Recycling Process of Polyester and PET Bottles

Last Updated on 27/09/2021

Recycling of Polyester and PET Bottles

Ashish Kumar Dua
M.Tech, Dept. of Textile Engineering,
Indian Institute of Technology (IIT), Delhi.


Polyester and Polyester Bottles:
Most synthetic fibers (approximately 70%) are made from polyester, and the polyester most often used in textiles is polyethylene terephthalate (PET).

reduce reuse recycle

PET is a synthetic fiber polymer made from condensation chemical reaction that results in a linear molecule. The benzene ring in the polymer chain assists in imparting crystallization and stiffness or firmness to the polymer. The aliphatic part of the chain provides flexibility at room temperature.

The majority of the world’s PET production – about 60% – is used to make fibers for textiles; about 30% is used to make bottles.

waste pet bottles

It’s estimated that it takes about 104 million barrels of oil for PET production each year – that’s 70 million barrels just to produce the virgin polyester used in fabrics.

percentage of various fiber

The reason polyester recycling (often written rPET) is considered a green option in textiles today is twofold, and the argument goes like this:

  • Saving energy (33% to 53% less energy than produce from virgin)
  • Estimate at 54.6% fewer CO2 emissions
  • Keeping bottles and other plastics out of the landfills.

Some major companies in polyester recycling-

  1. Tex America, Inc
  2. Napcar, USA
  3. Fleissner GmbH and Co.

Fun Facts About Polyester:
First PET bottle was recycled in 1977

FACTS about PET:

  • Recycling 1 ton of PET bottles saves 7.4 cubic yards of landfill space
  • It takes 5 recycled two-liter PET bottles to make one square foot of carpet.
  • PET bottles and containers are actually a form of polyester, which is why it is so easy to recycle bottles into T-shirts, sweaters and socks.
  • It takes 35 liter recycled PET bottles to make the soft filling inside a sleeping bag, called “fiberfill.”
  • Plastic makes up 8% of our trash by weight, but is 24% of the volume



Chemical Structure

  • Its having crystallinity around 60-65%.
  • Its having high glass transition temperature around 70-80ºC.
  • It is produced basically two routes by step growth polymerization.


Process to Make Polyester:

production of polyethylene terephthalate
Fig: Production of polyethylene terephthalate

Glycolysis process:

Bis (2-hydroxyetylterphthalate(BHET).
Bis (2-hydroxyetylterphthalate(BHET).

EG+ PET are taken in molar basic ratio 1:4 to 1:6 and 0.5 % zinc acetate as a catalyst.


  1. Resins
  2. Coating
  3. Laminates
  4. Dyes

Recycling of Polyester Bottles:
Common PET depolymerisation treatments for recycling.


Note- Current work aims at effective recycling of waste polyester from soft drink bottles by glycolysis method and thereby utilization of recycled product for coating application.

PET Waste Using to Various Textile Auxiliaries:
Softners-Conversion of BHET TO BHECL form.

BHET+thionyl chloride + 0.5% dimethyl formaldehyde in toluene as a catalyst after reaction excess toluene was collected via vacuum distillation.



Quaternarization of the amine derivative was carried out by adding dimethyl sulfate (1:1). Sodium carbonate was added as an acid quencher and the mixture was kept at 70°C for 3 hr. Upon distillation of toluene, the cationic softener product was obtained. Following were the fatty acids and amines tried. It gives the details of the reactants Since DETA reacted to BHECL has two free amine groups, whereas EDA reacted to BHECL has one free amine group and hence one mole of this amine combines with one mole of fatty acid.

Softners-Conversion of BHET TO BHECL form

details of reactants used and the products obtained

effect of softener on the bending length and tensile strength of finished cotton fabric

Use of Pet Waste to Make Hydrophobic Dyestuff:

preparation of benzothiazole from BHETsynthesis of dyesynthesis of dye b

color photographs of polyester fabric dyed with synthesized dyes

Alkyd Resins Derived From Glycolized Waste:

Alkyd resins derived from glycolized wastecuring reaction of the UPR with styrene

Preparation of Pet Polyol:
Glycolzed product is used for synthesis for PE polyol.

pe polyol

It is used with different isocyanete curing agent ratio NCO:OH (1:1) OF 1:1 Dimetyl formamide is used as a solvent to system.

Preparation of PE polyol coating

polyisocyanate curing agentsPREPARATION OF PET POLYOL

Recycle Paper Treated With Pet Resin Or Pet Coating:

  1. The PET dispersion can be used with other wet strength resin, such as poly amide-epichlorohydrin.
  2. PET not only add additional dry and wet strength but not repulable wet strength resin repulable.
Dry tensile strength of sheets treated with different polyesters
Fig: Dry tensile strength of sheets treated with different polyesters
Wet tensile of the sheets treated with different polyesters
Fig: Wet tensile of the sheets treated with different polyesters
  • LSE-Low surface energy product
  • HSE-High surface energy product
  • HTG-High Tg product

Advantages: Its having the high potential to save a large amount of trees and energy while limiting filling.

Recycled Pet Fiber in Concrete –Reinforcement Fiber:

apparatus for the indent marking and cutting of pet fiber

Development in Process Technology and Process Chemistry:

Development in process technology & process chemistryresults of the compression test

Applications of PET Fiber:

applications of the pet fibers


  1. The water dispersible polymer used in coating recyclable paper can be used as a wet end additive to improve paper dry and wet strength. We can make paper water repellent, paper stiff with good dry strength or both dry and wet strength good by treating with different resins.
  2. Waste PET was depolymerized via glycolysis product was used for synthesis of new polyester polygol. This was used for coating application having excellent mechanical properties like as flexibility, impact resistance, scratch and hardness, good chemical resistance.
  3. To produce a new material from plastic waste, PET was oligomerized by a poly-functional alcohol and mixed temp. The presence of oligomers enhanced thermal stability.
  4. PET waste is used in useful textile finishing softeners. By the high purity of virtual manner BHET, it can further converted into quaternary compound which used as softeners in textile finishing.
  5. Recycled PET does not adversely affect the resins properties based on recycled PET can help decrease the cost of polymer end product and reduce environment pollution.

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  3. An Overview of Glass Fibre
  4. Glass Fiber Composites: Properties, Manufacturing and Applications
  5. Different Types of Man Made Fibers with Their Application
  6. Nylon: The First Synthetic Fiber
  7. Kevlar Fiber: Types, Properties, Manufacturing Process and Applications
  8. Aramid Fibers: Types, Properties, Manufacturing Process and Applications
  9. High Performance Polyethylene Fibers – An Overview
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