Question

To manufacturing polymer blends, what are the two blending methods?Also, what are the advantages and disadvantages of each method? (4 pt)

Answer 1

Polymer blends are manufactured from to or more copolymers or homopolymers, depending upon the requirement of the product.

Blending is one of the processes which comes under polymer processing. It is done to provide more structural and mechanical strength to the polymer composite.

There are various methods to produce polymer blends in the manufacturing industries, and each is selected based upon the composition of blends and various additives, and the type of polymer blends(miscible, immiscible, homologous, isomorphic, compatible blends).

The various blending techniques are:

• Solution mixing
• Latex Blending
• Graft blending
• Melt mixing(very common)
• Block Mixing copolymerization.

Solution Blending:

• Polymers are allowed to enter a mixing reactor containing a particular solvent.
• The solvent may act as a medium of polymerization blending, heat absorbent in case of high heat of blending, or dilutant to prevent unwanted side reactions. (Advantage: Temperature control, no need of providing external cooling jacket; high rates and uniformity due to rapid mixing)
• After blending, the solvent is needed to be evaporated from the mix. (Disadvantage: The main disadvantage of this process is the cost of the evaporation of the solvent and its further processing to recycle it.)

Melt mixing:

• Polymers are melted separately and mixed in a tank. The mixing is not rapid.
• Advantage: There is no use of solvent and hence the cost of solvent evaporation and recycling is ruled out. It is the cheapest process.
• Disadvantage: As mixing is not happening, this results in the non-uniform mixture as the large-sized polymer molecules may not be able to mix well without proper agitation.