Public Thesis defense - IMCN

Ecofriendly Upcycling of PET: from bio-composites to blends and networks by Martial Aimé KUETE

The uncontrolled disposal of single use polyethylene terephthalate (PET) bottles generates a major world-wide issue of environmental pollution and waste of non-renewable resources. To contribute to the solution, original routes to recycle PET in the form of value-added (“upcycling”) environmentally-friendly thermoplastic composites, blends and thermosets were developed. The melt processing constraints of commercial (recycled) PET being incompatible with the thermal stability limits of natural fibres (e.g. flax and banana) and bio-based polymers like poly-lactic acid (PLA), PET was first been modified with bio-sourced reactants to produce co-polymers with moderate processing temperatures below 180°C.

Thermoplastic co-polymers with excellent ductility were obtained by building up the molar mass of the oligomers in an unusual “soft solid state” process. The best co-polymers had a Tg just below 50°C and, although crystallizable, remain amorphous under usual melt processing conditions. The composites with banana fibres showed high stiffness (4.8 GPa at 20% wt fibres) and moderate ductility, excellent dispersion of the fibres and high fibre-matrix interfacial cohesion. Blends with PLA were immiscible but showed excellent interfacial adhesion and increased the potential service temperature because of the crystalline nature of the PLA used. The flax composites had a Young’s modulus close to the maximum possible reinforcement.

A first approach to quantify the sustainable benefits of these thermoplastic PET recycling routes, based on a rational eco-selection method, showed that the composites and blends came close to low-end wood materials in terms of the stiffness/embodied energy balance. Moreover, this approach can easily be extended to many other natural fibres.

Finally, a thermoset recycling route was explored by combining some of the oligomers with glycidyl methacrylate (GMA) to yield a dual cured network (radical polymerisation of GMA and oxirane cycle opening with reactive end-groups of the oligomers), which was extensively characterised.

Jury members : 

• Prof. Christian Bailly (UCLouvain), supervisor
• Prof. Thomas Pardoen (UCLouvain), supervisor
• Prof. Maurice Ndikontar Kor (Univ. Yaoundé), supervisor
• Prof. Evelyne Van Ruymbeke (UCLouvain), chairperson
• Prof. Bernard Nysten (UCLouvain), secretary
• Prof. Jacques Devaux (UCLouvain)
• Prof. Jean-Marie Raquez (UMons)
• Prof. Jean-Marc Lefebvre (Université de Lille, France)

Pay attention :

The public defense of Martial Aimé Kuete scheduled for Monday 11 December at 04:00 p.m will also take place in the form of a video conference

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