Polymers

plastics..can be natural & synthetic

• versatile often requiring little surface finishing
• can be vacuum formed, injection moulded & blow moulded
• essentially 3 types:

1) Thermoplastics - can be reformed by applying heat (plastic memory)

2) Thermosetting - can't be reformed using heat

3) Elastomers - display elastic properties eg rubber

Thermoplastic are often used as packaging as they share common properties:

• lightwieght
• low cost
• recyclable
• can be printed on
• water-resistant
• impact resistant
• tough & durable

MANUFACTURE: crude oil is refined in fractioning tower to make hydrocarbon naphtha, it's cracked into monomers, these link up to form long chains through polymerisation.

Recycling ID: 1

PROPERTIES

• excellent transparacy
• very tough
• impenetrable to gases
• can withstand wide range of temperatures

USES

• fizzy drinks bottles
• food containers
• microwaveable food trays

ADVANTAGES

• glass-like transparacy allows products to be seen
• doesnt affect flavour of food products
• ideal for use as packaging for oven ready or microwavable products

Recycling ID: 2

PROPERTIES

• excellent chemical resistance
• good barrier to water

USES

• bottles & containers for washin up liquids
• cosmetic bottles
• thin sheet packaging

ADVANTAGES

• very suitable for containers designed to hold a wide range of liquids which need to be tough durable & flexible
• very common form of packaging

Recycling ID: 3

PROPERTIES

• rigid - can be flexible if plasticiers are added
• excellent chemical resistance
  
• good barrier to water/weather/gases

USES

• shrink wrapping & cling film
  
• blister packaging
• packaging for toiletries, pharmaceutical products
• food
• confectionary
• water
  
• fruit juices
  

ADVANTAGES

• versatile can be used for wide range of products
• chemical resistance makes PVC suitable for batteries or pharmaceutical products
  

Recycling ID : 4

PROPERTIES

• soft
• flexible
• excellent chemical resistance
• good barrier to water but not gases
  

USES

• stretch wrapping
• liquid proof coatings for card (eg milk cartons)
• carrier & other plastic bags
  

ADVANTAGES

• when combined with card it becomes very versatile & cost effective material
• plastic bags perform well as an inexpensive method of producing a thin protective layer for a wide range of goods
  

Recycling ID : 5

PROPERTIES

• very flexible
• withstand repeated folding
• can be steralised
  

USES

• food containers
• bags for dry food products
  
• bottle crates
• slot-together boxes
• yogurt & margarine tubs
• sweet & snack wrappers
• video cases
  

ADVANTAGES

• excellent chemical reistance (so PP can be used where other plastics cant
• extremely tough & durable (so wont break if dropped)
• flexible & resistance to fatigue (so material can be manufactured into boxes with 'intergral' hinges which can be folded repeatedly without snapping or tearing
  

Recycling ID : 6

PROPERTIES

• wide range of colours (inc transparent)
• stiff & hard
• can be made impact resistance
  

USES

• yogurt pots
• CD cases
• disposable cups & cutlery
• bubble packs
• prototype & architectural model
  

ADVANTAGES

• very suitable for vacuum forming
• very suitable for tough, durable & flexible containers desinged to hold wide range of liquids
  

Recycling ID : 6

PROPERTIES

• limited range of colours usually white
• impact resistance
• good heat insulator
• durable
• very buoyant on water
• low water absorption
  

USES

• take-away packaging
  
• egg cartons
• fruit, veg & meat trays
• hot drinks cup
• protective packaging for electrical goods
• expanded polystyrene 'peanuts' are used to pack void spaces in boxes to prevent products moving in transit
  

ADVANTAGES

• doesnt add significant weight
• good heat insulator so it's good for hot food products
  
• excellent protective layer to absorb impact, preventing damage to valuable & fragile products
  

Recycling ID : 7

PROPERTIES

• wide range of bright colours
• glossy finish
• hard
• brittle
• rigid
• heavy
  

USES

• high quality containers or closures for perfume products
• signage
• windows point of sale display
  

ADVANTAGES

• availiable in a wide range of bright colours with a hard,glossy surface finish making it ideal for signage & products which require visual impact
• little finishing required
  

• set with heat & therafter have little plasticity

• during polymerisation the molecules link side to side & end to end

• covalent bond
  

• becomes stiff & rigid

• cant be reformed

• long tangled chains of molecules, with limited number of smaller cross links

• weak van der waals forces

• heat weakens the bond, the material becomes pliable & easier to mould

• when heat is removed the chains reposition & becomes stiff