Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
Surface Modification of Cellulose Acetate with Cutinase and ...
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Subchapter 2.1<br />
major material <strong>of</strong> commerce, produced by the oxidation <strong>of</strong> ethylene followed by ring<br />
opening <strong>with</strong> water. The large-scale production <strong>of</strong> all PET monomers assures low-cost<br />
polymers <strong>and</strong> makes competition from new compositions <strong>of</strong> fiber-forming polymers<br />
very difficult.<br />
2.2. PET fibres properties<br />
PET fiber has excellent properties like convenient processability <strong>and</strong> tailorable<br />
performance, associated <strong>with</strong> low cost production. Undesired characteristics <strong>of</strong> the most<br />
widely used synthetic fibres based on polyethyleneterephthalates (PET) include<br />
difficulties in finishing, build-up <strong>of</strong> electrostatic charge, the tendency to pilling,<br />
insufficient washability <strong>and</strong> wearing comfort due to low water absorbency (East, 2005).<br />
Although alkaline treatment <strong>of</strong> PET can easily increase hydrophilicity, favourable<br />
properties such as strength are negatively influenced (Zeronian <strong>and</strong> Collins, 1989).<br />
3. Polyamides<br />
3.1. Aliphatic polyamides<br />
Aliphatic polyamides are macromolecules whose structural units are characteristically<br />
interlinked by the amide linkage –NHCO-. The nature <strong>of</strong> the structural unit constitutes a<br />
basis for classification. Aliphatic polyamides <strong>with</strong> structural units derived<br />
predominantly from aliphatic monomers are members <strong>of</strong> the generic class <strong>of</strong> nylons,<br />
whereas aromatic polyamides in which at least 85% <strong>of</strong> the amide linkages are directly<br />
adjacent to aromatic structures have been designated aramids (Reimschuessel, 1998).<br />
54<br />
3.1.1. Polyamide 6,6<br />
Among various nylon compositions, nylon-6,6 is by far the most important polyamide<br />
for the commercial production <strong>of</strong> fibers. Nylon 6,6 is a copolymer <strong>of</strong> diamine<br />
(hexamethylene diamine) <strong>and</strong> diacid (adipic acid). These molecules alternate along the<br />
chain, each donating 6 carbons to the polymer.