From the investigations it has been shown, that
- Pretreatment, using O2-plasma, UV-ozone or corona, results in a considerable increase of the joint strength for plastic/adhesive combinations, in general and for polyphenylene sulphide/adhesive and polyetherimide/adhesive, in particular.
- Cleaning of the substrate with isopropyl alcohol is, in general, sufficient enough to obtain good joint strength values; however, pretreatment is essential to polyphenylene sulphide.
- Optimized pretreatment process parameters are available.
- For each type of engineering plastic material, glued to itself or to dissimilar materials, a suitable 1 and/or 2 component adhesive system, that fulfils the requirements with respect to strength and flexibility, before and after environmental testing, has been developed and tested.
- A new test geometry (NTG) has been developed, that fulfils the set demands and that is suitable for the determination of characteristic material parameters.
- A developed failure criterion, used in combination with the NTG, has proved to be a powerful tool for predicting the strength of multiaxial loaded plastic adhesive joints.
Joining of engineering plastics is very often only possible by adhesives, especially in the case of combinations with other materials (metal, ceramic, glass). However, with adhesives available on the market it is often not possible to make adequate use of the specific benefits of these materials (high strength, temperature resistance, dimensional stability). In addition, the material surfaces are often difficult to bond and frequently adhesion failures occur, due to lack of knowledge about the nature of the surfaces, surface modification methods and environmental influence (temperature, humidity) on joints. Moreover, at present adhesive technology does not meet the sharply increasing (in-line) production requirements (cycle time, reproducibility, health, environment) and is often achieved after tedious trial and error experiments.
The aim of the project will be the development of adhesive technologies for engineering plastics, used in consumer products, domestic appliances and automotive applications that meet these product and production requirements.
This will be realized by the development of improved adhesive systems (adhesion, thermal stability, flexibility) and their processing, improvement of adhesion by surface characterization and appropriate surface modification techniques, as well as adequate test methods for strength and stability (creep, relaxation). Theoretical calculations of joint behaviour are performed for various load and environmental conditions (non-linear behaviour) enabling predictive modelling.
Successful completion should yield significant savings in joint manufacturing costs of (ca. 25%), development time (> 25%) and greatly reduce the use of hazardous solvents (safety, environment) in materials and processes. The results will be incorporated into internal codes of practice of the main partners in the project and may form a basis for later European norms.
Funding SchemeCSC - Cost-sharing contracts
CB2 4QA Cambridge