Accordion pleats

Narrow, regularly spaced straight creases, usually parallel, and capable of being closed up against each other.(sub category pleats)

Accordion pleats

Narrow, regularly spaced straight creases, usually parallel, and capable of being closed up against each other.

Accuracy (testing)

The degree of agreement between the true value of the property being tested and the average of the many observations made using the test method.
Note: The word 'bias' is also used in this sense.

Acetate (fibre) (generic name)

A manufactured fibre of cellulose ethanoate (acetate) wherein less than 92%, but at least 74% of the hydroxyl groups of the original cellulose are ethanoylated (acetylated). (See also Classification Table p.401.).
Note: In the U.S.A. acetate is defined as a manufactured fibre in which the fibre-forming substance is cellulose acetate. Where not less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description of the fibre.

Acetate Fiber

A manufactured fiber in which the fiber-forming substance is cellulose acetate (FTC definition). Acetate is manufactured by treating purified cellulose refined from cotton linters and/or wood pulp with acetic anhydride in the presence of a catalyst. The resultant product cellulose acetate flake is precipitated purified dried and dissolved in acetone to prepare the spinning solution. After filtration the highly viscous solution is extruded through spinnerets into a column of warm air in which the acetone is evaporated leaving solid continuous filaments of cellulose acetate. The evaporated acetone is recovered using a solvent recovery system to prepare additional spinning solution. The cellulose acetate fibers are intermingled and wound onto a bobbin or shippable metier cheese package ready for use without further chemical processing. In the manufacture of staple fiber the filaments from numerous spinnerets are combined into tow form crimped cut to the required length and packaged in bales.

Acetic Acid

An organic acid (CH3COOH) widely used in textile applications. It is used in textile wet processing dyeing and printing and in the manufacture of cellulose acetate and cellulose triacetate.

Acetic acid value

In the characterisation of cellulose acetates, the percentage by mass of combined ethanoyl (acetyl) radical expressed as ethanoic (acetic) acid.

Acetic Anhydride

Anhydrous acetic acid [(CH3CO)2O]. It is used in the acetylation process in the manufacture of cellulose acetate.

Acetone

Dimethyl ketone (CH3COCH3). One of the most powerful organic solvents. Acetone dissolves secondary cellulose acetate and other derivatives of cellulose. It is miscible with water and has a low boiling point (55-56°C).

Acetone Recovery

A process for reclaiming the acetone solvent from acetate fiber or plastics manufacture. Usually the recovery process consists of adsorption by activated carbon and re-distillation.

Acetyl

The radical (CH3CO-) of acetic acid.

Acetyl Value

A measure of the degree of esterification or combination of acetyl radicals with cellulose in acetate or triacetate products.

Acetylation

The process of introducing an ethanoyl (acetyl) radical into an organic molecule.
Note 1: The term acetylation is used to describe the process of combining cellulose with ethanoic (acetic) acid.
Note 2: A partial acetylation is sometimes applied to cotton in the form of yarn or fibre to change its properties.

Acid ageing

ageing in which a volatile acid is present in the vapour.

Acid dye

An anionic dye characterized by substantivity for protein, polyamide or other fibres containing basic groups. Acid dyes are often applied from an acidic or neutral dyebath.