Immiscible - Descriptive of two or more fluids which are not mutually soluble.

Impact Bar (specimen) - A test specimen of specified dimensions which is utilized to determine the relative resistance of a plastic to fracture by shock.

Impact Resistance - Relative susceptibility of plastics to fracture by shock, e.g., as indicated by the energy expended by a standard pendulum type impact machine in breaking a standard specimen in one blow.

Impact Strength - (1) The ability of a material to withstand shock loading. (2) The work done in fracturing, under shock loading, a specified test specimen in a specified manner.

Impregnation - The process of thoroughly soaking a material such as wood, paper or fabric, with a synthetic resin so that the resin gets within the body of the material. The process is usually carried out in an impregnator.

Impulse Sealing - A heat sealing technique in which a pulse of intense thermal energy is applied to the sealing area for a very short time, followed immediately by cooling. It is usually accomplished by using an RF heated metal bar which is cored for water cooling or is of such a mass that it will cool rapidly at ambient temperatures.

Infra-red - Part of the electromagnetic spectrum between the visible light range and the radar range. Radiant heat is in this range, and infra-red heaters are used in sheet thermoforming.

Inhibitor - A substance that slows down chemical reaction. Inhibitors are sometimes used in certain types of monomers and resins to prolong storage life.

Injection Blow Molding - A blow molding process in which the parison to be blown is formed by injection molding.

Injection Mold - A mold into which a plasticated material is introduced from an exterior heating cylinder.

Injection Molding - A molding procedure whereby a heat-softened plastic material is forced from a cylinder into a relatively cool cavity which gives the article the desired shape.

Injection Molding Cycle - The complete time cycle of operation utilized in injection molding of an object including injection; die close and die open time.

Injection Pressure - The pressure on the face of the injection ram at which molding material is injected into a mold. It is usually expressed in psi.

Injection Ram - The ram which applies pressure to the plunger in the process of injection molding or transfer molding.

Insert - An integral part of a plastics molding consisting of metal or other material which may be molded into position or may be pressed into the molding after the molding is completed.

Instron - An instrument utilized to determine the tensile and compressive properties of material.

Insulation - A coating of a dielectric or essentially non-conducting material whose purpose it is to prevent the transmission of electricity.

Insulation Resistance - The electrical resistance of an insulating material to a direct voltage. It is determined by measuring the leakage of current which flows through the insulation.

Intrinsic Viscosity - The intrinsic viscosity of a polymer is the limiting value of infinite dilution of the ratio at the specific viscosity of the polymer solution to its concentrate on moles per liter.

Ionomer Resins - A polymer which has ethylene as its major component, but containing both covalent and ionic bonds. The polymer exhibits very strong interaction ionic forces. The anions hang from the hydrocarbon chain and the reactions are metallic - sodium, potassium, magnesium. These resins have many of the same features as polyethylene plus high transparency, tenacity, resilience, and increased resistance to oils, greases and solvents. Fabrication is carried out as with polyethylene.

ISO - International Organization of Standardization.

Izod Impact Test - A test designed to determine the resistance of a plastics material to a shock loading. It involves the notching of a specimen, which is then placed in the jaws of the machine and struck with a weighted pendulum. See also Impact Strength.