Notes

1.Polymers: -
Classification of polymers: -
They are of three types.
Based on origin: -
1. Natural polymers: - They are polymers which are formed by naturally occurring substances.
2. Artificial polymers: - They are polymers which are formed by adding chemical modification to natural polymers
3. Synthetic polymers: - They are polymers which are synthesized by low mass molecular polymers.
4. Bio polymers: - They are polymers which have biological properties.
Based on nature: -
1. Organic polymers: - They are polymers whose backbone are made up of carbon atoms.
2. Hetro-organic polymers: - They are polymers which have half carbon atoms and rest are hetro atoms.
3. Inorganic polymers: - They are polymers which have no carbon atoms but are made up of inorganic atoms.  
Based on applications: -
1. Polycarbonates
2. Polyamides
3. Polyurethane
4. Polyacetals
5. Solid silicones
6. Teflon
Types of plastics: -
1. Thermoplastics: -
* Thermoplastics are made up of linear polymers
* The molecules are weak in nature
* The shape of the material can be changes by heating
* The material hardens on cooling
* Repeated heating and cooling of these materials does not loosen up the material
2. Thermosetting plastics: -
* Thermosetting plastics are made up of cross-linked polymers
* They are held together by strong covalent bonds
* They do not loosen up on continuous heating
* They are given a fixed shape while manufacturing
* On continuous heating charraring is occurred
1.Polyurethanes: -
Polyurethanes are obtained by treating diisocynate and diol.
Properties: -
* They are less stable than polyamides at elevated temperature.
* They are characterized by excellent resistance to abrasion and solvents.
2. Polystyrene: -
Polystyrene is prepared by polymerization of styrene in presence of benzoyl peroxide catalyst.
Properties: -
* Polystyrene is transparent, light, good light-stable, excellent moisture-resistance.
* At about 100 degrees C, it yields water-soluble emulsion.
Polyethylene terephthalate: -
Polyethylene terephthalate is prepared by the combination of ethylene glycol and terephthalic acid.
Properties: -
* PET is highly resistant to mineral and organic acids.
* It is less resistance to alkalis.
* These fibers have high stretch-resistance, high creep and wrinkle resistance.
Teflon: -
Teflon is obtained by polymerization of water - emulsion of tetrafluoroethylene in the presence of benzoyl peroxide under pressure.
Properties: -
* Teflon possesses good electrical and mechanical properties.
* It is extremely tough.
* It has high softening point.
* It resists the action of chemicals.
Nylon-6;6: -
Nylon 6;6 is obtained by the polymerization of adipic acid with hexamethylene diamine.
Properties: -
* It is translucent, whitish, horny, high melting (160 to 264 degree C) polymer.
* It possesses high temperature stability and good abrasion resistance.
* It is insoluble in common organic solvents and soluble in phenol and formic acids.
Conductivity in polyacetylene: -
* When the oxidative dopant, such as I2 is added, it takes away an electron from the pie - backbone of the polyacetylene chain. This creates positive center (hole) on one of the carbons.
* On further oxidation, a dipolaron (or) soliton is formed.
* These radicals then migrate and combine to form a backbone double bond.


2.Thermodynamics: -
Scope of thermodynamics: -
* Thermodynamics is helpful in determining how far a process will occur with given respect to pressure, temperature and concentration.
* Most of the physical chemistry laws couldn't have been derived if not for the thermodynamic laws.
* It helps in determining how far the process can take place.
Limitations of thermodynamics: -
* It helps in determining the time taken by the reaction in macroscopic system of mass elements but cannot on macroscopic system of individual atoms or molecules.
* It does not concern individual atoms or molecules.
Thermodynamic terms: -
System: - A system is a process in thermodynamic study. It consists of specific amount of specific substance.
*Heterogeneous system: - A system does not consist of uniform substance is called heterogenous system.
*Homogeneous system: - A system consists of uniform substance is called homogenous system.
Surroundings: - A system is a process in thermodynamic study. It consists of definite amount of specific substance.
Boundry: - The outer covering which separates the system from the surroundings is called the boundary.
Types of thermodynamic systems: -
* Isolated system: - The isolated system is a type of system where there is not exchange of either energy or matter with its surroundings.
* Open system: - The open system is a type of system where there is exchange of energy and matter with its surroundings.
* Closed system: - The closed system is a type of system where there is exchange of energy but not matter with its surroundings.
Properties of system: -
* Intensive property: - A property which does not depend on the quantity of matter present in the system is called intensive property.
* Extensive property: - A property which depends on the quantity of matter present in the system is called extensive property.
Different thermodynamic process: -
*Isothermal process: - The type of process which takes place with constant temperature is called isothermal process.
*Adiabatic process: - The type of process which does not allow heat transfer with its surroundings is called adiabatic process.
*Isobaric process: - The type of process which takes place with constant pressure is called isobaric process.
*Isochoric process: - The type of process which takes place with constant volume is called isochoric process.
*Cyclic process: - The type of process which completes its initial stage and completes a cycle and returns back to its original state is called cyclic process.