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. |