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GLOSSARY OF TERMS
A B C D E
F G H
I J K
L M N
O P Q
R S T
U V W X Y Z
Select the first letter of the word from the list above to
jump to appropriate section of the glossary.
- A -
- ABS (Acrylonitrile-Butadiene-Styrene) -
- A polymer produced from acrylonitrile and styrene
liquids, and butadiene gas, which are polymerized
together in a variety of ratios to produce the family of
ABS resins.
Abrasion Resistance -
The ability of a material to withstand mechanical action
(friction) such as rubbing, scraping, etc.
Absolute Pressure -
A quantity of pressure with respect to total vacuum;
equal to the sum of a pressure gauge reading and
atmospheric pressure (14.69 psia at sea level).
Absolute Zero -
The minimum point in the thermodynamic temperature scale
(-273.16ºC or -459.69ºF).
Absorption -
The penetration into the mass of one substance by
another.
Acetal -
A rigid thermoplastic with properties similar to zinc,
aluminum, and other metals. The molecular structure of
the polymer is of a linear acetal consisting of
unbranched polyoxymethylene chains.
Acid Resistant -
The ability of a material to withstand the corrosive
action of acids.
Additive -
A substance compounded into a resin to enhance certain
characteristics such as plasticizers (for flexibility),
light stabilizers, flame retardants, etc.
Aging -
The chemical and/or physical changes which occur in a
material after exposure to environmental conditions over
a period of time.
Alloy (polyblend) -
A composite material made by blending polymers or
copolymers with other polymers or elastomers.
Annealing -
A process of heating a material to a temperature just
below its melting point and then gradually cooling it.
This will relax stress caused during the molding process
without distortion of the shape.
Antioxidant -
Substances which prevent or slow down oxidation of a
polymeric material exposed to air.
Antistatic Agent -
Additives put in a resin or substance or applied to the
surface of the finished part for the purpose of
eliminating or lessening static electricity; acts to
permit the surface to be slightly conductive, preventing
the formulation of static charges.
ASTM -
American Society of Testing Materials
Autoclave -
A closed vessel for conducting chemical reactions under
high pressure and temperature.
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- B -
- Bleed -
- To give up color when in contact with water or a solvent;
undesirable movement of certain materials in a plastic
(ex: plasticizers in vinyl) to the surface of the
finished article or into an adjacent material.
-
- Bloom -
- A cloudy, greasy film on the surface of a plastic part or
film usually caused by the extraction of an additive,
such as a lubricant, stabilizer, etc.
-
- Brittle Temperature -
- The threshold temperature at which the material will
fracture due to cold induced loss of flexibility.
-
- Burning Rate -
- A term describing the tendency of plastics to burn at a
given temperature. Certain plastics will burn readily at
comparatively low temperatures. Others will melt or
disintegrate without actually burning, or will burn only
if exposed to a direct flame. The latter are referred to
as self-extinguishing.
-
- Burst Pressure -
- The pressure point at which the tube/hose will suddenly
and violently rupture.
-
- Butt Fusion (welding) -
- A process of joining the ends of thermoplastic parts by
heating the surfaces to be joined to their molten state
and then pressing them together to form a homogenous
bond.
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- C -
- Carbon Black -
- A multi-functional additive produced by the incomplete
burning of natural gas or oil and used in plastics as a
conductor of electricity, a pigment, a filler-extender,
and a stabilizer.
-
- Catalyst -
- A substance which speeds up the polymerization or cure of
a compound when added in minor quantity as compared to
the primary reactants.
-
- Cellulose -
- A naturally occurring polysaccharide consisting solely of
glucose units and found in most plants. It is the main
constituent of dried woods, jute, flax, hemp, etc.
-
- Cellulosics -
- A family of resins derived from cellulose. The three most
common types are: cellulose-acetate (CA),
cellulose-acetate-butyrate (CAB), and
cellulose-acetate-propionate (CAP).
-
- Coefficient of Friction -
- Resistance to sliding or rolling of surfaces of solid
bodies in contact with each other; stated as k=F/W in
which F is the force required to move one surface over
another and W is the weight pressing the surfaces
together.
-
- Co-Extrusion -
- The technique of extruding two or more materials through
a single die being fed by separate extruders.
-
- Compounding -
- The process of mixing the polymer with all the materials
necessary for the finished resin to be used by the
processor.
-
- Compressed Gas -
- Any material or mixture having in the container either an
absolute pressure exceeding 40 psia at 70ºF or an
absolute pressure exceeding 104 psia at 130ºF.
-
- Compressive Strength -
- Maximum load at which compression failure occurs in a
specimen divided by the original area of the specimen.
-
- Conductivity -
- The property of transmitting electricity, heat, etc.
-
- Copolymer -
- A compound resulting from the chemical reaction of two
chemically different monomers with each other.
-
- Core -
- The inner-most layer of a multi-layered product.
-
- Corona Resistance -
- The time that a material will withstand a specified level
of field-intensified ionization that does not result in
the immediate complete breakdown of the material.
-
- Corrosive -
- Any substance which chemically attacks materials with
which it comes in contact, such as metals or human
tissue.
-
- Crazing -
- Minute cracks near the surface of plastic materials.
-
- Creep (cold flow) -
- The dimensional change with time of a material under
physical load. Creep at room temperature is called
“cold flow.”
-
- Cross-Linking -
- The establishing of chemical links between the molecular
chains in polymers. Cross-linking can be accomplished by
chemical reaction, vulcanization, and/or irradiation.
-
- Crystallinity -
- A state of molecular structure in some resins denoting
uniformity and compactness of the molecular chains. This
characteristic is attributable to the existence of solid
crystals with definite geometric form.
-
- Cuff -
- A smooth end on an irregularly surfaced tube or hose
enabling the secure and leak-free fitment of the tube or
hose to its termination point.
-
- Cure -
- The changing of the physical properties of a material by
chemical reaction; usually by the action of heat and
catalysts, alone or in combination, with or without
pressure.
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- D -
- Decay Rate -
- The speed in which a material will drain a static
electrical charge.
-
- Deflection Temperature -
- The temperature at which a standard test bar deflects
0.010” under a load of 66 or 264 psi.
-
- Deformation -
- The result when an object does not return to its original
form or shape after pressure or stress is removed.
-
- Degradation -
- Deleterious change in the chemical structure of a plastic
reflected in the appearance or physical properties.
-
- Delamination -
- The separation of layers in a laminate through failure of
the resin binder or adhesive.
-
- Density -
- The mass per unit volume of a substance expressed in
pounds per cubic foot, grams per cubic centimeter, etc.
-
- Denier -
- a unit of weight for measuring the fitness of threads of
silk, rayon, nylon, etc., equal to .05 gram per 450
meters.
-
- Die, Extrusion -
- Placed at the exit of an extruder barrel through which
the resin emerges and is formed into film, rods, pipe,
profiles, sheet, tubing, etc.
-
- Dielectric -
- 1) any insulating medium which intervenes between two
conductors; 2) a material having the property that energy
required to establish an electric field is recoverable in
whole or in part, as electric energy.
-
- Dielectric Strength -
- The electric voltage gradient at which an insulating
material is broken down or “arced through,”
usually expressed in volts per mil of thickness.
-
- Dimensional Stability -
- The ability of a part to retain its shape when exposed to
external forces.
-
- D.O.P. (Dioctyl Phthalate) -
- An ester plasticizer derived from natural fats and oils;
can be modified to meet specific end use requirements.
-
- Ductility -
- Amount of plastic strain a material can withstand before
it fractures.
-
- Durometer -
- A trade name of the Shore Instrument Company for an
instrument that measures the hardness of a material. A
lower Shore scale number indicates a softer, more
flexible material.
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- E -
- Elastic Deformation -
- The portion of deformation of an object under load which
can be recovered after the load is removed.
-
- Elasticity -
- The property of a material of which it tends to recover
its original size and shape after deformation.
-
- Elongation -
- The fractional increase in length of a material stressed
in tension.
-
- Embossing -
- Technique using pressure with or without heat to make a
permanent marking in a material's surface.
-
- Encapsulating -
- Encasing an article in a closed envelope of plastic by
immersing the object in a casting resin and allowing the
resin to polymerize, or, if hot, to cool.
-
- End Thrust -
- The total force generated at the far end of a conduit by
the sudden release of a fluid under pressure (spike
pressure) into that conduit; measured in psi and
calculated: (¹ x radius [in.]) x spike pressure [psi].
-
- EPDM -
- Ethylene Propylene Diene terpolymer
-
- Ester -
- The reaction product of an alcohol and an acid.
-
- Ethylene Vinyl Acetate (EVA) -
- A copolymer member of the polyolefin family derived from
random copolymerization of vinyl acetate and ethylene
resulting in a resin with similar properties to that of
polyethylene but with greater flexibility and resistance
to impact and elongation.
-
- EVA -
- Ethylene vinyl acetate
-
- Extender -
- A substance added to a plastic compound to reduce the
amount of resin required per unit volume.
-
- Extrusion -
- The process of compacting and melting a plastic material
and forcing it through an orifice (die) in a continuous
fashion.
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- F -
- FDA -
- Food and Drug Administration
-
- FEP -
- Fluorinated ethylene propylene
-
- FRP -
- Fiberglass reinforced plastic.
-
- Filament -
- Fiber of extreme length used in yarns and other
compositions with little or no twist and usually without
the spinning operations required for fibers.
-
- Filler -
- A very inexpensive material which is typically added to a
plastic to make it less costly. They can be inert or can
alter various properties of the plastic, particularly
hardness, stiffness, and impact strength.
-
- Fish Eye (Gels) -
- A small globular mass in a transparent or translucent
plastic material caused by the incomplete blending of the
mass into the surrounding material.
-
- Flame Retardant Resin -
- The result of reactive compounds that become an integral
part of the polymer structure and/or additive chemicals
that are physically dispersed in a polymer to retard or
eliminate the polymer's tendency to burn.
-
- Flammability -
- The measure of the extent to which a material will
support combustion.
-
- Flaring -
- The enlargement of a tube/hose diameter by mechanical
pressure from the inside.
-
- Flash -
- Excess plastic around the area of the parting line on a
molded part.
-
- Flexural Modulus -
- Ratio of applied stress to strain in outer fibers of
plastic specimen during flexure.
-
- Flexural Strength -
- The resistance of a plastic material to cracking or
breaking during bending expressed as the tensile strength
of the outermost fibers at the moment of failure.
-
- Fluorescent Pigments -
- Colorants which absorb radiation of a given frequency and
then emit radiation of a different frequency, creating a
glowing effect.
-
- Fluoroplastics -
- Polyolefin polymers in which fluorine, fluorinated alkyl
groups, or other halogens replace hydrogen atoms in the
carbon chain resulting in a material with outstanding
electrical properties, excellent resistance to chemical
attack, low coefficient of friction, excellent fire
resistance, exceptionally good performance at high and
low temperatures, low moisture absorption, and
outstanding weatherability.
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- G -
- Gamma Radiation -
- An electromagnetic radiation of great penetrating power
emitted by the nucleus of a radioactive substance.
-
- Gauge -
- Thickness of plastic film measured in decimal inches or
mils.
-
- GMP -
- Good Manufacturing Process
-
- Gummy -
- Having the nature of gum; viscid; sticky.
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- H -
- Haze -
- Cloudiness in a plastic material.
-
- HDPE -
- High density polyethylene
-
- Heat Distortion Point -
- See: “Deflection Temperature.”
-
- Heat Gun -
- An electrically controlled gun for softening, curing,
drying, preheating, and welding plastics, as well as
shrinking of thermally reducible tubing.
-
- Heat Resistance -
- The ability to withstand the effects of exposure to high
temperature.
-
- Heat Sealing -
- A method of joining plastic films by simultaneously
applying heat and pressure to areas in contact.
-
- Homopolymer -
- A polymer consisting of only one monomeric species.
-
- Hydrolysis -
- The chemical decomposition of a substance by reaction
with water.
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- I -
- Impact Strength -
- The ability to withstand shock loading.
-
- Impregnation -
- The process of thoroughly soaking a material such as
wood, paper, or fabric with a synthetic resin.
-
- Impulse Sealing -
- A sealing process in which intense thermal energy is
instantaneously applied to the sealing area, immediately
followed by rapid cooling.
-
- Inert -
- Substances which do not react with other materials under
normal temperature and pressure.
-
- Inhibitor -
- Substances that slow or halt a chemical reaction;
sometimes used in certain types of monomers and resins to
prolong product life.
-
- Injection Molding -
- A process in which melted plastic is forced into a
relatively cool mold cavity which forms the plastic into
the desired shape.
-
- IR -
- Isoprene rubber
-
- Irradiation -
- Subjecting plastics or other compounds to radiant energy
to cure or produce a change in the material.
-
- Izod Impact Test -
- A test for shock loading wherein a notched sample bar is
held at one end and broken by striking.
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- J -
Nothing available at this time.
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- K -
- K factor -
- The coefficient of thermal conductivity; the amount of
heat that passes through a unit cube of material in a
given time when difference in temperature of 2 faces is
1º.
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- L -
- LDPE -
- Low density polyethylene
-
- Light-Resistance -
- The resistance of a plastic to change color or other
characteristics during exposure to sun or ultraviolet
light.
-
- LLDPE -
- Linear low density polyethylene
-
- Luminescent Pigments -
- Special colorants added to a compound to produce
eye-catching effects in the dark. Basically there are two
types: one is activated by U.V. radiation producing very
strong luminescence, and the other is a phosphorescent
which does not require a separate source of radiation.
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- M -
- Mandrel -
- A core around which material is wound as in filament
winding, which when removed, forms a hollow center in a
tube.
-
- Manifold -
- Configuration of piping in a block of metal or plastic
that takes a single channel flow and divides it into
various flow channels to feed more than one outlet.
-
- MDPE -
- Medium density polyethylene
-
- Melt Index -
- The amount, in grams, of a thermoplastic resin which can
be forced through an 0.0825 “ orifice when subjected
to 2160 gms force in 10 minutes at 190ºC.
-
- Memory -
- The tendency of a thermoplastic material which has been
stretched while hot to return to its unstretched shape
upon being reheated.
-
- Mer -
- The repeating structural unit of any high polymer.
-
- Migration -
- The extraction of an ingredient from a material by
another material, such as the migration of a plasticizer
from one material to an adjacent material with a lower
plasticizer content.
-
- Modulus of Elasticity -
- The ratio of stress to strain below the proportional
limit of the material.
-
- Moisture Vapor Transmission -
- The rate at which water vapor permeates through a plastic
at a specified temperature and relative humidity.
-
- Mold -
- A hollow form or cavity into which molten plastic
material is placed to produce the shape of the required
component.
-
- Molecular Weight -
- The sum of the atomic weights of all atoms in a molecule.
-
- Monomer -
- A single molecule which can join with another monomer or
molecule to form a polymer or molecular chain.
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- N -
- Natural Rubber (NR)-
- An elastic substance produced by coagulating and drying
the milky sap (latex) of various tropical plants,
especially a tree (Heva brasiliensis) of the spurge
family.
-
- Neoprene -
- A synthetic rubber produced by the polymerization of
chloroprene providing a high resistance to oil, light,
heat, and oxidation.
-
- Nitrile Resin -
- Polymers of which the principal monomer is acrylonitrile.
This provides the functionality of good chemical
resistance and gas barrier properties.
-
- Notch Sensitivity -
- Extent to which the sensitivity of a material to fracture
is increased by the presence of a surface inhomogeneity,
such as a notch.
-
- NSF -
- National Sanitation Foundation
-
- Nylon -
- The generic name for all synthetic fiber-forming
polyamides; characterized by great strength, toughness,
and abrasion resistance, good fatigue resistance and
lubricity, and low coefficient of friction. They can be
formed into a monofilament and yarn. Current types
include 6, 6-6, 6-10, 11, & 12.
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- O -
- Oil Resistance -
- Ability to withstand the deteriorating effects of an
article by the absorption of oil; usually causing
volumetric swell and/or hardening.
-
- Outgassing -
- The release of a volatile substance from a compound
during curing.
-
- Oxidant -
- A gas which supports combustion.
-
- Ozone Resistance -
- Ability to withstand the deteriorating effect of Ozone
(which generally causes cracking).
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- P -
- Parting Line -
- The line formed by the mating surfaces of the molded
part.
-
- Peristaltic Pump -
- A type of pump in which the forward movement of material
inside a tube is performed in a wave-like fashion caused
by the contraction and dilation of the tube in a
longitudinal direction.
-
- Permeability -
- The rate at which a liquid or gas under pressure passes
through a solid material by diffusion and solution.
-
- PFA -
- Perfluoroalkoxy
-
- Plasticize -
- To impart softness and flexibility in a plastic through
the addition of a plasticizer additive or the application
of heat.
-
- Plasticizer -
- A chemical agent added to a resin to increase its
workability during processing, and to impart flexibility
and other desired properties to the finished product;
usually of an organic ester having a high boiling point.
-
- Polyamides (PA)-
- A polymer in which the structural units are lined by
amide groupings. Many polyamides are fiber-forming.
-
- Polycarbonate (PC)-
- Polymers derived from the direct reaction between
aromatic and aliphatic dihydroxy compounds with phosgene
or by the ester exchange reaction with appropriate
phosgene derived precursors. Structural units are linked
by carbonate groups.
-
- Polyester -
- A family of resins produced by reaction of dibasic acids
with dihydric alcohols or by the polymerization of of a
hydroxy carboxylic acid.
-
- Polyethylene (PE)-
- A thermoplastic composed by polymers of ethylene;
normally a translucent, tough, waxy solid which is
unaffected by water and a large range of chemicals.
-
- Polymer -
- A high molecular-weight organic compound, natural or
synthetic, whose structure can usually be represented by
a repeated small unit, the MER. Synthetic polymers are
formed by addition or condensation polymerization of
monomers. Some polymers are elastomers, some plastics,
and some are fibers.
-
- Polymerization -
- The chemical reaction in which the molecules of monomers
are linked together to form polymers.
-
- Polypropylene -
- 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.
-
- Polystyrene -
- A water-white thermoplastic produced by the
polymerization of styrene (vinyl benzene) offering
outstanding electrical properties; relatively unaffected
by moisture.
-
- Polysulfone -
- An amorphous structure; this engineering thermoplastic
has inherent resistance to heat, hydrolysis, oxidation,
and radiation; self-extinguishing.
-
- Polytetrafluoroethylene (PTFE) -
- Member of the fluorocarbon family of plastics created by
the polymerization of tetrafluoroethylene and
characterized by extreme chemical inertness, very high
thermal stability and low frictional properties.
-
- Polyurethane (thermoplastic) -
- Polymers which have properties combining the advantages
of elastomers and plastics; formed by the reaction of
bifunctional polyols with diisocyanates.
-
- Polyvinyl Chloride (PVC) -
- Thermoplastic compounds formed by polymerization or
copolymerization of vinyl or vinylidene halides and vinyl
esters. They are strong, with good abrasion resistance
and superior aging properties than that of rubber.
-
- Porosity -
- The ratio of the volume of a material's pores (voids) to
its total volume; usually expressed as a percentage.
-
- Post-Cure -
- The operation on a thermoset part in which the part is
subjected to elevated temperatures for a period of time
to effect full cure, stress relaxation, etc., and to
enhance property levels.
-
- Postforming -
- The forming, bending, or shaping of fully cured thermoset
laminate.
-
- Pressure Drop -
- The difference in pressure between any two points of a
component or system.
-
- PSI -
- Pounds per square inch.
-
- PVDF -
- Polyvinylidene fluoride
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- Q -
- Nothing available at this time.
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- R -
- Radiopaque -
- Not allowing the passage of X-rays, gamma rays, or other
forms of radiant energy.
-
- Random Copolymer -
- A copolymer in which the molecules of each monomer are
randomly arranged in the polymer backbone.
-
- Reinforced Plastics -
- 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 resulting in enhanced strength properties.
-
- Reinforcement -
- A material used to reinforce, strengthen, or give
dimensional stability to another material.
-
- Resin -
- An organic substance of natural or synthetic origin
characterized by being polymeric in structure and
predominantly amorphous. 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.
-
- Resistivity -
- The ability of a material to resist passage of electrical
current either through its bulk or on a surface. The unit
volume resistivity is the ohm-cm, or surface resistivity,
the ohm.
-
- Retractable -
- The ability to draw back to an original form once tension
is relieved.
-
- Rockwell Hardness -
- A common method of testing for resistance to indentation
in which a diamond or steel ball, under pressure, is used
to to pierce the test specimen. The load used is
expressed in kilograms (kg) and a 10 kg pre-load is first
applied and the degree of penetration noted. The major
load (60 to 150 kg) is next applied and a second reading
obtained. The hardness is then calculated from the
difference between the two loads and expressed with nine
different prefix letters to denote the type of penetrator
used and the weight of the major load.
- RoHS -
- The acronym for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products. The substances banned under RoHS are lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE).
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- S -
- SAE -
- Society of Automotive Engineers
-
- Santoprene® -
- A thermoplastic rubber with good fluid and flex fatique
resistance. Commonly used in peristaltic pumps for both
medical and general industry.
-
- SBR -
- Styrene butadiene rubber
-
- Self-Extinguishing -
- A loosely-used term describing a material's ability to
stop burning once the source of the flame is removed.
-
- Shear Strength -
- The stress at which a material fails in shear or the
ability of a material to withstand shear stress.
-
- Shelf Life -
- The period of time during which a material or product may
be stored at ambient temperature and humidity without
measurable degradation of its physical properties.
-
- Shore Hardness -
- A common method of determining the hardness of a plastic
material as developed by the Shore Instrument Company.
The device used, called a durometer, consists of a small
conical hammer fitted with a diamond point and acting in
a glass tube. The hammer is made to strike the material
under test and the degree of rebound is noted on a
graduated scale. Generally, the harder the material, the
greater the rebound.
-
- Silicone -
- One of the family of polymeric materials in which the
recurring chemical group contains silicon and oxygen
atoms as links in the main chain. These compounds are
derived from silica (sand) and methyl chloride. Silicones
are characterized by their resistance to heat and low
thermal expansion.
-
- Sintering -
- The process of holding a fusible pressed-powder article
at a temperature just below its melting point for a
period of time to fuse (sinter) the particles together.
-
- Slitting -
- The process of making a long, straight, lengthwise cut in
an article.
-
- Solvent Bonding -
- A process of joining articles made of thermoplastic
resins by applying a solvent to soften the surfaces to be
joined, and then the surfaces are pressed together.
Adhesion comes from evaporation of the solvent,
absorption of solvent into the material surfaces, and/or
polymerization of the solvent.
-
- Specific Gravity -
- The ratio of the mass of any volume to the mass of an
equal volume of another substance taken as a standard.
The standard for solids and liquids is usually water, and
for gases the standard is air.
-
- Specific Heat -
- The amount of heat required to raise a specified mass by
one unit of a specified temperature at constant pressure.
-
- Stabilizer -
- An ingredient included in the compounding of some
polymers to assist in maintaining desirable physical and
chemical properties of the compounded material throughout
the life of the material; ex: heat or U.V. stabilizers.
-
- Sterilization -
- The process of applying great heat or chemical action to
an article in order to clean it of all living
microorganisms.
-
- Strain -
- Elastic deformation due to stress; measured as the change
in length per unit of length in a given direction, and
expressed in percentage or inches per inch, etc.
-
- Stress -
- The unit force or component of force at a point in a body
acting on a plane through the point; expressed in psi.
-
- Stress Crack -
- External or internal cracks in a plastic caused by
tensile stresses; often appear as a network of fine
cracks known as crazing.
-
- Stress Relaxation -
- Time dependent decreases in stress for a specimen
constrained in a constant strain condition.
-
- Synthetic Resin -
- Any complex organic liquid or solid formed from simpler
molecules by polymerization or condensation; any of
various chemically modified natural resins.
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- T -
- Tack -
- Stickiness of a material, measurable as the force
required to separate an adherend.
-
- Talc -
- An inert refined mineral product (hydrated magnesium
silicate) that is a reinforcing filler extender. Because
of its platy configuration, it tends to add stiffness to
the resin, while its low cost categorizes it as an
extender. Talc is also commonly applied to reduce the
tackiness of some plastic materials.
-
- Tear Resistance -
- The resistance of a material to a force acting to
initiate and then propagate a failure at the edge of a
test specimen.
-
- Tensile Strength -
- The maximum tensile stress sustained by the specimen
before failure in a tension (pull) test; usually
expressed in pounds per square inch (psi).
-
- Thermal Conductivity -
- Ability of a material to conduct heat.
-
- Thermoforming -
- Any process in which thermoplastic material is heated to
its softened point and then drawn and/or forced against
an open mold. Depending on the technique, the mold can
either be male or female, and the method of forming
either vacuum and/or pressure.
-
- Thermoplastic -
- A material which has a linear macromolecular structure
that will repeatedly soften when heated and harden when
cooled.
-
- Thermoset -
- A material that will undergo or has undergone a chemical
reaction by the action of heat, ultraviolet light,
catalysts, etc., leading to a relatively infusible and
cross-linked state.
-
- Torsion -
- The stress produced by twisting one end of an object
along its longitudinal axis while the other end is held
firm or twisted in the opposite direction.
-
- Toxic -
- Substances which chemically produce injurious or lethal
effects to humans; poisons.
-
- TPE -
- Thermoplastic Elastomer
-
- TPR -
- Thermoplastic Rubber
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- U -
- UHMWPE -
- Ultra high molecular weight polyethylene
-
- U.L. -
- Underwriters' Laboratories
-
- Ultrasonic Welding -
- A method of joining plastics using ultrasonic vibrations
which are produced by the mechanical motion of a
converter expanding some 20,000 times per second. The
vibratory energy creates frictional heat which is
channeled through a horn and applied to thermoplastic
materials to produce a molecular interaction that welds
the materials.
-
- USDA -
- United States Department of Agriculture
-
- U.S.P. -
- United States Pharmacopoeia
-
- U.V. (Ultraviolet Light) -
- The radiation from sunlight or artificial light having
wavelengths shorter than those of visible light and
longer than those of x-rays (250-400 millimicrons).
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- V -
- Vicat Softening Point -
- The temperature at which a flat-ended needle of 1 mm2
circular cross section will penetrate a thermoplastic
specimen to a depth of 1 mm under a specified load using
a selected uniform rate of temperature rise.
-
- Viscosity -
- The measure of the resistance of a fluid flow (either
through a specific orifice or in a rotational
viscometer). The absolute unit of viscosity measurement
is the poise (or centipoise). Kinematic viscosity is
expressed in stokes.
-
- Vulcanization -
- The chemical reaction which induces extensive changes in
the physical properties of a rubber or plastic and which
is brought about by the reaction of the material with
sulphur and/or other suitable agents. The changes
typically include decreased plastic flow, solubility, and
surface tackiness, along with increased elasticity and
much greater tensile strength.
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- W -
- Weld Lines -
- The marks visible on a finished part made by the meeting
of two flow fronts of resin during molding.
-
- Welding -
- Joining pieces by one of several heat-softening
processes.
-
- Working Life -
- The period of time during which a material or product
retains the physical properties for which it was created.
-
- Working Pressure -
- The maximum recommended pressure at ambient temperature
for continuous operation.
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- X -
Nothing available at this time.
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- Y -
- Yield Strength -
- The lowest stress at which a material undergoes plastic
deformation. Below this stress the plastic is elastic;
above it , viscous.
-
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- Z -
Nothing available at this time.
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