Definitions /Dictionary/Glossary - nptel

Delaminate: To split a laminated plastic material along the plane of its layers. It is the physical
separation or loss of bond between laminate plies.
Demold: To remove a part from a tool, or a tool from an intermediate model.
Denier: A direct numbering system for expressing linear density, equal to the mass in grams per
9000 meters of yarn, filament, fiber, or other textile strand.
Density: The mass per unit volume.
Density, Fibers: Mass per unit volume of the solid matter of which a fiber is composed,
measured under specified conditions.
Design Allowable: A limiting value for a material property that can be used to design a
structural or mechanical system to a specified level of success with 95 percent statistical
confidence. B-basis allowable: material property exceeds the design allowable 90 times out of
100. A-basis allowable: material property exceeds the design allowable 99 times out of 100.
Desorption: A process in which an absorbed or adsorbed material is released from another
material. Desorption is the reverse of absorption, adsorption, or both.
Deviation: Variation from a specified dimension or requirement, usually defining the upper and
lower limits.
Diallylphthalate (DAP): In reinforced plastics, a monomer which will polymerize with heat and
catalyst into clear, hard polymer.
Dibuthyl Phthalate: A lubricant for spray equipment.
Dielectric: A nonconductor of electricity. It is the ability of a material to resist the flow of an
electric current.
Dielectric Constant: The ratio of the capacity of a condenser having a dielectric constant
between the plates to that of the same condenser when the dielectric is replaced by a vacuum; a
measure of the electrical charge stored per unit volume at unit potential.
Dielectric Strength:
1) This is an electrical property and gives an indication of how well the material acts as an
electrical insulator. It describes how much of an electrical voltage can be built up on one
side of the material before it is communicated to the other side. Units - Volts per mil of
thickness (volts/mil). Higher numbers indicate materials which are better insulators. C
means that the material conducts electricity and therefore has no dielectric strength.
2) The average potential per unit thickness at which failure of the dielectric material occurs.
Diethylaniline (DEA): Accelerator used in conjunction with BPO catalyst or as a co-promoter
for cobalt/MEKP system.