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