Polyethylene Terephthalate (PET)
Polyethylene Terephthalate (PETThere are two major categories of plastic, thermoset and thermoplastic:
- Thermosets are produced by hardening a malleable substance (non-recyclable).
- Thermoplastics are produced by heating and shaping to form products (recyclable).
Polyethylene Terephthalate (PETPolyethylene terephthalate (PET or PETE) is a thermoplastic often used to produce beverage or food containers, clothing fibers, and other common products (see below). This type of plastic comprises about 9% of the total plastic industry mainly in the form of packaging. Its increasing pattern of demand follows that of total plastic production.
Common Uses & Applications
PET's versatility makes it ideal for various applications:
Food and Beverage Packaging
- Carbonated drink bottles
- Water bottles
- Food containers
- Condiment bottles
- Ready-meal trays
Textile Industry
- Polyester fibers
- Clothing
- Industrial fabrics
- Upholstery materials
Other Uses
- Medical packaging
- Film and sheet materials
- Strapping materials
- Electronic components
Chemical Structure & Properties
Polyethylene terephthalate (PET) is a thermoplastic polymer formed through a polycondensation reaction between terephthalic acid and ethylene glycol. Its molecular structure consists of repeating C10H8O4 units, creating long polymer chains that give PET its characteristic properties:
- High tensile strength
- Chemical resistance
- Clarity and transparency
- Excellent moisture barrier
- Good gas barrier properties
- Temperature resistance up to 70°C (158°F)
- Density of 1.38 g/cm³
Environmental Impact
Due to its lightweight and low density, PET tends to float which characterizes its environmental effect and the type of wildlife it encounters. In addition, the additives added during the manufacturing process may leach into the contents of the container and be consumed by humans.
Advantages
- Highly recyclable.
- Lower energy production footprint compared to glass.
- Lightweight reduces transportation emissions.
- Can be recycled multiple times.
Challenges
- A significant contribution to plastic waste.
- Microplastic generation through degradation.
- Marine ecosystem impacts.
- Long decomposition time (450+ years).
- The production relies on fossil fuel resources.
Recycling Process & Opportunities
PET can be indefinitely recycled to yield products like food containers, carpet fibers, or non-food containers. beverage containers (bottle-to-bottle), polyester fiber for clothing, carpeting materials, industrial strapping, food packaging materials, and construction materials.
The recycling process is summarized in the following steps:
- Consumer collection through recycling programs
- Automated sorting using infrared technology
- Manual quality control
- Separation by color and quality
- Crushing and grinding into flakes
- Washing to remove contaminants
- Separation from other plastics
- Drying and decontamination
- Melting and reforming