Polymeres/ Plastic

• classified as synthetic, inorganic or organic based on their source or composition

• number of different monomers can be combined to make copolymers => different arrangements possible

• large molecule, often out of 1000s small molecules together, ti form a macromolecule

• addition polymerization: with double bonds possible

  • Polyethylene

• condensation polymerization: reaction that joins monomers with loss of small molecules (H2O, HCl, NH3)

  • nylon out of adipic acid and hexane diamine

  • lactic acid

  • PET from ethylenglycol and terephtalic acid

• different sizes (sometimes not easy to control)

• different properties due to large molecular weight but in general stable! => ultra high molecular weight polyethylene is used for garbage bins due to its exceptional abrasion resistance

• linear, branches, cross linkes

  • enzymes cant break all of them (e.g. starch yes in humans, cellulose not)

• H-bondings: tensile strength (nylone)

• most insoluble in water

• little to no reactivity

• some elastic

• type of materials can be melted and shaped into different objects (bags, bottles, pipes)

• shaping and reheating for finite number of times => recycling)

• e.g. HDPE (linear) or LDPE (brnached), PLA (polylactic acid)

• lightly crosslinked rubber => elastic

• can be stretched to many times their original length and can bounce back into their original shape without permanent deformation => go back to higher entropy

• Tg < TR

• polyisoprene, natural rubber, polybutadiene

• vulcanized rubber

• sulfur for crosslinking polymer chains => stronger rubber that is not tacky when reheated

• shaping and reheating is only once possible (cause S-S-double bonds break)

• amorphous polymer has to have a glass transition temperature higher than room temperature

  • TG > TR

• additives are small molecules that are added to polymers to change their properties

• added during the polymerization reaction of manufacturing process

• colourants: dyes or pigments used to add colour

• flame retardants: compounds that help to minimize the flammability

  • most polyaromatic, able to do H-Bonds

• plasticizers: compounds that are added to improve flexibility

• stabilizers: aid in preventing degradation when the polymer is exposed to sun light, heat, oxygen

• fillers: help to improve mechanical properties such as strength or throughness

• processing compounds: aid in manufacturing, prevention of mold or blowing agents

• social, environmental and financing accounting framework for assessing financial benefits, social impact and environmental imapct

• resources are used again, instead of throwing them away

• environmentally-friendly products, can be composed

• resources: sugar cane, sugar beets => fermentation => lactic acid => PLA pellets => use of coffee capsules => compost => CO2, H2O, biomass

• increase reuse, recycling, green chemistry

compostable

• needs composting conditions like humidity and temperature

• aerobic microbial degradation

• yields CO2, H2O, inorganic compounds

• no toxic residue

biodegradable

• degradation results from the action of microorganisms like fungi, bacteria, algea

• anaerobic: CH4, H2O, biomass

• aerobic: CO2, H2O, inorganic compounds, biomass

• no mechanical or chemical ways to separate different polymers, additives in the products => multilayer polymers

• costs

  • may be more expensive to recycle (co2 emissions, emissions from cleaning,transport processing of polystyrene containers, processing)

• plastic-to-oil-pyrolysis

• larvae to eat plastic

• politics: prohibit use of plastic

• self-repairing plastics

  • bubbles in the plastic expand to press materials back to its form

• conduction polymers: conduct electricity: delocalized electrons in rings

nylon, polyethylene, polyester, teflon, epoxy

• doesnt include carbon atoms in the backbone

• polysulfides (S-S), polysiloxanes (Si-O), polysilanes (Si-Si)

from natural sources

carbohydrates: starch, cellulose

proteins

nucleic acid

lipids

• a number of different monomers can be combined to make copolymers

• addition copolymerization of monomers X and Y can result in different arrangements of monomers

• e.g. petroleum

• plants (natural products) => can be monomers or polymers

• then: purification and reactions => polymer

• colourants: dyes or pigments used to add colour

• flame retardants: compounds that help to minimize the flammability

  • most polyaromatic, able to do H-Bonds

  • Nomex: has amide bond => that is capable of doing H-bonds

• plasticizers: compounds that are added to improve flexibility

  
  

• stabilizers: aid in preventing degradation when the polymer is exposed to sun light, heat, oxygen

  
  

• fillers: help to improve mechanical properties such as strength or throughness

• substances/compounds that are added which aid in manufacturing, prevention of mild or blowing agents