Page 647 - Carrahers_Polymer_Chemistry,_Eighth_Edition

610 Carraher’s Polymer Chemistry

Melt spinning: Process of obtaining fibers by forcing molten polymer through holes in a spin-

neret and cooling the fi laments.
Molding powder or compound: Premix of resin and other additives used as a molding resin.
Multicellular: Open celled.
Neoprene: Trade name for polychloroprene.

Nonwoven textiles: Sheet produced by binding fibers with a heated thermoplastic.
Oil paints: Suspension of pigments in a drying oil.
Oil varnish: Polymer dissolved in a drying oil.
Parison: Short plastic tube that is heated and expanded by air in the blow-molding process.
Perlon: Trade name for some PU fi bers.
Photoconductive: Material that is conductive when exposed to light.
Photoresponsive: Material whose properties change when exposed to light.
Pigment: Coloring material; colorant.
Polyacetylene: Polymer whose conductivity increases when doped to be a conductor.
Printing ink: Highly pigmented coatings used in printing.

Pultrusion: Process in which filaments are dipped in a prepolymer, passed through a die, and
cured.
Rotational molding: Polymer added to a warm, rotating mold; centrifugal force distributes the
polymer evenly.
Rovings: Multiple untwisted strands of fi laments.
Runner: Channel between the spruce and the mold cavity.
Screen pack: Metal screen that prevents foreign material form reaching the die in an
extruder.
Specific strength: Strength based on mass rather than area.

Spinneret: Metal plate between the nozzle and runner.

Sprue: Tapered orifice between nozzle and runner. Term also used to apply to plastic material
in the sprue.
Structural foams: Polymeric foamed article with a dense surface.
Styrofoam: Trade name for foamed PS.
Technology: Applied science.
Tenacity: Fiber strength.
Thermoforming: Shaping of a hot thermoplastic sheet.
Transfer molding: Process in which a preheated briquette or preform is forced through an ori-

fice into a heated mold cavity.
Vehicle: Liquid in a coating.
Wet spinning: Obtaining fibers by precipitation of polymeric solutions.

EXERCISES
1. Which is more important: (a) polymer science or (b) polymer technology?
2. Name three important natural fi bers.
3. Name an important regenerated fi ber.
4. Why is secondary cellulose acetate more widely used than the tertiary cellulose acetate?
5. What is the difference between rayon and cellophane?
6. Name three important synthetic fi bers.
7. Name an elastomer produced by (a) cationic, (b) anionic, (c) free radical, and (d) step-reaction
polymerization techniques.
8. How is LDPE fi lm produced?
9. Why is there a trend toward the use of less solvent in polymeric coatings?
10. What is meant by trade sales?
11. What are the general steps needed before a new drug comes to market.

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