Definitions /Dictionary/Glossary - nptel

Standard Deviation: See Sample Standard Deviation.
Staple: Either naturally occurring fibers or lengths cut from filaments.
Starved Area: It is an area in a plastic part, which has an insufficient amount of resin to wet out
the reinforcement completely. This condition may be due to improper wetting or impregnation or
excessive molding pressure.
Starved Joint: It is a joint that does not have the proper amount of adhesive because of
insufficient spread or excessive pressure.
Step-Growth Polymerization: One of the two principal polymerization mechanisms. In sepgrowth
polymerization, the reaction grows by combination of monomer, oligomer, or polymer
molecules through the consumption of reactive groups. Since average molecular weight increases
with monomer consumption, high molecular weight polymers are formed only at high degrees of
conversion.
Stiffness: The relationship of load and deformation; a term often used when the relationship of
stress to strain does not conform to
the definition of Young's modulus.
Stop Motion: A device on a creel that quickly stops the winder when a strand breaks so that the
strand can be repaired /replaced for further winding.
Storage Life: The period of time during which a liquid resin or packaged adhesive can be stored
under specified temperature conditions and remain suitable for use. Also see "shelf life”.
Strain: the per unit change, due to force, in the size or shape of a body referred to its original
size or shape. Strain is a non-dimensional quantity, but it is frequently expressed in inches per
inch, meters per meter, or percent.
Strand: Normally an untwisted bundle or assembly of continuous filaments used as a unit,
including slivers, tow, ends, yarn, etc. Sometimes a single fiber or filament is called a strand.
Strand Count: The number of strands in a plied yarn; the number of strands in a roving.
Strand Integrity: The degree to which the individual filaments making up the strand or end are
held together by the sizing applied.
Strength, Flexural: The maximum stress that can be borne by the surface fibers in a beam in
bending. The flexural strength is the unit resistance to the maximum load prior to failure by
bending, usually expressed in pounds per square inch.
Strength: the maximum stress which a material is capable of sustaining.