Useful Glossary of Terms:
This glossary is to help familiarize you with key terminology within our industry
ANTI-STATIC AGENTS: Methods of minimizing static electricity in plastic materials. Two basic types of agents are:-
(1) Metallic devices which come into contact with the plastics and conduct the static to earth.
(2) Chemical substances added to the materials in minute quantities which reduce the tendency of film to develop and retain static electric charges. These give complete neutralization at the time; however, they do not modify the material, therefore leaving it prone to further static during subsequent handling.
COEXTRUSION: The co-extrusion process combines the output of two or more extruders. The finished product, in this case tube or sheet, is distinguished by discrete layers of material. The number of component layers theoretically is unlimited. Experience to date with the blown film process has been predominantly in the two or three-layer range.
DIELECTRIC STRENGTH: The electric voltage gradient at which an insulating material is broken down or “arced through,” in volts per mil of thickness.
ELMENDORF TEAR STRENGTH: The resistance to propagation by tearing from a precise slit through a specified length of material expressed in grams-force (ASTM D-1922).
EXTRUSION: The process of liquefying a resin material and forcing it through an orifice in more or less continuous fashion.
FLEXURAL STRENGTH: The strength of a material in bending, expressed as the tensile stress of the outermost fibres of a bent test sample at the instant of failure. With plastics, this value is usually higher than the straight tensile strength.
FLUOROCARBONS: The family of plastics including polytetrafluoroethylene (PTFE), polychlorotrifluorethylene (PCTFE); polyvinylidene and fluorinated ethylene propylene (FEP). They are characterized by properties including good thermal and chemical resistance and non-adhesiveness and possess a low dissipation factor and low dielectric constant.
HAZE: The measurement of the amount of scattered light that does not transmit through the film.
HYDROPHILIC: water-sensitive
HYGROSCOPIC: Tending to absorb moisture.
IRRADIATION (ATOMIC): As applied to plastics, refers to bombardment with a variety of subatomic particles, generally alpha-, beta-, or gamma-rays. Atomic irradiation has been used to initiate polymerization and copolymerization of plastics and in some cases to bring about changes in the physical properties of a plastic material.
NYLON: The generic name for all synthetic polyamides. Characteristics are superior toughness, strength and elasticity, high melting point, and good resistance to water and chemicals.
OPTICAL DENSITY: A measurement of the transmission of light through the crosshatch area (Densichron).
OXYGEN TRANSMISSION RATE: The time rate of oxygen flow normal to the sample surfaces under steady conditions. The test is run with one side of the film exposed to nitrogen and the opposite side to oxygen, both at a temperature of 73° F.
PLASTICIZER: Plasticizers are used with polymer systems to impart workability, flexibility, extensibility, and resilience. External plasticizers maintain their molecular identity and are compatible with the resin by virtue of hydrogen bonding and Van der Waals forces. Internal plasticizers, on the other hand, are bonded chemically in the polymer system.
POLYETHYLENE: A thermoplastic material composed of polymers of ethylene.
POLYPROPYLENE: A tough, lightweight rigid plastic made by the polymerization of high purity propylene gas in the presence of an organometallic catalyst at relatively low pressures and temperatures.
SEAL STRENGTH: The maximum force in pounds required to rupture a one inch wide specimen having a pre-made heat seal extending across the width of the specimen and positioned intermediate to the testing machine grips.
TENSILE STRENGTH: The maximum force required to rupture a one inch wide specimen. The force (breaking factor) is reported in pounds per inch for laminated materials.
ULTIMATE ELONGATION: The increase in length of the specimen at break expressed in percent (ASTM D-882).
WATER VAPOR TRANSMISSION RATE: The time rate of water vapour flow normal to the sample surfaces under steady conditions, through a unit area. The test is run with one side of film exposed to dry air at 100° F and the opposite side, to 90% RH 100° F air (ASTM E-96).