1.   Rheological properties of recycled PET/PBT blends 

• In this study, our aim is to analyze and improve the thermal stability of recycled PETs after applying the recycling process. It is to show that recycled materials can be used as raw materials after their properties have been improved and become available for industry.
• Considering these results, it has been observed that with the addition of a chain extender, the rheological properties change and the processability properties of the recycled PET vary as well. Moreover, blends of recycled PET with polybutylene terephthalate (PBT) at the blending ratios of 25-75%, 50-50%, 75-25% were prepared through melt blending in a twin-screw extruder. This was because PBT is a polyester polymer that has very similar to the structure of PET. Furthermore, it has very good mechanical, chemical and machinability properties that could also improve the processability and crystallization rate of recycled PET which are considered as PET’s drawbacks. In this way, the effects of the prepared polymer blends on the rheological properties have been examined. Although not being used simultaneously, the preparation of the polymer blends and the use of a chain extender, could both contribute to the rheological properties of recycled materials, a change in their rheological behavior and an increase in their processability properties.

2. PLA/TPU blend to improve mechanical properties  

• The aim of this research project is to develop polylactic acid (PLA)-based, high performance bio-products with superior mechanical, rheological, thermal, gas tightness and foaming properties using nano/micro fibrillation technology. In addition, for the first time in the literature the fibril network structure in the PLA matrix will be achieved by a single-stage (in-situ) nano/micro fibrillation process technology using a twinscrew extruder. The temperature profile of the twin-screw extruder (TSE) will be kept above the melting point (Tm) of PLA matrix and below the melting point of the reinforcing phase (TPU) so that the reinforcing polymer will not melt but will soften as it is above the glass transition temperature (Tg). As a result high shear and elongational forces will result in the formation of a fibrillated network structure. Through our proposed innovative technology, that is being filed as a patent, the fibrillation geometry and aspect ratio could further be controlled by the temperature profile variations, rpm value and screw configuration. All these parameters influence the viscoelastic properties of each polymer and hence the applied shear and elongational forces within the extruder would be significantly influenced. Thus, the control of nano/microfibril structures can be further enhanced by the use of polymers with different viscoelasticity.
• The long-term objective of this project is to develop and manufacture a high-performance PLA-based bioN/MFC in one step by developing an alternative innovative approach to the multi-stage MFC production process. As PLA is a bio-based, biodegradable and biocompatible polymer, it is an attractive candidate to substitute for petroleum-based polymers; but also, the disadvantages such as low melt strength and workability, fragility and low toughness, low service temperature and slow crystallization kinetics limit the use of PLA in structural applications. In this proposed research project, it is expected that the presence of the TPU in the nano/microfibril form in the PLA matrix will eliminate these obstacles so that PLA-based N/MFC systems with superior properties will be obtained at low cost.