Polymer Glossary

on 06 December 2024. Posted in Materials

See Articles - List of Tags, List of Categories, List of Articles, List of Glossaries, Nomenclature and Symbols, (See Polymer)

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ABS Plastic - Any of a class of plastics or plastics based on acrylonitrile-butadiene-styrene copolymers.
Acetal - Translucent to opaque resins produced by polymerization of formaldehyde and characterized by a high melting point, high strength and stiffness, and solvent resistance.
Acetone (Propanon) - A colourless flammable volatile compound. It is used as a solvent and as a raw material for making plastics.
Activator - A substance that increases the activity of a catalyst.
Active Packaging - Packaging that acts to help preserve products such as food because of substances like an antioxidant or a desiccant incorporated into the packaging material.
Addition Polymer - A type of polymer formed by the repeated addition of monomer units without the loss of any small molecules. The monomers used in addition polymerization typically contain a double bond or other reactive groups, such as alkenes, which allow them to react and link together in a chain reaction.
Addition Polymerization - A chemical reaction in which simple molecules are linked together to form long chain molecules.
Additive - Materials such as plasticizers, preservatives, slip agents, antistatic agents, processing aids, and others, added to a base material in order to achieve a specific result. The term is broadly applied to any material added in small amounts to formulated products such as inks, plastics, papers, adhesives, and so on.
Adherant - To stick together. To cause two surfaces to be held together by adhesion, for example, ink to stock.
Adherend - The surface or material to which an adhesive has been applied. One of the two surfaces to be joined by an adhesive.
Adhesion - An attraction between different substances on either side of a phase boundary. Adhesive is a substance used for joining surfaces together.
Adhesiveness - The ability of a material to adhere to other surfaces.
Adsorption - Attraction of a substance to a surface resulting from the attraction of molecules of the two substances, for example, the condensation or adhesion of gases, liquids, or dissolved substances on the surface of solids. The phenomenon occurs without any chemical reaction.
Alkalies - Compounds capable of neutralizing acids and usually characterized by an acrid taste. It can be mild, like baking soda, or highly caustic, like lye.
Alkyd Resins - A class of resins produced by condensation of a polybasic acid or anhydride and polyhydric alcohol.
Allyl Resins - A class of resins produced from an ester or other derivative of allyl alcohol by polymerization.
Alternating Copolymer - A polymer comprising only two types of repeat unit chemically linked in an alternating sequence.
Amine - Any of A class of organic compounds derived from ammonia by replacement of hydrogen with one or more alkyl groups.
Amorphous - Non-crystalline polymer or non-crystalline areas in a polymer.
Antioxidant - Substance which prevents or slows down the oxidation of material exposed to air.

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Baggey Edge - Rolls of film or laminate where one side of the material coming off the roll is loose or baggy while the opposite edge is taut.
Barrier Material - A material designed to prevent, to a specified degree, the penetration of water, oils, water vapor, aromatic components or other gases. Barrier materials may serve to exclude or retain such elements without or within a package.
Base - This is the material created in the form of rolls or sheets, which is used for the creation of lamination plastics. The base material is impregnated with a resin to produce the desired laminated plastics. Woven material, paper, glass fabric, cotton, or glass fiber mat, aramid fibers, felted asbestos are a few common base materials used in the plastic industry.
Base Color - The first color laid down that serves as a background on which other colors are printed.
Baume - One of the many hydrometer scales used to determine the relative density of liquids as compared to a standard liquid. There are two Baume scales: one for liquids lighter than water; the other for liquids heavier than water.
Benzene Ring - The basic structure of benzene, the most important aromatic chemical. It is an unsaturated, resonant 6 carbon ring having three double bonds. One or more of the hydrogen atoms of benzene may be replaced by other atoms or groups.
Binder - The adhesive component that holds together the nonadhesive components of a compound mixture such as a printing ink.
Biodegradable - A material that is capable of being converted by microorganisms into basic elements and compounds such as carbon dioxide and water.
Biaxial Orientation - This is the process of stretching a plastic film in two directions such that they produce molecular orientation in two directions
Block Copolymer - A polymer comprising more than one type of monomer repeat unit, in which each type of monomer is found in a homopolymerized block within the polymer chain.
Blow Hole - In shrink film, a hole or area melted through by excessive heat or poor sealing.
Bonding Range - The time after the adhesive is applied within which a satisfactory bond can be made when the substrate surfaces are brought together. See also open time.
Branched Polymer - A type of polymer where the main chain of the molecule has side chains or branches attached to it. These branches are composed of the same or different monomer units as the main chain. The branching alters the physical and chemical properties of the polymer compared to a linear polymer.
Branching - Describes a polymer chain that has additional side chains branching away from the main or linear chain.

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Cast resin - A resinous product prepared by pouring liquid resins into a mold and heat treating the mass to harden it.
Catalysis - The acceleration (or retardation) of a chemical reaction by the presence of a comparatively small amount of a foreign substance called a catalyst.
Cellulose - A natural polymer found in wood and other plant material. Cellulose is a complex carbohydrate, or polysaccharide, made up of glucose molecules linked together in long chains. It is one of the primary components of the cell walls in plants, giving them structural support and rigidity.
Clarified - A polymer that contains a clarifier additive. Clarifiers help to increase the clarity of a polymer and are commonly used in polypropylene random copolymers.
Crystal - A mass of molecules arranged in a neat and orderly fashion. In polymer crystal the chains are lined up neatly like new pencils in a package.
Compatibilizer - A substance used to stabilize blends of incompatible polymers.
Composite Polymer - A filled or reinforced plastic.
Condensation Polymer - One in which two or more molecules combine resulting in elimination of water or other simple molecules, with the process being repeated to form a long chain molecule.
Configuration - Related chemical structure produced by the making and breaking of primary valence bonds.
Copolymer - A polymer made from two or more different types of monomer units that are chemically bonded together. By combining different monomers, copolymers can be tailored to have properties that are intermediate or even superior to those of homopolymers.
Crate grade - High density polyethylene with a melt index of 7 to 10 grams/10 minutes.
Creep - Cold flow of a polymer.
Cross-Linked Polymer - A type of polymer where the long chains of molecules are connected by covalent bonds to form a three-dimensional network structure. These connections, called cross-links, can occur during the polymerization process or through chemical treatment after the polymer is formed.

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Degradation - Any deleterious change in the chemical composition, appearance, physical or mechanical properties of a plastic material.
Dendritic Polymer - A highly structured spherical polymer grown in successive generations from a central core moiety, in which every monomer in a generation contains a branch point and allows the attachment of more than one repeat unit in the next generation, such as poly propylene imine.
Desiccant - An additive added to a plastic to help absorb moisture. Often used in film packaging applications.
Dilute Solution - A solution in which the sum of the volumes of the domains occupied by the solute molecules or particles is substantially less than the total volume of the solution.
Discoloration - Any change from original color. Discoloration is often caused by overheating, light exposure, irradiation or chemical attack.
Double-Strand Chain - Ladder chain: a chain that comprises constitutional units always joined to each other through four atoms, two on each constitutional unit.
Dry Bonding - The process of laminating or joining two surfaces using an adhesive system from which all solvents or volatiles have been removed prior to the mating of the surfaces. Dry bonding must be used when joining any two surfaces that are not porous enough to allow the rapid escape of volatiles.
Durometer - A numerical scale for measuring the hardness of rubber or plastic based on the depth of penetration of an indenter point on the surface of the test specimen.

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Emulsion Polymerization - A polymerization performed in an oil-in-water emulsion (monomer in the oil droplets, surfactant and initiator in the aqueous continuous phase) using a water-soluble initiator where initiation occurs in the aqueous continuous phase. The polymerization occurs mainly in the monomer-swollen surfactant micelles in the continuous phase, fueled by diffusion of monomer from the droplets to the micelles, and not in the monomer droplets themselves. The result is a polymer latex, a dispersion of polymer particles usually less than 1 μm in diameter with a narrow size distribution.
Environmental Stress Cracking (ESC) - Cracking caused by the combined influence of a mechanical stress and a chemical or surface active substance. Environmental stress cracking results in a brittle failure, especially in amorphous polymers.
Environmental Stress Cracking Resistance (ESCR) - The ability of a polymer to resist slow crack growth or environmental stress cracking.
Epoxy resin - Straight-chain thermosetting resins containing at least one three-membered ring consisting of two carbon atoms and one oxygen atom.
Ester - A compound formed by the elimination of waste during the reaction between an alcohol and an acid; many esters are liquids. They are frequently used as a plasticizer in rubber and plastic compounds.
Extrusion Coating - Extrusion coating is the coating of a thermoplastic polymer onto a substrate material. Substrate materials are often paper, paperboard, cardboard, foils, non-wovens or plastic film.
Extrusion Bonding - A process wherein a film of molten polymeric material is extruded and immediately pressed between two substrate materials while still hot. The cooled polymer will bond the two materials together.
Extrusion Lamination - A process for joining two webs of material by feeding them through a machine that extrudes a thin layer of plastic between them to act as an adhesive.

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Fixture Time - The amount of time it takes for the adhesive to build strength to specific levels, usually enough to continue with the manufacturing process. This is not an industry standard and varies from part to part, and adhesive to adhesive. Temperature, and other conditions such as bond configuration and substrate properties affect fixture time.
Fluorination - This is an extra process in which a thermoplastic article (container or closure) is exposed to fluorine gas. The fluorine substitutes with some hydrogen atoms in the polymer chain, creating a barrier and surface enhancement. Benefits include improved barrier properties and reduced solvent absorption and permeation.
Free Radical - A chemical component that contains a free electron which covalently bonds with a free electron on another molecule.
Full Cure - The full curing time is the time needed for an adhesive system to achieve its ultimate mechanical properties and complete its polymerization.

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Gamma Stabilizer - Additives that are added to a polymer to improve its resistance to gamma sterilization.
Gas Fading - Gas fading is a yellow or pink discoloration that occurs when atmospheric pollutants like nitrogen oxide gases react with phenolic-type antioxidants. It is common in polyethylene and polypropylene films.
Gas Phase Polymerization - Gas phase polymerization is a widely used polymerization technique for gaseous monomers such as ethylene, vinyl chloride and polytetrafluoroethylene. This method has the advantage that it does not require any solvent and that no residual catalyst remains in the powder or pellet after polymerization.
Glass Transition Temperature - The temperature where a polymer changes from a rigid, glassy material to a soft, viscous material. For amorphous polymers a temperature of 15-20°C below the glass transition temperature represents the upper useful temperature limit.

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Haze - Haze is a measure of clarity. A resin with a haze of 5% allows 95% of the light to pass through the film.
Hexene - A comonomer used to produce linear low density polyethylene.
High Load Melt Index (HLMI) - Used to measure the melt index of high molecular weight, very low flowing materials, most notably polyethylene.
Homopolymer - A type of polymer composed of only one type of monomer unit. In other words, the repeating structural unit in the polymer chain is identical throughout. Homopolymers are characterized by their uniform chemical structure, as they are derived from a single type of monomer.
Hydrogen Bonding - A bond that is primarily an electrostatic force of attraction between a hydrogen atom and another electronegative atom bearing a lone pair of electrons. Hydrogen bonds are responsible for many of the physical and chemical properties of compounds containing nitrogen, oxygen and fluorine.

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Impact Modifier - A rubber or elastomer modifier added to a polymer to improve the toughness and impact resistance.
Impact Strength - Impact strength or toughness of a material is defined as its ability resist to fracture by a blow or a sudden applied load or force.
Inhibitor - A substance that slows down chemical reactions. Inhibitors are sometimes used in monomers and resins to prolong storage life.
Initiation - The first step in a chain growth polymerization in which an active species reacts with the first monomer of the polymer chain.
Injection Blow Molding - A blow molding process where a pre-form is first injection molded, then is re-heated and blown. Pre-forms typically have fully formed threads that have high dimensional tolerances that cannot be achieved in extrusion blow molding.
Injection Molding - Method of forming a plastic to the desired shape by forcing heat-softening plastic into a relatively cool cavity where it rapidly solidifies.
Injection Stretch Blow Molding (ISBM) - Similar to injection blow molding, except that during the blowing phase, the pre-form is stretched and blown in the radial and longitudinal directions.
Irregular Polymer - A substance composed of irregular macromolecules.
Izod Impact Test - A test designed to determine the resistance of plastic material to shock loading. It involves notching a specimen, which is then placed in the machine's jaws and struck with a weighted pendulum.

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Jet Molding - A modified version of an injection molding technique characterized by the fact that more heat can apply to the material rather than from a heating cylinder, as is done in ordinary processes.
Jetting - A defect in injection molding that occurs when the molten plastic is injected at a high velocity and does not make initial contact with the mold wall. Also called snaking.
J Fold - The folding of a plastic film along its length to obtain a two layered product with one layer wider than the other.

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Kevlar - A strong, synthetic heat resistant fiber. Kevlar was first used as a replacement for steel wire in racing tires. Kevlar fiber is used in plastic compounds for friction and wear applications.
Kirksite - An alloy of aluminum and zinc used in the construction of molds. It is known for its high thermal conductivity.
Knit Lines - Also known as weld lines or mold lines, it can occur when the mold or material temperatures are set to low or when the melt reforms after going around a mold feature.

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Let Down Ratio (LDR) - The level at which a masterbatch is added into a base polymer. Typical let down ratios for color and additive masterbatches are 1% to 5%.
Linear Polymer - A type of polymer in which the monomeric units are connected in a straight or single continuous chain, with minimal or no branching. The repeating units are linked end-to-end, forming a linear molecular structure.
Living Polymerization - Polymerization reaction in which there is no termination, and the polymer chains continue to grow as long as there are monomer molecules to add to the growing chain.
Long Chain Branching (LCB) - Long chain branches are formed in the high pressure polymerization process used to make low density polyethylene (LDPE) and ethylene vinyl acetate (EVA). These long chain branches occur at random intervals along the length of the main polymer chain. The long chain branches themselves can contain branches.
Long Term Heat Aging (LTHA) - Special additives that are added to a polymer (often polypropylene) to provide retention of properties at elevated temperatures and long periods of time.
Low Water Carry-Over (LWCO) - Special additives used in polypropylene to help reduce water from adhering to the surface of PP films and tapes when they pass through cooling water baths. Any water adhering to the film surface can cause issues further down the manufacturing process.

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Magnetic Detectable Additives - Additives that are added to a plastic compound so that it can be detected by metal detectors. These additives are often used in plastic compounds that are used in the food processing industry. These additives help detect any plastic pieces that could potentially get into food products.
Melt Flow Index (MFI) - The mass of resin that exits the melt index tester in 10-minutes under specific test conditions of temperature and load. Inversely related to molecular weight. Melt flow index is typically used for materials other than polyethylene.
Melt Flow Rate (MFR) - The mass of resin that exits the melt index tester in 10-minutes under specific test conditions of temperature and load. Inversely related to molecular weight. Melt flow rate is the same as melt flow index and is typically used for materials other than polyethylene.
Melt Index (MI) - The mass of resin that exits the melt index tester in 10-minutes under specific test conditions of temperature and load. Inversely related to molecular weight. Melt index is typically only used in describing polyethylene.
Melt Volume Rate (MVR) - Similar to melt flow rate except the test measures the volume of material through the die in 10 minutes, rather than the mass of material.
Metallocene Catalyst - A single site catalyst that produces a polymer with a narrow molecular weight distribution and a narrow short chain branching distribution.
Melting Temperature - A temperature at which crystalline or semi-crystalline polymers melt to form an amorphous phase.
Molecular Weight - The mass of a molecule relative to the unified atomic mass unit or the gram per mole. It is a fundamental property of a chemical compound and is calculated by summing the atomic masses of all the atoms in a molecule. The molecular weight is used to determine the amount of substance, in moles, present in a given mass of a substance.
Monomer - A molecule that can be polymerized to form a polymer.

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Natural Polymer - Polymers are chains of repeated molecules linked together. Natural polymers are those that occur naturally and are found in living things such as plants and animals. There are three main types of structures found in natural polymers, proteins, sugars, and nucleotides.
Nucleating Agent - Nucleating agents are additives which provide sites for crystal growth. This results in a finer crystal size which improves clarity and transparency and reduces processing cycle time.
Nylon - A polymer used commonly in the textiles industry. Nylon is a type of synthetic polymer, it is part of the family of polyamides, made from repeating units linked by amide bonds. Nylon was the first synthetic fiber made entirely from petrochemicals and became a revolutionary material due to its strength, elasticity, and versatility.

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Octene - A comonomer used to produce linear low density polyethylene.
Olefin - Any of a group of unsaturated open chain hydrocarbons possessing one or more double bonds, the simplest which is ethylene.
Oligomer - A small macromolecule consisting of around 10 to 100 chemically bonded monomer repeat units.
Opaque - A term describing a material or substance which will not transmit light.
Outgassing - To remove occluded gases by heating.
Oxidation - The addition of oxygen to a compound. Oxidation can occur due to exposure to elevated temperature, UV or chemicals.

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Parison - A tube-like piece of plastic that is extruded at the beginning of the blow molding process. Once the parison is extruded, the mold closes, and air is blow into the parison to expand it to the shape of the mold.
Phenolic Resin - Resins made by the reaction of a phenol compound or tar acid with an aldehyde, more commonly applied to thermosetting resins made from pure phenol.
Pinking - Pinking is a pink discoloration that occurs when atmospheric pollutants like nitrogen oxide gases react with phenolic-type antioxidants. It is common in polyethylene and polypropylene films.
Plastic - Moderate intermolecular forces; can be either thermoplastics or thermosetting. The intermolecular and intramolecular interactions within plastic materials that determine their mechanical, thermal, and physical properties. Plastics are polymers composed of long chains of repeating units (monomers), and the molecular forces in these polymers dictate their strength, flexibility, and durability.
Plasticizer - A chemical added to a plastic to make it more flexible and less brittle. Plasticizers are commonly added to rigid PVC to turn it into flexible PVC.
Polymer - A large molecule composed of repeating structural units called monomers, which are covalently bonded together in a chain or network. Polymers can be naturally occurring, like DNA, proteins, and cellulose, or synthetic, like plastics, rubber, and nylon. Polymers are widely used due to their versatility, being found in materials with diverse characteristics, such as strength, flexibility, or elasticity.
Polymeric Processing Aid - These are additives, often based on fluoropolymers, that help to improve the process efficiency and quality of high molecular weight polymers. They are often used to help eliminate surface defects such as melt fracture and shark skinning.
Polymerization - A chemical reaction that converts monomer molecules to macromolecules.
Polystyrene - A polymer commonly used in packaging.
Pot Life - The time available before a multi-component product no longer exhibits the same properties as it did upon initial mixing. This can be variable due to difference in ambient conditions.
Propagation - The chemical reaction of monomer units to incorporate them into a growing chain.
Protein - A wide variety of naturally occurring polyamides made from amino acid monomers, which are used in a multitude of biological processes.

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Quinacridones - Quinacridones are organic compounds used as pigments, most commonly in red-violet colors.

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Random Copolymer - A polymer comprising more than one type of repeat unit, chemically linked in as arbitrary sequence.
Rubber - A versatile and elastic material derived from natural or synthetic sources. It has a unique ability to stretch and return to its original shape, making it useful in a wide range of applications. Natural ribber is made from the latex of rubber trees. Synthetic rubber is made from petrochemical-derived polymers such as styrene-butadiene rubber, neoprene, or nitrile.

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Semi-Crystalline Polymers - Polymers that contain both amorphous regions as well as crystalline, ordered regions in their structure. The crystalline regions are highly ordered and have well defined melting points.
Semi-Synthetic Polymer - It is a type of polymer derived by chemically modifying natural polymers. These modifications are carried out to enhance or alter the properties of the original natural polymer to make it more suitable for specific applications.
Shear Thinning - When a polymers viscosity decreases as the shear rate in increased. Branched polymers like LDPE and EVA have high shear thinning characteristics.
Short Chain Branching (SCB) - Shorth chain branches are short chains, typically less than 8 carbon atoms long. In polyethylene, short chain branches are based on butene, hexene or octene. Short chain branches break up the crystallinity and reduce the melting point of the polymer.
Slurry Loop Reactor - Slurry loop reactors are primarily used to make high density polyethylene. In this process the slurry consists of undissolved polymer in a liquid mixture of diluent, ethylene, comonomer, and catalyst. The diluent and comonomer must be separated from the slurry exiting the reactor.
Solution Polymerization - A polymerization carried out in a one-phase system with monomer, polymer, and initiator dissolved in a common solvent, in which the final polymer product is also soluble.
Star Polymer - A polymer in which three or more linear polymer chains radiate from a central, multifunctional moiety to which they are all chemically attached, either by coupling or by being grown from that moiety in the polymerization step.
Suspension Polymerization - A polymerization performed in an oil-in-water emulsion using an oil-soluble initiator (monomer and initiator form the oil droplets, surfactant is in the aqueous phase). The polymer is formed in the emulsified oil droplets and the resulting size distribution reflects that of the starting emulsion droplet size distribution.
Synthetic Polymer - There are many synthetic polymers, and every synthetic polymer has specific uses. These uses can range from applications in clothing, body armor, pipes, and upholstery. Synthetic polymers can be classified into four main categories: thermoplastics, thermosets, elastomers, and synthetic fibers. Each of these categories have several polymers within them.

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Tackifier - Chemical compounds used in formulating hot melt adhesives to help improve the tack or stickiness. They are usually low molecular weight chemicals (high flow) with high glass transition temperatures.
Tearing Bond - A paper bond having sufficient strength that is necessary to tear fibers of one or the other adhered surfaces in order to separate them, while, at the same time, there is no failure in adhesion or cohesion of the adhesive.
Thermoplastic Polymer - A category of polymers that become soft or pliable when heated and harden upon cooling. This process is reversible, meaning thermoplastics can be repeatedly melted and reshaped without significantly altering their chemical properties, making them highly versatile and recyclable.
Thermoset - A polymer that chemically cures (crosslinks) upon heating into a form that does not soften on reheating.
Thermosetting Polymer - A category of polymer materials that, once cured or hardened through the application of heat, chemical reactions, or irradiation, cannot be remelted or reshaped. These materials form a rigid, three-dimensional molecular structure that is highly durable and resistant to deformation under heat or pressure.

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Vacuum forming - Method of sheet forming in which the plastic sheet is clamped in a stationary frame, heated, and drawn down by a vacuum into a mold.
Vented Film - A plastic film that has small holes that will allow contained produce to breathe.
Vinyl Chloride - The monomer used in PVC production.

Virgin Material - Any plastic compound or resin that has not been subjected to use or processing other than that required for its original manufacture.
Volatile Organic Compounds (VOC) - Organic chemical compounds that have a high vapor pressure at room temperature. VOCs can be found in many products such as plastics, paints, pharmaceuticals, and refrigerants.

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Warpage - Dimensions distortion in a plastic object after molding.
Weather Resistance - The ability of plastic to retain its original physical properties and appearance upon prolonged exposure to outdoor weather.
Wetting Agent - Wetting is produced when this surface active agent decreases the cohesion within a liquid. For wetting to occur, the adhesive force between the two phases (solid and liquid) is greater than the cohesive force within the liquid.
Wetting Agent - Wetting is produced when this surface active agent decreases the cohesion within a liquid. For wetting to occur, the adhesive force between the two phases (solid and liquid) is greater than the cohesive force within the liquid.

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Yellowing - A discoloration that can be caused by excessive temperature or time at elevated temperature.

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