Presentation on theme: "It’s a material world. What is a material? Activity: What are some materials? Individually write down a list of 10 different materials. Share them with."— Presentation transcript:
Activity: What are some materials? Individually write down a list of 10 different materials. Share them with the class. Now divide up the list on the board into synthetic (‘man made’) and natural materials.
Activity: Define material Individually write down a definition for what a material is. Share your definition with the person next to you and rewrite your definition together. One member of each pair is to then read out their definition to the class. Copy down the class definition from the board.
Ford’s Biological Car On August 14, 1941 Henry Ford unveiled the biological car! 70% of the car was made from straw, cotton, hemp, pine. The other 30% was made from soymeal and bioresin. The only steel in the car was the frame. The car was the result of 12 years research. Henry Ford proved the durability of the car by swinging an axe into it
Activity: What’s in a car? In a group of 4 make a list of the components from a car that might be made from plastics? Compare your groups list to another group. Was there anything you missed? High tech car Low tech car
Monomers Small individual molecules are called monomers. A process called Polymerisation combines individual monomers to form large chains. Mushroom MonomersStar Monomers
Polymers The large chains formed by polymerisation are called Polymers. Polymer is the scientific name for what people generally call plastic. “Poly-Star” polymer “Poly-Mushroom” polymer
Another way of thinking about it: Paper Clips If there was a monomer called ‘paper clip’, a string or chain of ‘paper clips’ would be a polymer. This polymer would be called “poly-paper clip”. Monomer = “Paper Clip” Polymer = Poly -“Paper Clip”
Co-polymers To create new polymers different monomers are combined. These are called co-polymers. There are two types: Random co-polymers: Monomers are randomly dispersed. Block Co-polymers: one polymer chain is added to another. Random Co-polymers Block Co-polymers
Examples of Monomers and Polymers MonomerPolymer Vinyl ChloridePoly (Vinyl Chloride) EthylenePolyethylene StyrenePolystyrene PropenePolypropylene
Plastics can be classified as either thermoplastic or thermosetting depending on what they do when they are heated.
Thermoplastic When lightly heated many plastics soften or melt and can be remoulded into new shapes. When cool they reset. Examples are PVC, polythene (Plastic bags) and acrylic. The molecules in these materials are arranged in a parallel chain. When heated they are able to slide over each other and form a new shape. (Melt → Reset) Heat Linear chains move apart
Thermosetting Thermosetting plastics cannot be remoulded. The polymers have crosslinks between the chains. This makes thermosetting plastics: Hard (Scratch resistant) Brittle (Will shatter when dropped) Rigid (Not able to be bent) However when heated thermosettings will char (or burn), not soften. Heat Crosslinks Branch
An easy way to remember the difference between Thermoplastic and Thermosetting plastic is to recall what happens when they are subjected to a flame…
Thermoplastic melts Because thermoplastics can be melted into new shapes they are recyclable.
Alternatives: Plantic® is a type of biodegradable plastic produced by the Plantic Company, which is based in Australia. It is derived from starches found in corn, rather than petrochemicals (like oil), making it sustainable and very environmentally friendly. Plantic is designed to break down quickly and naturally, ensuring that their component starches return to the earth, rather than remaining in landfills Plantic can be found in Cadbury milk trays
What is a fibre? A fibre is any substance that can be woven or knitted into a fabric. Fibres can be either: Natural: Derived from animals or plants. Synthetic: Chemical modified natural fibres or artificially made. Natural Synthetic
Natural Fibres Hair, fur, cotton silk are all examples of natural fibres. In the past natural fibres were knitted and woven into clothing, blankets, rugs, carpet, mats, rope, baskets and bags. CottonSilkFlax LinenFur
Synthetic Fibres Nylon, Lycra, Kevlar, spandex, polyester are all synthetic fibres. Although most synthetic fibres are base on synthetic polymers, some use natural polymers as starting material. LycraMixturesKevlarSpandex
Collecting Body Products and Fibres Whether a fibre is synthetic or derived from an organism it can be examined under a comparison microscope. However finding a match from one fibre at a crime scene and one from a suspect is strong circumstantial evidence but not conclusive
How synthetic fibres are made Synthetic fibres are produced by the extrusion of a polymer though a Spinneret. Mixtures of different polymers can be combined prior to extrusion to form new fibres. Multi-Holed Spinneret
Science at Work: Spider Silk Spider silk is a protein that is formed as a liquid by silk glands and squeezed out of spinnerets Some types of spider silk are stronger than a steel thread of the same diameter Some spiders produce different kinds of silk for different functions: Wrapping prey Making eggs Building webs
Science at Work: Spider Silk “You have to admit it’s a bit weird that we live in houses that we make out of stuff that squirts out of our butts!