Molecular mass of polymers

The size, mass, and structure of polymers play an important role in giving distinct properties to polymers. Different physical properties such as tensile strength, viscosity, etc., are all determined by the molecular mass of polymers.

The relationship between the number of moles in a polymer and the molar mass of the polymers can be better understood using the Molecular Weight Distribution (also known as the Molar Mass Distribution). The formula mass of a material is expressed in nuclear mass units and equals the sum of the normal nuclear masses of all the molecules included in the compound equation. A covalent compound’s equation mass is often referred to as the molecular mass of polymers.

To calculate the molecular mass of a polymer chain, one must multiply the mass of each repeating unit by the degree of polymerisation and then add the mass of end groups.

Many small repeating units make up the macromolecules found in polymers, which can be as massive as 100 kilodaltons in size or more. As a result, the molecular mass of a polymer is high.

High molecular mass macromolecules called polymers are repeating structural units derived from monomers. The molecular mass of polymers is up to 103–107u. In a polymer, strong covalent bonds connect different monomer units. Natural and synthetic polymers can be used to produce these materials— for instance, polymers like polythene, rubber, and nylon 6, 6.

Average molecular weight

The mass of each chain is included in the average molecular weight (Mw) measurement technique, which adds to the polymer’s overall molecular weight. It is based on the idea that larger molecules are heavier than smaller ones. Consequently, molecules with bigger masses contribute more to the average molecular weight. Mw takes into account the size of the molecule. Light scattering is an excellent example of a property that depends on the average molecular weight.

When calculating the average molecular weight, add up all of the chains’ weights and divide by the total number of chains. Polymers can be characterised by their average molecular weight. To express average molecular weight, you can use one of the following:

Number average Molecular mass, Mn

Number mean or simple arithmetic mean, represents the weight of all molecules divided by the number of molecules. Number average molecular weight plays an important role in thermodynamic measurements, including osmotic pressure, freezing point depression, and colligative characteristics. Number average molecular mass of polymer is also calculated in the end-group analysis.

• Average molecular weight, Mw

Weight average molecular weights are derived from measurements of molecular weight that take into account the relative contributions of different molecules. Examples of this type of procedure include light scattering and ultracentrifuges.

As a rule, the number average molecular weight is greater than or equal to the mass average. The polydispersity of a polymer mixture is measured by the weight average and number average molecular weight ratios, which indicate how widely distributed the molecular weights are in the mixture. 

According to this formula, the range of molecular weights in the mixture is small if the ratio is close to 1.0; if it’s higher, it implies that the molecular weights are spread out more widely. All synthetic polymers are polydisperse, with a few notable exceptions.

Polyethene molar mass 

Ethylene polymerisation produces polyethene (PE), a light and flexible synthetic plastic. It belongs to the family of polyolefin resins. It is the most common type of plastic on Earth, including plastics that are used as clear food wraps, shopping bags, detergent bottles and automotive fuel tanks. Synthetic fibres can be made by slicing or spinning them into yarn or a rubber-like material.

In ultrahigh molecular weight versions, linear polyethene is produced. The linear polyethene’s molar mass is 3,000,000 to 6,000,000 atomic units, as opposed to 500,000 atomic units for high-density polyethene (HDPE). It is possible to spin these polymers into fibres and then draw them into a crystallised state, resulting in high stiffness and tensile strength many times greater than steel. These fibres are used to make bullet-proof jackets.

Polymer Applications

Due to the very large molecular mass of polymer, it has various applications in our day to day life.

• There are numerous applications for polypropene, from textile and packaging to packaging and stationery to plastics and aeroplanes.
• One of the most widely used plastics, polystyrene, is widely used in packaging. Polystyrene goods include bottles, toys, containers, trays and plates, tv cabinets, and lids. As a result, it can also be used as an electrical insulator.
• Polyvinyl chloride (PVC) is mostly used to make sewage pipes. Cable insulators are also made of this material.
• In addition to being used in apparel and furniture, polyvinyl chloride is also becoming increasingly popular in manufacturing doors and windows. 
• A wide range of products can be made using urea-formaldehyde resin because of the high molecular mass of these polymers. This includes products like adhesives, moulds, laminated sheets, and more.
• Paints, coatings, and lacquers are all made with the polymer glyptal.
• In addition to electrical switches and kitchenware, bakelite is also used in jewellery and guns, as well as insulators and computer discs.

Conclusion 

Polymer properties are affected by their size, mass, and structural composition. This article talks about the different molecular masses of polymers and how they provide different properties to the polymers. It is possible to determine the molecular mass of polymers using various techniques. The Molecular Weight Distribution (MWD) provides a clearer picture of the relationship between the molecular mass of polymers and their number of moles (also known as the Molar Mass Distribution). It is the total of the normal nuclear masses of all the molecules included in the compound equation used to express the formula mass of material. Polymers, which can be as large as 100 kilotons in weight, contain macromolecules made up of many small repeating units. As a result, the molecular mass of polymers is very high.