Semi-Synthetic Polymers

There are three types of polymers which include natural polymers, synthetic polymers and semi-synthetic polymers. Semi-synthetic polymers are those that are derived from nature itself but are made to undergo chemical processes to enhance their quality. Some semi-synthetic polymers examples are Rayon, vulcanized rubber and gun cotton. The advantages of natural polymers over synthetic polymers are more because of their environmentally-friendly qualities. 

What are Semi-Synthetic Polymers?

Semi-synthetic polymers are those that occur naturally, but they are extracted in their valuable forms through chemical processes. Therefore, semi-synthetic polymers are those that are naturally occurring and also synthetically made. Semi-synthetic polymers are usually derived from the naturally occurring polymer, cellulose. 

Semi-synthetic polymers are also called thermoplastic polymers. Cellulose is made to go through a process called acetylation; that is, acetic anhydride is used along with sulphuric acid, which forms a polymer called cellulose diacetate. This material is usually used to make film glasses that are thread-like. Some of the semi-synthetic polymers examples include vulcanized rubber which is used in making tyres, and also gun cotton, which is cellulose nitrate that can be used in the making of explosives. 

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Some Semi-Synthetic Polymers: Examples

There are many semi-synthetic polymers. The most common one is Rayon, and it is a derivative of cellulose as well, just as cellulose nitrate and cellulose acetate are. Viscose rayon appears in the form of a thin transparent layer, and this layer is also called cellophane. When mixed with glycerol, cellophane becomes soft, and unlike plastic sheets, cellophane uses a lot of water. 

Rayon: The most common Semi-Synthetic Polymer

Rayon is an artificial substance that is made through purified cellulose, and it is in the form of long fibres. Purified cellulose is made by reacting cellulose with cold sodium hydroxide, and then in the next step, it is treated with CS2 to create a viscose solution. This is the reason why Rayon is also called viscose rayon. 

In the next step of chemically producing Rayon, the viscose solution is made to go through a metal cylinder with minute pores, and then it is mixed with dilute H2SO4. In this way, long fibres of Rayon are produced. 

Rayon is technically cotton because it has the same chemical composition as cotton. However, it has a shine like that of silk. This is the reason why Rayon is also called artificial silk. Rayon is used at an industrial scale to make textiles, surgical dressings, carpets and tyre cords. The most significant aspect of this semi-synthetic polymer is that it can take in moisture and is bio-degradable. 

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Advantages of Natural Polymers over Synthetic Polymers

Apart from semi-synthetic polymers, there are two other polymers, known as natural polymers and synthetic polymers. As the names suggest, natural polymers can be easily found in the environment, and they need only to undergo a minimum amount of chemical processes in order to be usable. While synthetic polymers are not found in nature, they have to be chemically produced. 

There are several advantages of natural polymers over synthetic polymers. Some of which are mentioned below:

1. Natural polymers are less toxic compared to synthetic polymers. In fact, synthetic polymers are highly toxic, and though they are easy to manufacture, they are preferred less because of the damage they are capable of causing to the environment.
2. Natural polymers are biodegradable and synthetic polymers are not biodegradable. This means that natural polymers can be recycled for use, and even if discarded in nature, they will not cause harm to the ecosystems. However, this is not the case with synthetic polymers because they will harm either the wildlife that might ingest them or pollute the ecosystem.
3. Natural polymers are easy to find and derive from nature. Whereas synthetic polymers require a complicated process of production which can not only be difficult but also cost a lot of energy and finances. 
4. While both natural and synthetic polymers are biocompatible, the biocompatible quotient of natural polymers is marginally higher than the synthetic polymers because natural polymers are polysaccharides that dissolve easily. 
5. Natural polymers are abundant in the environment and have a wide application, whereas synthetic polymers are scarce, energy-expensive, and their use is limited.
6. Natural polymers can be derived from various sources such as microorganisms, plants and animals.
7. Furthermore, natural polymers have a high capacity to retain water, and this is why they are also used in medical and pharmaceutical fields.

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Conclusion

Semi-synthetic polymers are the ideal blend of synthetic and natural polymers because it has the beneficial features of both types of polymers. That is why Rayon, which is one of the semi-synthetic polymers examples, is widely used in various industries, be it medical or technology.