Polymer vs Plastic
Polymers are large molecules, which have the same structural unit repeating over and over. The repeating units are called monomers. These monomers are bonded to each other with covalent bonds to form a polymer. They have high molecular weight and consist over 10,000 atoms. In the synthesis process, which is known as polymerization, longer polymer chains are obtained. There are two main types of polymers depending on their synthesis methods. If the monomers have double bonds between carbons from addition reactions, polymers can be synthesized. These polymers are known as addition polymers. In some of the polymerization reactions, when two monomers are joined, a small molecule like water is removed. Such polymers are condensation polymers. Polymers have very different physical and chemical properties than their monomers. Moreover, according to the number of repeating units in the polymer, properties differ. There are a large number of polymers present in the natural environment, and they play very important roles. Synthetic polymers are also used widely for different purposes. Polyethylene, polypropylene, PVC, nylon, and Bakelite are some of the synthetic polymers. When producing synthetic polymers, the process should be highly controlled to get the desired product, always. Polymers are used as adhesives, lubricants, paints, films, fibers, plastic goods, etc.
Plastic is also polymer, which has a large molecular mass. The monomers of plastic can be natural or synthetic. Plastic is synthesized from petrochemicals. Thermoplastics and thermosetting polymers are two types in plastics. Thermoplastics becomes soft when heated and when cooled it solidifies again. With continuous heating and cooling, the shape can be changed without a problem (e.g. polyethylene, polypropylene, PVC, polystyrene). However, when thermosetting polymers are heated and cooled it becomes hardened permanently. When heated, it can be molded, but if heated again, it will decompose (E.g.: Bakelite, which is used to make handles of pots and pans). Plastics are widely in use in different forms, such as bottles, bags, boxes, fibers, films, etc. Plastics can be very resistant to chemicals, and they are thermal and electric insulators. Different plastics have different strengths, but are light weighted. Plastics can be produced by condensation, addition reactions. Cross linking is possible between polymer chains in the synthesizing process. For instance, Polyethylene is produced by an addition reaction of the monomer ethylene. Its repeating unit is –CH2-. Depending on the way it is polymerized, the properties of the synthesized polyethylene changes. PVC or polyvinyl chloride is similar to polyethylene, with a monomer of CH2=CH2Cl, but the difference is, PVC has chlorine atoms. PVC is rigid and used to manufacture pipes.
Plastic has become a very controversial issue at the present day due to its incapability of degradation. Plastics make up a considerable percentage in our garbage; therefore, it keeps on increasing on the earth surface. This problem has caught the attention of researchers, and recycled plastics have been synthesized.
Difference between Polymer and Plastic
- Plastics are a type of synthetic polymers.
- The monomers of plastic can be natural or synthetic.
- Plastics are light in weight but can be very strong, and they are electric and thermal insulators.