The Nature of Plastics and Their Societal Usage

HERVÉ MILLET, PATRICIA VANGHELUWE, CHRISTIAN BLOCK, ARJEN SEVENSTER, LEONOR GARCIA AND ROMANOS ANTONOPOULOS

ABSTRACT

The purpose of this chapter is to review the history of plastics, describe the different kinds of plastics, their applications and their benefits, giving several examples of plastics found in our daily lives. The current chapter also provides deep insight into the qualitative characteristics of plastics, while describing their chemical nature in simple terms.

1 Plastics in a Nutshell

The term "plastic" is derived from the Greek words "plastikos", meaning "fit for moulding" and "plastos" meaning "moulded". Both terms refer to the material's malleability or plasticity during manufacture, that allows it to be cast, pressed, or extruded into a variety of shapes; such as films, fibres, plates, tubes, bottles, boxes and much more.

In addition, the wide range of possibilities to change their chemical structure or formulations and therefore their final properties allow them to be used in numerous and various applications. We can find them packaging the food that we eat, in the houses we live in, the cars we drive, clothes we wear, the toys we play with and in the televisions we watch. Plastics contribute to our convenience, as well as providing several solutions in our everyday lives, and help to improve the environmental impact of products in many applications.

When it comes to their chemical nature, plastics are synthetic or semisynthetic materials; they are organic materials, such as wood, paper or wool. Mostly derived from crude oil, they can also be produced from renewable raw materials.

In scientific terms, there are two main categories of plastic materials: thermoplastics and thermoset plastics. Thermoplastics can be heated up to form products, if these end products are re-heated the plastic will soften and melt again. Plastic bottles, films, cups, and fibres are some examples of thermoplastic products. On the other hand, thermoset plastics can be found in products such as electronic chips, dental fillings and the lenses of glasses, they will no longer melt after the "setting" process.

At the end of their useful life, plastic products can either be recycled back into new products or chemical raw materials or, where this is not possible or sustainable, used for energy recovery as a substitute for virgin fossil fuels.

1.1 The History of Plastics

For more than a century, plastics have been providing significant solutions for humans. The development of plastic materials started with the use of natural materials with plastic properties (e.g., chewing gum, shellac), they then evolved with the development of chemically modified natural materials (e.g. rubber, nitrocellulose, collagen, galalith). Finally, the wide range of completely synthetic materials that we would recognise as modern plastics started to be developed around 100 years ago. The first was discovered by Alexander Parkes in 1862 and is commonly known as celluloid today.

The development of plastic materials passed through various historical phases, becoming today the most widely used material globally. In particular, global plastics production ramped up from 1.5 million tonnes in 1950 to 335 million tonnes in 2016.

1.1.1 19th Century: The First Polymers. Although it is largely known that plastics are a modern invention, 'natural polymers', such as amber, tortoiseshell and horn, are abound in nature. These materials have a similar structure to manufactured plastics and they were often used to replace glass (amber) in the 18th century.

The original breakthrough for the first semisynthetic plastics material – cellulose nitrate – occurred in the late 1850s and involved the modification of cellulose fibres with nitric acid.

Cellulose nitrate had many false starts and financial failures until a Briton, Alexander Parkes exhibited the so-called "Parkesine" as the first world's man-made plastic, in 1862. However, the failure of this product, due to its high manufacturing costs, led to the creation of Xylonite by Daniel Spill. This new material started finding success in the production of objects such as ornaments, knife handles, boxes and more flexible products such as cuffs and collars.

It was in 1869 that an American, John W. Hyatt, made a revolutionary discovery, a process to produce celluloid, a product that could be used as a substitute for natural substances such as tortoiseshell, horn, linen, and ivory. This product entered mass production in 1872.

1.1.2 20th Century: The Revolution of Plastics Starts. Up until the early 1900s, it was impossible to use cellulose nitrate at very high temperatures, because it was flammable. The development of cellulose acetate brought about a solution to this problem, as it started being used as a nonflammable 'dope' to stiffen and waterproof the fabric wings and fuselage of early airplanes and was later widely used as cinematographic 'safety film'. In the meantime, casein formaldehyde was developed, based on fat-free milk and rennin, and used for shaping buttons, buckles and knitting needles. The next years saw a revolution in plastics, making them an integral part of our daily lives.

1.1.3 Beginning of the 20th Century: The Discovery of Bakelite. In 1907, Belgian Leo Baekeland (who coined the term plastic later on), discovered Bakelite, which was largely used in the expanding automobile and radio industries at that time.

In 1912, polyvinyl chloride (PVC) and polyvinyl acetate (PVA) were discovered by a German chemist, Fritz Klatte. The following year, Jacques E. Brandenbergen, a Swiss engineer, invented Cellophane, a clear, flexible and waterproof packaging material.

1.1.4 1920s: Staudinger and Polymers. In 1921, the first injection moulding press appeared, invented by Arthur Eichengrün.

Meanwhile, a revolution came in 1922, when a German, Herman Staudinger, father of macromolecular chemistry, claimed molecules could join to form long chains and therefore become 'macromolecules' or polymers. Staudinger provided enough evidence for his macromolecular concept and promoted it, despite the strong opposition of several chemists.

Staudinger provided the theoretical basis for polymer chemistry and significantly contributed to the rapid development of the polymer and plastic industry – which are the reasons why he was awarded with Nobel Prize for chemistry in 1953.

Another important scientific...