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DEGRADATION. A deleterious change in the chemical structure of a plastic. (See DETERIORATION.)
DELAMINATION. The separation of the layers in a laminate.
DETERIORATION. A permanent change in the physical properties of a plastic evidenced by impairment of these properties.
DIAPHRAGM GATE. Gate used in molding annular or tubular articles.
DIE-ADAPTOR. That part of an extrusion die which holds the die block
DIE BLOCK. That part of an extrusion die which holds the forming bushing and core.
DIE BODY. That part of an extrusion die used to separate and form material
DIELECTRIC HEATING. (See HIGH-FREQUENCY HEATING.)
DIFFUSION. The movement of a material in the body of a plastic.
DILATANT. A dilatant fluid, or inverted pseudoplastic, is one whose apparent viscosity increases instantaneously with increasing rate of shear; i.e. the act of stirring creates instantly an increase in resistance to stirring.
DILUENT. In an organosol, a liquid component which has little or no solvating action on the resin, its purpose being to modify the action of the dispersant.
DISC GATE. (See DIAPHRAGM GATE.)
DISHED. Showing a symmetrical distortion of a flat or curved section of a plastic object so that, as normally viewed, it appears concave, or more concave than intended. (See WARP.)
DISPERSANT. In an organosol, a liquid component which has a solvating or peptizing action on the resins, so as to aid in dispersing and suspending it.
DISPERSION. A heterogeneous system in which a finely divided material is distributed in a matrix of another material. In plastics technology, a dispersion is usually the distribution of a finely divided solid in a liquid or solid. For example: pigments or fillers in molded plastics, plastisols, or organosols. (See PLASTISOL, ORGANOSOL.)
DOCTOR ROLL; DOCTOR BAR. A device for regulating the amount of liquid material on the rollers of a spreader.
DOMED. Showing a symmetrical distortion of a flat or curved section of a plastic object, so that, as normally viewed, it appears more convex than intended. (See WARP.)
DOPING. Coating the mold or mandrel with a substance which will prevent the molded plywood part from sticking to it and will facilitate easy removal.
DOWEL. Pin used to maintain alignment between two or more parts of a mold.
DRAFT. The degree of the taper of the side wall or the angle of clearance designed to facilitate removal of molded article from the mold.
DRAPE-ASSIST FRAME. In sheet thermoforming, a frame (made of wires or bars) shaped to the peripheries of the depressed areas of the mold and suspended above the sheet that is to be formed.
DRAPE FORMING. A method of forming a thermoplastic sheet in which the sheet is clamped into a movable frame, heated, and draped over the high points of a male mold. Vacuum or air pressure is then applied to complete the forming operation.
DRY COLORING. The method commonly used for coloring plastics by tumble blending uncolored particles of the plastics material with selected dyes and pigments.
DRY SPOT. Area of incomplete surface film on laminated plastics; in laminated glass, an area over which the interlayer and the glass are not bonded.
DUPLICATE CAVITY-PLATE. Removal plate that retains cavities, used where two-plate operation is necessary for loading inserts, etc.
DUROMETER HARDNESS. The hardness of a material as measured by the Shore Durometer.
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