Pre-History Stone Flint Wood

20,000 BCE Gold Easy to form (Malleable) Although 20,000 BCE is an estimate, gold is the earliest metal to be processed by humans.

7,000 BCE Copper, Silver Native metals (gold, copper, silver) were discovered and found to be ductile thus easy to form

5,000 BCE Pottery Cement Glass Smelted copper Heating and reducing substances (like charcoal) that react with the oxidizing elements

3,500 BCE Tin Bronze Alloy of Copper and Tin. Earliest Bronze pieces had about 2% tin, suggesting it was an accident Later tin content increased and suggests intention

3,000 BCE Papyrus Second polymer in use (after wood) First processed polymer Stems of papyrus plant are stripped, rotted (retted), and pressed into a polymer sheet

1,500 BCE Iron Needs higher temperature than bronze Much more abundant than copper

1,000 BCE Lacquer Extracted from tree sap Used to preserve wood

100 BCE – 100 CE Amber Horn Paper Starting to develop more methods of extracting natural resources and converting to modern needs

800 CE Gutta percha Natural latex is produced from the sap of the percha Bioinert, resilient good electrical insulator Sap was left in sun to evaporate, leaving thermoplastic latex

1000 CE Crucible steel Iron + carbon

1500 CE Iron smelting Rubber

1700 CE Platinum Cobalt Zinc Nickel Tungsten Zirconium Uranium Strontium Titanium

1800-1850 Magnesium Aluminum Silicon Cellulose Nitrate Flash paper, guncotton Vulcanized rubber Reinforced concrete

1850-1900 Ebonite Bessemer steel Glass fiber Cellulose acetate First inexpensive purification method Glass fiber Cellulose acetate Aluminum oxide

1900-1920 Bakelite Stainless steel Synthetic rubber Nylon First truly synthesized polymer Thermoset phenol formaldehyde Stainless steel Synthetic rubber Nylon

1920-1940 Neoprene PMMA PVC PU PET PTFE Plutonium

1940-1960 Formica Lycra PS Composites Super alloys Acetal POM PC PP Amorphous metals Metallic glasses

1960-1980 Polyimides Polysulfone PPO LLDPE Shape memory alloys Carbon fiber

1980-2000 PEEK PES PPS Warm superconductors Nano materials Biopolymers

Reliance on materials We are totally dependent on materials We have shifted from renewable to non-renewable Transportation, communications, ordinance

Materials Consumption About 10 tons per person per year in US Thomas Malthus, 1798: The power of population is so superior to the power of the Earth to produce subsistence for man that premature death must in some shape or other visit the human race.

Consumption Club of Rome (1972) …if [current trends] continue unchanged … humanity is destined to reach the natural limits of development within the next 100 years.

Is this the end? World Commission on Environment and Development (1987) many aspects of developed societies are approaching saturation, in the sense that things cannot go on growing much longer without reaching fundamental limits. This does not mean that growth will stop in the next decade, but that a declining rate of growth is foreseeable in the lifetime of many people now alive. In a society accustomed to 300 years of growth, this is something quite new, and will require considerable adjustment.

Competence Humans differ from other species in our competence to make things from materials Termites, beavers, birds, etc. make things Difference is competence shown by humans Ability to expand and adapt through research and development Are materials the servant or master?

Exercise It takes energy to make materials, called “embodied energy” and expressed in terms of the energy per unit mass (MegaJoules/kilogram = MJ/kg). If you could reduce consumption by 10%, rank the following 5 Engineering materials in order of greatest global energy savings to least. Explain your conclusions and show calculations to support them. Details on next page show embodied energy and total tons (1,000 kg) consumed in a year.

Material Embodied Energy (MJ/kg) Annual Global Consumption (tons/year) Steels 29 1.1 billion Aluminum alloys 200 32 million Polyethylene 80 68 million Concrete 1.2 15 billion Device grade silicon 2,000 5,000