GLOSSARY
Activators
Sometimes referred to as “accelerators,” these products start the polymerization process required to cure acrylic based adhesives. The term activator may also refer to surface preparation products that allow substrates to be more easily bonded.
A type of adhesive made from synthetic thermosetting polymers containing epoxide groups. This type of epoxy adhesive bonds aluminum substrates. An example is Devcon Aluminum Putty and Devcon Aluminum Liquid.
AR
AR or “Acid Resistant” indicates that a material resists the chemical degradation normally associated with long-term exposure to acids. Long-term exposure to acids can break down polymer chains, rendering a polymeric material brittle and weak. AR-designated products like Devcon Epoxy Coat™ 7000 AR are suitable for applications where exposure to acids is expected.
Cementitious
A material that derives its physical & mechanical properties from cement in its formulation; for example grout. Cementitious products like Densit and Chockfast outperform cement and must be used in place of it when a more flexible material is needed. High strength cementitious grouts are found in several industries: Wind, Industrial Flooring, Wear Protection, and Securities. The primary product brands to consider using are Ducorit, Densiphalt, Densit Wearflex, Densit Wearcast, Densit Wearspray
Chockfast®
The Chockfast brand of epoxy grouting and chocking compounds is designed for lasting alignment and support of machinery and equipment. The mixture sets permanently and precisely with fast cure, minimal shrinkage, and resistance to expansion under hot running machinery. The Chockfast range of products are used in a wide range of industries including chemical, petrochemical, mining, and industrial construction.
Coating
A material added to a surface as a protective layer to help protect or repair the area from corrosion/erosion caused by exposure to harsh environments.
Cohesive Failure
Occurs when pulling apart two substrates results in the rupture occurring within the adhesive layer, so that the adhesive remains bonded to both surfaces, as opposed to Adhesive Failure, which occurs when the rupture happens between the adhesive and the substrate(s).
Coefficient of Friction (COF)
The coefficient of friction is the amount of friction created by two surfaces relative to the forces keeping them together. It’s important to take this property into account when dealing with wear and abrasion.
Compression Casting Rebuild
A process where titanium putty is used to rebuild and repair the complex shapes & features of cast assemblies to original dimensions that can be machined once the titanium putty hardens, for example water box channels that have experienced corrosive wear from salt water in power generation applications.
Curing
Curing refers to the collection of chemical and physical processes that occur during the period that a liquid adhesive becomes fully polymerized. There are many curing mechanisms including polyaddition by humidity, polymerization driven by exposure to UV light, and free radical polymerization. The curing process can be affected by ambient conditions such as temperature, humidity, joint-configuration, or the presence of other chemical materials.
Cure Time
Also known as “cure speed”, cure time is the rate at which a liquid adhesive polymerizes at specific conditions. It is often directly related to the time in which the majority of an adhesive’s final strength is reached.
Densit®
The original Ultra High Performance Concrete (UHPC). Densit technology was developed in 1978 by Hans Henrik Bache using densified systems with ultra-fine particles, widely known today as UHPC. Today, Ducorit® grouting solutions that fall under the Densit brand are a crucial structural component of onshore & offshore wind turbine foundations. They have been used in more than 2,500 installations around the world to help the movement towards sustainable energy.
Devcon®
Devcon was originally established in Danvers, Massachussets, USA. Devcon® Plastic Steel® Putty – The original metal filled epoxy putty, was developed by Al Creighton in 1954. Devcon Plastic Steel Putty was the result of Creighton’s efforts to develop an economical, non-flammable alternative to welding. Devcon coating solutions cover a wide range of products for industrial maintenance and repair. These include epoxy, urethane, and methacrylate compounds for repairing metal, rubber, concrete, and other materials & coatings for protecting surfaces. Some examples are: Plastic Steel Putty (A), Plastic Steel Liquid (B), Aluminum Putty (F), DFense Blok, Wear Guard Fine Load, Titanium Putty, Ceramic Repair Putty, and Brushable Ceramic – EZ Spray.
Devcon brand epoxy and urethane coating solutions are widely used in metal repair, rubber repair, belt repair, corrosion repair, and floor repair applications. Wear & abrasion occur when foreign materials rub against a metal part. Metal surfaces undergoing high or continuous impact experience deformities, chipping, and fatigue to their surface. High temperature thermal cycling and corrosion can also lead to metal wear. This is where protection comes into play. Acid Resistant (AR) steel plates, ceramic tile, urethane, rubber, UHMWPE (ultra high molecular weight polyethylene), and chemical coatings are possible solutions.
Dissimilar Metal Bonding
When two different types of metals come into contact with one another, they form an anode-cathode relationship, causing galvanic corrosion. Plexus metal-bonding adhesives create an intermediate insulating layer that prevents this corrosion. For example, stainless steel can be bonded to aluminum; or G90 galvanized to cold rolled steel. With Plexus adhesive, metal can also be joined to thermosets, thermoplastics, and fiber reinforced plastics.
Elongation
Elongation is strongly associated with the toughness of a material or how much force it can take before breaking. High elongation products put less stress on bonded parts, and often lead to longer life for assemblies subjected to stress loads. An adhesive with high elongation is like a rubber band – flexible, stretchy, and able to absorb a lot of force before breaking. Lower elongation material is stiffer, like a plastic bottle (or a similar material). Elongation properties refer to cured adhesive, and we test for it with our “dogbone” tensile test specimens.
Bonded assemblies transfer stress throughout their structure, stopping the build-up of force in small areas. How that behavior performs depends a lot on the material’s modulus (the energy needed to deform the material) – usually closely and inversely related to elongation.
Elongation is also important when bonding dissimilar materials. Materials behave differently under different temperature conditions. For example, an aluminum panel bonded on the entire length of a highway coach (bus) will expand or contract as much as 5-10mm more than the stainless steel frame. If the adhesive modulus is lower than the force placed on it by the expanding panel, it will deform. The adhesive’s elongation would have to be high enough to accommodate the resulting movement, or the joint may fail.
EPDM
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber used in automotive and construction industries for sealing against the elements like UV, rain, ozone and general weathering. Two-part methacrylate adhesives like Plexus MA420 can be used to bond EPDM rubbers.
Epocast®
The Epocast brand of chocking compound offers a complete chocking solution for ships and other marine applications. Epocast chocking systems are ideal for retrofits or new builds and are easy to use, serving in a variety of industries including commercial marine.
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.
Full Cure
The full curing time is the time needed for an adhesive system to achieve its ultimate mechanical properties and complete its polymerization. For most Devcon products this is 7 Days, while for Plexus products this is an hour to a few hours depending on the specific product.
Functional Cure
Time it takes for a chemical to react enough that it can be used in service. For wear and abrasion solutions this is typically around 80% of its full strength.
Gap Fill
This refers to an adhesive’s ability to fill gaps or space between substrates being bonded. Gap-filling capabilities are generally quoted as the maximum possible gap that can be bridged based on the chemical or physical properties of the liquid adhesive.
GB
GB or “Glass Beads” are glass or polycarbonate beads of defined size that can be added to adhesives, for example Plexus MA830 and MA832, that are used to act as spacers to define a minimum bond thickness.
Grouting and Chocking Systems
ITW has several grouting systems and chocking systems. When looking for chocking and grouting repairs and installations, consider the Chockfast range, Epocast range, Densit range, and Devcon Deep Pour Grout.
Impeller Repair
If an impeller from an intake pump has wear & tear, even extreme wear, Devcon Titanium Putty can be used to save the form of the impeller. Abrasion protection is added when Devcon Brushable Ceramic is used to coat the impeller. Once restored, the impeller will have increased pump efficiency.
Industrial Adhesives
Industrial adhesives are used as an effective joining method in place of welding, riveting, mechanical fasteners, and soldering. Through surface bonding (adhesion) and internal strength (cohesion), industrial adhesives bond a number of substrates and withstand static and dynamic loads comprised of shear, tensile, and peel forces, high impact, and exposure to weathering or chemicals. Plexus is a proven example of an industrial adhesive widely used in multiple markets including transportation, marine, wind, signs and general industrial manufacturing.
Industrial Coatings
Used to repair and rebuild, industrial coatings are created to withstand high impact, and wear & tear. To prevent damage, wear, and corrosion on industrial equipment, a good surface finish is advisable. This eliminates machine down time and keeps production flowing. Applying an industrial coating is time-saving and much easier than welding and other repair alternatives. Additionally, equipment needs far fewer repairs when protected by a coating with good compressive strength.
ITW Performance Polymers manufactures wear-resistant coating solutions and repair compounds for several markets including mining, petrochemical, cement/steel processing and the pulp & paper industry.
Insulcast®
Insulcast epoxies & silicones are potting and encapsulation compounds designed to protect electrical components from heat damage while also providing industrial strength adhesion.
Korrobond®
This two-part epoxy functions as a tough but flexible backing compound to protect against impact and shock vibrations, increasing plant productivity. Korrobond is commonly used as a reinforcing layer on machinery and equipment used for crushing rocks.
Lap Joint
Lap joints are one of the most common joints for adhesive bonding. A lap joint might also be called an “overlap joint” as pieces of material overlap each other. The width of the overlap depends on the shear strength of the adhesive and the joint design requirements.
Lap Shear
Lap shear is one of the most common forces that adhesive joints are subjected to, and are caused when force is exerted to move two substrates in a plane, in opposite directions. Examples are panels or brackets bonded vertically on a frame. Lap shear testing is performed on bonded joints to show just how successful a bonding or coating project is in terms of strength and adhesion to the substrate.
Maintenance, Repair & Operation or Overhaul (MRO)
The MRO market includes industries like mining and petrochemical. As part of the day-to-day responsibilities on these job sites, you can expect to find equipment damaged from impact and abrasion, that calls for products like Devcon, Permatex, Chockfast, Densit and Korrobond. These abrasion-resistant epoxy coatings, and high-strength flooring repair solutions solve the problems of long periods of down-time waiting for repairs, as well as making fewer repairs down the road.
Metal Adhesive
Sometimes referred as a metal glue, metal adhesives are specifically designed to bond metal substrates. Engineers and technicians need high performance metal bonding glues like Plexus to adhere secondary substrates to metal (such as metal to plastic, or metal to composite). Metal adhesive also prevents corrosion, especially when dealing with metal to metal bonding. Plexus brand MMA metal adhesives are great metal glues for projects demanding high performance. Metal glue also bonds well to structural acrylic and cyanoacrylates.
Mix Ratio
Ratio of adhesive to activator (or resin to hardener) specified by weight or volume.
MMA Technology
Methyl methacrylate (MMA) is a monomer that is an essential part of many industrial strength glues and adhesives like Plexus. Used in an array of acrylic products, MMA polymers don’t shatter like glass the way some epoxies do, making it reliable & durable. Notably, MMA monomer is an acrylic resin that is easily recycled and exhibits high weatherability. It’s also known as methacrylic acid and methyl ester.
Monomer
Individual molecular units that are repeated to form polymers.
Permatex®
Permatex brand products have a wide range of uses, from gasket-maker and flange sealant to thread-filler/thread-locker, and silicone adhesive/sealant. The products in this brand are used for preventive maintenance and can handle the most severe industrial environments.
Plexus® Adhesives
Plexus was originally established in Danvers, Massachusetts, USA. Plexus® represents the first commercially relevant methyl methacrylate adhesive. The first Plexus adhesive was co-developed in 1986 by Donald Gosiewski using Core Shell Technology. Plexus MMA adhesives have since become the standard in bonding thermoplastics, metal, and composite parts for the Transportation, Marine, Wind and Industrial OEM markets.
Plexus adhesives are a wide range of structural adhesive products, used to join a variety of substrates including metal to metal bonding, plastic, composites, and dissimilar substrates. Plexus adhesives are a perfect option for replacing welding and rivets, and are known for their high level of toughness, durability, and ability to cross bond many different materials.
Post Bake Cure or Oven Bake Cure
This refers to the process of curing a product with heat after the assembly of the structure. There are many limitations that come with a product that requires a post bake, notably the size limitations imposed by the need to have an oven large enough for the part to go into when post bake is required. Also, if the material requiring post bake is only one component of a larger system, it must be disassembled to take it to an oven, and then reassemble when completed. The baking process is costly, and may be damaging to equipment, and parts avoiding heat in the manufacturing process is desirable.
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.
Sealants
An industrial strength sealant are used to prevent liquid or gas from moving in or out of structures or assemblies. Whether working with the Permatex range of gasket and flange sealants or Devcon urethane sealants, choose a high performance sealant that works correctly the first time.
Shelf Life: Time from date of manufacturing that a product, when stored under proper conditions (refer to product Technical Data Sheet) will continue to exhibit its original properties.
Shiplap Bonding
Typically, shiplap refers to exterior siding made up of horizontal planks that overlap each other. In the Transportation industry, shiplap construction is used to join panels such as truck/trailer walls and roofs. For shiplap bonding, Plexus is a fast curing adhesive that improves the durability & quality of the panel structure, improves vehicle appearance, allows joining of dissimilar materials, and bonds & seals in one-step.
Skin Over Time
The time it takes for the very top layer of an adhesive to cure. Note: Though the surface may be dry to touch, additional curing is still be needed for the rest of the adhesive to achieve final mechanical and adhesion properties.
SMC
SMC, or (Sheet Molding Compound) is a mixture of polymer, filler, and other additives that is pressed into finished parts using a heated mold. SMC parts are lightweight and easy to manufacture.
Spraycore®
This line of sprayable syntactic materials and specialty sprayable fillers/primers are known for being both lighter and stronger than materials applied by hand.
Structural Adhesives
Structural adhesives are adhesives that add strength, and rigidity to assemblies, complementing their ability to absorb & distribute stress and impacts with flexibility that increases performance & durability by allowing for movement within the structure. ITW Performance Polymers manufactures structural adhesive solutions for several industries including transportation, marine, wind and Industrial OEM markets.
Plexus structural adhesives are the primary product brand for many bonding applications. Though aesthetically pleasing as compared to using metal fasteners, a structural adhesive is formulated to be durable and permanent – not meant to be removed. Plexus adhesives give designers the freedom to create form factors that are not possible with mechanical fasteners or welding, as well as joining dissimilar materials in various configurations & combinations.
Substrate
Also known as an “adherend,” the layer or material to be bonded or coated. Examples include metals such as stainless steel and aluminum, plastics including acrylic or vinyl, and composites like gelcoats and fiberglass.
Syntactic Materials
Spraycore is an example of a syntactic material. Used to strengthen a structure or component, the benefit to using syntactic materials are that they are lightweight in addition to their ability to fortify the material to which they adhere.
TG (glass transition temp)
A term referenced by Insulcast potting customers. The point when a material transitions in hardness from its normal state @25C to either a harder or softer state. Epoxies (which are usually fairly hard at room temperature) typically become softer are 70C (RT cure properties) and 120C+ (heat cure epoxies). Silicones (flexible at room temperature) typically get harder around -50C. Key Takeaway: If flexibility at a low temperature is crucial, use a silicone.
Thermosets
Also known as “thermosetting plastics” or “thermosetting polymers,” thermosets are polymers that are irreversibly, permanently cured to form a hardened plastic from soft solids or gluey liquid prepolymers or resins. Heat or even a certain amount of radiation are used for curing. To encourage curing, high pressure or mixing the resin with a reagent will help. Thermosets are not to be confused with thermoplastics which can be re-melted or re-shaped numerous times. Both of these terms are common within injection molding applications, as well as the broader plastics, molding and composites industries.
Transportation Adhesives
Truck, bus, trailer, automotive, and other transport manufacturers often use adhesives in place of welding or rivets for a strong, but far more aesthetic look. Using a high performance adhesive with a long shelf life resistant to wear and tear needs to be used which is why the Plexus brand of transportation adhesive is a good choice.
Two Part Adhesive
Also known as “two component system” or “2K,” a two-part adhesive is an adhesive that consists of two separate components in the nonreacted state. These materials must be thoroughly mixed at specific ratios to achieve the desired properties of the cured product.
Types of Testing Performed
Lap Shear
Tensile
Compression
Salt Fog
Pull Adhesion
Chemical Resistance (Immersion Test)
Humidity Testing
Temperature Cycling
Side Impact
T-Peel
Cross Peel
Wet Abrasion
Taber Abrasion
Roller Peel
Shore Hardness
Volumetric Shrinkage
Viscosity
How thick or thin a material is. It’s not to be confused with tack which might refer to something’s stickiness.
VOC
This refers to Volatile Organic Compounds or materials based on organic chemistry that evaporate readily under room-temperature (or warmer) conditions. These materials are regulated, and if present in a product, are listed in the corresponding safety data sheet.
Wetting
This refers to direct, intimate contact with the surfaces being bonded. Adhesives require good wetting to achieve maximum adhesion. The ability to wet a surface is determined by the surface tension (surface energy) of the adhesive and the substrate. Generally, an adhesive should have a lower surface energy that the substrate. Pre-treatments such as surface activators, primers, or treatments like flame or corona processes can improve substrate surface energy. Similarly, some components of an adhesive formulation can have the same effect.
Working Time
Also known as “work time,” “open time,” or “pot life” (typically used with epoxies), this attribute of an adhesive refers to the time available to work with, and apply the adhesive, and marry the two substrates together with an adhesive system before it cures beyond the point that the two surfaces will be properly wetted, or the properties of the liquid adhesive are no longer suitable for the application (pot life). After the working or open time is expired, the adhesive may not properly adhere – due to the lack of wetting – or may not flow or be properly compressed into the joint configuration. When working in high temperatures, working time shortens, whereas low temperatures lengthen work time. The working life of a product is listed on its Technical Data Sheet.