Addition/chain polymerization:

  1. The monomer must have at least two identical or diff. groups which can interact each other to undergo condensation reaction.
  2. It is endothermic process.
  3. It is a slow process.
  4. Molecular Weight is high.
  5. Monomers condensed to give polymer with elimination of by product HCL, H2O,NaCl
  6. Generally produce 3-dimensional cross linked polymer.
  7. Mostly thermosetting plastics are obtained by this process.
  8. Catalyst used-mineral acids or base.  Eg. NYLON, PF, UF.

Condensation polymerization:

  1. The monomer must have at least two identical or diff. groups which can interact each other to undergo condensation reaction.
  2. It is endothermic process.
  3. It is a slow process.
  4. Molecular Weight is high.
  5. Monomers condensed to give polymer with elimination of by product HCL, H2O,NaCl.
  6. Generally produce 3-dimensional cross linked polymer.
  7. Mostly thermosetting plastics are obtained by this process.
  8. Catalyst used-mineral acids or base.   Eg. NYLON, PF, UF.

composite materials :

  • Composites arc engineered materials, comprising of metals, glasses & polymers.
  • The macroscopic-judicious combination of two or more distinct material is known as composite material.
  • Polymer phase is known as matrix phase (solvent) & composite used for mixing is known as dispersed phase (solute) & boundary between the two phases is known as interphase.
  • On the basis of the dispersed phase used in matrix phase polymer composites are of two types 1) fiber reinforced composites 2) particlereinforced composites.
  • The composites possesses better characteristics as compared to those possesses by its constituents.

Properties:

  • High toughness, tensile strength.
  • High heal & dimensional stability, low cost production.

Applications:

  • Automobile bodies, refrigerator, cooler, windows, aircraft body parts.
  • Sports goods, musical instruments.
  • High speed machinery.

 

Weight average molecular weight (Mn) :

  • Molecular weight of the polymer decides the properties of that polymer; therefore molecular is important factor to understand the quality of polymer.
  • Let polymer bulk comprises of N number of polymer molecule of which N1 molecule have molecular weight M1 , N2 molecule have molecular weight M2 & N3 molecules have molecular weight M3 ------ & so on.
  • Then total number of molecules---

Numbers of fractions of N I species

 

 

 

 

 

 

 

 

 

 


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