OUR GROUP 6 SCIENCE PRESENTATION

1. OUR GROUP 6 SCIENCE PRESENTATION • By: • Ryan Teo (Group Leader), • Yong Ming , • Shao Wei and • Daren Tung

2. CONTENTS Slide 1 – Introduction & Contents Slide 2 to 5 – Glass Slide 6 to 8 – Plastics Slide 9 - References

3. GLASS • Glass is basically sand • It can be coloured or colourless, transparent, translucent or opaque. • It is lightweight, waterproof, readily cleaned and reused, durable and fragile, and often very beautiful. • Its optical properties are exceptional, in camera and spectacle lenses. • They are used for cups, bowls, dishes and windows. Close up of sand Calcium carbonate Computer image of sodium carbonate

4. Cathedral windows

5. Roman glass objects have been recovered across the Roman Empire. • Glass was used primarily for the production of vessels, although mosaic tiles and window glass were also produced. • Production of raw glass was undertaken in geographically separate locations to the working of glass into finished vessels. • By the end of the first century AD large scale manufacturing resulted in the establishment of glass as a commonly available resource. A Munich Cage Cup, dated to back to the mid-4th century AD.

6. The main types of glass are described below:1) Commercial glass or Soda-lime glass: • The most common commercial glass and least expensive. • Itscomposition : 60-75% silica, 12-18% soda, and 5-12% lime. • Smooth and nonporous surface that allows glass bottles and packaging glass to be easily cleaned • Disadvantages : not resistant to high temperatures and sudden thermal changes. • Primarily used for bottles, jars, everyday drinking glasses and window glass. 2) Borosilicate glass: • Borosilicate glass is mainly composed of silica, boric oxide and smaller amounts of the alkalis and aluminum oxide. • Borongives greater resistance to thermal changes and chemical corrosion. • It is resistant to thermal shock . Glass vases Shattered glass

7. PLASTICS Plastics are materials made up of long, chainlike molecules are called polymers. The word plastic is derived from the words plasticus (Latin for “capable of molding”) and plastikos (Greek “to mold,” or “fit for molding”). • Properties of Plastics : - • Lightweight • Durable • Reusable • Waterproof • Chemical resistant • Non-conductor of electricity • Does not rust or rot Plastics can be made hard as stone, strong as steel, transparent as glass, light as wood, and elastic as rubber. Types of Plastics :- 1) Impact-resistant (shatterproof) plastic 2) Heat-resistant plastic Plastics are moldable, synthetic (chemically-fabricated) materials derived mostly from fossil fuels, such as oil, coal, or natural gas Plastics are indispensable in our modern way of life. They are widely used in computers, furniture, utensils, recreational equipment, etc.

8. Plastics are "one of the greatest innovations of the millennium“ BUT Impact on health and environment:- • Most plastics do not pose any hazards, but some substances that are used in manufacturing plastics, have been proved to cause cancer for example nylon. Even though recycling continues to reuse plastics, most plastics do not rot and cannot be reused. Unfortunately, this will soon become an environmental problem. However, new technologies are being developed to make plastic from biological substances like corn oil. These types of plastics would be biodegradable and better for the environment. Recycling Machine Waste plastic

9. REFERENCES Slide 3 - http://www.memories-in-glass.com/glass-what-is-it1.htm Slide 3 - http://EzineArticles.com/?expert=Sylvia_Kittens Slide 4 - http://ezinearticles.com/?The-History-And-Use-of-Glass-Crystal&id=954784 Slide 4 – http://www.featurepics.com/StockPictures/Stained-Glass-655573.aspx picture Slide 5 - http://en.wikipedia.org/wiki/Roman_glass Slide 6 - http://www.lenntech.com/glass.htm Slide 7 - http://en.wikipedia.org/wiki/Plastic • Slide 8 - http://library.thinkquest.org/C003844/a_effects.htm Slide 8 picture -http://img.alibaba.com/photo/11284159/Waste_Plastic_PE_PP_ABS_Recycling_Machine.jpg

10. Q & A