Polymers - Thermoplastics, Thermosetting Plastics, Elastomers

Polymers - Thermoplastics, Thermosetting Plastics, Elastomers

Thermoplastics

  • Thermoplastics are a type of polymer that can be heated and reshaped numerous times, with their structure becoming more fluid when heated.
  • Common examples of thermoplastics include polyethylene, polypropylene, PVC, and acrylic.
  • Polyethylene is used in a variety of applications, including packaging and bottles due to its low cost and flexibility.
  • Polypropylene is also versatile, known for its resistance to chemicals and is frequently used in car parts, containers, and ropes.
  • PVC (Polyvinyl Chloride) is utilised in pipes, cable insulation and clothing as it is durable, low cost and has good resistance to chemicals and the weather.
  • Acrylic is used in place of glass due to its strength and transparency, making it ideal for use in signs, lenses and light fittings.
  • Features of thermoplastics include recyclability, resistance to chemicals, and impact resistance.

Thermosetting Plastics

  • Thermosetting plastics, unlike thermoplastics, cannot be reshaped upon heating. Once set, these polymers remain in a solid state.
  • Popular types of thermosetting plastics include phenol formaldehyde, urea formaldehyde, epoxy resin, and melamine.
  • Phenol formaldehyde is heat and chemical resistant, used in the production of electrical parts and adhesives.
  • Urea formaldehyde is also known for being a good electrical insulator and is used in electrical fittings, Adhesives and laminate floorings.
  • Epoxy resin is extremely durable and has excellent chemical resistance. It’s often employed in the manufacturing of adhesives, coatings and composites.
  • Melamine is a strong material used in kitchenware and laminate surfaces due to its heat resistance and the ability to retain colour.
  • Thermosetting plastics are typically more durable and heat resistant than thermoplastics, but they are not recyclable due to their cross-linked structure.

Elastomers

  • Elastomers are polymers with the capacity to return to their original shape after being stretched or deformed.
  • Widely used elastomers include rubber, silicone, and thermoplastic elastomers (TPEs).
  • Rubber is extremely flexible and is commonly used in tyres, seals, and gaskets.
  • Silicone is known for being resistant to extreme temperatures and is used in insulations, seals, and cookware.
  • Thermoplastic Elastomers (TPEs) blend the properties of thermoplastics and elastomers, providing both the flexibility of rubbers and processability of plastics, they are used in car parts, footwear and medical devices.

Examining Properties of Polymers

  • Understanding the physical and mechanical properties of polymers is important for determining their suitability for specific applications.
  • Tensile strength tests can be utilised to determine the extent a polymer can be stretched before breaking.
  • Hardness of polymers measured to understand the resistance to indentation.
  • The Glass Transition Temperature (Tg) is an important property that indicates the temperature at which the polymer transitions from a hard, glassy state to a viscous state.
  • The operating temperature range of a polymer plays a crucial role in its selection for certain applications as some polymers can deform or degrade at high temperatures.

Processing of Polymers

  • Polymers, including thermoplastics, thermosetting plastics, and elastomers, can be processed in a variety of ways.
  • Common shaping techniques for polymers include injection moulding, extrusion, and blow moulding.
  • Other processes like casting, machining, and 3D printing can also be employed to create polymer products.
  • The inherent health and safety considerations should be taken into account when working with polymers, including dealing with high-processing temperatures and potentially harmful fumes.

This revision material provides an understanding of various categories of polymers - thermoplastics, thermosetting plastics, and elastomers - their properties, processing methods, and important factors to be considered while working with them.