Polymer Science

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Polymers are large molecule which is made by repetition chains of small, simple chemical units called “Monomers”. Chains can be branched or interconnected to form 3D networks.

The use of polymers is predominant in day to day products starting from a toothbrush to the windshields in airplanes. Polymer science deals with the study of kinetics, chemistry, and applications of polymers.

Polymers are high molecular weight macromolecules and usually measured based on the number of repeated units and the weight of each repeated unit.

Most polymer-based plastics, rubbers or fibers weigh between 8000 to 1000000. The process by polymers formed by repetitions of monomers is called “Polymerization”.

Polymers are classified based on the polymerization process as Condensation or Addition polymers (Step or chain-growth polymerization), based on Branching, based on molecular weight and based on texture.

They are also classified based on crystal structure as Amorphous and Crystalline.

Amorphous polymers are those which irregular crystal structure but are flexible whereas crystalline has a regular or patterned crystal structure.

The commercial methods of processing polymers which are: Bulk, Cationic, Anionic, Interfacial, and Suspension polymerization. After knowing the processing it’s time to know the mechanism of how polymers are formed which is studied under chemical kinetics.

Chemical kinetics deals with studies with rates and directions through which reaction proceeds. Through kinetics, we can have an idea of how atoms are colliding in the formation of polymer and also chain length or degree of polymerization.

Polymers are processed with the help of a Twin-screw extruder, Injection molding machine, Compression molding machine or Sigma Type mixer, Melt spinning, vulcanization, pultrusion, etc.

After knowing the processing techniques, kinetics and solid-state chemistry of it, now it’s time to understand the mechanical properties and methods to enhance it.

We understand the mechanical properties by XRD (x-ray diffraction) curves and a DSC (differential scanning calorimetry) curve, through these curves the crystallinity is determined, by crystallinity influences the hardness, the tensile strength, Young’s Modulus and the stiffness.

In order to enhance the properties, we intermix polymers with dominant properties this process is called “Blending”. After blending we compare the mechanical properties and thermal stability with conventional polymers by DSC and XRD curves.

Considering commercial or real-life applications, the plastic carry bags are made of (polyethylene) polymer, the pipes which we use for household application are made of PVC (Polyvinyl chloride), all the disposable cutlery, packing material, foams cups or plates are made of polystyrene, the nonstick pan or cooking utensils are made of Teflon, all the laboratory equipment are PP(Polypropylene) blends, the Tupperware products are made of a mixture of polymers like HDPE(High-density polymer ethylene), PET(polyethylene terephthalate ), PVC, PP BPA.

plastic polymer
Photo by Magda Ehlers

So we can see from the applications, we are surrounded by polymers starting from the toothbrush to automobile interiors, apart from these researches are conducted meticulously to discover new polymers which are economically feasible, light, harmless, stiff, easily degradable (cellulose acetate is a degradable polymer used in cigarette butts, textiles).

polymer interiors
Photo by Kelson Downes

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