Impact of Impurities of Polypropylene and Silicone Inclusions on the Properties of Polyamide 6.6 Regranulates Derived from the Re-Processing of Airbags

The following article presents the results of selected properties of regranulates of polyamide 6.6, regranules of polyamide contaminated with polypropylene and regranules of polyamide contaminated with silicone. The tested materials came from the reprocessing of polyamides 6.6 originally derived from production of airbags from renowned world producers (material for the research came from production waste). The results of examination were referred to regranulates of uncontaminated polyamide but also obtained from waste from the production of these airbags. The influence of impurities on properties of regranulates such as their density and melt flow index was assessed. The tests allowed to show a significant impact of impurities on the density but above all on the mass and volume flow rate index which ranged from 47 to 116 g/10 min. In the case of standardized test specimens selected thermal and mechanical properties were analyzed. Differential scanning calorimetry was used to assess the impact of impurities on the thermal properties of polyamides, allowing primarily identification of materials and impurities (especially polypropylene) as well as characteristic temperatures and the enthalpy of melting of the materials being analyzed. The mechanical properties were assessed using a DMA device. DMA research allowed to determine changes in mechanical properties in a wide temperature range of tested materials. It allowed to obtain full characteristics of changes in material stiffness under the influence of two factors, i.e. temperature and content of impurities, like polypropylene or silicone.