ABS is a thermoplastic polymer made from acrylonitrile (CH2=CH-CN), butadiene (CH2=CH-CH=CH2) and styrene (CH2=CH-C6H5). It is used to make moulded parts with a high impact resistance.
Polyvinyl acetate (PVA)
PVA is a polymer made from vinyl acetate (CH2=CH2-O-CO-CH3), usually in dispersion in water. It is used as a cement additive and in adhesives. Vinyl acetate is also polymerized with ethylene forming a copolymer called EVA (ethylene – vinyl acetate).
Term used to characterize a polymer made from acrylates and/or methacrylates, generally in water dispersion. Acrylic polymers are known to have good ageing properties and low yellowing. They are also used as binders in paints.
Acetone is a volatile and flammable solvent with a strong smell, with good degreasing properties. Its chemical formula is CH3-CO-CH3.
Adhesive (from the ASC-CATIA-FEICA Adhesives and Sealants Classification Manual, 2012 Ed.)
An adhesive is a compound that adheres or bonds two or more substrates together. Adhesives may come from either natural or synthetic sources. Adhesive is a general term and includes, among others, cement, glue, mucilage, and paste. All of these terms are often used interchangeably.
Milk protein. It´s the fraction of milk that forms a skin when it is heated or boiled.
Term used to define conditions under which a chemical reaction is speeded up (like in a reactive glue) under similar temperature conditions. Heterogeneous catalysis uses active surfaces whereas homogenous catalysis uses a catalyst dissolved in the reactive mixture. Glues and sealants often use homogenous catalysts. For example, silicone sealants contain a small amount of tin derivatives to accelerate the reaction with humidity.
Term used to characterize chemical groups carrying positive charges in molecules. To ensure electrical neutrality, the molecules are in the presence of anions of equal charge. The attraction between opposite charges facilitates adhesion to mineral surfaces such as teeth, for example.
Water-insoluble natural polymer found in plants. It is made from a chain of sugars (the repeating unit is ẞ-D-glucose). Cellulose can be chemically modified to make it water-soluble, for example in wallpaper adhesives. Cellulose is the main constituent of plants.
Cement (from the Free Dictionary)
a. A building material made by grinding calcined limestone and clay to a fine powder, which can be mixed with water and poured to set as a solid mass or used as an ingredient in making mortar or concrete.
b. A substance that hardens to act as an adhesive; glue.
Internal resistance to failure under external force. Contributes to maintaining the integrity of a bond.
A compound is a mixture of several chemical substances from synthetic or natural sources tailored to specific applications. It is used interchangeably with the terms "formulation", "mixture" or "preparation".
An adhesive which is usually first coated on both sides of objects to affix to each other. After a short drying period, the objects form a strong bond when pressed together with light to moderate force.
Process of "cold combustion" consisting of exposing a polymer surface for a fraction of a second to an electrically ionised gas. The superficial oxidation of the polymer increases its surface tension making it easier to wet and therefore improves the adhesion to glues, paints or inks.
The chemical reaction taking place in a reactive adhesive.
Methyl cyanoacrylate (CH2=C(CN)-CO-O-CH3) has the property of polymerizing very quickly by a cationic mechanism in the presence of humidity. It’s the main component of cyanoacrylate glues.
Definition of Durability Classes (EN 204)
D1: Interior use, in which the moisture content of the wood does not exceed 15 %.
D2: Interior use with occasional short-term exposure to running or condensed water and/or to occasional high humidity provided the moisture content of the wood does not exceed 18 %.
D3: Interior use with frequent short-term exposure to running or condensed water and/or to heavy exposure to high humidity. Exterior use not exposed to weather.
D4: Interior use with frequent long-term exposure to running or condensed water. Exterior use exposed to weather but with protection by an adequate surface coating.
EN 14257 (WATT 91): Interior and exterior uses where the glue line could be exposed at elevated temperatures.
Very fine dispersion of a liquid insoluble in another liquid, stabilized with a surface-active agent (surfactant). The surfactant resides at the liquid/liquid interface preventing the less dense liquid from floating to the surface. For example, mustard’s surfactant properties help oil emulsifying in vinegar. Milk and hevea latex are examples of naturally-derived emulsions.
Term used to define chemical substances containing CH2OCH- groups. Epoxy resins react with amine groups forming highly cohesive polymeric networks. In two-component epoxy adhesives, the epoxy resin is mixed with an equal amount of amine-containing resin.
Flammable gas with sweet odour used as a raw material in the chemical industry, for example in the manufacturing of EVA or ethylene-vinyl acetate copolymer. This gas is also present in nature and serves to ripen fruit.
Fungicides are added to sealants used in wet or humid environments to prevent the superficial formation of moulds.
A sticky liquid preparation used to affix objects to each other.
An adhesive in the solid state at room temperature, which converts to a liquid by heating during application and then solidifies again upon cooling.
A water-dispersible derivative of cellulose, frequently used in wallpaper adhesives.
Mucilage (from the Free Dictionary)
a. any of various, usually liquid, preparations of gum, glue, or the like, used as an adhesive.
b. a gummy or gelatinous substance present in plants.
Neoprene is a trade mark owned by DuPont since 1931. It is the first synthetic rubber. It is made in solution or in emulsion from chloroprene of formula CH2=CH-CCl=CH2.
See Working Time
A thick liquid preparation used to affix objects to each other if it has adhesive properties.
A thermoplastic polymer made from ethylene, a gas of formula CH2=CH2. Polyethylene is commonly made into films and is used to make bags. Its surface has a low surface tension and is generally difficult to glue. A Corona treatment increases surface activity and improves adhesion.
A thermoplastic polymer made from propylene, a gas of formula CH2=CH-CH3. Polypropylene has a low surface tension making it difficult to glue unless special surface treatments are used, such as Corona. Polypropylene is used to make textile fibres (carpets, ropes, bags).
Polyurethane resins are supplied either as finished products such as preformed insulating foams or as preparations containing reactive precursor chemical groups named isocyanates. When applied and in the presence of humidity, isocyanates form carbon dioxide gas. The resulting foam expands which make it particularly useful for caulking. In adhesives, isocyanates form very strong chemical bonds on some substrates such as wood.
Polyvinyl Chloride (PVC)
Chlorine-containing thermoplastic polymer, very resistant to ageing (with additives) and widely used in construction. It is used to make window frames and drain pipes. It is also used to make blood bags useful for surgery.
The time required for a reactive adhesive to double its viscosity.
It is an indication of working time.
A mixture of natural and/or synthetic chemical substances. This mixture is prepared according to a formula.
Reactive adhesives will form strong bonds only when reacted with an external ingredient (a curative, a catalyst, moisture, a substance inactivating an inhibitor), or activated with an external energy source (light, heat, radiation).
The operation consisting of mounting a sheet covered with adhesive by passing a roller back and forth or a brush or a sponge to the edges, to remove entrapped air.
Sealant (from the ASC-CATIA-FEICA Adhesives and Sealants Classification Manual, 2012 Ed.)
A sealant is a soft, pliable material that is used to seal cracks or joints where structural strength is not required. The sealant, initially a fluid or semi-fluid, or alternatively hot applied, placed between two opposing solid materials, becomes solid itself (by solvent evaporation, chemical reaction or both), and bonds to the surfaces to which it is applied. Thus, it accommodates joint movement without adhesion loss. The sealant purpose is to prevent excessive absorption of water, penetration of other liquids, gaseous substances, or airborne particulates. A sealant has the adhesive and cohesive properties to form a permanent seal.
Set time is the time it takes to form an acceptable bond when two or more substrates are combined with an adhesive.
Silicones are semi-inorganic polymers containing a silicon atom in the backbone. Their general formula is –(Si02-O)n-. Depending on their use, silicones are sold either as finished articles such as kitchenware or seals, as emulsions (haircare products) or as formed-in-use preparations such as sealants or dental mould products. Silicones are resistant to ageing but their low surface tension makes them difficult to paint or to glue. However, silicone glues are very effective in some cases.
Structural adhesives are generally capable of making load-bearing structures; they are often stronger than the substrates being bonded.
Substance capable of ensuring the compatibility with water of an insoluble hydrophobic substance. Detergent surfactants work by lifting and by dispersing surface dirt.
The force necessary to separate objects coated with an adhesive immediately after contact.
Working Time or Open Time
Working time is the time after which a reactive adhesive can no longer be used. Pot life is a good indication of working time.
Open time is the time after adhesive is applied during which a serviceable bond can be made. Many factors affect open time and pot life, including temperature, substrate, adhesive, and amount of adhesive applied.