Polymers: Shaping Our World
Jan 12, 2016
Have you ever been walking down the aisle of a grocery store, seen an interesting package, and had the urge to pick it up to see if you could find out what polymer was used? I must confess it happens to me all the time. Product appearance is the second-most important attribute in determining product sales in a grocery store (shelf space being the most important attribute). This places enormous importance on product packaging, and the ability of the package to catch the consumer’s eye. While a wide variety of materials can be used in packaging, polymers are at the forefront due to their ability to be formed into a wide variety of shapes, performance and functionality, low cost, and light weight.
Polymers are macromolecules consisting of long chains of repeating or alternating units of monomers. Literally, the word polymer means “many parts”, with “poly” derived from the Greek “polois” meaning many, and “mer” from the Greek “meri” meaning parts. Most polymers are derived from hydrocarbon resources, especially from oil. However, it may surprise people to find out that the vast majority of oil is burned as either a transportation fuel or as a heat source; chemical applications account for only about 8% of the barrel with polymers accounting for about half of this (Figure 1; chemical applications account for only about 6% of hydrocarbon consumption if both oil and natural gas are considered).
Polymers are converted into a wide range of products including film, bottles, sheet, window and door profiles, fibers, and injection molded parts through a number of fabrication processes – most of which rely on a process called extrusion whereby polymer pellets are melted, mixed, and forced through an orifice or into a mold to give the desired shape. Polymers are transformed into their desired shape by a group of firms called fabricators. These firms are typically smaller than either the polymer producers (such as Dow Chemical or ExxonMobil Chemical for example) or their customers (i.e. packaged goods companies such as P&G, or OEMs like car companies), meaning that the fabricators have little pricing leverage over either their suppliers or customers. Consequently, polymer fabrication has historically been the “weakest link” in the polymer value chain.
There are many polymers that have been synthesized over the past several decades, although many of those have been determined to have little or no commercial utility. The polymers commonly used today (illustrated in Figure 2), range from low-cost “commodity” materials, to highly specialized – and very expensive – performance materials which target metal replacement, weight reduction, extremely hostile environments, or very demanding applications.
Most polymers exhibit the characteristics of a mature, commodity business, with material sold largely on the basis of price and availability. Prices in different regions track each other, and are impacted by global events; hurricanes in the US Gulf Coast impact pricing in China (Figure 3)!! Prices track each other because these materials are relatively easy to transport, so arbitrage opportunities keep regional pricing within relatively narrow bands.
I have worked in and consulted to the polymer industry for decades, learning the intricacies of its components, especially polymer production and fabrication. I now teach a three-day introductory course on polymers and polymer fabrication, where I share my knowledge and experience with students. Hopefully, I also share my excitement of learning about polymers, and interest in all the ways polymers have been used to yield the forms and shapes that we as consumers have come to enjoy.
Hope to see you in my course!