Definitions /Dictionary/Glossary - nptel

Antioxidant: Substance that, when added in small quantities to resin, prevents oxidation and
degradation while maintaining the resin’s properties.
Antistatic Agents: Agents added to a molding material or applied to the surface of a molded
object to make it more conductive and prevent the fixation of dust or buildup of electrical charge.
Arimid: A highly oriented organic material derived from polyamide with an aromatic ring
structure that is used primarily as a high-strength, high-modulus fiber. Examples include Kevlar
and Nomex.
Arc Resistance: Ability to withstand exposure to an electric voltage. It is also, the total time in
seconds that an intermittent arc may play across a plastic surface without rendering it conductive.
Ash Content: Proportion of solid residue remaining after a reinforcing substance has been
incinerated (charred or intensely heated).
Aspect Ratio: Ratio of length to diameter of a fiber.
A-Stage: Early stage in the polymerization reaction of certain thermosetting resins (especially
Phenolic) in which the material, after application to the reinforcement, is still soluble in certain
liquids and is fusible. It is also called resole. See B-Stage and C-Stage
ASTM: American Society of Test Methods.
Autoclave: Closed vessel for conducting and completing a chemical reaction or other operation
under pressure and heat.
Autoclave Molding: Process in which an assembly is placed in a heated autoclave, usually at 50
to 200 psi, after lay-up, winding or wrapping. Additional pressure permits higher density and
helps remove volatiles from the resin. Lay-up is usually vacuum bagged with a bleeder and
release cloth.
Autosprue: Automatic gate at the inlet sprue of the mold that eliminates the need to remove
the resin supply during injection.
Axial Winding: Filaments that are wound parallel or at a small angle to the axis (0° helix angle).
Bagging: Applying an impermeable layer of film over an uncured part and sealing the edges so
that a vacuum can be drawn.
Bag Molding: It is the process in which fluid or gas is applied through a flexible membrane to
consolidate material in a mold.
Balanced Construction: Equal parts of warp and fill in fiber fabric. Construction in which
reactions to tension and compression loads result in extension or compression deformations only,