Durability of Wood Flour-Recycled Thermoplastics Composites Under Accelerated Environmental Conditions <ul><li>Kamal Adhik...
<ul><li>Background  </li></ul><ul><li>Objectives </li></ul><ul><li>Experimental Programs </li></ul><ul><li>Results and Dis...
<ul><li>Total MSW generation in 2006 in USA was 251 million tons (USEPA 2006). Recycled 82 million tons of MSW (32.5 %). <...
Background <ul><li>Total MSW generation in 2006 in USA was 251 million tons.  </li></ul><ul><ul><li>Plastics comprise 11.7...
Background <ul><li>Recycled plastics and wood waste  are , </li></ul><ul><li>Lower cost than competitive materials (especi...
What is Wood-Plastic Composite? <ul><li>Wood-plastic composite is manufactured by dispersing wood particles into molten pl...
Objectives <ul><li>Investigate the performance of wood-plastic composites (WPCs) made of recycled plastics and sawdust </l...
Experimental:  Materials <ul><li>1: Wood filler  </li></ul><ul><ul><li>Pinus radiata  sawdust </li></ul></ul><ul><ul><li>F...
Experimental: Composite preparation <ul><li>Mixing/compounding of wood flour and plastic: using a  </li></ul><ul><li>co-ro...
Wood-plastic composite manufacturing process flow Sawdust (wood-flour) Mixing/Compounding Recycled Plastics WPC’s panel (F...
Composite formulations (% by weight)
Accelerated weathering tests <ul><li>Accelerated freeze-thaw cycles </li></ul><ul><ul><li>Samples exposed to Accelerated F...
Testing and analysis <ul><li>Water absorption & thickness swelling tests (ASTM D570-98).  </li></ul><ul><li>Mechanical pro...
Results 2 h Water Absorption Water absorption by WPCs in Water Submersion 24 h Water Absorption
24 h Thickness Swelling (%) Results Contd…… Thickness Swelling by WPCs in Water Submersion
Flexural MOR of the WPCs Flexural MOE of the WPCs Results Contd…… Flexural properties of WPCs
Results Contd…… Changes in flexural properties of WPCs after 12 FT cycles
Results Contd…… Surface colour measurement ΔE – Discoloration; ΔL*- lightening; Δa*and Δb*-chromaticity coordinates
Discoloration values ( Δ E) for UV-Weathered PP-wood flour Composites Results Contd……
Results (contd.) SEM images of rPP50W50 (a) control and (b) UV-weathered samples Microstructural characterization
Results (contd.) SEM images of rPP45W50CA5 (a) control (b) FT-weathered samples Microstructural characterization
Results contd….. DSC thermograms (2 nd  heating) for PP based control and FT weathered composites Thermal properties of WP...
Results (contd.) Thermal properties <ul><li>Melting enthalpy and crystallinity of UV-weathered composites was decreased co...
Conclusions <ul><li>The results of this work so far provided the evidence that the recycled thermoplastics (HDPE and PP) a...
Property Comparison 0.42-2.5 0.98-4.1 1.06-1.97 14.4-25.5 HDPE based WPC 24 h thickness Swelling (%) 24 h water absorption...
Potential Applications <ul><li>Low Stress Applications: </li></ul><ul><ul><li>Residential/Commercial decking products </li...
Acknowledgements <ul><li>Mr Jeremy Warnes and Mr Ross Anderson of Scion on extrusion experiments </li></ul><ul><li>Mr Murr...
Thank you. <ul><li>Any questions, comments, suggestions?? </li></ul>
Additives (Contd…) Modification scheme for esterification reaction between wood particles and maleated polyolefins: (a) mo...
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Adhikary 7416

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Adhikary 7416

  1. 1. Durability of Wood Flour-Recycled Thermoplastics Composites Under Accelerated Environmental Conditions <ul><li>Kamal Adhikary, Shusheng Pang and Mark Staiger </li></ul>Department of Chemical and Process Engineering University of Canterbury Christchurch, New Zealand Ecocity World Summit 2008, San Francisco, USA 22-26 April 2008
  2. 2. <ul><li>Background </li></ul><ul><li>Objectives </li></ul><ul><li>Experimental Programs </li></ul><ul><li>Results and Discussions </li></ul><ul><li>Conclusions </li></ul>Presentation outline
  3. 3. <ul><li>Total MSW generation in 2006 in USA was 251 million tons (USEPA 2006). Recycled 82 million tons of MSW (32.5 %). </li></ul><ul><li>1.3 billion tonnes of MSW generated in Europe </li></ul><ul><li>Worldwide plastics production: 245 million tonnes ( PlasticEurope 2008 ). </li></ul>Background
  4. 4. Background <ul><li>Total MSW generation in 2006 in USA was 251 million tons. </li></ul><ul><ul><li>Plastics comprise 11.7 percent </li></ul></ul><ul><ul><li>Wood follows at 5.5 percent </li></ul></ul><ul><ul><li>9.4% of wood generated was recovered </li></ul></ul><ul><ul><li>6.9% of plastics waste generated was recovered/ or recycled </li></ul></ul><ul><li>Recovery rate of post-consumer end-of-life plastics in Europe was 50% in 2006. </li></ul><ul><li>About 35,000 tonnes (13.48% of total imported virgin plastics) was recycled in 2004 in New Zealand </li></ul>Increased use of recycled plastics and wood waste offers the prospect of lessening waste disposals and reducing the product costs
  5. 5. Background <ul><li>Recycled plastics and wood waste are , </li></ul><ul><li>Lower cost than competitive materials (especially those based on synthetic polymer), For example, HDPE recycled pellet and flake is 31- 34% less expensive than virgin </li></ul><ul><li>Renewable resources </li></ul><ul><li>Additional market for recycled plastics and wood waste </li></ul><ul><li>Reduce waste disposal burden </li></ul><ul><li>Properties are comparable to virgin plastics </li></ul>Development of new value added wood-plastic composite material utilizing recovered plastics and wood waste will have a greater importance from both engineering and economic points of view
  6. 6. What is Wood-Plastic Composite? <ul><li>Wood-plastic composite is manufactured by dispersing wood particles into molten plastic with coupling agent/ or additives to form composite material that can be processed like a conventional plastic and has the best features of wood and plastics </li></ul><ul><li>Advantages over its constituent’s materials </li></ul><ul><li>Compare to wood it has lower water uptake, thickness swell, and highly durable against bio-deterioration, also reduce the machine wear and tear of processing equipment, and lowers the product cost against inorganic fillers </li></ul><ul><li>Compare to polymer it has higher mechanical properties, thermal stability, and more resistant to ultraviolet light and degradation </li></ul>
  7. 7. Objectives <ul><li>Investigate the performance of wood-plastic composites (WPCs) made of recycled plastics and sawdust </li></ul><ul><ul><li>Evaluate dimensional stability, mechanical properties, morphology and thermal properties of WPCs </li></ul></ul><ul><ul><li>Examine durability performance for outdoor applications </li></ul></ul>
  8. 8. Experimental: Materials <ul><li>1: Wood filler </li></ul><ul><ul><li>Pinus radiata sawdust </li></ul></ul><ul><ul><li>Fresh sawdust was dried and grounded to fine flour (0.18 and 0.5 mm) </li></ul></ul>Size distribution of radiata pine flour <ul><li>2: Thermoplastic polymer </li></ul><ul><ul><li>Recycled thermoplastics (HDPE and PP) collected from Local Plastics Recycling Company. </li></ul></ul><ul><ul><li>Virgin HDPE (grade GM4755) and virgin PP (Hyundai Séetec M1600, polypropylene co-polymer) </li></ul></ul><ul><ul><li>Coupling agent: Maleated polypropylene (Epolene G-3015) </li></ul></ul>21 Recycled PP 25 Virgin PP 0.07 Recycled HDPE 0.1 Virgin HDPE Melt flow index, g/10min/(190°C / 2.16 kg) Polymer type
  9. 9. Experimental: Composite preparation <ul><li>Mixing/compounding of wood flour and plastic: using a </li></ul><ul><li>co-rotating twin screw extruder. </li></ul><ul><li>Composite formulation used: </li></ul><ul><ul><ul><li>Wood flour: 0, 30, 40, 50 and 60 wt. % </li></ul></ul></ul><ul><ul><ul><li>MAPP content: 3-5 wt. % </li></ul></ul></ul><ul><li>Pressing mold temperature: 170  C for HDPE series and 190  C for PP series; hot pressed for 5 min under 5 MPa, and then cold pressed under same pressure. </li></ul><ul><li>Target panel density: 800-950 kg/m3 </li></ul><ul><li>Composite panel size: size: </li></ul><ul><li>165 mm  152 mm  6.4 mm </li></ul>
  10. 10. Wood-plastic composite manufacturing process flow Sawdust (wood-flour) Mixing/Compounding Recycled Plastics WPC’s panel (Final product) Hot/Cold pressing of pellets Wood-plastics Pellets
  11. 11. Composite formulations (% by weight)
  12. 12. Accelerated weathering tests <ul><li>Accelerated freeze-thaw cycles </li></ul><ul><ul><li>Samples exposed to Accelerated Freeze–Thaw Cycles (ASTM D6662–01) for 12 full cycles. </li></ul></ul><ul><ul><li>One complete weathering cycle consisted of: </li></ul></ul><ul><li>(i) Water soaks until no further weigh gain </li></ul><ul><li>(ii) Freezing for 24 h (Chest freezer at –27°±3°C) </li></ul><ul><li>(iii) Thawing for 24 h (21°C±3°C and 50±5% RH) </li></ul><ul><li>2. Accelerated UV-exposure </li></ul><ul><ul><li>Samples exposed to Fluorescent UV light-exposure apparatus (ASTM D4329-99). </li></ul></ul><ul><ul><ul><ul><ul><li>Exposure for 2000 h </li></ul></ul></ul></ul></ul><ul><li>Lamp type: UVA-340 </li></ul><ul><li>Irradiance: 0.77 W/m 2 (~ wavelength of 340 nm) </li></ul>
  13. 13. Testing and analysis <ul><li>Water absorption & thickness swelling tests (ASTM D570-98). </li></ul><ul><li>Mechanical properties: Flexural properties (ASTM D790) using Universal Testing Machine. </li></ul><ul><li>Morphology of the fracture surface of bending test specimens are investigated by using high resolution field emission scanning electron microscopy. </li></ul><ul><li>Surface color of control and weathered samples are measured using Minolta Spectrophotometer (ASTM D2244). </li></ul><ul><li>Thermal properties are measured by using Differential Scanning Calorimetry- Scanned from 50 to 200 o C at a heating and cooling rate of 2 o C/min. </li></ul>
  14. 14. Results 2 h Water Absorption Water absorption by WPCs in Water Submersion 24 h Water Absorption
  15. 15. 24 h Thickness Swelling (%) Results Contd…… Thickness Swelling by WPCs in Water Submersion
  16. 16. Flexural MOR of the WPCs Flexural MOE of the WPCs Results Contd…… Flexural properties of WPCs
  17. 17. Results Contd…… Changes in flexural properties of WPCs after 12 FT cycles
  18. 18. Results Contd…… Surface colour measurement ΔE – Discoloration; ΔL*- lightening; Δa*and Δb*-chromaticity coordinates
  19. 19. Discoloration values ( Δ E) for UV-Weathered PP-wood flour Composites Results Contd……
  20. 20. Results (contd.) SEM images of rPP50W50 (a) control and (b) UV-weathered samples Microstructural characterization
  21. 21. Results (contd.) SEM images of rPP45W50CA5 (a) control (b) FT-weathered samples Microstructural characterization
  22. 22. Results contd….. DSC thermograms (2 nd heating) for PP based control and FT weathered composites Thermal properties of WPCs <ul><li>Crystallization temperature ( Tc) and enthalpy (ΔHc) were measured from 1 st cooling run </li></ul><ul><li>Peak melting temperature ( Tm ) and enthalpy (ΔHm) were measured from 2 nd heating cycle </li></ul><ul><li>Crystallinity (Xc): </li></ul><ul><li>ΔH f :Expt. heat of fusion, ΔH f 100 is the theoretical heat of fusion for a 100% crystalline thermoplastic (ΔH f 100=205 J/g for PP and ΔH f 100=293 J/g for HDPE), and w is the mass fraction of thermoplastic in the composite samples </li></ul>
  23. 23. Results (contd.) Thermal properties <ul><li>Melting enthalpy and crystallinity of UV-weathered composites was decreased compared to corresponding control samples. </li></ul><ul><li>Peak melting temperature and peak crystallization temperature changed slightly. </li></ul><ul><li>Wood fibers in composite act as nucleating agent and retards the crystallization rate. </li></ul><ul><li>Loss of crystallinity due to weathering degradation resulted the decrease in composite properties. </li></ul>
  24. 24. Conclusions <ul><li>The results of this work so far provided the evidence that the recycled thermoplastics (HDPE and PP) and wood sawdust can be successfully used to produce stable and strong wood plastic composites. </li></ul><ul><li>Improved stability can be achieved by increasing the polymer content or by addition of coupling agent. </li></ul><ul><li>Properties degradation is observed after Freeze-Thaw and UV weathering. </li></ul>
  25. 25. Property Comparison 0.42-2.5 0.98-4.1 1.06-1.97 14.4-25.5 HDPE based WPC 24 h thickness Swelling (%) 24 h water absorption (%) Flexural MOE (GPa) Flexural MOR (MPa) Property 1.7-3.8 (1h) 2.6 - 0.8-1.5 2-3 (1h) 17.2 <0.01 1.2-3.7 3.0 7.9 1.39 1.7-2.5 40.0 80.0 28.7 17.4-39.6 Regular MDF (3mm) Pine lumber PP lumber PP based WPC
  26. 26. Potential Applications <ul><li>Low Stress Applications: </li></ul><ul><ul><li>Residential/Commercial decking products </li></ul></ul><ul><ul><li>Boardwalks and Docks </li></ul></ul><ul><ul><li>Windows and door parts </li></ul></ul><ul><ul><li>Siding and accessories </li></ul></ul><ul><ul><li>Fencing </li></ul></ul><ul><ul><li>Others: Roofing, Outdoor furniture, Landscape timbers, Playground equipment </li></ul></ul><ul><ul><li>Exterior building trim </li></ul></ul><ul><ul><li>Industrial flooring </li></ul></ul>
  27. 27. Acknowledgements <ul><li>Mr Jeremy Warnes and Mr Ross Anderson of Scion on extrusion experiments </li></ul><ul><li>Mr Murray Taylor and Mr Henry Baker of AgResearch (Lincoln) on hot press experiments </li></ul><ul><li>New Zealand Plastics Recycling Ltd. to supply the recycled plastics </li></ul><ul><li>Technicians from Departments of Mechanical Engineering, and Chemical and Process Engineering </li></ul><ul><li>New Zealand Development Scholarships (NZDS) scheme of NZAID </li></ul><ul><li>Funding from New Zealand Foundation for Research, Science and Technology </li></ul>
  28. 28. Thank you. <ul><li>Any questions, comments, suggestions?? </li></ul>
  29. 29. Additives (Contd…) Modification scheme for esterification reaction between wood particles and maleated polyolefins: (a) monoester and (b) diester formation.

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