Plastics After Use

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Chapter 5


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Introduction Plastics have a wide range of uses. There are many

products that we use in our daily life. Some of them arerecycled and others are thrown out along with otherwaste.

Most materials undergo an undesired change in someof their physical and chemical properties with time

when exposed to unsuitable conditions.

Materials like wood, plastics, metals, etc. degrade withtime.


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Degradation The irreversible chemical change taking place in

the polymer material due to reaction with theenvironmental factors, resulting in the change of

certain properties of the material such as color,strength etc is called degradation.


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Examples of Degraded Plastics


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Examples of Degradation Degradation is common to many materials but the

speed at which degradation occurs is different anddepends on the type of material and the environment.

Examples of degradation are:

Decay of wood

Corrosion of metals

Degradation of plastics


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Decay of wood

This occurs primarily due to the action of biologicalorganisms.

Corrosion of metals

This occurs primarily due to the reaction with gases, likeoxygen from the atmosphere, in the presence ofmoisture.


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Degradation of Plastics Degradation of plastics is very different from the

degradation of wood or metals.

In plastics the very long molecular chains are brokenin to shorter chains and then later they get broken toeven smaller chains.

This leads to change in properties like lessertransparency, lower strength, reduced f lexibility, etc.


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Degradation of Plastics Plastics can also be broken into smaller pieces due to

chemical and mechanical action.

In the process of degradation, the plastics productdecreases in size and in the end becomes many smallpieces reaching even up to tiny micrometer sizes.


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Rate of Degradation Though it depends on the environmental conditions

we can say that generally materials like food, wood andmetals degrade faster than plastics.

Material Time to DegradeCotton 1-5 months

Paper 2-5 months

Wool 1 to 5 years

Cigarette butts 1 to 12 years

Plastic bags 10 to 20 years

Nylon fabric 30 to 40 years

Aluminum cans 80 to 100 years

Glass bottles 1 million years


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Factors in Degradation of plastics

Many factors play a major role in the degradation ofplastics:

Sunlight Heat

Chemicals (oxygen, copper, etc.)

Moisture and micro-organisms (bacteria, fungi, etc.)

Mechanical Action


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Plastics After Use

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