Structure of Non-Polymer Fibers

In the field of tissue engineering, more information on and a better understanding of the wettability and permeability of nanofiber yams, as well as their structural properties as a function of biodegradation, should lead to the development of highly functional tissue scaffolds and wound dressings. Successful electrospinning of other materials, such as metals and non-oxide ceramics, and better control over the crystallinity of electrospun polymer fibers will lead to significant advances in nanofiber reinforced composite materials. 

Non-crystalline polymers or copolymers can also be used to generate fibers with relatively low softening temperatures. Such fibers can be blended with regular fibers, e.g. staples, and bonded together by applying sufficient heat to melt the low-temperature component. Such fibers need not be exotic. The use of undrawn, amorphous fibers suffices for many such purposes, for example, bonded nonwo-ven webs formed from a mix of drawn and undrawn PET staple fibers. Without crystalline structure, the undrawn fibers will soften and become tacky at relatively low temperatures, so providing bond sites. 

When n is odd and 5, the unit cells are orthorhombic and contain either two (n = 1 5) of four (n = 3) chains. The fiber repeat consists of two chemical moieties and the methylene spacers are extended. When n = 7 9, the unit cells are I-centered monoclinic and similar to the those observed for n = 6 8. In the series where n is large and odd (AZMEP-n, n = 11, 13 15), the unit cells are triclinic and closely resemble the triclinic cells found for the high even polymers (n = 10). However, the observed fiber repeats in polymers where n is odd and 7 necessitate the presence of non-trans conformers in the aliphatic portions of the chains. The thermal and mechanical properties of the homologous series of polymers are discussed in light of the observed solid state structures. 

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