Ziel
Materials, processes and machinery necessary to manufacture new higher added value products from single polymer recycled fraction of PET and PP have been produced. These results have been reached by using innovative techniques for material processing and modification based on Reactive extrusion (REX) and Solid State Poly-Addition (SSPA). These procedures permitted to modify recycled PET resins reaching targeted melt strength, molecular weight and rheology properties. These specific properties were required to develop new modified materials such as chopped glass fibres reinforced and high melt elasticity resins (e.g. foamable PET or high speed spinnable POY fibres). The new modified materials recovered from the recycled resources were utilised in the preparation of fabricated parts such as Thermoplastic composites, Foamed sheets, POY Fibres for Textile industry and RTM Sandwich Panels.
The Extruded glass reinforced PET sheets with 30 to 40% reached elastic moduli ranging between 10 to 12 GPa and the impact strength of 140 J/m (Izod).
The Injected PET samples with a glass fibre content of 30% (in weight) achieved a final elasticity modulus of about 10 GPa. The impact strength was 44 KJ/m{2} (Charpy). The Polypropylene RTS (Reinforced Thermoplastic Sheets) and injected samples with a glass fibre mat and chopped fibres reached about 5 GPa..
A new machinery was specifically designed, set-up and tested for continuously extrude PET foams of constant properties and different apparent densities around 100 kg/m{3}, closed and uniform cellular structure. The technology and chemical modification defined in this project have been applied by M&G to the recycled polymer producing resins that can be foamed to the desired density and appropriate mechanical properties.
The resulting foams presented a closed cellular structure and higher thermal stability (up to 220°C) and flexural and compression strengths (4 MPa and 2 MPa, respectively) compared to those of the conventional foams (i.e. max. Working temperature of 80-100°C and strengths even 3/4 times lower). One of the most important results of the present project could be referred to the production of unsaturated polyester Resin Transfer Moulded (RTM) sandwich panels with the mentioned foamed core. This achievement has been completed in a very satisfactory manner. The resulting sandwich panels presented a strongly improved shear resistance due to the improved adhesion between the foam and the external composite skin and to the higher mechanical strength of the foam itself.
Fibres have been produced according to a POY standard process and at speeds up to 5000 m/min. The mechanical properties of the POY material thus generated give tenacity and elongation values at break of about 2.5 cN/dtex and 70%, respectively. Dyeing properties and dye up-takes are comparable or even higher than for standard PET.
Second recycling of such products produced materials and samples of mechanical characteristics comparable with those of the starting first recycled materials.
Solid State PolyAddition reactions following a reactive extrusion mixing stage will be used to modify polymeric matrices derived from recycled materials.
Recycled materials available in various E.E.C. countries will be collected, analysed and selected to fit the requirements as raw materials for fabricated products for structural and esthetic performance.
The above said modified matrices will be used:
- to make reactive low viscosity polymer melts to impregnate glass mats and fillers for reinforced thermoplastics; to be upgraded for good mechanical properties in the mould of afterwards;
- to make high melt viscosity for foams to be used as core for TRM parts;
- to increase the molecular weight to be used in POY production and high performance fibres.
An especially designed extruder prototype will be built to perform the reactive extrusion mixing with recycled materials and the materials thus obtained will be characterised physically and mechanically and experimental parts will be produced. The further recycling of parts will be also investigated.
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86077 Pozzilli Isernia
Italien