Polymer Blend - Basic Concepts

Basic Concepts

Polymer blends can be broadly divided into three categories:

• Immiscible polymer blends (heterogeneous polymer blends): This is by far the most populous group. If the blend is made of two polymers, two glass transition temperatures will be observed.
• Compatible polymer blends: Immiscible polymer blend that exhibits macroscopically uniform physical properties. The macroscopically uniform properties are usually caused by sufficiently strong interactions between the component polymers.
• Miscible polymer blends (homogeneous polymer blend): Polymer blend that is a single-phase structure. In this case, one glass transition temperature will be observed.

The use of the term polymer alloy for a polymer blend is discouraged, as the former term includes multiphase copolymers but excludes incompatible polymer blends.

Examples of miscible polymer blends:

• Homopolymer - Homopolymer:
  • Polyphenylene oxide (PPO) - polystyrene (PS): Noryl developed by General Electric Plastics in 1966 (now owned by SABIC). The miscibility of the two polymers in Noryl is caused by the presence of an aromatic ring in the repeat units of both chains;
  • Polyethylene terephthalate (PET) - Polybutylene terephthalate (PBT);
  • Poly(methyl methacrylate) (PMMA) - Polyvinylidene fluoride (PVDF);
• Homopolymer - Copolymer:
  • Polypropylene (PP) - EPDM;
  • Polycarbonate (PC) - Acrylonitrile butadiene styrene (ABS): Bayblend, Pulse, Anjablend A.

Polymer blends can be used as thermoplastic elastomer