Definitions /Dictionary/Glossary - nptel

Hydraulic Press: A press in which molding force is created from pressure exerted by a fluid.
Hygroscopic: Material that absorbs moisture from the air.
Hysteresis: The energy absorbed in a complete cycle of loading and unloading. Mechanical
energy is converted into friction energy (heat).
Ignition Loss: With glass, the difference in weight before and after binder or size has been
burned off.
Impact Strength-Izod: A moving load is one that is moving when it strikes a bar. The effect of
such a load is denoted by the work "impact". The impact strength of a material is a measure of
how much energy is absorbed by the bar when it is broken by a moving weight. Izod is one of
many different test methods for measuring impact. Units are measured in foot pounds per inch of
width; sometimes given as foot pounds per inch of notch. Joules/Meter (J/M). Higher numbers
mean that the material will absorb more energy before it is broken by a moving weight.
Impact Test: It is the measure of the energy necessary to fracture a standard sample by an
impulse load.
Impregnate: In reinforced plastics, to saturate reinforcement, especially fiberglass, with a resin.
Inhibitor: A substance that retards polymerization, thus extending shelf life of a monomer. Also
used to influence gel time and exotherm.
Initiator: Peroxides used as sources of free radicals. They are used in free-radical
polymerization, for curing thermosetting resins, as cross-linking agents for elastomers and
polyethylene, and for polymer modification.
Injection Molding: Method of forming plastic to the desired shape by forcing a heat-softened
thermoplastic polymer into a relatively cool cavity under pressure or thermosetting polymer into
a heated mold.
Inorganic Pigments: Natural or synthetic metallic oxides, sulfides, and other salts that impart
heat and light stability, weathering resistance, color, or migration resistance to plastics.
Insert: An integral part of plastic molding consisting of metal or other material that may be
molded into the part or pressed into position after the molding is completed.
In-Situ: In place. In the position which it will finally occupy, e.g. molding or forming foam.
Instron: Instrument for determining the tensile and compressive properties of materials.
Interface: A surface that lies between two different materials.