CHEMISTRY OF FABRICS AND DYES

HISTORY OF FABRICS

5,000 B.C….Flax- a material that is used to make linens by spinning and weaving.

3,000 B.C….Cotton was used by the Egyptians. Cotton is made from a whiteish yellow vegetable fiber and will produce different qualities based on different plants.

3,000 B.C….Wool also dates back to around 3,000 B.C. and it was used by people in the Stone Age. Wool comes from the fleece of sheep and lamb and is a much thicker fabric.

NATURAL FABRICS VS. SYNTHETIC FABRICS

Natural fabrics- made of fiber that either comes from an animal, a vegetable or a mineral.

-Examples: Wool, Silk, Linen, Cotton, Flax, and Hemp.

Synthetic fabrics (manufactured fabrics)- developed based on their use, such as in ropes.

-Examples: Rayon, Spandex, Acetate, and Acrylic.

Wool Fabric

Natural Fabrics

Silk Fabric

Flax Fabric

Cotton FabricLinen Fabric

Hemp

Synthetic Fabrics

Rayon Fabric

Acetate Fabric

Acrylic Fabric

Spandex Fabric

SYNTHETIC MATERIALS

Chemical process to form synthetic materials: 1. All synthetic textiles start in a molten liquid

form. 2. That liquid is then forced through a spinneret. 3. Liquid synthetic fabric strings are then cooled

and dried 4. They can then be woven into textiles.

CHEMISTRY OF NYLON

CHEMISTRY OF POLYESTER

CHEMISTRY OF SPANDEX

CHEMISTRY OF RAYON

HISTORY AND GENERAL INFORMATION OF DYES

In aqueous solutions Dye vs. pigment….dyes = soluble and

pigments = not soluble Technique of dying dates back to prehistoric

times Natural vs. synthetic….natural dyes = first

created in 1856 but quickly replaced with synthetic (man made) dyes

Classified according to how they are used in the dyeing process

CLASSIFICATION OF DYES

Organic/Inorganic Natural/Synthetic Area and method of application Chemical classification- Based on the nature

of their respective chromophores. Nature of the Electronic Excitation(i.e, energy

transfer colorants, absorption colorants and fluorescent colorants).

According to the dyeing methods Anionic(for Protein fibre) Direct(Cellulose) Disperse(Polyamide fibres)

DIFFERENT TYPES OF DYES

Group Application

Direct Cotton, cellulosic and blended fibers

Vat Dyes Cotton, cellulosic and blended fibers

Sulfur Cotton, Cellulosic fibers

Organic pigments Cotton, cellulosic, blended fabric, paper

Reactive Cellulosic fiber and fabric

Disperse Synthetic fiber

Acid Wool, silk, paper, synthetic fibers, leather

Basic Silk, wool, cotton

ACID DYES

water-soluble anionic dyes applied to fibers such as

silk, wool, nylon and modified acrylic fibers

Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber.

Stick to fibers by hydrogen bonding, Van der Waals force, and ionic bonding

Structure is made up of Azo dyes, Triphenylmethane, and Anthraquinone

BASIC DYES

water-soluble cationic dyes

applied to acrylic fibers, but find some use for wool and silk

soluble in acid and insoluble in basic solution

Bonded by ionic bonds

DIRECT (SUBSTANTIVE) DYES

Bright and deep colors can be azo compounds,

stilbenes, oxazines, or phtalocyanines

Contain solubilising groups (mainly sulphonic acid groups) in an aqueous solution

dye molecules being held in place mainly through Van der Waals forces and hydrogen bonds

MODIFIERS

Common methyl and ethyl modifiers can be added

Example:

Original dye: red colorAdd four methyl groups to get violet color