Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
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Glass Transition: The reversible change in an amorphous polymer or in amorphous regions of a<br />
partially crystalline polymer from (or to) a viscous or rubbery condition to (or from) a hard and<br />
relatively brittle one.<br />
Glass Transition Temperature ( T g ): The approximate midpoint of the temperature range over<br />
which the glass transition takes place.<br />
Glint: A visual defect in a fiberglass reinforced cured organic (usually corrosion resistant resin)<br />
panel. The defect appears as many small visible unwet or foreign substances - a salt and pepper<br />
effect. The defect is not visible before cure but appears at exotherm of the panel.<br />
Graphite: A form of carbon. Structural graphite is used in composite structures due to its<br />
strength and stiffness.<br />
Graphite Fibers: See Carbon Fibers.<br />
Graphitization: The process of pyrolization at very high temperatures (as high as 5400(F) that<br />
converts carbon to its crystalline allotropic form.<br />
Greige: Fabric that has received no finish.<br />
GRP: Glass-reinforced plastic, polymer, polyester. this derivation is commonly used in Europe.<br />
Guide Pin: A pin, which guides mold halves into alignment on closing.<br />
Hand Lay-up: A process in which components are applied either to a mold or a working<br />
surface, and the successive plies are built up and worked by hand.<br />
Handling Life: The out of refrigeration time over which, a material retains its handleability.<br />
Hard Tool: A tool made of metallics or any "hard" material that is generally impervious to<br />
damage during normal use.<br />
Hardener: A substance or mixture added to a plastic composition to promote or control the<br />
curing action.<br />
Hardness: Resistance to deformation; usually measured by indention. Types of standard tests<br />
include Brinell, Rockwell, Knoop, and Vickers.<br />
Heat Cleaned: It is a Glass or other fibers which have been exposed to elevated temperatures to<br />
remove preliminary sizing or binders which are not compatible with the resin system to be<br />
applied.