Hydro extraction

Removal of liquid from textile material.

Hydroentangled fabric

A nonwoven fabric made from a fibre web or batt, in which entanglement by high-pressure water jets provides the bond.

Hydroentangling

Process for forming a fabric by mechanically wrapping and knotting fibers in a web through the use of high-velocity jets or curtains of water. (Also see SPUNLACES FABRIC.)

Hydroextractor

See CENTRIFUGE.

Hydrogenation

The process of passing hydrogen into an unsaturated chemical in the presence of a catalyst to convert the material to a more saturated state (i.e. containing more combined hydrogen.)

Hydrolysis

A double decomposition reaction involving the addition of the elements of water and the formation of an acid and a base an acid and an alcohol or an acid and phenol. © 2001 Celanese Acetate LLC

Hydrophilic

Having strong affinity for or the ability to absorb water.

Hydrophobic

Lacking affinity for or the ability to absorb water.

Hydroscopic

Having the ability to absorb moisture from the atmosphere. All fibers have this property in varying degrees.

Hydrostatic head test

The ability of a fabric to withstand penetration by water in specified circumstances. Water may be under pressure (e.g., hydrostatic head test) or in the form of drops hitting the surface of the fabric.

Hydroxyl End Group

A polymer chain-terminating (-OH) group.

Hygral expansion

The reversible changes in length and width of fabrics containing of changes in regain.

Hygroscopic

See HYDROSCOPIC.

Hysteresis

1. In tire cord a measurement of work lost through heat during dynamic operation. 2. In tensile testing loss of linear recovery following repeated loading and relaxation. © 2001 Celanese Acetate LLC I