BASIC POLYMER CHEMISTRY

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BASIC POLYMER CHEMISTRY

• Plastics vs Polymers
• Polymer long chain molecule (poly mer Greek)
• Thermoset vs Thermoplastic
• Commodity vs Engineering plastics
• (Nearly) all are petrochemical based

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BASIC POLYMER CHEMISTRY

• Common packaging structures include
• PE (polyethylene)
• HDPE high density polyethylene
• LDPE low density polyethylene
• LLDPE linear low density polyethylene
• PP (polypropylene)
• BOPP biaxially oriented polypropylene
• OPP oriented polypropylene

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BASIC POLYMER CHEMISTRY

• PS (polystyrene)
• EPS expanded polystyrene
• PET (polyethylene terephthalate)
• PETG polyethylene terephthalate glycol
• EVA (ethylene vinyl acetate)
• EVOH (ethylene vinyl alcohol)
• PVC (polyvinyl chloride)

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BASIC POLYMER CHEMISTRY

• Elements are polymer molecules with these
  important properties
• POLARITY melting point, coef of friction,
  solubility, barrier properties, adhesiveness
• MOLECULAR WEIGHT melt point, stiffness,
  solubility
• MOLECULAR SHAPE crystallinity, clarity,
  barrier, melt pt
• THERMAL HISTORY performance characteristics
• MECHANICAL HISTORY various effects

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BASIC POLYMER CHEMISTRY

• POLARITY
• Magnetic-like attractions (strong) for opposite
  charge
• Van der Waals forces are weaker but significant
  (often transient)
• PP PE are normally nonpolar
• Most other packaging plastics are polar
• The higher the polarity, the higher the melt
  index
• Solubility like dissolves like ie polar film
  in a polar fluid
• Barrier 1/permeation polar gasses pass through
  polar films
• Friction highly polar films have strong
  attractive forces
• Chemical bonding (PRINTING) is difficult on
  nonpolar surfaces

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BASIC POLYMER CHEMISTRY

• POLARITY

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BASIC POLYMER CHEMISTRY

• HYDROCARBONS POLYMERS
• Based on the carbon atom
• Form 4 bonds with other atoms (valence)
• Joins to itself to form long chains other
  shapes
• Polymerization results from this
• Ethylene -gt polyethylene
• Propylene -gt polypropylene
• Styrene -gt polystyrene
• Vinyl chloride -gt polyvinyl chloride

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BASIC POLYMER CHEMISTRY

• OLEFINS MOLECULAR WEIGHT
• Composed of only H C
• Methane 1 C
• Ethane 2 C
• Propane 3 C
• Butane 4 C
• Pentane 5 C
• Low Molecular Wt gasses. As m/w increases,
  properties change

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BASIC POLYMER CHEMISTRY

• HYDROCARBONS POLYMERS

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BASIC POLYMER CHEMISTRY

• POLYMERIZATION
• Addition Polymerization
• Most packaging plastics
• Needs the correct conditions of temperature
  pressure
• Catalysts promoters aid the process
• Condensation Polymerization
• PET polyamide (nylon)
• Joins 2 reactive monomers and releases water

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BASIC POLYMER CHEMISTRY

• POLYMERIZATION
• Addition Polymerization
• Condensation Polymerization