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Glossary of Plastics Technology

ABS acrylonitrile/butadiene/styrene (an amorphous copolymer)  
amorphous without (regular) form, glassy, noncrystalline, a condition of great disorder or absence of structure  
anisotropy condition in which properties depend on direction (i.e., properties are different in different directions)  
catalysis acceleration of a chemical reaction by catalysts  
cavity specially shaped open space in a mold, which is filled with the material  
cellulose most commonly occurring carbohydrate; cotton, jute, flax, and hemp are almost pure cellulose  
carbon-fiber-reinforced plastic (CFRP) carbon-fiber-reinforced plastic (CFRP)-a composite material of carbon fibers and a polymer matrix  
CNC Computer controlled machining  
Computer-aided design (CAD) to produce a single unambiguous digital definition of geometry in such format as to be suitable for integrated, seamless design and manufacture  
cross-linking linking together of polymer molecules (macromolecules) by primary valences, resulting, in most cases, in a three-dimensional network; cross-linking of certain plastics can be carried out chemically by the addition of appropriate bridge-building monomers  
CRP carbon-reinforced plastic; see CFRP  
crystalline consisting of numerous tiny crystals that are not completely formed  
crystalline melting temperature crystalline regions of a thermoplastic melt at this temperature (Tm)  
Decomposition temperature the temperature (Td) at which a material is destroyed by chemical decomposition  
delamination detachment of the fibers from the matrix, or a crack in the matrix running parallel to a laminate layer  
elongation the change in the length of a body pulled in one direction by the application of a force  
EPS expanded polystyrene (foamed polystyrene)  
Filament a continuous thread of a specified diameter, e.g. silk (natural fiber) or rayon (synthetic fiber); the opposite of a fiber with a finite length, such as wool or cotton  
flow temperature temperature above which a thermoplastic can be reshaped with little force  
FRP fiber-glass-reinforced plastic is a composite material consisting of glass fibers  
gel coat resin layer (usually colored) that protects the underlying resin/glass fiber laminate from external influences such as impact, UV light, chemicals, etc.; the side of the molded part that remains most visible or external after demolding, hence the gel coat is the first layer applied to the mold  
glass transition temperature amorphous regions of a thermoplastic soften at this temperature (Tg)  
granulate plastic starting material for primary processing; particles are usually in the form of lentil-shaped cylinders  
hardener second chemical component required for activating the cross-linking reaction of prepolymers, in order to manufacture thermosets or elastomers  
holding pressure conveys additional melt into the molded part as it solidifies in the injection molding process, thus minimizing shrinkage (loss of volume) that would otherwise occur as the injection-molded part cools; it also compresses the internal structure of the part  
hydraulic operated by the pressure of a liquid  
injection molding cycle represents the total of the durations of all operations performed within the injection molding machine and necessary to manufacture a part  
injection pressure pressure applied by the screw against the molding compound to push it into the mold in the injection process  
isotropy condition in which properties are completely independent of direction (isotropic), i.e., the same in all directions  
laminate the cured thermoset matrix or the cooled fiber-reinforced composite (with a thermoplastic matrix)  
layered structure structure and arrangement of the individual layers (laminate) of a fiber-reinforced composite  
locking force force required to close the mold while being filled or during the hardening phase (in the case of thermosets)  
matrix material material that binds the fibers  
melt molten molding compound  
melting temperature range temperature range (Tf) within which a solid material changes to a liquid state  
modulus of elasticity (E-modulus) constant ratio of stress to deformation within the elastic range of a material, determined by tensile test, compression test, and bending test; because of the viscoelastic characteristics of plastics, dependence on time is an important consideration  
molded part plastics part produced by primary processing; can often be used without subjecting it to a finishing operation  
molding compound an unformed or preformed material that can be processed by noncutting methods of shaping (primary processing) within a certain temperature range to form a molded material, which may be a molded part or semifinished product  
monomer basic building block from which macromolecules are created; for example, ethylene is the monomer of polyethylene ("monomer" is derived from the Greek word for "single part")  
multifunctional multiple functions combined in a single component; for example, a cable on a ceiling light may bear the weight of the lamp itself while also conducting the electrical energy to the lamp  
nonwoven nonwoven, solid, flat sheet consisting of bundled glass filaments or glass staple fibers (surfacing mat)  
orthotropy also known as orthogonal or rhombic anisotropy, it indicates that properties depend on direction; the properties are symmetrical in relation to a system of three perpendicular (orthogonal) planes  
PA polyamide (a sernicrystalline thermoplastic)  
PC polycarbonate (an amorphous thermoplastic)  
PE polyethylene (a sernicrystalline thermoplastic)  
PEEK polyether etherketone (a semicrystalline thermoplastic)  
PES polyether sulfone (an amorphous thermoplastic)  
plasticizers substances that bring about softening of plastics; in a physical sense, plasticizing means decreasing the glass transition temperature (Tg) of a polymeric material, generally to a point below room temperature so that plastics that are initially hard, rigid, and brittle become soft, flexible, and impact resistant  
Plasticate (plastify) describes the conversion of a plastic material to a thermoplastic condition by the introduction of heat  
Polarity (of plastics) formation of electrical charge distributions within the macromolecules produces various polarities  
polymers long molecular chains (chain molecules) formed from monomers occurring as repetitive "building blocks" or monomer units in these chains ("polymer" is derived from the Greek word for "many parts")  
POM polyoxymethylene (a semicrystalline thermoplastic), also known as polyacetal  
prepregs molding compounds consisting of flat or linear glass reinforcements preimpregnated with thermosetting resin compounds; molding com­ pounds prepared in this way are mostly glass fiber mats or glass filament cloths processed to form molded parts or semi-finished products by hot-press molding  
PVC polyvinyl chloride (an amorphous thermoplastic)  
quasi-isotropic a condition in which properties are nearly identical in all directions; in fiber­ reinforced composites; this condition can be attained by providing at least three directions with reinforcement in similar layer thicknesses  
Rapid prototyping (RP) The production of a limited number of components originating directly from a CAD definition in a time-compressed manner  
Rapid tooling (RP) The direct use of CAD data in the production of a mold or fixtures for the manufacturing of a part. It also includes the production of a mold utilizing time reducing technologies.  
raw material naturally occurring starting material used to manufacture a product, such as petroleum, coal, ores, wood, hides, and cotton, as well as water and air; the intermediate product (semi-finished product) is formed from the raw material during the production process, and the finished (manufactured) products are produced from the intermediate product  
recycling reutilization of raw or used materials; for example, plastic sprues from injection-molded parts are recycled by processing them to form a granulate, which is then returned to the injection molding process  
resin amorphous material with a consistency that can vary from soft to rigid; then-nosetting resins form the basis for thermoset plastics  
resin injection process a closed mold is used to manufacture molded parts from resin, and reinforcing materials are inserted into the molded parts  
RIM reaction injection molding, which refers to an integrated mixing and injection process for plastics from two or more highly reactive components  
roving refers to a certain number of approximately parallel glass strands combined to form a larger strand (or glass roving); an individual glass strand consists of a certain number of individual glass filaments that have been combined without twisting to form a thread of uniform size, and these filaments are arranged in a mostly parallel relationship  
SLA Stereolithography  
SLS Selective laser sintering  
sandwich flat multilayer composite design consisting of two high-strength outer layers and a light, thick inner layer; this design provides a high surface moment of inertia and great stiffness  
sealing point time at which the molding compound inside the sprue channel has become solid enough to prevent any further flow  
self-extinguishing ability of a burning plastic to extinguish itself without external influence  
semifinished product intermediate product made of plastic (e.g., pipes and sheets), which will be further processed (reshaped) to form a finished product  
shear strength (interlaminar) property defined as the force sufficient to cause a rupture within the area subjected to shear divided by the area subjected to shear  
sonotrode welding tool used in ultrasonic welding to transmit vibrations to the plastics part being welded  
sprue bush part of an injection mold that lies against the nozzle of the injection unit and through which the molding compound flows into the mold  
stabilizers chemical additives that make a plastic more resistant to certain influences (e.g., UV radiation, heat, oxidation, weathering)  
synthesis formation of chemical compounds from the basic elements or basic chemicals with a simpler structure ("synthesis" is derived from the Greek word for "put together")  
Thermoplastics (semicrystalline) thermoplastics displaying crystalline and amorphous regions; plastics that can be melted (softened) by application of heat  
thermoset polymer in which the chain molecules are cross-linked in three dimensions through covalent bonds  
ultimate elongation the elongation that the body exhibits before breaking at the maximum amount of force; specified as a percentage of the starting length  
unidirectional aligned in one direction  
viscoelastic condition of a body that is both elastic (Hookean) and viscous (Newtonian)  
vulcanization chemical cross-linking process that alters the properties of natural rubber to make it elastic and resistant to distortion