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.

Keywords: PET, Plastic, Polymersation, Molecular Weight, fibres, films, tapes

Type of Technology: Process

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