Plastics

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 Plastic is also a polymer like many synthetic fibre . But the monomers in plastic acn be arranged in two ways. Some are in linear chains and others are cross linked . 

     Plastics are available in different shapes and sizes. They have a wide variety of  uses. They have different code numbers. 

      


Inventor of Plastic

Alexander Parkes
  
   Alexander Parkes is creator of first plastic-
"Parkesine". One of many triumphs of modern science which is completely ecompassed the day to day life across the world is invention of plastics. The synthetically produced material was first presented in 1862 in London by Alexander Parkes. To prepare this Parkes heated nitrated cotton which previously soaked in sulphuric acid and made fabric soft and elastic with camphor and oil . The end product was an ivory coloured material that disorted when subjected to heat . This is named as parkesine. Based on these intial efforts plastic evolved as base for many modern materials.
      
              

                  Alexander Parkes

 Types of Plastics   

Thermoplastics

Plastics which get deformed easily on heating and can be bent are known as thermoplastics. Some of the thermoplastics are polythene and PVC . They are used in manufacturing toys , combs and various types of containers . It turns into a liquid when heated and freezes into a glassy state.
         

Thermosetting Plastics

There are some plastics which moulded once can't softened by heating. They are called thermosetting Plastics . Bakelite and melamine are some examples of Thermosetting Plastics . Thermosetting Plastics are synthetic materials which gain strength during moulding by heating.  but cannot be moulded after initial heating. This Plastics are used to make handles for kitchen ware. It is also used for making electric appliances and switchboard. 
         


    Plastics and environment

Excessive use of plastic bags and their unregulated disposal has been choking lakes,ponds and urban sewerage systems . 
The polythene bags are thrown around are responsible for clogging drains . Animals in urban areas especially cows , eat polythene bags containing of polythene bags. If we burn plastic, it creates a lot of air pollution. Plastics take several years to decompose as compared to other materials like peels of fruits, vegetables and food stuff which decompose in short period . Slow decomposition causes environmental pollution. The burning of synthetic material is also slow and can't be burnt completely . The process of burning , releases a lot of poisonous fumes into air causing air pollution. So it is better to avoid or minimize the use of plastics. Chlorinated plastic may release harmful chemicals which can go into the soil and seep into ground water or surrounding waters.
          



4R Principle

  1. Reduce
  2. Reuse
  3. Recycle 
  4. Recover
By following the 4R Principle we can minimize the usage of plastics.
     

Recycling codes

There are 60,000 types of plastics available in world as on today . There are only 6 from these 60,000 types we use regularly. 

  1. PET(Code 1):- Polythene Terephalete.
  2. HDPE(Code 2):- High Density Polythene. 
  3. PVC (Code 3):- Polyvinyl Chloride.
  4. LDPE (Code 4):-Low Density Polythene.
  5. PP(Code 5):- Polypropylene.
  6. PS(Code 6):-Polystyrene.
  7. Other (Code 7)
 PET and HDPE are commonly recycled. But LDPE is not recycled. Similarly PVC used for pipes are also not recycled . The PS used for making coffee cups , food packing can be recycled.
     

  

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