الفهرس 
Natural protein fibers
Chemical propertiesOnly 14 pages are availabe for public view
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Abstract
Surface modification by means of finishing is very versatile and allows a large number of effects. Nowadays textiles with multifunctional purposes such as ultraviolet (UV) resistance, anti-wrinkle, antibacterial, etc., become more and more popular. Multifunctional effects are essential for producing higher value added textiles. So value addition is converting of raw material into finished product. It increases the aesthetics look of the garment but does not have any effect on the quality of the product. The key aspects of value addition are high price, uniqueness, attractiveness and focusing a business more closely on its targeted market segments. In this thesis, value added can be produced by multifunctional finishing, printing and some embroidery stitches.
The following steps were done:
1. Scouring wool and silk fabrics were selected, taking into consideration the availability in Egyptian market.
2. After testing the durability of fabrics treated with ZnO and PU separately against antibacterial and crease recovery angle and due to the lake of durability of ZnO alone (not durable after 20 washing cycles), so, the addition of polyurethane dispersion which is self-crosslinking binder supports the durability was used.
3. Different mixture of polyurethane concentrations (25, 50, 75, 100 g/L), with zinc oxide concentrations (1, 3, 6, 9 g/L), curing temperatures (100, 110, 120, 130°C) and curing times (2, 3, 4, 5 min.) for polyurethane /zinc oxide mixture were studied. The optimum results obtained were 75 g/L, 6 g/L, 110°C and 2 min respectively in both antibacterial activity and wet crease recovery angle.
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4. Enhancement in the antibacterial activities of the finished wool and silk fabrics against gram positive and gram negative bacteria (Staphylococcus aureus, Escherichia coli) were evaluated. In wool fabric, the percent of bacterial reduction was 95% and 92 % for gram negative and gram positive bacteria respectively. But in silk fabric, the percent of bacterial reduction was 95% and 94% for gram negative and gram positive bacteria respectively. These results may be attributed to the possible mechanism for ZnO antibacterial reduction that caused a release of Zn+2. Zn+2 are toxic to bacteria at very low concentration either in free or in combined state. It kills bacteria via deformation of the cell membrane.
5. Wet crease recovery angle was enhanced in wool and silk fabrics about 354°, 332° respectively due to the presence of polyurethane. Polyurethane has an isocyanic group (—NCO) in its chemical structure which can readily react with the amino group of the fabrics and form a thin layer on the surface of the fiber. This layer forms multispot linkages between fibers, and thus, they lose the freedom of relative mobility.
6. Then, the durability of the finished of both fabrics to repeated laundering cycles were evaluated and showed excellent results, also an enhancement in the durability for the fasbrics finished with the PU/ZnO mixture even after 20 cycles. After 20 cycles, in wool fabric the percent of bacterial reduction was 98 and 93 % for gram positive and gram negative bacteria respectively and in wet crease recovery angle was 356°. But in silk fabric, the percent of bacterial reduction was 98 and 96 % for gram positive and gram negative bacteria respectively and in wet crease recovery angle was 334°. This durability of antibacterial activity and wet crease recovery angle of finished wool and silk fabrics may be attributed to the chemical bonds
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between PU functional groups and amino acid of wool and silk macromolecule.
7. The values of ultraviolet protection factor (UPF) were calculated for finished wool and silk fabrics. It was found that the values for wool fabric gave an excellent protection even after 20 washing cycles (68.71) more than silk fabric that gave a good protection (28.69). This may be due to the reduction in wool fabric porosity associated with consolidation shrinkage, thus, the spaces between the yarns decrease consequently UV protection increased. Wool and silk fabrics were improved after finishing, this is may be due to the metal oxides particles that trapped and covered the entire fabric surface, results more area for diffuse reflection, scattering, and absorption of UV radiation.
8. The physico-mechanical properties (tensile strength, elongation, fabric stiffness, resistant to tearing, air permeability and wettability) of wool and silk fabrics were studied. In wool fabric, the result showed a remarkable enhancement in wettability (from 433 sec. to 8 sec.), resistance to tearing (from 1800 kg to 2733 kg) and air permeability (from 322 cm3/s/cm2 to 371 cm3/s/cm2), increase in stiffness (from 469 mg/m to 570 mg/m) and no obvious effect in elongation and tensile strength. In silk fabric, the result showed a remarkable enhancement in wettability (from 300 sec. to 22 sec.) and resistance to tearing (from 2500 kg to 3400 kg), an increase in stiffness (from 261 mg/m to 350 mg/m) and no obvious effect on the elongation, tensile strength and air permeability. The evident enhancement of tearing strength in both fabrics were due to the existence of PU resin that resists yarn slippage, also the evident enhancement in wettability due to the presence of the hydrophilic functional groups (-OH) of the soft segment of the polyurethane backbone.
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9. Dyeing the wool and silk fabrics with (C.I. Acid Violet 48) before and after finishing to polyurethane only, zinc oxide only and their mixture. In case of finishing then dyeing of polyurethane/zinc oxide mixture of wool and silk fabrics obtained a color strength (K/S) about (13), (3.5) respectively, bacterial reduction % for S. aureus and E.coli about (96 and 98), (94 and 99) respectively and wet crease recovery angle about (358°), (334°) respectively. When comparing this mixture with the unfinished, finished PU only and finished ZnO only, it was found that polyurethane can causative the increase in affinity between the fabric and the dye stuff that enhances the dye uptake but ZnO causative the decrease in the K/S due to the ability of its white pigment as zinc white (ZnO) to raise the lightness of a colored, gray or black fabrics.
10. The fastness properties to wash and light of dyed wool and silk fabrics after finishing were evaluated. In case of wool fabric, the results showed that enhancement in the wash fastness (5) may be attributed to that polyurethane act as a binder make a strong fixation between wool with dye; also, there is an enhancement light fastness (4). But in case of silk fabric, the result showed that there was a slightly decreased of wash fastness (3) and slightly increased in light fastness (6).
11. Six designs were created for women and children clothes, the first was done by draping technique but the remaining designs were executed via pattern method. The polyurethane/zinc oxide treated wool and silk fabrics were used to accomplish these designs and acquire value added properties (Antibacterial activity, U.V. protection, hydrophilicity and wrinkle free) thus maximizing the worth of clothes. Tie & dye and embroidery with hand stitches were used to finish these fashionable designs.