Polymer recycling at SP Chemistry Materials and Surfaces. Anna Jansson, PhD,

Transcription

1 Polymer recycling at SP Chemistry Materials and Surfaces Anna Jansson, PhD,

2 During the past ten years several people have worked with recycling of polymers. Ignacy Jakubowicz Jonas Enebro Viktor Emanuelsson Nazdaneh Yarahmadi Many students

3 Polymer Recycling The Waste Hierarcy Our research cover the top of the waste hierachy

4 Our focus in polymer recycling Collection Durability durable products minimised waste Quality of recycled materials mechanical properties and durability of recyclates. Understanding of degradation caused by recycling processes New products Reprocessing

5 Polymer durability Polymer durability is dependent on the amount of protective additives i.e. antioxidants uv-stabilizer etc. Durability of for example building materials are tested to achieve different certification marks to guide consumers to buy durable products.

6 Auto-oxidation and ageing of polymers RH = polyolefin molecules + Anti-oxidants Secondary AO Primary AO Anti-oxidants Prolong service life Consumed over time Degradation reaction rates are accelerated by increased temperatrue. Ageing of materials at elevated temperatures is used to determine durability of virgin and recycled polymers. Evaluation of material properties are made by for example Tensile Testing, DSC, FTIR etc.

7 Quality: Blends of Bio-based and fossil based materials Transition period towards bio-based materials Increasing demands/legislations for recycling Conventional plastics Recycling of bio-based plastics! Bio/petro blends Bio-based plastics

8 PA12 PA1010 Quality of recycled bio-based/fossil polyamide Compounding Brabender Plasti-Corder Labstation + TSE 20/40D 100% PA1010 Bio based PA 1010 (Castor Oil) 90% PA % PA1010 Differentiation (separation) FTIR Purity (mixed recyclate) DSC Effect on properties Tensile testing 5% PA % PA12 Fossil based PA 12

9 Quality: Differentiation of pure materials and mixtures by FTIR Differentiation (separation) FTIR 100% PA % PA1010 Only minor differences (overall match 94%) Differentiation could be a problem! 50% PA1010 5% PA % PA12

10 Effect on properties Tensile testing Quality: Influence of mixing on mechanical properties Reduced properties: 15 % reduction of ε B 10 % reduction of σ B as compared to PA1010

11 Elongation at break (%) Understanding: Tensile testing physical and chemical effects 700 Extrusion Ageing Step (extrusion or ageing C) A ten-year-old recycled material has been extruded and aged several times. Both physical and chemical effects are detected by tensile testing

12 Elongation at break (%) Understanding: Tensile testing (PP) continued Ageing seems to degrade material, extrusion improves the properties, why? Extrusion does not seem to influence the material properties the subsequent ageing has severe effects Ageing Repeated extrusion Extrusion Ageing Step, ageing followed by extrusion Step, extrusion followed by ageing

13 Normalised Signal Understanding: Surface oxidation measured by ToF-SIMS Surface Cross-section C 2 H 3 18 O + signals from surface and cross section of low stabilized LDPE (2mm thick) film after different exposure times at 70 C Exposure time (hours) The exposure cell

14 Hydroperoxide content (mmol/kg PP) Understanding: Hydroperoxide content in PP samples measured by iodometry Heat decomposes hydroperoxides, the radicals then accelerate degradation, therefore reprocessing degrades recycled materials mm thick compression moulded films of non-stabilised PP 80 Ageing Re-processed Ageing time at 70 C (days)

15 New recycling projects CONSTRUCTIVATE recycling of construction and demolition waste (CDW) (Co-ordinated by Chalmers industriteknik) One work package focus on material waste streams and one of them is plastics. REBUS quality of materials from CDW

16 Wishes for the future Find solutions! Find applications for polymer waste. To find what type f plastics to be recyled and not Don t produce so much low quality plastic products!

17 Thank you!