1)What do you mean by the term monomers?
2)name the scientist who discovered rayon?
3)write the uses of nylon?
4)write the uses of rayon?
5)write the process of acrylic fibre?
6)differentiate between thermoplastic and thermosetting plastic ?
7)write the disadvantage of plastic ?
1)What do you mean by the term monomers?
2)name the scientist who discovered rayon?
3)write the uses of nylon?
4)write the uses of rayon?
5)write the process of acrylic fibre?
6)differentiate between thermoplastic and thermosetting plastic ?
7)write the disadvantage of plastic ?
1)
A monomer is a molecule that forms the basic unit for polymers. They may be considered the building blocks from which proteins are made.
2)
Rayon was the first manufactured fiber developed, it made from wood or cotton pulp and was first known as artificial silk. The Swiss chemist, Georges Audemars invented the first crude artificial silk around 1855, by dipping a needle into liquid mulberry bark pulp and gummy rubber to make threads.
3) Some of the most important uses Nylon are:
1. Nylon is a high strength fibre. It is used for making fishing nets, ropes, parachutes and type cords.
2. It is used for making fabrics in textile industry.
3. Crinkled nylon fibres are used for making elastic hosiery.
4. Nylon is widely used as plastic for making machine parts.
It is blended with wool to increase the strength.
4)
The uses of Rayon are :
1. It is used in textile industry for making textiles.
2. Rayon is used for making tyre cords.
3. It is also used for making carpets and surgical dressings.
5)
Acrilonitrile is the main raw material for the manufacture of acrylic fibres. It is made by different methods. In one commercial method, hydrogen cyanide is treated with acetylene:
acetylene + Hydrogen cyanide --> Acrilonitrile
2nd Method
Ethylene--Air Oxidation--> Ethylene oxide + HCN--> Ethylene cyanahydrin--Dehydration at 300 deg C (catalyst)--> Acrylonitrile
In a continuous polymerisation process, 95% acrylonitrile and 6% methyl acrylate (400 parts) 0.25% aqueous solution of K2S2O8(600 parts), 0.50 % Na2S2O5 solution ( 600 Parts) and 2N sulphuric acid (2.5 Parts) are fed into the reaction vessel at 52 deg C under nitrogen atmosphere giving a slurry with 67% polymer. The slurry is continuously withdrawn, filtered and washed till it is free from salts and dried.
Acrilonitrile is dry spun. The material is dissolved in dimethyl formamide, the solution contains 10-20 polymers. It is heated and extruded into a heated spinning cell. A heated evaporating medium such as air, nitrogen or steam moves counter current to the travel of filaments and removes the solvent to take it to a recovery unit. The filaments are hot stretched at 100 to 250 C depending on the time of contact in the hot zone, to several times their original length.
6)
Thermoplastic polymers Thermosetting polymers These are formed by addition polymerisation These are formed by condensation polymerization Monomer used in these is generally bifunctional In this monomer used is tri, tetra or polyfunctional They are long chain linear polymer with negligible cross links These have three- dimensional network structure with number of cross links They have low molecular wt. They have high molecular wt They are soft, weak , brittle They,are hard, strong and more brittle They can be softened and reshaped and reused. They cannot be softened and reshaped again once again. e.g.- polyethylene, polystyrene, PVC, PVA etc. e.g.- phenol formaldehyde, ureaformaldehyde, nylon 6:6 etc.
7)
Disadvantages
1.when plastics are burned,they produce toxic gases and smoke
2. most plastic wastes littering the roadsides cause disease causing microorganisms.
3. plastics dumped in water bodies pose a threat to aquatic life.
4. the toxic substances present in plastics which are dumped in water bodies can cause reproductive failure in aquatic organisms.
5. plastics prevent the rainwater from seeping into the ground.
6.dumping of plastics in the ground affects the plants growing in the area as they dont get enough water from the soil.
A monomer is a molecule that forms the basic unit for polymers. They may be considered the building blocks from which proteins are made.
2)
Rayon was the first manufactured fiber developed, it made from wood or cotton pulp and was first known as artificial silk. The Swiss chemist, Georges Audemars invented the first crude artificial silk around 1855, by dipping a needle into liquid mulberry bark pulp and gummy rubber to make threads.
3)
Some of the most important uses Nylon are:
1. Nylon is a high strength fibre. It is used for making fishing nets, ropes, parachutes and type cords.
2. It is used for making fabrics in textile industry.
3. Crinkled nylon fibres are used for making elastic hosiery.
4. Nylon is widely used as plastic for making machine parts.
It is blended with wool to increase the strength.
4)
The uses of Rayon are :
1. It is used in textile industry for making textiles.
2. Rayon is used for making tyre cords.
3. It is also used for making carpets and surgical dressings.
5)
Acrilonitrile is the main raw material for the manufacture of acrylic fibres. It is made by different methods. In one commercial method, hydrogen cyanide is treated with acetylene:
acetylene + Hydrogen cyanide --> Acrilonitrile
2nd Method
Ethylene--Air Oxidation--> Ethylene oxide + HCN--> Ethylene cyanahydrin--Dehydration at 300 deg C (catalyst)--> Acrylonitrile
In a continuous polymerisation process, 95% acrylonitrile and 6% methyl acrylate (400 parts) 0.25% aqueous solution of K2S2O8(600 parts), 0.50 % Na2S2O5 solution ( 600 Parts) and 2N sulphuric acid (2.5 Parts) are fed into the reaction vessel at 52 deg C under nitrogen atmosphere giving a slurry with 67% polymer. The slurry is continuously withdrawn, filtered and washed till it is free from salts and dried.
Acrilonitrile is dry spun. The material is dissolved in dimethyl formamide, the solution contains 10-20 polymers. It is heated and extruded into a heated spinning cell. A heated evaporating medium such as air, nitrogen or steam moves counter current to the travel of filaments and removes the solvent to take it to a recovery unit. The filaments are hot stretched at 100 to 250 C depending on the time of contact in the hot zone, to several times their original length.
6)
| These are formed by addition polymerisation | These are formed by condensation polymerization |
| Monomer used in these is generally bifunctional | In this monomer used is tri, tetra or polyfunctional |
| They are long chain linear polymer with negligible cross links | These have three- dimensional network structure with number of cross links |
| They have low molecular wt. | They have high molecular wt |
| They are soft, weak , brittle | They,are hard, strong and more brittle |
| They can be softened and reshaped and reused. | They cannot be softened and reshaped again once again. |
| e.g.- polyethylene, polystyrene, PVC, PVA etc. | e.g.- phenol formaldehyde, ureaformaldehyde, nylon 6:6 etc. |
7)
Disadvantages
1.when plastics are burned,they produce toxic gases and smoke
2. most plastic wastes littering the roadsides cause disease causing microorganisms.
3. plastics dumped in water bodies pose a threat to aquatic life.
4. the toxic substances present in plastics which are dumped in water bodies can cause reproductive failure in aquatic organisms.
5. plastics prevent the rainwater from seeping into the ground.
6.dumping of plastics in the ground affects the plants growing in the area as they dont get enough water from the soil.
