Definitions /Dictionary/Glossary - nptel

Allotropy: The existence of a substance in one or more forms.
Alloy: It will made by mixing traditional polymers, which have already been formed. The
mixing results in a single-phase material because the polymers have some interaction that
combines them together. The properties of the alloy depend upon the physical interactions of the
polymers.
Alternating Stress: According to law determined in terms of the time, it is a stress varying
between two maximum values that is equal but with opposite signs.
Ambient: The surrounding environmental conditions such as pressure or temperature.
Amine Resins: A synthetic resin derived from the reaction of urea, thiourea, melamine or allied
compounds with aldehydes, particularly formaldehyde.
Amorphous: Describes polymers that have no order to their molecules, thus no crystalline
component.
Anelasticity: A characteristic exhibited by certain materials in which strain is a function of both
stress and time, such that, while no permanent deformations are involved, a finite time is
required to establish equilibrium between stress and strain in both the loading and unloading
directions.
Angle ply: Same as Cross ply.
Anisotropic: Not isotropic; having mechanical and/or physical properties which vary with
direction relative to natural reference axes inherent in the material. It is also defined as the
tendency of a material to exhibit different properties in response to stresses applied along axes in
different directions.
Anisotropic Laminate: One in which the strength properties are different in different directions.
Anisotropy of Laminates: The difference of the properties along the directions parallel to the
length or width into the lamination planes; or parallel to the thickness into the planes
perpendicular to the lamination.
Antimony Trioxide: An additive used to give special flammability characteristics to polyester.
Antioxidant: It is a substance that, when added in small quantities to the resin during mixing
prevents its oxidative degradation and contributes to the maintenance of its properties.
Anti-Static Agents: Agents which, when added to the molding material or applied on the
surface of the molded object, make it less conducting (thus hindering the fixation of dust).