Polymers have different properties depending on key characteristics, including their molecular weight, meaning that no two are the same. The molar mass distribution of a polymer chain is described by polymer molecular weight (MW), which establishes the weight of the macromolecule itself.
Image Credit: Jordi Labs
Due to the sheer diversity of polymeric structures at the molecular level, this can be a challenging subject to unravel. It is almost impossible to achieve consistent molecular weights within polymer species, so the distribution of molecular weight values is evaluated using a series of numeric averages.
To put the theory into context, the typical molecular weights of some common polymers are discussed in this article.
Polyethylene Terephthalate (PET)
Polyethylene terephthalate (PET) is a pervasive thermoplastic polymer resin that has a typical molecular weight of around 8,000 – 31,000.
It helps fabricate a variety of industrial and commercial products, including tire cord filaments, windows, and plastic bottles for carbonated drinks. More than 60% of the world’s PET is utilized to make synthetic fibers for industrial and apparel purposes.
High Density Polyethylene (HDPE)
A lightweight, high-strength engineering polymer, High Density Polyethylene (HDPE) typically has a molecular weight of around 100,000 – 250,000 and is known for its exceptional strength-to-density ratios. HDPE is usually utilized to make plastic bags and bottles, toys, and pipe systems.
The main advantage of HDPE is its resistance to an extensive range of solvents and corrosives, leading to low molecular weight degradation in the presence of harmful substances. Polyethylene can also be seen in high and ultrahigh MW versions with molecular weights in the millions of Daltons.
Polycarbonate (PC) is a thermoplastic polymer designed with good formability and high toughness to provide excellent functionalities for both industrial and commercial applications. It features one of the broadest polymer molecular weight ranges, with typical values measuring between 50,000 – 300,000.
This durable material is employed to produce tough electronic components, and structural components for transit applications.
The processability of PC is heavily dependent on its molar distribution, with lower mass grades showing higher degrees of formability over higher grades. However, this comes with a proportional drop in the polymer’s strength values.
Polyamide, or Nylon 6, is a lightweight polymer chain made up of a variety of amide bonds. They exhibit comparatively low molecular weights of 10,000 – 50,000 and are widely used to manufacture packaging materials and non-woven fabrics. It is most frequently employed in the automotive sector for application as interior textiles.
Polyurethane (PU) chains show similar molecular weight profiles to polycarbonates, between 50,000 – 300,000. Yet, for improved malleability, they are synthesized using urethanes as opposed to carbonate elements.
Despite their similar molecular weight ranges, PU chains are more frequently employed to fabricate flexible or insulating components such as textiles and foam sponges.
Polystyrene (PS) is one of the most widely used packaging mediums in the world and is among the most instantly recognizable inorganic polymers. It exhibits a large molecular weight range of 100,000 – 400,000 and is regularly used to fabricate car parts, tissue culture trays, and packaging for a limitless variety of commodities.
Molecular Weight Analysis with Jordi Labs
Jordi Labs is an expert in the field of polymer molecular weight analysis. They operate one of the country’s leading gel permeation chromatography (GPC) facilities for establishing the molecular weight of polymer products with fast turnarounds.
This information has been sourced, reviewed and adapted from materials provided by Jordi Labs.
For more information on this source, please visit Jordi Labs.