Module 4: Environmental concerns Flashcards
Recycling Polymers:
Discarded polymers organised into types - polymers chopped into flakes - washed - dried - melted - cut into pellets and reused
PVC Recycling:
-Grinding PVC to be reused
or
-Using solvents to dissolve the polymer - high-grade PVC then recovered by precipitation and solvent reused.
Using waste polymers as fuel:
Some polymers are difficult to recycle but have a high stored energy value - incinerated to produce heat - generate steam - turn a turbine.
Feedstock Recycling:
Chemical and thermal processes that reclaim monomers, gases, or oil from waste polymers.
Can be used for mixed and unsorted polymers.
Products can be used as raw materials to produce new polymers.
Biodegradable polymers:
They are broken-down by microorganisms into water, CO2, and biological compounds. They are usually made from starch, cellulose or they contain additives that alter their structure to allow for them to be digested by microorganisms.
Photodegradable Polymers:
Photodegradeable oil-based polymers have their bonds weakened by sunlight - start degrading.
Light absorbing additives can also be used.
Why is recycling PVC hazardous:
It has a high chlorine content - landfill is not sustainable - when burnt releases corrosive hydrogen chloride gas and other pollutants.
Bioplastics:
Bioplastics are produced from plant starch, cellulose, plant oils, and proteins. They offer a renewable and sustainable alternative to oil-based products)
Compostable polymers:
They degrade leaving behind no visible or toxic substances. Based on lactic acid.