Different Types of Plastics and their Properties

Plastics

• Versatile;
• Coloured during manufacturing;
• Processed in a number of ways to produce complex shapes very quickly;
• Cheap packaging material;
• Suitable for vacuum forming, injection or blow molding;
• Two main types of plastic:
  • Thermosetting:
    • Once set, cannot be remolded;
    • Rigid plastics, resistant to higher temperatures (up to 400 degrees celcius) and stronger than thermoplastics;
    • Harder to recycle;
  • Thermoplastics:
    • Become soft when heated;
    • Easily moulded and remoulded;
    • Most common;
    • Many types available:
      • Acetate
        • Often used for food packaging, especially for products that benefit from visibility. Common examples include cake boxes with ‘windows,’ candy containers, and some types of food trays.
        • Often seen in packaging for cosmetics, toys, and small electronics.
        • Transparency: Allows customers to see the product clearly.
        • Rigidity: Provides structure and protection.
        • Glossiness: Gives a high-quality appearance.
        • Food safety: Generally considered safe for food contact.
        • Acetate boxes: Fully transparent containers, often used for gift packaging.
      • Expanded Polystyrene:
        • Lightweight, insulating, and cushioning – often used in packaging;
        • Good sound and heat insulator;
        • Can be cut using a hot-wire cutter, but the fumes are toxic – forced air-extraction must be used and never do when the wire is red-hot;
        • Styrofoam
          • A trademarked brand name for a type of expanded polystyrene foam
          • Used for cups
• HIPS (high impact polystyrene)
  • tough, rigid plastic with good impact resistance.
    • Common uses: Food packaging, electronics packaging, medical device trays, and general-purpose containers.
    • Durable and shatter-resistant
    • Lightweight

• Acrylic (also known as Perspex)
  • Rigid, hard (although can be scratched).
  • Glossy, can be clear, with good optical properties;
  • Aesthetics: Gives a premium, high-quality appearance
  • Many colours;
  • Does not accept applied finishes;
  • Weather resistant;
  • Durability: More shatter-resistant than glass, although still quite brittle.
  • Acrylic’s durability makes it suitable for packaging designed to be reused multiple times.
  • Higher cost compared to some other packaging materials
  • Can be used for: high-end display packaging; point-of-sale displays, product showcases in retail environments, counter-top display units;
• PVC (Polyvinyl chloride):
  • Can be rigid or flexible;
  • Hard, tough, lightweight;
  • Good chemical and weather resistance;
  • Excellent transparenc;
  • Provides good barrier properties;
  • Easily thermoformed;
  • Cost-effective;
  • Not generally food safe (can leach harmful chemicals);
  • Used for: Vacuum forming, blister packs – packaging with a pre-formed plastic cavity or pocket (the “blister”) which is backed or sealed with a paper, foil, cardboard, or plastic layerTray inserts;
• Polyethylene (PE) – sometimes called polythene
  • Tough, durable, impact resistant;
  • lightweight;
  • Can be soft and flexible (low density polyethylene) or harder and more rigid (high density polyethylene);
  • Available in a wide range of colours;
  • Weather and chemical resistant;
  • Used for: plastic shopping bags (high-density polyethylene), shrink-wrapping products, often onto a card backing; lining / sealing cardboard so it is waterproof (also referred to as “poly-coated” or “PE-coated” cardboard); bottles and food containers;

[thin plastic sheet, self-adhesive vinyl, polymorph, – IG]

[show a working knowledge of the following:
– thermoplastics (nylon, low and high density polyethylene [LDPE and HDPE],
polyethylene terephthalate [PET], polyvinyl chloride [PVC], acrylic [PMMA], polystyrene [PS],
polypropylene [PP], acrylonitrile-butadiene-styrene [ABS])
– thermosetting plastics (polyester resin including GRP, melamine formaldehyde [MF],
urea formaldehyde [UF] , phenol formaldehyde [PF] and epoxy resin) – IG]

[show an understanding of the term composite and be aware of the practical applications for each of the following composite materials:
– Kevlar®
– carbon fibre reinforced plastic (CFRP)
– glass reinforced plastic (GRP) – IG]

[Plastics (synthetic polymers)

• [The working properties, stock forms, sizes and extrusions, common uses and environmental impact of
  the following:
  – thermoplastics
  ○ acrylic (PMMA)
  ○ nylon
  ○ polyvinyl chloride (PVC)
  ○ polystyrene (PS)
  ○ polypropylene (PP)
  ○ high and low density polyethylene (HDPE) (LDPE)
  ○ high impact polystyrene (HIPS)
  ○ polycarbonate (PC)
  ○ acrylonitrile butadiene styrene (ABS)
  ○ polyethylene terephthalate (PET)
  – thermosetting plastics
  ○ polyester resin
  ○ melamine formaldehyde (MF)
  ○ urea formaldehyde (UF)
  ○ epoxy resin
  – elastomers
  ○ neoprene
  ○ silicone
  ○ thermoplastic elastomer (TPE).]

[Composite materials: fibre reinforced materials
○ glass fibre reinforced plastic (GRP)
○ carbon fibre reinforced plastic (CFRP).]

[Biodegradable plastics:

• The working properties, common uses and environmental impact of the following:
  – polylactide (PLA)
  – polyhydroxybutyrate (PHB), e.g. BIOPOL®
  – plastic made from corn/potato starch.
  A biodegradable material is one that will decompose or break down naturally as a result of microbial action.]

Students should also be familiar with composite materials (a manufactured material that combines two or more materials with different properties), smart materials, modern materials and biodegradable materials.

Note: You can identify plastic types by their recycling codes.