Polylactide fibers (PLA), textured by false twist at different temperatures (135, 150 and 165º C) and draw ratios (1.30, 1.35 and 1.40) were stabilized by the application of a continuous thermal treatment at 100º C and 50 m/min. The effect of thermal stabilization on the microstructure was determined by physicochemical tests such as iodine sorption or differential solubility. Iodine sorption and differential solubility are closely related to the crystallinity of the samples. Stabilization enhances crystallinity and orientation with the result that differences between the samples are diminished. Color value differences, albeit reduced, in some cases exceed the accepted limits. Color absorption is mainly dependent on the orientation and accessibility of the amorphous phase
Actually the yarn cross-section and the cotton fibre cross-section are neither in the form of a circular nor hexagonal. The yarn cross-section tends to concentrate the structure packed form of irregularly polygonal with elliptical form appearance along the length of the yarn, due to tension, twist and yarn count. In the earlier research works (parts 1, 2 and 3) we approached equations to calculate the mayor and minor yarn diameters (D, d) of the RS, OE, and VS spun yarns as elliptical model. In this research work a study of the yarn cross-sectional properties (minor diameter d, mayor diameter D, Eccentricity e, profile cross-section area Ap, real elliptical area Ar, profile circumference Up, real elliptical circumference Ur, the packing density Pd and spun deformation factor Df) as a Comparison between the Ring Spun yarns RS, Open End yarns and Vortex Spun yarns VS. As results the packing density of the VS spun yarns was higher than the OE cotton yarns and less than the RS cotton yarns, by other mean found that the RS cotton yarns more compacted than the VS (6%) and OE cotton yarns (16%). The minor OE yarn diameters (d) increase 14% and 8% than the RS and VS minor diameters respectively while the mayor diameter (D) increase 8% and 5% only respectively, in the same time the minor (d) and mayor (D) VS yarn diameters increase 6% and 3% only respectively than the RS diameters (d, D). The deformation factor of the open end yarns (Df(OE)) was more than the deformation factor of the ring spun yarns (Df(RS)) and vortex spun yarns (Df(vs))
Naik, A.; Montero, L.; Riva, A.; Prieto, R.; Riba, M.; Vidal, E.; Cayuela, D. International Textile, Clothing & Design Conference p. 142-145 Presentation's date: 2010-10 Presentation of work at congresses
Electronic version of an article published as "Enzyme and microbial technology", 08 Desembre 2009, p. 1-5
Wool fibres have been modified with nordihydroguaiaretic acid (NDGA) to improve their performance at use. This water insoluble bi-functional phenolic compound has been grafted on wool through a laccase enzyme catalyzed reaction in an aqueous-ethanol mixture. The capacity of laccase to oxidise NDGA in this aqueous-organic medium has been studied electrochemicaly. The increase of CH2, CH3 and aromatic groups signal in the DRIFT spectra, together with SEM images of the enzymatically-modified fabrics confirmed the covalent grafting of NDGA on wool. This one step enzymatic process for grafting of NDGA improved the physical and mechanical properties of wool fabrics such as shrink resistance, crease recovery and tensile strength. Furthermore, the NDGA imparted to the textile material strong antioxidant activity and UV-protection.