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| Term | Definition |
|---|---|
| Polybutenes |
The family of polymers of isobutene, butene-1, and butene-2. Depending on molecular weight, they range from oils through tacky waxes, crystalline waxes, and rubbery solids. |
| Polycarbonate |
Polycarbonates are strong, stiff, hard, tough, transparent engineering thermoplastics that can maintain rigidity up to 140oC and toughness down to -20°C or special grades even lower. Properties of polycarbonate plastic are toughness, dimensional stability, optical clarity, high heat resistance and excellent electrical resistance. Because of these attributes, polycarbonate is used in a wide variety of common products including digital media (e.g. CDs, DVDs), electronic equipment, automobiles, construction glazing, sports safety equipment and medical devices. Some popular tradenames for polycarbonate are Lexan (SABIC), Calibre (DOW), Makrolon (Bayer), and Makrolife (Arlaplast). |
| Polyester Resins |
Saturated A family of polyesters in which the polyester backbones are saturated and hence unreactive. The most common commercial types are polyethylene terephthalate (PET), a thermoplastic which may be extruded, injection or blow molded. Unsaturated Unsaturated polyesters thermoset and used in the reinforced plastics industry for applications such as boats, auto components, etc. |
| Polyethylene |
A family of resins obtained by polymerizing the gas ethylene. By varying the catalysts and methods of polymerization, properties such as density, melt index, crystallinity, degree of branching and crosslinking, molecular with distribution can be regulated over wide ranges. Further modifications are obtained by copolymerization, chlorination, and compounding additives. |
| Polyisobutylene |
See Polybutene. |
| Polymer |
The product of polymerization reaction. See Polymerization. The product of polymerization of one monomer is called a homopolymer, monopolymer, or simply a polymer. When two monomers are copolymerized, the product is called a copolymer. The term terpolymer is used for polymerization products of three monomers. |
| Polymer Process Aid (Ppa) |
Additives incorporated into plastics as a modifier to aid in the extrusion of film, pipe, sheet, etc. |
| Polymerization |
A chemical reaction in which the molecules of a simple substance (monomer) are linked together to form large molecules whose molecular weight is a multiple of that of the monomer. |
| Polyolefins |
The class of polymers made by polymerizing relatively simple olefins, including ethylene, propylene, butenes, isoprenes, and pentenes. |
| Polyproylene |
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. |
| Polyvinyl Acetate |
A thermoplastic material composed of polymers of vinyl acetate in the form of a colorless solid. Used extensively in adhesives for paper and fabric coatings. |
| Polyvinyl Alcohol |
A thermoplastic material composed of polymers of the hypothetical vinyl alcohol. |
| Polyvinyl Chloride |
Thermoplastic compounds formed by polymerization or copolymerization of vinyl or vinylidene chlorides and vinyl esters. |
| Porosity |
The ratio of the volume of air or void contained within a material to the total volume (solid material plus air or void), expressed as a percentage. |
| Port Lines |
See Spider Lines |
| Preform |
The formation of an intermediate part to be formed into the final part. |
| Pressure Roll |
In extrusion coating, a roll used to apply pressure to consolidate the substrate and the plastic film with which it has been coated. |
| Proportional Limit |
The greatest stress which a material is capable of sustaining without deviation from proportionality of stress and strain (Hooke |
| Pseudoplastic Fluid |
A pseudoplastic fluid is one whose apparent viscosity or consistency decreases instantaneously with increase in rate of shear i.e., an initial relatively high resistance to stirring decreases abruptly as the rate of stirring is increased. |
| Punching |
Method of producing components, particularly electrical parts, from flat sheets of rigid or laminated plastics by punching out shapes by means of a die and punch. |
| Purging |
In extrusion of injection molding, the cleaning of one color or type of material from the machine by forcing it out with the new color or material to be used in subsequent production, or with another compatible purging material. |
| Pyrolysis |
The decomposition of a complex organic substance to one of simpler structure by means of heat in the absence of others. Some polymers will depolymerize in the presence of excessive temperatures, either to polymers of lower molecular weight, or, in some cases, back to the monomers from which they were derived. |
| Pyrometer |
An instrument for measuring heat. The type most widely used in plastics processing equipment consists of a thermocouple and a millivoltmeter for measuring the voltage, which is proportional to the temperature of the junction. |
| Quench |
A process of shock cooling thermoplastic materials from the molten state. |
| Radical |
A group of atoms existing in a molecule, which is capable of remaining, unchanged through many chemical reactions. |
| Random Copolymer |
A copolymer consisting of alternating segments of two monomeric units of random distribution, including single molecules. A random copolymer usually results from copolymerization of two monomers in the presence of a free-radical initiator. |
| Reciprocating Screw |
Extruder system in which the rotating screw is pushed backwards by the molten polymer collecting in front of the screw. When sufficient material has been collected, the screw moves forward and forces the material through the head and die at a high speed. |
| REDCO Precision Board™ |
REDCO Precision Board HDU (High Density Urethane) is a rigid, closed cell, high density urethane material. It can be sandblasted, routed, carved, sanded, or machined. It will not crack, twist or curl after long exterior exposure, making it the ideal replacement for wood. Precision Board is a trade mark of Coastal Enterprises. |
| Regrind |
Waste material such as sprues, runners, excess parison material and reject parts from injection molding, blow molding and extrusion operations, which has been reclaimed by shredding or granulating. Regrind is usually mixed with virgin compound at a predetermined percentage for reprocessing. |
| Reheat Blow Molding |
In reheat blow molding, parisons are stretched axially by an external gripper or an internal stretch rod, and then stretched radially by blow air to form the finished product. This process orients the molecules biaxially resulting in the improved barrier properties. |
| Reinforced Plastic |
Molded, formed, filament wound, or shaped plastic parts consisting of resins to which reinforcing fibers, mats, fabrics, etc., have been added before the forming operation. Strength properties are improved. |
| Residual Monomer |
The unpolymerized monomer that remains incorporated in a polymer after the polymerization reaction is completed. |
| Resin |
An organic substance of natural or synthetic origin characterized by being polymeric in nature. Most resins, though not all, are of high molecular weight and consist of long chain or network molecular structure. Usually resins are more soluble in their lower molecular weight forms. |
| Restricted Gate |
A very small orifice between runner and cavity in an injection or transfer mold. When the piece is ejected this gate breaks cleanly, simplifying separation of runner from piece. |
| Restrictor Ring |
A ring-shaped part protruding from the torpedo surface which provides increase of pressure in the mold to improve, e.g. welding of two streams. |