Adhesion refers to the adhesive forces (due to molecular forces) between two contact surfaces. This can either be the case for two identical or two different substances. Specifically for adhesives, this means the adhesive force of the adhesive layers on the surfaces of the parts to be joined.

Polymers that are composed of two or more different types of monomer are called copolymers.

EVA – ethylene vinyl acetate
PA – polyamide
PE – polyethylene
PP – polypropylene
PUR – polyurethane

Bonding is the usually inseparable connection/joining of identical or different materials.
If the materials cannot be joined together by welding, an adhesive is used. This is applied to or between the materials.

This firm and permanent connection of the surfaces through a layer of adhesive is called bonding.
In the past, the term adhesive was also used. However, this is an outdated term, as in the technical field we speak of glue/adhesives.

According to DIN 923, an adhesive is a "non-metallic material that can join parts by surface adhesion (see adhesion) and internal strength (see cohesion)". The word "adhesive" is a generic term and includes other terms commonly used for adhesives, which are categorized according to various aspects: For example, glues, pastes, solvent adhesives, dispersion adhesives, contact adhesives and reactive adhesives. They are essentially made up of base materials, auxiliary materials and sometimes also solvents or dispersants.

Polyamides (abbreviation PA) are polymers whose repeating units have the amide group as a characteristic feature. The amide group can be described as the condensation product of a carboxylic acid and an amine. This creates a bond called an amide bond. It can be hydrolytically cleaved again. Polyamides have good resistance to solvents and chemicals as well as high strength, rigidity and toughness. They are mostly semi-crystalline thermoplastic polymers and have good processing characteristics.

Polyethylene (abbreviation PE - also known as polyethylene or polyethene) is a thermoplastic produced by the polymerization of ether. As an adhesive film or adhesive tape (Gluetex adhesive films EKF 210, EKF 220, EKF 230), it is particularly suitable for bonding polypropylene.

Polyurethanes (abbreviated PU or PUR) belong to the urethane group and are plastics or synthetic resins. They are formed from the polyaddition reaction of diols or polyols and polyisocyanates. The areas of application for polyurethanes are very versatile. As they have good adhesion properties and good resistance to solvents, chemicals and weathering, they are used particularly in various areas of textile coating and bonding.

Hot melt adhesives, also known as hot glues, hot adhesives or (in Switzerland) hot glue, are solvent-free products that are more or less solid at room temperature, which are applied to the bonding surface when hot and form the bond when they cool. This group of adhesives, also known as hotmelt, is based on various chemical raw materials.