Abstract:

During the academic year 2017/18 several problems proposed by factories and companies of the area have been presented to students of the subject "Eco-efficient Materials" of the second year of the “Master en Ingeniería, Procesado y Caracterización de Materiales”. These problems will be carried out as Laboratory practices.

Due to the students are from the last Master course, they are supposed to have the competences, acquired throughout the previous Degree and Master programs, such as knowledge in Structure and Techniques of Characterization of Advanced Materials, Composite Materials, and Research Methodology. This knowledge enable them to be able to approach the situations proposed and develop them successfully.

This work has a double objective: on the one hand, the students recreate on a pilot scale a work that can be developed in a factory and thus, they can face real life problems. On the other hand, this work can be a showcase of their profiles towards the company that suggests the work. The work proposed to the students is about the recycling of plastic materials coming from the selective collection of bottle caps. This activity is included in a solidarity initiative that began in 2011, where a company close to the university is the responsible for recycling.
For the development of the work, the “flipped classroom/flip teaching” methodology has been applied with the aim of reinforcing the necessary competences. With this methodology, the students watched at home, videos contributed by the teacher. The videos are related to the steps to follow in a recycling of plastics process. Thus, during the class time, the students did all the practical work.

The work was done, on a pilot scale in the university laboratories, following the steps: washing of the caps in wash tubs, milling, extrusion, injection of caps and characterization of the products by various techniques: Melt Flow Index (MFI), Fourier-Transform Infrared spectroscopy (FTIR) , Differential Scanning Calorimetry (DSC) and mechanical characterization (tensile, impact and hardness test).

The material obtained from the recycling process made by the students presented an acceptable quality. It is a high density polyethylene (HDPE), bluish-grey in colour, which mechanical properties are 20% lower than a virgin HDPE.

Once the work was completed, a visit to the company that proposed the work was planned. The students could see, in situ, how a recycling company works and its facilities. In addition, they made a presentation of their work, showing the main properties of the material obtained, explaining the development of the process and highlighting the problems they faced and the solution adopted.

Keywords:

Recycling, Polyethylene, Waste, Pilot scale, Characterization.