E-glass

Abbreviation for "electrical glass," borosilicate glass fibers, which have high electrical resistivity. Most often used in conventional polymer matrix composites.


Elastic limit

The greatest stress a material is capable of sustaining without permanent strain remaining after complete release of the stress (see stress and strain).


Elasticity

The property of materials to recover immediately their original size and shape when load is removed after deformation.


Elongation

The fractional increase in length of a material loaded in tension. When expressed as a percentage of the original length, it is called percent elongation.


End

A general term for a single strand of roving, which is a continuous, ordered assembly of essentially parallel, collimated filaments, with or without twist.


End count

The exact number of strands contained in a particular roving.


Engineering plastics

A general term covering all plastics, with or without fillers or reinforcements, that have mechanical, chemical and thermal properties suited for use as construction materials or in components for machines and chemical processing equipment.


Epoxy

A thermosetting polymer containing one or more epoxide or oxirane groups, curable by reaction with amines or alcohols; used as a resin matrix in reinforced plastic products and as the primary component in certain structural adhesives. Cured epoxy resin is highly resistant to chemicals and water and its performance properties are relatively unaffected by extreme temperatures.


Exotherm

Heat released during a chemical reaction. Uncontrolled exotherm during cure of a composite component can lead to heat build up, which can result in part warpage and/or mold damage and, in extreme cases, could produce an explosion.