Homogeneous and heterogeneous polymerisation.

Polymerisation process

The polymerisation process is classified into homogeneous and heterogeneous polymerisation.
In homogeneous polymerisation as name suggest the reactants i.e monomer, initiator, solvents and polymer obtained are miscible and compatible.
In heterogeneous polymerisation the monomers, catalyst and polymers obtained are immiscible.
Homogeneous polymerisation comprises of bulk/mass polymerisation and solution polymerisation.
Heterogeneous polymerisation comprises of bulk, solution, suspension, emulsion, gas phase, precipitation and interfacial polymerisation.

Homogeneous polymerisation

1) Bulk/mass polymerisation

In case of homogeneous bulk polymerisation the monomer is miscible in polymer obtained.
Here the radical initiator is dissolve in pure liquid monomer in the absence of any solvent.
The reaction is initiated by exposing the mixture to light or by heating .
As reaction proceeds solution mixture becomes more viscous and a polymer is obtained.
This method is suitable for producing pure polymers.
This method is exothermic.
Styrene is produce by this method.

2) Solution polymerisation

In Solution polymerisation the monomer, catalyst and polymer obtained are soluble in a solvent.
In this method the monomer and catalyst are dissolve in a solvent to form a solution which reacts without any heat or cooling or any special handling to give polymers.
High density polyethylene is prepared from this method.

Ring opening polymerisation.

Comments

Determination of molecular weight by osmotic pressure method

Determination of molecular weight by osmotic pressure method. Osmotic pressure method is also called membrane osmometry. This method is widely used to determine the number average molecular weight of polymers. This method is based on the phenomenon of osmosis. If a pure solvent is separated from a solution through a semipermeable membrane, due to concentration (chemical potential) difference between the solvent and solution, the solvent will flow into the solution through semipermeable membrane. The pressure applied on the solution to completely stop the flow of solvent into it through semipermeable membrane is called osmotic pressure. The theory of osmotic pressure also applies to a solution of polymers. Ordinary solution obeys Van't Hoff equation i.e π=cRT/M Where π is osmotic pressure, c is concentration in mass per unit volume, R is gas constant, T is temperature and M is molar mass. The polymer solution are non ideal. Taking into account their deviation and us...

Polypropylene (PP)

Polypropylene (PP). Polypropylene (PP) is also known as polypropene. Polypropylene is made from the polymerisation of propylene gas in the presence of Zeiglar Natta catalyst or metallocene catalyst. Polypropylene. Thus propene (or propylene) is the monomer of polypropylene. Polypropylene is a highly flammable material. It is sensitive to microbial attacks, such as bacteria and mold. It exhibits excellent resistance to diluted and concentrated acids, alcohols and bases. Polypropylene is used to make lunch boxes, margarine containers, yogurt pots, syrup bottles etc. Disposable syringes is the most common medical application of polypropylene. Polypropylene rope and twine are very strong and moisture resistant very suitable for marine applications. Polypropylene, highly colorfast, is widely used in manufacturing carpets, rugs and mats. Uses of Polypropylene. Questions on polypropylene; Q1) What is polypropylene? Ans) Polypropylene is a polymer of propylen...

Polylactic acid/PLA.

Polylactic acid/PLA. Polylactic acid is a biodegradable thermoplastic polymer . Polylactic acid is obtained from lactic acid monomer. Polylactic acid. Polylactic acid is stable to UV radiation. Polylactic acid has good resistance to moisture. Polylactic acid has good elasticity. Polylactic acid is an aliphatic polyester . It can be used as a food packaging polymer. Polylactic acid is suitable for textile fibre applications such as shirts, carpets, sportswear etc. Polylactic acid is used in implants and medical devices (screws, sutures etc). Polylactic acid is suitable for use in floor mats. Uses of Polylactic acid. Questions on Polylactic acid/PLA; Q1) What is Polylactic acid? Ans) Polylactic acid is a biodegradable thermoplastic polymer. Q2) What is the monomer of Polylactic acid? Ans) Polylactic acid is obtained from lactic acid monomer. Q3) Write some properties of Polylactic acid? Ans) Some properties of Polylactic acid are given below; ...

Polymers

Search This Blog