Question

1. Polymer Recycling Pick 2 common plastics (from those which correspond to 1-6 recycling codes) and discuss the process or methods used in recycling that polymer. Discuss the recycling processes most commonly applied to that polymer. Include general energy requirements and list other needed chemicals and equipment, as well as the resing products from separation/degradation. Give 3 examples of materials which can be made from these "down-cycled" plastics. Give two challenges of each recycling process, respectively.

Answer 1

The two common plastic which will be discussed further are -

1) Polyethylene Terephthalate ( PETE or PET) corresponding to code 1 is the most commonly used plastic. It is used for packaging materials like bottles and containers  

Recycling process or method used- Sorting, crushing washing, separating and drying. Further treatment involves melt filtering which leads to complete purification and removal of non melting contaminants.

List of chemicals and equipment needed - Steam is used for pre washing. Materials are identified using Near infrared sorting equipment, metal detectors and manual sorting belts are also used.

Resulting products from separation or degrfromadation-- after sorting the PET material is ground into particles known as flakes. These flakes undergo further separation with washing and air classifications and finally grinding and melt filteration so prepare it for reuse and manufacturing  

Repurposed to make - textiles, carpets, life jackets, sleeping bags and luggage.

2) High density polyethylene (HDPE) corresponding to code 2 is widely used packaging resin owing to its toughness  

Recycling process or method used - separation, cleaning, granulation a

Plastic is sorted and cleaned, to remove any unwanted debris. The plastic then needs to homogenised, so that only HDPE will be processed.

HDPE is then shredded and melted down to further refine the polymer. The plastic is then cooled into pellets which can be used in manufacturing.

List of the chemicals and equipment needed - Near infrared radiation.

Resulting products from separation or degradation - degradation leads to formation of granules which undergoes further process to make new products  

Repurposed to make - rope toys, piping trash cans.

Challenges of recycling - Recycling of different plastic together is a big challenge. Handling of flexible plastic is problematic during collection and sorting stage .