Adhesives as composite materials and composites

The development and evaluation of customized materials and adhesives is a central focus of our institute's work. Adhesives as composite materials play a major role in this. The outstanding properties of these adhesives are due to the fact that the composite has different properties than the individual components. This is also where the great potential lies, because there is a wide range of raw materials that - cleverly formulated - can optimize the final properties of an adhesive. This gives the adhesive certain properties, such as electrical or thermal conductivity, toughness, flame retardancy and also recyclability, which is increasingly in focus.


Composite materials enable the functionalization of adhesives and bondings

According to DIN, a composite material is a material made of two or more joined materials. The composite material has different material properties than its individual components. For example, the fire behavior of a material can be reduced by adding flame retardants, or its resistance to temperature effects can be improved by adding stabilizers. The chemistry of all the various components plays a decisive role here. Only when these interact with the parts to be joined are improved manufacturing processes or component properties achieved. For example, simultaneous improvement of strength and elongation at break or low curing shrinkage and coefficient of thermal expansion (CTE) can be achieved or compensated for.

Significant process costs can also be saved. For example, by influencing rheology and curing speed, a furnace process can be reduced from 150°C to 100°C. In addition to cost savings, this also results in a lower carbon footprint.


Adhesives with thermal conductivity

The production of adhesives with thermal conductivity is one of our core competencies. Adapting or additively achieving the thermally conductive properties to those required by the end-user without degrading other important properties is a major task. For example, the addition of highly thermally conductive fillers is often accompanied by an impairment of the rheological behavior. However, by further additive addition and the right mixing technique, many systems can be further adapted. It is precisely for this purpose that we have developed customized solutions based on our many years of experience and our extensive analytical methods. 


Reduction of the CO2 footprint through recycling and the use of renewable raw materials

The topic of sustainability is becoming increasingly important across all industries. Among other things, the recycling of materials plays a major role here. Up to now, this has been a major challenge in the case of adhesives due to the strong bond between different materials. Our institute therefore deals both with the use of renewable raw materials to produce biocomposites from environmentally friendly and fully degradable raw materials and with issues relating to the debonding of bonded joints. A synergistic coupling of both competences is quite reasonable and possible but not mandatory. Corresponding products can be used in various markets; developments in this area have been carried out, for example, in the packaging industry or the agricultural industry, but there is also strong demand and work in the construction sector and the automotive industry. 


Many advantages through the use of nanocomposites

Adhesives with nanocomposites consist of a polymer matrix and nanoparticles used as fillers in the matrix. Nanoparticles offer many advantages over other fillers: they distribute evenly in the matrix and thus prevent cracking, which increases the service life of components. In addition, nanoparticles can be used to produce new properties without having to accept negative effects such as lower strength or toughness. In addition, their use is often a cost-effective alternative because, taking into account issues such as the wear of pumps and metering devices during adhesive application, nanocomposites cause far less abrasive wear.


Your contact on the subject of composites

Dr. Thomas Kowalik is Deputy Head of the "Adhesives and Polymer Chemistry" department. For more than 20 years, he has been involved in the development of composite-based adhesives to give them special material properties. In this context, he accompanied the development of microelectronics through work on special electrically conductive adhesives, as well as optimized UV initiators. The use of nanocomposites to increase the toughness of matrix resin systems in lightweight fiber composite construction, as well as application-adapted thermally conductive adhesives and thermally conductive pastes are the subject of research and development within the department. The topics of debonding on demand and flame retardancy have been worked on for almost as long. In recent years, the focus has been placed strongly on adhesives based on renewable raw materials and the recyclability of bonded joints.