Effective Thread Turns - The number of full 360 degree turns on a threaded closure that are actually in contact with the neck thread.

Ejector Pin (on Sleeve) - A pin or thin plate that is driven into a mold cavity from the rear as the mold opens, forcing out the finished pieces. Also Knockout Pin.

Ejector Return Pins - Projections that push the ejector assembly back as the mold closes; also called Surface Pins and Return Pins.

Ejector Rod - Bar that actuates the ejector assembly when mold is opened.

Elastic Deformation - The part of the deformation of an object under load which is recoverable when the load is removed.

Elastomer - A material which at room temperature stretches under low stress to at least twice its length and snaps back to the original length upon release of stress. See also Rubber.

Electroformed Molds - A mold made by electroplating metal in the reverse pattern on the cavity. Molten steel may be then sprayed on the back of the mold to increase its strength.

Electronic Treating - A method of oxidizing a film of polyethylene to render it printable by passing the film between the electrodes and subjecting it to a high voltage corona discharge.

Electroplating - The deposition of a layer of metal on a base of metal or conducting surface by electrolysis.

Elongation - The fractional increase in length of a material stressed in tension.

Embossing - Techniques used to create depressions of a specific pattern in plastics film and sheeting.

Emulsion - A suspension of fine droplets of one liquid in another.

Encapsulating - Enclosing an article (usually an electronic component or the like) in a closed envelope of plastic, by immersing the object in a casting resin and allowing the resin to polymerize or, if hot, to cool.

Endothermic Reaction - A chemical reaction in which heat is absorbed.

Entrance Angle - Maximum angle at which the molten material enters the land area of the die, measured from the center line of the mandrel.

Environmental Stress Cracking - The susceptibility of a thermoplastic article to crack or craze formation under the influence of certain chemicals and stress.

Epoxy Resins - Based on ethylene oxide, its derivatives or homologues, epoxy resins form straight-chain thermoplastics and thermosetting resins, e.g., by the condensation of bisphenol and epichlorohydrin.

ESC or ESCR - See Environmental Stress Cracking.

Ester - The reaction product of an alcohol and an acid.

Ethylene Plastics - Plastics based on polymers of ethylene or copolymers of ethylene with other monomers, the ethylene being in greatest amount by mass.

Ethylene-vinyl Acetate - Copolymers from these two monomers form a new class of plastic materials. They retain many of the properties of polyethylene, but have considerably increased flexibility for their density - elongation and impact resistance are also increased.

Exotherm - The temperature/time curve of a chemical reaction giving off heat, particularly the polymerization of casting resins. (2) The amount of heat given off. The term has not been standardised with respect to sample size, ambient temperature, degree of mixing, etc.

Exothermic Reaction - A chemical reaction in which heat is evolved.

Extender - A substance generally having some adhesive action, added to a plastic composition to reduce the amount of the primary resin required per unit area.

Extrudate - The product or material delivered by an extruder, such as film, pipe, the coating on wire, etc.

Extrusion - The compacting of a plastic material and the forcing of it through an orifice in more or less continuous fashion.

Extrusion Coating - The resin is coated on a substrate by extruding a thin film of molten resin and pressing it onto or into the substrates, or both, without the use of an adhesive.