Polymer, Plastics and
Rubber Techonologies -
Preparation of PET and its Products
Introduction
The Poly(oxyethyleneoxyterphthaloyl, hereinafter refered
as PET is the most important polyester, used in the
form of fibres, films and as moulding material. The
presently adopted method comprises of two steps i.e.
polymerization of low molecular weight PET to high molecular
weight PET followed by spinning to obtain the final
product. This has disadvantages like limitation of the
material with respect to end use, excessive degradation
of final product due to increased reaction time and
temperature, low diffusivity of condensate products
out of polymer chips, need to dry-off the solvent from
PET and plasticisation of the dried PET before spinning,
etc. These disadvantages result in lengthy process and
lowering the quality of final product. A new process
has therefore been developed overcoming all these disadvantages
and also as a single step process.
Low molecular weight PET chips are
flattened, dried and hanged in the solvent/solvent system
using wires of inert material so that the PET chips
are completely dipped in the said solvent. The solvent
is maintained at the prescribed reaction temperature
for a specific duration of time during which inert gas
is bubbled through the solvent. This results in the
formation of ultra high molecular weight PET which are
not taken out from the solvent. The reaction temperature
is then increased to dissolve the hanged PET chips to
produce the reacted mass, which is transferred to a
specially designed chamber. Through the application
of inert gas pressure, the reacted mass is extruded
in the form of a jet or a sheet, which in turn is lead
to a rotating bobbin or a moving plate dipped in the
organic solvent for producing ultrahigh molecular weight
PET finre or sheet.
Special Features:
Enables to produce PET having desired Number Average
Molecular Weight (NAMW) for the manufacture of products
for various applications. Single step processing, Reduction
in the reaction parameters and reaction time, Better
quality of end product
Prospective
Users: Manufacturers of
plastic goods for various end usages, like audio &
video tapes, food packaging films, soft drink bottles,
dielectric materials for capacitors, synthetic fibres,
injection and blow moulding products, etc.
Developed by
: Dr Deepak Agarwal Department: Chemical
Engineering
Contact:
Managing Director
Foundation for Innovation and Technology Transfer (FITT)
Indian Institute of Technology, Delhi
Hauz Khas, New Delhi-110016, INDIA
Tel : 91-011-26597167, 26857762, 26581013, 26597153
Fax : 91-011-26851169
E-mail : drkdpn@gmail.com
