Brydson's Plastics Materials

Marianne Gilbert

• Publisher: Butterworth-Heinemann
• Year: 2016
• ISBN:
  9780323370226
• Edition: 8
• Topic: Tecnología e ingeniería
• Subtopic: Ciencias de los materiales

Brydson's Plastics Materials, Eighth Edition, provides a comprehensive overview of the commercially available plastics materials that bridge the gap between theory and practice. The book enables scientists to understand the commercial implications of their work and provides engineers with essential theory.

Since the previous edition, many developments have taken place in plastics materials, such as the growth in the commercial use of sustainable bioplastics, so this book brings the user fully up-to-date with the latest materials, references, units, and figures that have all been thoroughly updated.

The book remains the authoritiative resource for engineers, suppliers, researchers, materials scientists, and academics in the field of polymers, including current best practice, processing, and material selection information and health and safety guidance, along with discussions of sustainability and the commercial importance of various plastics and additives, including nanofillers and graphene as property modifiers.

With a 50 year history as the principal reference in the field of plastics material, and fully updated by an expert team of polymer scientists and engineers, this book is essential reading for researchers and practitioners in this field.

• Presents a one-stop-shop for easily accessible information on plastics materials, now updated to include the latest biopolymers, high temperature engineering plastics, thermoplastic elastomers, and more
• Includes thoroughly revised and reorganised material as contributed by an expert team who make the book relevant to all plastics engineers, materials scientists, and students of polymers
• Includes the latest guidance on health, safety, and sustainability, including materials safety data sheets, local regulations, and a discussion of recycling issues

Chapter 1

Plastics Materials

Introduction and Historical Development

Professor Marianne Gilbert

Abstract

This chapter serves to introduce the reader to the background of plastics development, the variety of plastics available, their uses in Europe and worldwide, and important contemporary issues associated with their use. The history of plastics from pre-1900 until 2000 is described briefly. Sources of raw materials used for plastics production, and changes in these are then discussed. Types of plastics in current use and their applications are introduced, including figures for the world production of plastics. Current issues concerning health and safety and the environment and sustainability of plastics are considered.

Keywords

Applications of plastics; Biodegradable plastics; Consumption of plastics; History of plastics; REACH; Sources of monomers; Sustainability; Types of plastics

1.1. Introduction

This chapter reviews the history of the development of plastics, covering plastics which are now little used in more detail. Raw materials used in plastics are considered. Growth of the plastics industry to the present time is discussed together with likely future developments. Important current issues such as Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), sustainability, and recycling are addressed.

1.2. The First Plastics

Historians frequently classify the early ages of the mankind according to the materials used for making implements and other basic necessities. The most well known of these periods are the Stone Age, the Iron Age, and the Bronze Age. Such a system of classification cannot be used to describe subsequent periods because with the passage of time man learnt to use other materials, and by the time of the ancient civilizations of Egypt and Babylonia a range of metals, stones, woods, ceramics, glasses, skins, horns, and fibers were employed. Until the nineteenth century inanimate possessions, homes, tools, and furniture were made from varieties of these eight classes of material.

During the twentieth and twenty-first centuries, two new closely related classes of materials were introduced and developed, which have not only challenged the older materials for their well-established uses but have also made possible new products which have helped to extend the range of activities of the mankind. Without these two groups of materials, namely rubbers and plastics, it is difficult to conceive how everyday features of modern life such as motor vehicles, telephones, and the television sets could ever have been developed.

While the use of natural rubber was well established by the start of the twentieth century, the major growth period of the plastics industry was from 1930. This is not to say that some of the materials now classified as plastics were unknown before this time since the use of the natural plastics may be traced well into antiquity.

In the book of Exodus (Chapter 2) we read that the mother of Moses “when she could no longer hide him, she took for him an ark of bulrushes and daubed it with slime and with pitch, and put the child therein and she laid it in the flags by the river's brink.” Biblical commentaries indicate that slime is the same as bitumen but whether or not this is so, we have here the precursor of our modern fiber-reinforced plastics boat.

The use of bitumen is mentioned even earlier. In the book of Genesis (Chapter 11) we read that the builders in the plain of Shinar (ie, Babylonia) “had brick for stone and slime they had for mortar.” In Genesis (Chapter 14) we read that “the vale of Siddim was full of slimepits; and the Kings of Sodom and Gomorrah fled, and fell there; and they that remained fled to the mountain.”

In Ancient Egypt mummies were wrapped in cloth dipped in a solution of bitumen in oil of lavender which was known variously as Syrian Asphalt or Bitumen of Judea. On exposure to light the product hardened and became insoluble. It would appear that this process involved the action of chemical cross-linking, which in modern times became of great importance in the vulcanization of rubber and the production of thermosetting plastics. It was also the study of this process that led Niepce to produce the first permanent photograph and to the development of lithography.

In Ancient Rome, Pliny the Elder (c. 23–79) dedicated 37 volumes of Natural History to the emperor Titus. In the last of these books, dealing with gems and precious stones, he describes the properties of the fossilized tree resin, amber. The ability of amber to attract dust was recognized and in fact the word electricity is derived from elektron, the Greek for amber. Amber is a much prized gem material, and is extensively used in jewelry to the present day.

Horn and tortoiseshell were recognized as the predominant early natural plastics. The first known reference to the Horners of London Company was in 1284, making it one of the most ancient of livery companies.

Another natural resin, lac, had already been used for at least a thousand years before Pliny was born. Lac is mentioned in early Vedic writings and also in the Kama Sutra of Vatsyayana. In 1596 John Huyglen von Linschoeten undertook a scientific mission to India at the instance of the King of Portugal. In his report he describes the process of covering objects with shellac, which came to be known as Indian turnery.

Early records also indicate that cast moldings were prepared from shellac by the ancient Indians. Shellac was produced from lac, the secretion of the lac insect parasitic on certain trees in various Asian countries. In Europe the use of sealing wax based on shellac can be traced back to the Middle Ages. The first patents for shellac moldings were taken out in 1868. However, the material was extremely brittle, and is now only used in coatings such as wood treatment and nail polish.

The introduction to western civilization of another natural resin from the east took place in the middle of the seventeenth century. To John Tradescant (1608–1662), the English traveler and gardener, is given the credit of introducing gutta percha, which consists primarily of the trans-isomer of polyisoprene. The material became of substantial importance as a cable insulation material and for general molding purposes during the nineteenth century and it is only since 1940 that this material has been replaced by synthetic materials in undersea cable insulation. Golf balls were first made of gutta percha in 1848, and balls with a rubber core and gutta percha casing were introduced at the end of the nineteenth century. Gutta percha casings were eventually replaced by balata, a similar but cheaper material.

Prior to the eastern adventures of Linschoeten and Tradescant, the sailors of Columbus had discovered the natives of Central America playing with lumps of natural rubber. These were obtained, like gutta percha, by coagulation from a latex; the first recorded reference to natural rubber was in Valdes La historia natural y general de las Indias, published in Seville (1535–1557). In 1731 la Condamine, leading an expedition on behalf of the French government to study the shape of the earth, sent back from the Amazon basin rubber-coated cloth prepared by native tribes and used in the manufacture of waterproof shoes and flexible bottles.

The coagulated rubber was a highly elastic material and could not be shaped by molding or extrusion. In 1820 an Englishman, Thomas Hancock, discovered that if the rubber was highly sheared or masticated, it became plastic and hence capable of flow. This is now known to be due to severe reduction in molecular weight on mastication. In 1839 an American, Charles Goodyear, found that rubber heated with sulfur retained its elasticity over a wider range of temperature than the raw material and that it had greater resistance to solvents. Thomas Hancock also subsequently found that the plastic masticated rubber could be regenerated into an elastic material by heating with molten sulfur. The rubber–sulfur reaction was termed vulcanization by William Brockendon, a friend of Hancock. Although the work of Hancock was subsequent to, and to some extent a consequence of that of Goodyear, the former patented the discovery in 1843 in England while Goodyear's first (American) patent was taken out in 1844.

In extensions of this work on vulcanization, which normally involved only a few percent of sulfur, both Goodyear and Hancock found that if rubber was heated with larger quantities of sulfur (about 50 parts per 100 parts of rubber) a hard product was obtained. This subsequently became known variously as ebonite, vulcanite, and hard rubber. A patent for producing hard rubber was taken out by Nelson Goodyear in 1851.

The discovery of ebonite is usually considered as a milestone in the history of the rubber industry. Its importance in the history of plastics materials, of which it obviously is one, is generally neglected. Its significance lies in the fact that ebonite was the first thermosetting plastics material to be prepared and also the first plastics material which involved a distinct chemical modification of a natural material. By 1860 there were a number of manufacturers in Britain, including Charles Macintosh who is said to have started making ebonite in 1851. There are reports of the material having been exhibited at the Great Exhibition of 1851.

In 2008, to celebrate its 75th anniversary, the British Plastics Federation (BPF) published an eight-page timeline of the development of plastics. This excellent summary has been used extensively in the revision of Sections 1.3–1.7. Further information was obtained from a special issue of Plastiquarian, the journal of the Plastics Historical Society.

1.3. Pre-1900

While Hancock and Goodyear were developing the basic processes of rubber technology, other important discoveries were taking place in Europe. Following earlier work by Pelouze, Schönbein was able to establish conditions for controlled nitration of cellulose. The product soon became of interest as an explosive and in the manufacture of collodion, a solution in an alcohol–ether mixture. In the 1850s the English inventor Alexander Parkes “observed after much research, labor and investigation that the s...