Textile fibers surface study

Crystallinity and disorder are important structural parameters for understanding relationships between structure and physical properties. Flaws and distortions are the main features that limit the ultimate properties of textile fibers. Some of these crazes, cracks and voids are revealed under the electron microscope, either on the surface or in cross sections stained with heavy metals (J, 2). However, these staining techniques (that reveal the main morphological features) make it much more difficult to determine the degree of distortion of the crystalline fraction. Theoretically, line profile studies permit separation of effects due to crystalline size from those due to structural distortions. However, the lack of peaks in semicrystalline fiber x-ray patterns hinders that approach. 

IGC has been used at zero surface coverage to characterize the surfaces of cellulose (5), cellophane (6), and poly(ethylene terephthalate) film (7 ). Surface properties of Intact textile fibers were also studied by IGC (8). Domlngo-Garcla et al. (9 ) have recently characterized graphite and graphltlzed carbon black surfaces with this method, and some zero coverage results on carbon fibers have appeared (10). 

Synthetic fibers do not contain natural impurities although there are added impurities such as sizing materials and oil stains. Therefore, their pretreatment process is simpler than other natural fibers. However, synthetic fibers such as polyester and acrylic have poor wettability, dyeability, and antistatic behavior. After plasma treatment, the fiber surface gets physically altered, and hydrophilic functional groups are introduced to the fiber surface, which improves the wettability of the fiber significantly. In recent years, many researchers have studied ways to modify polyester textile materials, and good results have been obtained (Morent et al., 2008). 

The scanning electron microscope has proven to be a very useful instrument for the assessment of fiber morphology. The three dimensional images produced clearly show surface features, such as the presence of surface modifications, finish applications, wear and the nature and cause of fiber failure. The great depth of field, simple specimen preparation and high resolution have resulted in the SEM providing a major contribution to the study of textile fibers. 

PLA fiber has a number of characteristics that are similar to many other thermoplastic fibers, such as controlled crimp, smooth surface and low moisture regain. One unique property in comparison is that it is the only melt-processable fiber from annually renewable natural resources. The physical properties and structure have been studied by several researchers, and these works confirmed that this polymer has significant commercial potential as a textile fiber. Its mechanical properties are considered to be broadly similar to those of conventional PET, and, probably due to its lower melting and softening temperatures, comparisons to polypropylene are also appropriate. A r6sum6 of the properties is given, although further detail about specific properties will be covered, as appropriate in Section 6.4, PLA Applications ... 

For more profound textile surface modifications, gases such as tetrafluoromethane (CF4) are useful. Specifically, tetrafluoromethane will form a thin hydrophobic layer over textile fibers after use within a plasma discharge. There are a number of studies which indicate that ablation accompanies the deposition of these thin films on fiber surfaces. In reference [30], Yip et al. suggested that shorter CF4 plasma exposure time will lead to more efficient polymerization effects, whereby longer CF4 plasma exposures lead to better surface ablation and lowered surface tension. 

The applications of chitosan for improving dyeability of cotton fabric has been widely studied [73, 177, 48], In the textile area, the higher the active site of chitosan favors the higher the dye adsorption (including natural dye) as well as film formation on fiber surface [92]. Chitosan can easily adsorb anionic dyes, such as direct, acid and reactive dyes, by electrostatic attraction due to its cationic nature in an acidic condition. It is postulated that the affinity of chitosan to cotton would be by Van der Waals forces between them because of the similar structures of chitosan and cotton. 

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