Composites have several advantageous properties including being cheap and easy to process, having high specific strength, stiffness, toughness, and impact strength, withstanding high temperatures, and exhibiting low thermal expansion, high dimensional stability, good corrosion and wear resistance. Liquid crystals combine properties of liquids and crystalline solids, allowing them to flow like liquids but behave elastically like solids. Mesogens are rigid rod-like or disc-like elements incorporated into polymer chains to make liquid crystal polymers stiffer than normal flexible polymers, restricting chain mobility and differentiating main chain and side chain polymer liquid crystals based on mesogen position.

19. Classification Based on Reinforcement

20. Properties of Composites:
1. They are cheap and easy to process.
2. They have high specific strength.
3. They have high stiffness, toughness and impact strength.
4. They can withstand high temperature.
5. They have low thermal expansion and high dimensional stability.
6. They have better corrosion and oxidation resistance.
7. They have good wear resistance.

22. Liquidcrystals
Liquid crystals are materials which combine properties of liquids and
crystalline solids. They can flow like liquids and behave elastically like
crystallinesolids.

24. Mesogens
Mesogens are rod like or disc like rigid elements which are incorporated in
polymer chains to make liquid crystal polymers from normal flexible polymers.
They contain 2 to 3 aromatic rings and act like stiffeners. They put restriction
on the mobility of polymer chains. Depending on the position of mesogens
the polymer liquid crystals are of two types:
Main chain
polymer liquid
crystals (MC-PLC)
Side chain polymer
liquid crystals (MC-
PLC)