Sustainable Plastics -March/ April 2021 - 29

sustainable materials

A bit of isosorbide
makes a big change

PEIT polymers developed
by SK Polymers are suitable
for hot-fill applications.

Copolyesters are formed when modifications are made to polyesters. These
modifications can considerably modify the performance profile of the polyester in
question. Case in point: PEIT. By Karen Laird.

P

olyethylene
terephthalate, or PET,
as this polyester
is more familiarly
called consists of the two main
building blocks ethylene glycol
and terephthalic acid, which
are then combined to form
a polymer chain. Strong and

food-safe, PET has become
one of the mainstay materials
of the packaging industry and
is used in everything from bottles and trays to blisters and
clamshells.
There are, however, areas
where the material performs
less well. A good example is in

hot-fill applications. Marked
improvement can be achieved
through the incorporation of
an alternative comonomer,
which modifies the performance profile of the material.
More specifically, it has long
been known that replacing
the monoethylene glycol as

a diol with isosorbide beneficially modifies the properties
of PET, boosting, among other things, its glass transition
temperature and the optical
properties of finished packaging. Ethylene glycol is still
predominantly a petrochemcontinued on page 31
March/April 2021

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4/15/21 10:48 AM

Sustainable Plastics -March/ April 2021

Table of Contents for the Digital Edition of Sustainable Plastics -March/ April 2021