Upcycling of semi-crystalline polymer via extrusion-based 3D printing with maximal printability
Ph.D. Student Mohammad Sagor Hosen
Department of Mechanical Engineering, University of Canterbury
Time & Place
Mon, 12 Jul 2021 11:00:38 NZST in E12, Engineering Core
An extrusion-based 3D printing (3DP), fused deposition modelling (FDM), is proving to be a disruptive manufacturing as well as upcycling technology for semi-crystalline polymers. Extrusion of a recycled semi-crystalline polymer depends mainly on two properties, i.e., viscosity and degree of crystallinity. Thermal and mechanical degradation of polymeric chains during extrusion hampers the following extrusion cycles altering the viscosity and degree of crystallinity of the recycled semi-crystalline polymers. The purpose of this research is to optimize the thermal (temperature) and mechanical (shear stress and shear rate) parameters of the extrusion process for upcycling the semi-crystalline materials with minimal degradation. This study investigated the thermal (under Nitrogen) and oxidative (under air) degradation of the commercial-grades of PET using thermogravimetric analysis (TGA). The rheological analysis examined the viscosity at various temperatures and shear rates. Fourier-transform infrared (FTIR) spectroscopic analysis was used to identify molecular components and structures of various PET grades. Moreover, the melting temperature and the degree of crystallinity were measured using differential scanning calorimetry (DSC). TGA analysis shows significantly higher isothermal oxidative degradation starts from 260 oC under air than nitrogen environment. The rheological analysis exhibits a significant impact of temperature and shear rate on the viscosity of various grades of PET. Further studies on average molecular weight (Mw) and molecular weight distribution (MwD) measurement are needed to measure the polymeric degradation quantitively.
Supervisor: Associate Prof Mark Staiger