POLYMER PROPERTIES

• WHAT ARE THE TWO TYPES OF POLYETHENE?

  HDPE (high density polyethene) or LDPE (low density polyethene)
• WHAT ARE THE CONDITIONS REQUIRED TO FORM POLYETHENE?

  • high temperature (200 degrees Celsius)
  • high pressure (2000 atm)
  • homogenous reagents (e.g. O2)
• WHAT PROCESS IS LDPE FORMED BY?

  free radical mechanism
• WHAT ARE THE USES OF LDPE?

  • bags
  • clingfilm
  • squeezable bottles
  • containers/ trays
  • tubing
• STRUCTURE OF LDPE?

  loosely packed molecules due to branching
• PHYSICAL CHARACTERISTICS OF LDPE?

  • flexible
  • soft
  • stretchy
• MELTING POINT OF LDPE?

  120 degrees Celsius
• CONDITIONS REQUIRED WHEN FORMING HDPE?

  • temperature slightly above room (60 degrees Celsius)
  • pressure slightly above room (2 atm)
  • Ziegler-Natta catalyst
• USES OF HDPE?

  • buckets
  • bottles
  • containers (milk/ detergent bottles)
  • folding chairs
  • tables
  • pipes
• STRUCTURE OF HDPE?

  tightly packed molecules
• PHYSICAL PROPERTIES OF HDPE?

  • stiffer
  • tough
  • harder
• MELTING POINT OF HDPE?

  130 degrees Celsius