Читать книгу Packaging Technology and Engineering - Dipak Kumar Sarker - Страница 17

Rubber used in sealings and liddings became a mainstay of commercial packaging when, in 1849, Charles Goodyear and Thomas Hancock developed a method that destroyed the ‘tacky–sticky’ property of the material and added extra elasticity to natural rubber. In 1851 hard rubber, often referred to as ebonite, became commercially available in the Western world. A completely new revolutionary form of packaging was created in the invention of plastic. The innovative original artificial plastic was created by Alexander Parker in 1838 and was displayed at the Grand International Fair in London in 1862. This ‘parkesin’ rigid ‘resin’ was thought to be able to replace natural materials such as hardwoods and ivory. In 1892 William Painter patented the still ubiquitously used ‘crown cap’ closure (see Figure 3.3c) for bottles shaped from glass [1], which kept air (containing degrading oxygen) out and product flavours locked in. Also, in 1870 Hyatt took out a patent for ‘celluloid’ produced from cellulose in highly controlled conditions, under high pressure and temperatures. This created a polymer with low nitrate content for many different types of product wrappings. This discovery is now thought of as the first commercialised plastic and remained the only ‘plastic’ until 1907, when Baekeland produced ‘Bakelite’ (also spelt as Baekelite). Bakelite was universally used until the 1970s but was replaced by a new wave of plastics. A more exact understanding of plastics arose in 1920, when Hermann Staudinger's revolutionary idea was extolled and the notion of a plastic as a physical property rather than a chemical class came into fruition. All plastics, rubber, and cellulose are polymers or macromolecules but notably some do not show significant plasticity or deformability without brittle rupture. Staudinger's pioneering work concerning ‘polymer science’ was awarded the Nobel Prize in 1953.