9. Biodegradable polymers Flashcards
What are the two categories that bio-polymers can be split into?
- natural bio-polymers
- synthetic bio-polymers
What are natural bio-polymers?
- made from natural materials
- cellulose
- starch
- polysaccharides
What are synthetic polymers?
- made from renewable resources but chemically engineered (synthesised) to break down more quickly
What are biodegradable polymers?
- can be made from finite resources such as crude oil
- contain additives that cause it to degrade more quickly than traditional polymers
What are the disadvantages of biodegradable polymers?
- produce methane gas when decompose in landfill
- can take high temps to decompose and may leave behind toxic gases
- cannot be recycled
What are the disadvantages of bio-polymers?
- natural bio-polymers need land to grow
- cannot be recycled
What are biodegradable polymers?
(examples)
- corn starch polymer
- potatopak
- biopol (bio-batch additive) (polyhydroxybutyrate, PHB)
- polylactic acid (PLA)
- polyhydroxyalkanoate (PHA)
- lactide
- glycolide (Lactel and Ecofilm)
What are the properties of corn starch polymer?
- natural bio-polymer
- made from high-starch vegetables (corn, potatoes, maize)
What are the uses of corn starch polymer?
- packaging products
- straws
- vending cups
- disposable cutlery
- bags
- takeaway food containers
What are the properties of potatopak?
- natural bio-polymer
- made from potato starch
What are the uses of potatopak?
- single-use food items such as bowls, cutlery, food trays and serviettes
- packaging beads or ‘peanuts’
- bin bags
What are the properties of biopol?
- natural bio-polymer
- made from bacteria grown in cultures
- additive to promote degradation
- usually 1% added to thermoplastics
What are the uses of biopol?
- packaging products such as film and carrier bags
- vending cups
- nappies
- surgical stitches
- pill coverings
What are the properties of PLA?
- synthetic bio-polymer
- made from corn kernels or cane sugar
- fermented to produce lactic acid
- synthesised to produce polylactic acid
What are the uses of PLA?
- packaging
- single-use bottles
- carrier bags
- plant pots
- disposable nappies
- medical sutures
- 3D printing
What are the properties of PHA?
- natural bio-polymer
- made from bacteria grown in cultures
- fully compostable
What are the uses of PHA?
- packaging
- medical uses such as slow release medication patches, films, screws and bone plates
What are the properties of lactide?
- synthetic bio-polymer
- fully compostable
- water soluble
- PLA and cellulose based
What are the uses of lactide?
- biomedical applications
- slow release medication
- bone repair fixings
- detergent washing sachets
What are the properties of glycolide?
- synthetic bio-polymer
- fully compostable
- PLA and cellulose based
What are the uses of glycolide?
- food film
- bags
- packaging wrap
- bin bags
- agricultural ground sheet
- flower wrap
What does degradation occur in the presence of?
- light (photo-degradable)
- oxygen (oxy-degradable)
- water ((hydro-degradable)
What is photo-degradation?
where polymer bonds are weakened and the polymer breaks down with exposure to UV lights
What is oxy-degradation?
where the polymer turns into a fine powder with exposure to oxygen
- is subsequently degraded by the action of micro-organisms
What is hydro-degradation?
where the polymer quickly breaks down with exposure to water
- is subsequently degraded by the action of micro-organisms
Why does degradation occur?
- due to the action of micro-organisms
- convert material into water, CO2, biomass and possibly methane
What is the ability of a polymer to degrade dependent on?
- the structure of the polymer
