PLA bioplastic for recyclable LED lights

Designed for a circular life cycle, Luminaire-Cycle lights are based on the use of individually replaceable LEDs. This reduces waste to a minimum and allows the lamps to be used independently for a long time. The diodes, which are mounted on copper-coated plastic clips, can be inserted into LED panels via connectors or into passively cooled sockets, depending on the output power.
The panels and sockets are made of aluminum and PLA plastic. The components are designed for longevity and can be reused. This allows the components to circulate in a deposit system. The PLA diffuser body of the sample lights can be playfully disassembled at the end of use and shipped back with the components for recycling.

video of Lukas’ presentation

student:Lukas Keller
project:full circle
examined bioplastic:

polylactic acid
material expert support:

Dr. Stephan Kabasci
Dr. Philip Mörbitz
Fraunhofer UMSICHT

full concept text

Polylactic acid (PLA) is one of the few bio-based plastics that is available in industrial scale and can be used in all common plastic processing methods. For the production of PLA, carbohydrates are extracted from plants, fermented by bacteria to lactic acid and polymerized to plastic. In this way, CO2 can be bound by the production. Due to the occupation of agricultural land and a resource-intensive manufacturing process, the use of PLA in circular use concepts is particularly sustainable. The recycling of plastics is generally associated with significant quality degradation, as it is not possible to sort different additives and blends of a plastic in the collection processes. It therefore makes sense to develop closed-loop concepts in which plastic blends can circulate in consistent quality.

For the Luminaire-Cycle concept, a PLA blend is used in a variety of components for circulating LED lights. In this closed product cycle, the specific heat-resistant PLA blend can be carried along in up to 8 recycling cycles.

LEDs are sustainable compared to other light sources in terms of energy efficiency. In manufacturing, LEDs are normally soldered to circuit boards and bonded with thermal conductive adhesives. This makes replacement or recycling very difficult.

The basic element of the concept are individually replaceable LEDs. These are soldered onto perforated, copper-coated plastic clips. They can be inserted into panels or passively cooled sockets, depending on the power output of the LED.

The LED panels consist of an aluminum composite plate with a PLA core. The aluminum layers serve as poles, and the PLA forms an insulating layer between the two poles. The LED clips can be inserted into the panels via clamp connectors.

The panels are suitable for a service concept due to the simple maintenance process. At the end of the usage period, the panels can be reused by the manufacturer and recycled if defective.

The aluminum PLA composite can be separated in a mechanical recycling via heat.

The socket for more powerful LED clips can be used in a deposit system. After the usage time, all parts of the socket can be separated, recycled or reused if not broken. In this way, parts such as the heat sink, which are very costly to produce and are not subject to material fatigue, can be used again and again. This makes a return system economical for the manufacturer.

The diffuser bodies of the example luminaires are designed on the basis of recyclability. Like all other plastic parts, they are made of the same transparent PLA. Due to the optimized FDM 3D-printing settings, the PLA plastic is only selectively bonded together. On the one hand, this creates a crystalline optical effect, which diffuses the light. On the other hand, the diffuser body can be pulled apart with force and uncoiled into a long plastic thread. Together with the components of the socket, this can be returned and recycled very easily.

The focus of the concept is on long-term use, through the interchangeability of individual light-emitting diodes and the reusability of the components. This allows the integration into different circular business concepts.The recycling of the PLA plastic is integrated into the circular concept of the luminaire, only in combination the return and recycling becomes economical.