure 11). It showed a somewhat porous structure at lower... 

IR spectra of treated and untreated bristle coir fibers have also been studied [178], No significant change was noted in the acetic acid-treated fibers in the alkali-treated fibers, a small absorption peak at 1740 cm (perhaps due to carbonyl group) disappeared. With the alkali treatment, the absorption band of 910-1200 cm of the untreated fibers changed to a strong absorption peak at 1020 cm The HCl-treated fiber exhibited a light shift in the absorption peak from 1600 cm to 1620 cm ... 

The swelling of bast and leaf fibers in alkaline solutions is a complex phenomenon. Their structure is more complicated than in the case of pure cellulose. Different components of the middle lamella react in different ways, and rates, in relation to each other and to the cellulose. In addition, the composition of the fiber changes with the time of treatment. A part of the... 

After ultrasonication treatment, the rice straw cellulose fiber changed into small size fibrils. The SEM pictures showed the appearance of untreated (figure 16a) and treated (figure 16b) rice straw cellulose fiber. 

Coalescer pads ineffective temperature too hot/pH incorrect/fibers have the same charge as the droplets/surface tension negative system/wetting properties of fibers changed/fibers weathered and need to be replaced/flow rate too slow... 

A vital property of these model proteins is that they are more ordered above the transition temperature defined by the binodal or coexistence line in Figure 5.3. The polymer component of this water-polypeptide system becomes more ordered or structured on increased temperature from below to above the transition. This behavior is the inverse of that observed for most systems, as discussed above. In particular, we developed the term inverse temperature transition when the precursor protein and chemical fragmentation products of the mammalian elastic fiber changed from a dissolved state, and therefore when molecules were randomly dispersed in solution, to a state of parallel-aligned twisted filaments as the temperature was raised from below to above the phase transition. - ... 

The same generic dry spinning process can be used to fabricate the precursor fiber for a carbon fiber from an infusible polymer, such as polyacrylonitrile, for a polycrystalline aluminate fiber from a sol-gel or for a polycrystalline alumina fiber from a slurry. Again, a high temperature curing step is required to convert the as-spun, amorphous precursor fiber into the final functional fiber. In these cases, however, an amorphous polycrylonitrile precursor fiber changes into a carbon fiber, and an amorphous aluminate precursor fiber into a crystalline aluminate fiber. The final functional fiber is therefore directly derived from a solid and amorphous precursor fiber and only indirectly from a liquid phase, i.e., a melt or sol-gel, respectively. 

This new structure is thermally stable (infusible). Also, it has been reported that during stabilization, CH2 and CN groups disappear while C=C, C=N and = C-H groups form. At the same time the color of precursor fiber changes gradually and finally turns black when carbonized [36]. Research shows that optimum stabilization conditions lead to high modulus carbon fibers. Too low temperatures lead to slow reactions and... 

---