Abstract
During the last years many companies have implanted quality systems to ensure
quality for both materials and processes; this new philosophy has arrived to recycling
industry on which quality considerations are of maximum relevance. So, some
recycling companies, with minimum enterprise projection, have developed quality
systems that ensure certain quality levels for materials they offer. Otherwise, we have
no data to think about the use of this philosophy to material reception.
In the present work, we analyse the different variables that take part on the upgrading
process for polystyrene wastes coming from packing industry; we make a
differentiation between those parameters related with the material structure and those
related with processing conditions. Once we have identified these critical variables they
are individually investigated by using different analytical techniques such as differential
scanning calorimetry (DSC), infrared spectroscopy (FTIR), thermogravimetrical
analysis (TGA) and gas chromatography-mass spectrometry (GC-MS). The use of
these techniques has allowed to identify changes on polystyrene characteristics when
subjected to certain conditions such as temperature, environmental agents action
(mainly UV radiation), presence of small amounts of impurities (mainly PP).
This study about high impact polystyrene has allowed to know much more about the
critical variables influencing on its characteristics (mechanical, thermal,…).
Furthermore, we have used and optimized different techniques to evaluate changes on
its behaviour. All these studies have established the main aspects to be considered to
develop a rigorous quality control process also for material reception and for final
material. This study will help recycling companies to define the basis to obtain a quality
certificate for upgraded high impact polystyrene.