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Physical Ageing by Ultra Violet Degradation of Recycled Polyolefin Blends

By Attwood Julienne Carol


This thesis covers the investigation of the weathering behaviour of mixed waste plastics. It includes a review of the literature on polymer degradation mechanisms with particular emphasis on environmental degradation from ultra violet radiation. Products manufactured from recycled polyolefin blends were subjected to accelerated weathering conditions and subsequent tests. Field–aged products were tested also. Samples were analyzed for changes in mechanical, rheological and chemical properties. Scanning Electron Microscopy and Electron Probe Microanalysis were used to examine samples for both impurities and signs of degradation. Data obtained in this study, by means of tensile and melt flow tests, with GPC, gloss and colour analyses carried out by Rapra1, showed that the effect of UV exposure, whether in the field or artificial environments, was not significant as far as the mechanical properties of the materials were concerned. There was some change in the surface characteristics but such surface effects would not compromise the mechanical integrity of the product when recycled. During reprocessing of the materials, it is likely that stabilizer is brought to the surface of any new moulding, thus renewing the surface characteristics. Hence damaged or end-oflife products need not be discounted from recycling. However, surface appearance may be an issue. SEM EDX Analysis was useful in identifying impurities in the recyclate, but there was no conclusive evidence of degradation as a direct result of exposure to UV radiation. The variation in field-aged materials and the artificially aged materials showed that it is likely that the difference in results for field aged and artificially aged material was due to variability in the source materials and showed that in practice, it is difficult to control the composition of the mix coming from the waste suppliers. This was more significant for the 1 properties of the materials than any UV exposure. This increase could be due to degradative cross-linking. However, it was more likely to be caused by variability in the batches of raw material. Chain scission in polypropylene and cross–linking in polyethylene in mixed blends could have a compensating effect on each other and lead to non–degradative effects although evidence for this was inconclusive. Overall, the study has shown that all the materials tested have generally maintained their mechanical properties with little change under accelerated UV exposure. This has positive implications for the use of plastic recyclate of this nature in manufacturing processes

Topics: H100 General Engineering, H700 Production and Manufacturing Engineering, H800 Chemical Process and Energy Engineering, J500 Materials Technology not otherwise specified
Year: 2007
OAI identifier:

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  1. (2000). Accelerated and Outdoor/Natural Exposure Testing of Coatings, doi
  2. (1996). Accelerated Weathering Induced Degradation of unprotected multilayer Polyethylene Slabs II doi
  3. (1995). Accelerated Weathering Induced Degradation of unprotected multilayer Polyethylene Slabs, doi
  4. (1987). Acceleration Shift Factor and its Use in Evaluating weathering Data,
  5. (2000). Alteration of molecular characteristics of polyethylene under the influence of UV radiation doi
  6. (2000). Alterations of Molecular Characteristics of Polyethylene under the influence of UV-radiation, Polymer, doi
  7. (1983). An Introduction to the Mechanical Properties of Solid Polymers (2nd Ed) doi
  8. (2001). Artificial Aging of high-density polyethylene by ultra-violet irradiation European Polymer Journal doi
  9. (2002). Assessment of Thermal and Thermo-oxidative Stability of Multi-extruded Recycled PP, HDPE and a Blend Thereof , Polymer Degradation and Stability doi
  10. (2002). Automotive Plastics Recycling: Successful Projects doi
  11. (1996). Comparison of the UV-degradation chemistry of unstabilized and HALS-stabilized Polyethylene and Polypropylene, Polymer Degradation and Stability, doi
  12. (2003). De Paoli M-A Effect of conducting carbon black on the photostabilization of injection molded poly(propylene-co-ethylene) containing TiO2 Polym. doi
  13. (1999). Degradation and Aging of Polymer Blends I. Thermomechanical and Thermal Degradation Polymer Degradation and Stability doi
  14. (1989). Degradation and Stabilization of High Density Polyethylene during Multiple Extrusions, Polymer Degradation and Stability doi
  15. (1991). Degradation of Polyolefins during Melt Processing, Polymer degradation and Stability doi
  16. (1999). Degradation of Polyolefins during Various Recovery Processes, Macromolecular Symposia doi
  17. (2001). Double stage oxidation of polyethylene as measured by chemiluminescence, Polymer Degradation and Stability doi
  18. (1979). Effect of Thermal and Oxidative Degradation on the
  19. (1998). Effects of Increased Solar Ultraviolet Radiation on doi
  20. (1988). Environmental Degradation of Polypropylene Polymer Degradation and Stability doi
  21. (1990). European Artificial Weathering Standards,
  22. European parliament and Council Directive 94/62/EC, 20 /12/94 on Packaging and Packaging waste, doi
  23. (1995). Foundations of Vision , Sinauer Assoc. doi
  24. (1996). FTIR and DSC Study of HDPE Structural Changes and Mechanical Properties Variation When Exposed to Weathering Aging During Canadian Winter doi
  25. (2000). Global Exposure Models for Automotive Coating Photo-oxidation, Polymer Degradation and Stability doi
  26. (1999). HDPE Bottle Crates – Closed Loop Recycling Example from Greece, Paper at Recovery, Recycling, Re-integration Conference doi
  27. (2002). Importance of Weathering Factors other than UV Radiation and Temperature doi
  28. (1997). Influence of Oxygen Pressure and Temperature on the UVDegradation Chemistry of Polyethylene, Polymer Degradation and Stability doi
  29. (2000). Interpreting weathering Acceleration Factors for Automotive Coatings using Exposure Models, Polymer Degradation and Stability doi
  30. (1997). Investigation on the Melt Flow Properties of Polyethylene and Polypropylene Blends, Polymer Testing doi
  31. (1997). Material Recycling of Plastics Waste for Demanding Applications: Upgrading by Restabilization and Compatibilization Trends in Polymer Science
  32. (2000). Mechanical Recycling of Post- Used HDPE Crates Using the Restabilization Technique II: doi
  33. (1999). Mechanical Recycling of postused High Density Polyethylene Crates using the Restabilization Technique. 1. Influence of Reprocessing, doi
  34. (1970). Mechanisms of oxidative photodegradation and of UV stabilization of polyolefins doi
  35. Natural and Accelerated Photoaging of Linear Low-Density Polyethylene: doi
  36. (1999). Natural and Accelerated Weathering of Stabilized Copolymer Ethylene-Propylene (Low Ethylene Content), doi
  37. (1998). Oxygen Uptake Measurements to Identify the Cause of Unexpected Differences between Accelerated and Outdoor weathering, Die Angewandte Makromolekulare Chemie doi
  38. (1998). Peroxy-Initiated Chain Degradation, Crosslinking and Grafting in PP-PE Blends, doi
  39. (1981). Photo-Oxidation of Thick Polymer SamplesPart 1: The Variation of Photo-Oxidation with Depth in Naturally and Artificially Weathered Low Density Polyethylene Polymer Degradation and Stability doi
  40. (1996). Photo-oxidative Degradation of Mechanically Stressed Polyolefins, Polymer Degradation and Stability doi
  41. (1997). Photooxidation of Polypropylene under Natural and Accelerated weathering Conditions , doi
  42. (1995). Physical Aging of Polymers Progress doi
  43. Plastic Bottle Recycling in the UK, Waste Resource Action Programme,
  44. (1996). Polydispersity Index and Molecular Weight Distributions of Polymers Eur. doi
  45. (1999). Polymer Chemistry: An Introduction (3rd Edition), doi
  46. (2000). Polymer Degradation and Stability doi
  47. (1999). Polymers and the Environment (1st Edition), Royal Society of Chemistry,
  48. (1995). Quality assessment of Polymeric Recyclates. Part 1: Repeated Processing and Thermo-oxidative Ageing of LDPE, Polymer Recycling
  49. Reaction of SO2 and NO2 with Polymers, doi
  50. (2001). Recycled and Restabilized HDPE Bottle Crates: retention of Critical Properties after Heat Aging, Polymer Engineering and Science doi
  51. (1992). Recycling of Degraded Polyethylene: doi
  52. (1997). Recycling of High Density Polyethylene Containers, Polymer Degradation and Stability doi
  53. (1999). Rheological and Mechanical Properties of Recycled Polypropylene Polym. doi
  54. (1995). Sitek F Improving the quality of recyclates with additives Hanser,
  55. (1995). Sitek.A & Pfaendner R Upgrading of Recycled Plastics by Stabilization doi
  56. (2003). Standards and Specifications Affecting Plastics Recycling in the UK, Waste Resource Action Programme,
  57. (1999). Structural Modifications induced by Recycling of Polypropylene, Polymer Engineering and Science, doi
  58. (1995). Surface and Bulk Analyses of the Oxidation of Polyolefins Polymer Degradation and Stability doi
  59. (2003). Survey of Applications, Markets & Growth Opportunities for Recycled Plastics in the UK. WRAP (Waste Resource Action Programme) Publication,
  60. (1997). The Effect of Multiple Extrusion Passes During Recycling doi
  61. (1995). The Effects of UV Stabilizers in Post-Consumer Recycled High Density Polyethylene’ ANTEC Vol III,
  62. (1997). The Environmental Aspects of Polymers Polimery
  63. (1969). The Photo-oxidation of Polypropylene: Some effects of molecular order, doi
  64. (1997). The Producer Responsibility Obligations (Packaging waste) Regulations 1997, Statutory Instrument doi
  65. (1999). The Recycling of Thermoplastics:
  66. (1997). The Role of Physical Structure and Morphology in the photodegradation behaviour of Polypropylene, Polymer Degradation and Stability doi
  67. (1973). The Weathering Degradation of Plastics, Predicting Plastics Performance, doi
  68. (2003). Thermal Degradation Kinetics of Isotactic and Atactic Polypropylene doi
  69. (1998). Thermo-mechanical Degradation of Polypropylene, Low Density Polyethylene and their 1:1 Blend, Polymer Degradation and Stability doi
  70. (1998). Thermogravimetric Evaluation of the Kinetics of Decomposition of Polyolefin Blends, Polymer Degradation and Stability doi
  71. (1985). Thermomechanical Degradation of Blends of Isotactic Polypropylene and High Density Polyethylene Polymer Degradation and Stability doi
  72. (1999). Thermomechanical Degradation of Compatibilized and uncompatibilized nylon 6/Polypropylene Blends, Polymer Degradation and Stability doi
  73. (1999). Two-Step Degradation of HighDensity polyethylene During Multiple Extrusion, doi
  74. (1978). Unsolved Problems doi
  75. (1995). Upgrading of recycled Plastics by Restabilization. An Overview, Polymer Degradation and Stability doi
  76. (1995). UV-Exposure of Stabilized and Non-stabilized HDPE Films: Physico-chemical Characterization, Polymer Degradation and Stability doi
  77. (1998). Weather Ageing Characterization of the Mechanical Properties of the Low Density Polyethylene, Polymer Degradation and Stability doi
  78. (2001). Weathering Effects on
  79. (1977). Weathering of polyolefins (polyethylene and polypropylene) Popular Plastics
  80. (1997). Zaikov The Initiation of Polypropylene Oxidation, Polymer Degradation and Stability doi

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