Research

This project serves to support the project partners of the Josef Ressel Center "Restex", in which various recycling strategies for blended textile fabrics, primarily polycotton (cotton-polyethylene terephthalate blended fabrics), are developed and analyzed. During their service life and especially during thermal reprocessing, the polyester chains are degraded by chemical (detergent), thermal, mechanical or hydrolytic influences. Re-granulated polyethylene terephthalate (PET) is shear-sensitive and thermally sensitive during thermoplastic reprocessing. As a result of the reduced molecular weight the melt viscosity, melt strength and mechanical properties are drastically reduced compared to virgin polyesters. Hence the reuse of the polyester in equivalent applications is limited. The services provided by the Institute of Environmental Biotechnology (Bioplastics Technology Group) include the preparation of the textiles for the subsequent separation processes of cellulose and polyester as well as the performance of extrusion trials for the production of Re-PET granulates on a laboratory and production scale. The primary aims of these tests are (i) to optimize the mechanical properties of the recovered polyesters by means of analyses and (ii) to adapt the preparation and compounding process and, if necessary, (iii) to add additives to the recovered polyesters or surface modifications of the cellulosic residues.

The aim of the BIOBUILD project is to develop and demonstrate fully bio-based building materials with thermal energy storage function that can replace high environmental footprint products. Our solution demonstrates functional incorporation of bio-based phase change materials (bioPCMs) into solid wood and wood fibres bound by plant oil resins, lignin, or fungal mycelium to produce novel bio-composite building materials with significantly improved thermal properties. The novel materials possess a high multifunctional performance, meet requirements for sustainable “green” production, and ensure end-of-life options and recycling. Environmental and social impacts and benefits are fully integrated into the life-cycle perspective.

In this project, a recycling strategy for polyvinyl chloride (PVC) coated polyethylene terephthalate (PET) mesh fabrics is developed while avoiding melting of the PET fibres. Thermal reprocessing of this polyester is usually associated with degradation of the polymer chains as a result of thermal damage, acting shear forces and hydrolytic chain scission. To avoid this polymer damage, which occurs in the course of re-granulation, the use of PET fibres as reinforcement in plastics which are distinguished by significantly lower melting temperatures is being tested. The requirements for achieving high strengths and thus for the success of this possible application are (i) the separation of the fabric into individual fibres while maintaining high fibre lengths, (ii) enabling continuous feeding into the production machine and (iii) homogeneous dispersion of the fibres in the plastic matrix. Due to the minimum fibre lengths necessary to achieve high mechanical strengths, the separation of the fibres by means of a heating-cooling mixer is tested with variation of the settings and different fabric concentrations between 10 and 40%. Profile extrusion of the three blends into strip profiles will be tested using the NCT 55 conical co-rotating production extruder. To evaluate this application possibility, the bending properties as well as the Charpy impact strength will be determined on the profiles.