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Glossary

5-Phenyltetrazole:  A high process temperature exothermic foaming agent generating nitrogen gas.

Acidic:  Term used to describe a material having a pH of less than 7.0 in water.

Acid Scavenger:  A group of additives, mostly basic metallic oxides and salts, which have high affinity to acidic residues, and neutralize them.  They are used whenever an acidic condition can be harmful.

Additive:  A supplementary material combined with a base material to provide special properties.

Alkaline:  Term used to describe a material that has a pH of greater than 7.0 in water.

Antifog/Antidrip Additives:  A group of additives (mostly surface-active compounds) which are added to films or sheets in order to eliminate fogging and/or dripping that is caused by excess humidity.

Antioxidants (AO):  A group of additives which provide thermal protection, mostly by intervening within the oxidation process.

Antistatic Properties:  The ability of a fabric to disperse an electro static charge and prevent buildup of static electricity.

Artificial Exposure:  An experimental set-up whereby a sample is subjected to artificial weathering conditions. In most cases, these conditions will be purposefully exaggerated in order to accelerate their effect.

Azodicarbonamide:  A yellow-colored efficient exothermic foaming agent generating mostly nitrogen gas. Azodicarbonamide is well suited for injection molding and sheet or profile extrusion in a wide variety of polymers.

Beer-Lambert’s Law:  A law which states that the amount of light absorbed by a body is proportional to the amount of absorbing particles in it.  This means that it will be proportional to the concentration of that additive multiplied by the thickness of that body (the path length of the light through the body).

Bicarbonate / Acid:  A white endothermic foaming agent with the widest application capabilities.  This chemistry provides small cell structure and smoother part surfaces.

Black Body:  A surface that absorbs all radiation falling upon it, and then re-emits it in a wavelength which is related to its absolute temperature.

Blocking:  The adhesion of two adjacent layers of film, a problem most associated with polyethylene and polypropylene film production,  and to a lesser extent in extrusion coated or laminated products. The most effective method for combating these handling issues is to add an antiblock masterbatch.

Calender:  A machine consisting of cylinders or rolls that manufactures sheet and film, and also can be used to mechanically finish a fabric.

Carbonyl:  A Carbon-Oxygen double bond.  A molecular group which can be created via oxidation process.  It can also act as as a chromophore, and its amount is usually taken as an indication to the advancement of polymer degradation (for example Carbonyl Index).

Card:  A machine that combs or works fibers between fine surfaces or points to separate, clean and align the fibers.

Carding:  A process that transforms entangled fiber mats into parallel strands.

Chain Scission:  A process of breaking polymeric chains by free radicals.  This kind of process may bring about degradation of the polymer.

Chromophore:  A molecule capable of absorbing light, mainly in the visible or UV range.

Combing:  The part of the carding process when nap is removed and fibers are aligned.

Compatibility:  A property which describes the affinity of a polymeric material and an additive.  The amount of compatibility is generally linked to the similarity of the physio-chemical properties of the polymer and additive.  In case there is no compatibility, the additive will tend to migrate to the surface of the product.

Concentrate:   A pelletized plastic material containing highly loaded pigments which is used in a polymer system to change the final color and/or properties of a plastic part.

Controlled Atmosphere:  A term which defines our ability to control the chemical (gaseous) composition of an enclosed volume of air. Mainly used in connection with packaging, but is also applicable for greenhouses and other agricultural constructions.

Co-stabilizers:  A group of additives which augment the protective abilities of other stabilizers (for example: acid scavengers).

Crimp:  Waviness or kink in a fiber.

Cross-linking:  A process of bonding polymeric chains.  This kind of process has the effect of producing gel in a thermoplastic polymer or converting it into a thermo set polymer.

Decitex (Dtex):  One-tenth of a tex, which is equal to the weight in grams of 1 kilometer of a fiber.

Decomposition Temperature:  The polymer’s melt temperature above which the chemical foaming agent generates gas.

Degassing Time:  Gases generated in a polymer by a foam concentrate are expired and replaced by air after processing.  Bicarbonate / acid foam agents generate carbondioxide that defuse through most polymers more quickly than nitro gengenerated by azodicarbonamide.  Rapid degassing time allows shorter timespans between part molding and painting.

Degradable Mulch:  A mulch which is intended to disintegrate at the end of the growing season, by photodegradation in order not to interfere with the next crop.

Denier:  The weight in grams of 9,000m of material.

Denier Per Filament (DPF):  The denier of an individual continuous filament, or an individual staple fiber if it were continuous; in filament yarns, the yarn denier divided by the number of filaments.

Direct/Indirect Light Transmission:  Amount of light transmitted through a sample, directly in-line with the incident light, or at a certain angle (usually around 5-10°) from it. The ration of these two values is the Haze which is a measure of diffused light.

Dispersion:  The breaking down of a pigment aggregate into its individual particles, by the application of mechanical work.

Distribution:  The level of uniformity of dispersed pigment particles in a plastic part or film.

Drawing:  Controlled stretching of a fiber or filament by a factor of 4 to 10, causing the molecular chains to align along the fiber axis.

Endothermic:  A foaming agent’s chemistry causing heat to be absorbed when the gas is generated.

Exothermic:  A foaming agent’s chemistry causing heat to be generated when gases are released.

Far-Red Radiation:  A part of the visable radiation (700-800nm).  The ratio of far-red/red can have a special effect on crops by influencing their growth and development.

Fiber:  Unit of matter characterized by a high ratio of length to width.

Filament:  A fiber of an indefinite length.

Finishing:  Property enhancing processes carried out after web is formed and bonded; includes embossing, printing, creping and coating.

Fluorescence:  An optical process by which energy is transferred from a certain range into a longer wavelength range.

Foaming Agents:  May be chemical dry powders (azodicarbonamide, bicarbonate/acids, phenyltetrazoles)that generate gas or physical (compressed carbon dioxide, nitrogen, air or hydrocarbons) that are already a gas in the polymer melt process.  Foam concentrates are formulated with chemical foaming agents.

Fumigation:  A process by which the soil is sterilized from any insect, disease or weed, prior to the growing of a crop. This is usually done by covering it with mulch and injecting a Fumigant (gas or low-boiling liquid) into the soil.

Greenhouse Effect:  The ability to keep the air temperature within the greenhouse construction higher than outside temperature especially during night time and in cooler growing climates.

Geotextile:  Fabric used in civil engineering applications such as roads, dams, airfields,and roofs.

HALS:  Hindered Amine Light Stabilizers, a group of additives having a common chemical structure (a pipe ridine ring) as part of their molecule.  These highly effective UV stabilizers protect the polymer by scavenging free radicals.
Hydrophilic:  Water loving, the property of a chemical that is polar, and is soluble in water.

IR Reflective:  Additives: A group of additives which diffuse heat by reflecting the NIR energy.

Interfacial Tension:  The difference in surface tension between two media.

IR Thermal:  A group of additives which preserves heat by absorbing the NIR energy.

IR Transmitting:  Allows the transmission of the NIR radiation to warm the environment underneath the plastic.

Kly:  Kilo-Langley.  Langley is a unit of irradiation energy: 1Kly-1 Kcal/cm²  On average -140 Kly relate to 1 year outdoor exposure in Florida.

Light Diffusion:  An optical property that is caused by the interaction of particles with the light rays.  This property is very important in greenhouses since it will determine the actual amount of photosynthetic light available for the plants by controlling the amount of light scattering within the greenhouse.  Diffused light will help prevent shadows in the greenhouse allowing lower leaves of plants to be exposed to light.

Masterbatch:  A pelletized plastic material containing highly loaded pigments which is used in a polymer system to change the final color and/or properties of a plastic part.

Meltblowing:  A method of forming fabric from thermoplastic resins; the resin is melted, extruded and blown with fast-moving air that stretches or attenuates the fibers, which are then condensed and compressed.

Micron:  One-millionth of a meter.

Mid-IR Radiation:  The range of electromagnetic radiation from 2500+ nm.  This energy does not exist within solar radiation.  Soil and plants can emitt energy in this range (like a black body at the appropriate temperature) at 7-12µ, as a result of NIR absorption changes from the sun.

Mil:  One-thousandth of an inch.

Mulch:  An agricultural protective layer over the ground, which covers an area upon which a crop is grown and is used to enhance productivity by conserving moisture and preventing evaporation, suppressing weed growth, extending growing seasons, and aid in fumigation and fertilization.

Needlepunching, Needling:  Method of mechanically interlocking fiber webs by physically repositioning some of the fibers from a horizontal to a vertical orientation.

NIR Absorbing Dyes:  A group of dyes which relieves heat-stress by selectively (more or less) absorbing radiation in the Near IR range.

NIR Radiation:  The range of electromagnetic radiation from 800-2500nm which includes all the thermal portion of solar radiation.

NIR Reflecting Pigments:  A group of pigments which relieve heat-stress by selectively (more or less) reflecting radiation in the Near IR range.

Optical Filters:  Additives which selectively absorb, reflect, or transmit a certain area of the solar energy spectrum,  thus enabling manipulation of that radiation in a desired way.

Pesticide Sensitivity:  A problem, mostly associated with HALS (and to a lesser degree with Nickel compounds) which arises from the basic character of these molecules as they are alkaline in nature.  Pesticides commonly contain Halogenor Sulfur (or both) atoms in their molecules.  The alkaline amine might react with these Halogen or Sulfur containing compounds (or their degradation products which are acidic) thus becoming inactive by forming amine salts.

Photosynthetically Active Radiation(PAR):   Energy from the visible range of solar radiation, (400 – 800 nm), the wavelengths most active in photosynthesis.

Primary Backing:  The fabric, usually woven or nonwoven polypropylene or jute, into which a carpet is tufted.

Post Blow:  Parts molded with a foam concentrate continues to swell after molding because of insufficient cooling prior to de-molding.

Quenchers:  A group of additives, mostly Organo-Nickel compounds, which stabilize irradiated organic materials by quenching excited molecules.

Radicals:  (Free Radicals) A molecule which has at least one unpaired electron.  In polymers, such a species will be formed, most probably, as a result of chemical bond breakage by heat or light energy.  These free radicals are very active, and in their attempt to pair their lone electron, are capable of breaking other chemical bonds.  Thus, they can cause degradation in a polymer.

Screeners:   Pigments or additives which, apart from being active in the visible range, screens out UV radiation and/or visible radiation by absorbing or reflecting it.

Sink Marks:  Depression defects in a molded parts surface caused by uneven cooling shrinkage of some polymer.  Foam concentrates create an internal pressure to flatten the polymer to the mold surface and eliminate sink marks.

Slow/Timed Release:   A technology which deals with the controlled release of a chemical from a certain product.

Spunbonding:  Process of forming fabric by layering filaments on a screen and immediately bonding.

Staple Fibers:  Fibers cut to specific lengths.

Structural Foam:  Describes a molded or extruded object possessing a smooth solid skin and a cellular core. Structural foam provides improved part strength to weight ratios.

Surface Energy:  A property of a medium which describes the attraction that draws the surface molecules inward.

Tex:  The weight in grams of 1 km of material.

Thermoplastic:  A plastic that melts upon heating.

Thermoset:  A plastic that, when formed, does not melt.

Tow:  A bundle of continuous filaments.

UVA:  UV Absorbers, a group of additives which protect organic materials by absorbing the UV radiation.

UV Barriers:  A class of UVAs which totally block UV light.

UV Stabilizers:  Additives which stabilize organic materials against UV radiation.

UV Radiation:  The range of electromagnetic radiation from 150-400nm.  In solar radiation, there is a significant amount only over 250nm.

Visible Radiation:  The range of electromagnetic radiation from 400-800nm.