Definitions /Dictionary/Glossary - nptel

Thixotropic: The property of becoming a gel at rest, but liquefying again on agitation.
Tooling Gel Coat: It is a gel coat formulated for mold surfaces.
Transfer: The smooth and successful transition from one roving doff to another during
processing.
Translucent: Permits a percentage of light to pass but not optically clear like window glass.
Trapped End: A loop embedded into doff during the roving process that gets stuck during runout
with such tenacity that it prevents the entire strand from running freely to the chopper.
Tube Stoppage or Plug: The failure of glass to run through metal tubes or guide-eyes from the
creel to the chopper. It is usually caused by a large knot or small birdnest becoming stuck inside
the tube or guide-eye.
Turn: One 360° revolution of the components around the axis of the strand.
Turnaround: The portion of the roving doff where the roving changes direction when it is
pulled out of doff.
Twist and Ply Frames: Machines used to twist and ply glass yarns.
Ultimate Tensile Strength: The ultimate or final stress sustained by a specimen in a tension
test; the stress at moment of rupture.
Undercut: Having a protuberance or indentation that impedes withdrawal from a rigid two-piece
mold; any such protuberance or indentation, depending on the design of the mold (tilting a model
in the mold may eliminate an apparent "undercut").
Unidirectional: Strength lying mainly in one direction. It is a glass reinforcement in which the
fiber is oriented in one direction.
Untied Ends: The lack of a knot or splice between two doffs, one on top of the other, which
prevents successful transfer from the top doff to the bottom doff in a creel par.
Untreated: A descriptive term for glass fiber yarns having no applied chemicals or coatings
other than minimal lubricant or binder for controlling intra-fiber abrasion.
UV Stabilizer: Chemical compound which improves resistance to degradation from ultraviolet
radiation.
Vacuum Bag Molding: Process in which a sheet of flexible transparent material, bleeder cloth
and release film are placed over the lay-up in the mold and sealed at the edges. A vacuum is
applied between the sheet and the lay-up. Entrapped air is mechanically worked out of the lay-up