Exploring Materials

Polymers and Composites Most materials are made up of polymers. A polymer is a large, complex molecule built from smaller molecules (monomers). Starches and proteins found in food are examples of natural polymers. Polyester, nylon clothing and plastic are examples of synthetic polymers. Starches

Most polymers rely on the element carbon (C) Most polymers rely on the element carbon (C). Carbon is present in several million known compounds. Different structures of carbon bonds: Ring chain Straight chain Branched chain Ring chain

Composites Composites combine 2 or more substances in a new material. Many composites include one or more polymers. Ex. Wood is a natural composite because it is made of 2 polymers: cellulose and lignin. Fishing rod and fiber glass are synthetic composites. They are light and strong.

Why synthetic polymers can be a source of pollution? Therefore it is very important to recycle plastic instead of throwing away. Because they are strong and last for a long time (thousands of years). Because they are strong and last for a long time (thousands of years).

Metals and Alloys Metals are shiny, malleable, ductile, conductors and solid at room temperature (except mercury).

Alloys are a mixture of metals that have better properties. Brass is a mixture of what? Copper and zinc. Used in musical instruments and jewelry Bronze is a mixture of what? Copper and tin. Used for screws and grillwork. Copper and zinc. Stainless steal is a mixture of what? Iron, carbon, nickel and chromium. Used in kitchenware and for surgical instruments

Ceramics and Glass

Ceramics and glass are brittle (break easily), but resist to moisture and don’t react easily. Some ancient ceramics are in good condition even today.

What are ceramics made from? From clay that is heated above 1000⁰ C. Pottery Bricks

What is glass made from? Glass is used to make windows, glasses, lenses, telescopes, optical fiber. From heated sand mixed calcium and sodium. From heated sand mixed calcium and sodium.

Radioactivity Radiation is produced during the radioactive decay. Natural radioactive decay can produce: Alpha decay Beta decay Gamma Radiation

Radioactive Isotopes Radioactive isotopes are used to provide energy, treating diseases, to determine the age of natural materials on earth. Some nuclear plants use radioactive isotopes (Uranium -235) to produce electricity. It is very important to manage radioactive materials carefully because they are dangerous. Chernobyl Fukushima