What Is Plastic?
What Is Plastic? A plastic, in the modern sense of the word, is a synthetic or man-made material which can be formed into various shapes. The first plastic material was celluloid, made in 1868 by an American, John W. Hyatt, by dissolving nitrocellulose under pressure. The use of plastics began slowly, but shortages of natural materials caused by two world wars forced scientists to develop substitutes.
Since the Second World War the making of plastics has become a gigantic industry, which has grown so fast that many people still have only a hazy idea what plastics are. In fact, the term “plastics” is as general as the word “metals”. The high-temperature cone of a rocket and the highly inflammable table-tennis ball are both plastics, just as lead and steel are both metals.
However, all plastics have some things in common: first, they are entirely man-made and not found in nature; secondly, they consist of large molecules of an organic nature, thirdly, at some stage in their manufacture they are liquid and can be shaped; and fourthly, in their final state they are solid. Most of the raw materials for plastics are produced by the petroleum and coal industries. Scientists are able to produce different properties in plastics so that they can be used in a tremendous variety of articles.
Due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials, such as wood, stone, horn and bone, leather, paper, metal, glass, and ceramic, in most of their former uses.
In developed countries, about a third of plastic is used in packaging and another third in buildings such as piping used in plumbing or vinyl siding. Other uses include automobiles (up to 20% plastic), furniture, and toys. In the developing world, the ratios may be different – for example, reportedly 42% of India’s consumption is used in packaging.
Plastics have many uses in the medical field as well, to include polymer implants; however the field of plastic surgery is not named for use of plastic materials, but rather the more generic meaning of the word plasticity, with regard to the reshaping of flesh.
The world’s first fully synthetic plastic was bakelite, invented in New York in 1907 by Leo Baekeland who coined the term ‘plastics’. Many chemists have contributed to the materials science of plastics, including Nobel laureate Hermann Staudinger who has been called “the father of polymer chemistry” and Herman Mark, known as “the father of polymer physics”.
The success and dominance of plastics starting in the early 20th century led to environmental concerns regarding its slow decomposition rate after being discarded as trash due to its composition of very large molecules. Toward the end of the century, one approach to this problem was met with wide efforts toward recycling.
Plastic Compounds
The development of plastics has evolved from the use of natural plastic materials (e.g., chewing gum, shellac) to the use of chemically modified, natural materials (e.g., natural rubber, nitrocellulose, collagen, galalite) and finally to completely synthetic molecules (e.g., bakelite, epoxy, polyvinyl chloride). Early plastics were bio-derived materials such as egg and blood proteins, which are organic polymers. In 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines. Treated cattle horns were used as windows for lanterns in the Middle Ages. Materials that mimicked the properties of horns were developed by treating milk-proteins (casein) with lye.
In the 1800’s, as industrial chemistry developed during the Industrial Revolution, many materials were reported. The development of plastics also accelerated with Charles Goodyear’s discovery of vulcanization to thermoset materials derived from natural rubber.
Parkesine (nitrocellulose) is considered the first man-made plastic. The plastic material was patented by Alexander Parkes, In Birmingham, UK in 1856. It was unveiled at the 1862 Great International Exhibition in London. Parkesine won a bronze medal at the 1862 World’s fair in London. Parkesine was made from cellulose (the major component of plant cell walls) treated with nitric acid as a solvent. The output of the process (commonly known as cellulose nitrate or pyroxilin) could be dissolved in alcohol and hardened into a transparent and elastic material that could be molded when heated. By incorporating pigments into the product, it could be made to resemble ivory.
In 1897, the Hanover, Germany mass printing press owner Wilhelm Krische was commissioned to develop an alternative to blackboards. The resultant horn-like plastic made from the milk protein casein was developed in cooperation with the Austrian chemist (Friedrich) Adolph Spitteler (1846–1940). The final result was unsuitable for the original purpose. In 1893, French chemist Auguste Trillat discovered the means to insolubilize casein by immersion in formaldehyde, producing material marketed as galalith.
In the early 1900’s, Bakelite, the first fully synthetic thermoset, was reported by Belgian chemist Leo Baekeland by using phenol and formaldehyde.
After World War I, improvements in chemical technology led to an explosion in new forms of plastics, with mass production beginning in the 1940’s and 1950’s (around World War II). Among the earliest examples in the wave of new polymers were polystyrene (PS), first produced by BASF in the 1930’s, and polyvinyl chloride (PVC), first created in 1872 but commercially produced in the late 1920’s. In 1923, Durite Plastics Inc. was the first manufacturer of phenol-furfural resins. In 1933, polyethylene was discovered by Imperial Chemical Industries (ICI) researchers Reginald Gibson and Eric Fawcett.
In 1954, polypropylene was discovered by Giulio Natta and began to be manufactured in 1957. In 1954, expanded polystyrene (used for building insulation, packaging, and cups) was invented by Dow Chemical. Polyethylene terephthalate (PET)’s discovery is credited to employees of the Calico Printers’ Association in the UK in 1941; it was licensed to DuPont for the USA and ICI otherwise, and as one of the few plastics appropriate as a replacement for glass in many circumstances, resulting in widespread use for bottles in Europe.