Fibers cross-linking

Further improvements in the properties of PAN-based carbon fibers are likely to emerge through improved stabilization, that is, by creating the ideally cross-linked fiber. On the other hand, as purer pitch precursors become available, further improvements in mesophase pitch-based carbon fibers are likely to arise from optimized spinnerette designs and enhanced understanding of the relationship between pitch chemistry and its flow/orientation behavior. Of course, the development of new precursors offers the potential to form carbon fibers with a balance of properties ideal for a given application. 

Polymerization of methyl methacrylate monomer with cobalt-60 as source of y-rays, Free radical formation is involved in both cross-linking and polymerization reactions This technique is also being applied in the textile finishing field for grafting and cross-linking fibers with chemical agents for durable-press fabrics. 

There are two main ways to incorporate bioactive tags the first is to include the sequence prior to assembly (see Sections 4.1 and 4.2 above for other examples). The second is to link the sequence following assembly either by covalent capture or by chemical cross-linking. Fibers that display these tags not only have typical dimensions of ECM proteins but can interact with cells in a similar way to the ECM. 

Preparation of chemically cross-linked fibers Chemical cross-linking was achieved by extrusion of solutions of E- and K- pairs of polymers at equal concentrations of functional groups into a saturated solution at 50 C of water soluble carbodiimide (EDC, l-(3-dimethy-laminopropyl)-3-ethylcarbodiimide) to form amide bonds between the carboxyl of glutamic acid (E) residues and the e-amino groups of lysine (K) residues. When in an adequately hydrophobic elastic protein-based polymer, the charged carboxylate and amino functions experience a driving force for ion-pairing. The force... 

Figure 6. Mechanical properties of chemically cross-linked fibers.

Glass transition temperature, crystallinity, cross-linking, fiber fillers, plasticizers Molecular weight, chain orientation, reinforcement, rubber additions Molecular motion, reactive groups Free motion of electrons... 

The recovery of direct dye by adsorption on cross-linked fiber was developed and appeared technically feasible. The concentration of amino group fixed in the adsorbent phase was 3.30 mol/kg dry fibers. Atypical direct dye, brilliant yellow was used. The breakthrough cmves for adsorption of the dye were measured for different flow rates, bed heights, influent concentration of the dye, and temperature (Hiroyuki et al., 1997). Chitosan fibers have been studied for the recovery of dyes and amino acids (Yoshido, 1993) but less attention has been paid to the use of this conditioning of the polymer for the recovery of metal ions. 

Co-cross-linking. The azetidinium group reacts with carboxylates on the fiber surface and the covalent bonds are formed. The PAE resin can form chemical bonds with the surfaces of several fibers, hence effectively cross-linking fibers together. When the paper is re-wetted, these chemical bonds remain intact, even after the water has broken all hydrogen bonds between fibers. This mechanism tends to lead to a higher level of wet-strength. 

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