UPSC Prelims 2022 Q46: Polyethylene Terephthalate (PET) — Explained

With reference to polyethylene terephthalate, the use of which is so widespread in our daily lives, consider the following statements:

1. Its fibres can be blended with wool and cotton fibres to reinforce their properties.

2. Containers made of it can be used to store any alcoholic beverage.

3. Bottles made of it can be recycled into other products.

4. Articles made of it can be easily disposed of by incineration without causing greenhouse gas emissions.

Which of the statements given above are correct?

  1. 1 and 3
  2. 2 and 4
  3. 1 and 4
  4. 2 and 3

Answer: (a) 1 and 3

Statement-wise explanation

  • 1: correct — PET is the most common polyester fibre. It is strong, durable, crease-resistant and dries quickly. It is routinely blended with cotton (as poly-cotton) and with wool (as poly-wool) so the fabric holds its shape, resists wrinkles and lasts longer, while the natural fibre adds comfort and absorbency.
  • 2: incorrect — PET is used for some drinks, but not every alcoholic beverage can safely go into it. Ordinary PET lets oxygen and carbon dioxide pass through slowly. That spoils wine and beer, and carbonated drinks lose their fizz, which is why these mostly stay in glass or in PET with special barrier layers. The word 'any' makes this statement false.
  • 3: correct — PET bottles are among the most recycled plastics. Recycled PET (rPET) is made into polyester staple fibre and yarn, strapping, sheets and new bottles. PIB has reported that India collects more than 90% of its PET waste. In November 2021 India changed its rules to allow PET waste imports by authorised recyclers, because these recyclers supply yarn makers and did not have enough raw material.
  • 4: incorrect — PET is a carbon-based polymer made from fossil feedstock, so burning it always gives off carbon dioxide. The OECD's Global Plastics Outlook (2022) calls incineration the most emission-intensive way to dispose of plastic, at about 2.3 tonnes of CO2-equivalent per tonne of plastic. 'Without causing greenhouse gas emissions' cannot be true for burning any plastic.

How to eliminate

Basic chemistry and absolute words settle this question. Statement 4 is clearly false: anything containing carbon gives off CO2 when it burns, and PET is made from petroleum. That removes the two options containing 4 and leaves '1 and 3' or '2 and 3'. Statement 3 is in both, so you only need to judge 1 against 2. Statement 2 uses the absolute word 'any' ('store any alcoholic beverage'). Claims that one material suits every case of something are usually false. Statement 1 is everyday knowledge: clothing labels often read 'polyester-cotton' or 'poly-wool'. Facts to remember: PET = polyester, recyclable (resin code 1), and burning it emits CO2.

Know more

Polyethylene terephthalate (PET) is a thermoplastic polyester. It is made by polymerising ethylene glycol with terephthalic acid, both usually taken from petroleum. J.R. Whinfield and J.T. Dickson of the Calico Printers' Association, Manchester, patented it as a fibre ('Terylene') in 1941. The same polymer is sold as 'polyester' in textiles and as 'PET' in packaging.

Two big uses

Form Uses Property exploited
Fibre (polyester) Clothing, poly-cotton and poly-wool blends, carpets, fibrefill Strength, crease resistance, quick drying
Resin/film Water and soft-drink bottles, food trays, films Clear, light, shatter-proof, good moisture barrier

Recycling. PET carries resin identification code 1. Bottles are collected, shredded into flakes and washed, then:

  • melted and spun into recycled polyester staple fibre (the main outlet in India), or
  • turned back into food-grade pellets for new bottles (bottle-to-bottle).

Indian policy links

  • Plastic Waste Management Rules, 2016 (amended 2021 and 2022) are the legal framework.
  • The 2022 Extended Producer Responsibility (EPR) guidelines set targets for producers, importers and brand owners: reuse of rigid packaging, minimum recycling, and minimum recycled content in packaging.
  • Imports of solid plastic waste were banned in 2019. In November 2021 the rules were changed to allow PET imports by authorised recyclers to fill a shortage of feedstock.

Disposal. PET does not biodegrade on a human time-scale. Burning it releases CO2, and incomplete burning releases harmful by-products. This is why policy prefers reduce → reuse → recycle over incineration.

In the news

In February 2022 the Environment Ministry notified EPR guidelines for plastic packaging under the Plastic Waste Management Rules. They set mandatory recycling and recycled-content targets. Together with the late-2021 decision to allow PET waste imports for recyclers, this put PET recycling in the news just before Prelims 2022.

NCERT Concepts to Revise

  • Extended producer responsibility: India's EPR guidelines make brand owners responsible for collecting and recycling plastic packaging such as PET bottles, which is the background to statement 3.
  • Circular economy: Recycling PET bottles into fibre keeps the material in use, while burning it ends the loop; statements 3 and 4 turn on this.

Read more