Polymer morphology: the arrangement of
polymer molecules.
− Thermoplastics have either amorphous or
semi-crystalline structures.
• Amorphous thermoplastics
consist of amorphous region with
randomly arranged polymer
chains. Amorphous polymers are
softer, have lower melting points,
and are penetrated more by
solvents than are their crystalline
counterparts.
• Semi-crystallinity is a desirable
property for most plastics
because they combine the
strength of crystalline polymers
with the flexibility of amorphous.
Semi-crystalline polymers can be
tough with an ability to bend
without breaking.
• The so-called semi-crystalline plastics include
polyethylene, polypropylene, poly (vinyl chloride),
polyamides (nylons), polyesters and some
polyurethanes.