Dipak Kumar Sarker

Packaging Technology and Engineering


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of course to make paper and cardboard but also for direct use in pallets and crates (tertiary packaging). Wood can also be used as a source of cellulose for cellophane and in modern‐day bioplastics, which are made from hydroxypropyl methyl or ethyl celluloses (see Sections 3.4 and 3.4.1). Plant and animal materials may include starch and gums for use in paper and bioplastics, proteins, waxes, exudates such as natural rubber or amber, leather, and natural biodegradables. Finally oil and gas are most routinely used to make polyolefins (plastics), waxes, dyes, and synthetic polymers [6]. Figure 2.1b highlights the inter‐relationships and end products of the principal sources of raw materials and also of the process aids used in making the packaging. The five starting materials are also sources of key functionalising additives, including pigments, silicates (for paper sizing), natural biodegradable materials, dyes, and the polymers that are used across all packaging media. Smelting of ore is a prime example of taking a crude starting commodity in the form of an inorganic mineral ore and creating an entirely different material. When extracting the metal for direct or indirect further use, this can create many derivative product materials; common examples would be bauxite (aluminium) or haematite–magnetite (iron). High temperatures are needed in this energy‐intense and highly polluting fabrication process [7], such as 1560 °C for iron and 660 °C for aluminium (see Table 3.9). Glass‐making (discussed in Section 2.4) takes various adjuvants and sand, cullet, soda, and lime and occasionally other compounds such as boric oxide to create a supercooled highly viscous amorphously structured fluid or ‘glass’. Pigments such as cobalt are used to give the glass a blue hue or colour.

      Wood chips, another starting material, are mechanically or chemically degraded to fabricate paper that, after further bleaching processing, produces white paperboard. Plant and animal matter can be used to harvest cellulose and exudates or proteins [8] that can be used in bioplastics and leather. Finally, crude oil, by processes such as cracking and fractional distillation, is used to create polyolefin plastics such as PE. The breakdown products of the oil and gas industries such as aniline are also used to create a range of nitrogenous azo dyes, such as mauveine (aniline purple), which was invented by William Perkin in 1856.

Illustration of commodities and raw materials, core ingredients, and fabrication aids used in their manufacture: Iron and steel; aluminium; glass; paper; plactis; and wood.

      The iron ore blast furnace as the basis for all iron‐ and steel‐making via the production of pig iron is used in a form that is little altered from the original 1855 Bessemer configuration or the simpler format that Abraham Darby used in 1709. At the base of the furnace is a hearth (at 1300 °C); above this portion of the furnace is a zone called the bosh (at 1700 °C), which is the hottest part; at the bosh, molten iron exits the furnace and liquid or gaseous fuel and air are injected via tuyère pipes. The bosh lies below the barrel (at 1500 °C), which ascends up the furnace to the upper portion and to the stack, the throat (at 1000 °C), and finally the flue (at 500 °C). The lining of the blast furnace is constructed from refractory fire bricks that insulate the material and retain a suitable melt temperature in the core of the furnace. Chemical energy is also supplied to the liquid pool of metal via oxygen fuel burners and oxygen lances. Oxygen fuel burners use natural gas mixed with oxygen or a blend of oxygen and air. Heat is transferred to the metal by flame radiation and convection by the hot products of combustion, and heat is transferred within the molten metal by simple conduction. Modern cylindrical blast furnaces can be 20–40 m tall with a maximal width at the base hearth of 5–15 m. Output varies but modern production can make between 1000 and 10 000 tonnes of pig iron per daily campaign. The modern blast furnace process starts with a means of placing the iron ore as a starting point in the furnace with a top‐loading filling device, which charges the furnace with coke, iron ore, recycled iron, and limestone. At the base of the furnace is a sage hole to remove waste and a tap hole to extract the liquid pig iron. Waste gases such as carbon dioxide, carbon monoxide, and various sulfurous gases leave via the stack and through the flue gas [7].

      There are, in principle, six main types of materials used for packaging materials (Figure 2.2). The main categories are aluminium, steel‐iron, glass, paper, plastics (of which there are many types), and wood. Of course, as shown in the figure, the individual types and sourcing for all materials have a large influence on the manufactured end product. Taking wood as an example, there are softwood and hardwood varieties with different grain structures that can be used to produce different types of transport crates, palettes, or shipping boxes as well as different grades of paperboard and paper. With metals, plastics, and glass the background concentration of impurities