Effects of tempering time and tempering temperature of caustic mercerization on the spectral and electrical properties of Egyptian cotton fibres

Abstract

Several samples of Egyptian cotton fabric strips were subjected to various caustic mercerization conditions, varying in temperature and time. On these samples extensive measurements were undertaken, comprising X-ray diffraction, IR absorption spectra and the temperature-dependence of DC-electric conductivity.The phase constitution, % crystallinity, IR band assignment, activation energies for conduction and energy gap were evaluated as a function of caustic mercerization. The results obtained were correlated and discussed in detail, leading to valuable information of use in the cotton fabric strip industries.Cellulose is a polycrystalline aggregate consisting of small crystalline regions separated by amorphous regions. It is a polymorphic polymer which in its native state crystallizes in a lattice called cellulose I, The mercerizing of cotton fabrics with aqueous solutions of sodium hydroxide alters the molecular arrangement of native cellulose (cellulose 1) with a decrease in the overall crystallinity. Changes in crystallinity and lattice type of cottons after both treatments have been pointed out by many workers.A previous publication [1] described changes in the fine structure and mechanical properties of cotton fibres after mercerization in sodium hydroxide or liquid ammonia~ Fibres at three levels of maturity were treated slack and under tension (small bundles). Both reagents changed the morphology and fine structure, with only slight differences between caustic and ammonia mercerizations. A comparative study of "ammonia and conventional mercerizations" as pretreatments for cotton fabric subsequently crosslinked with butadienediepoxide (BDO) was reported by Jung et al. [2]. BDO was selected as the finishing reagent because it can John Wiley & Sons, Limited, Chichester Akad$miai Kiadr, Budapest

Study on Electrophysical Properties in KMnO4-Doped Grade "Xorazm-150" Cotton Fibers

“…In this case, the temperature coefficient of electrical conductivity is positive, and this is a characteristic of the semiconductor material. Similar properties of CF have been observed by other scientific groups [12]. It was found that the activation energy of KMnO 4 -doped "Xorazm-150" grade of CF is 0.54 eV through the temperature dependence of electrical conductivity.…”

Mechanical and dielectric characterization of hemp fibre reinforced polypropylene (HFRPP) by dry impregnation process

“…Thus, the dry impregnation process does not modify basically the results observed classically. [30] respectively as the cellulose is expected to be the only crystalline constituent in plant fibre. Using synchrotron radiation and neutron diffraction, Nishiyama et al [31] specifies that the structure consisted of two parallel chains having slightly different conformations and organized in sheets packed in a 'parallel-up' fashion, with all hydroxymethyl groups.…”