Section 3 – pg 306 Polymers and Composites Chapter 8 Section 3 – pg 306 Polymers and Composites

Carbon’s Chains and Rings Pg 306 Carbon’s Chains and Rings Bonded carbons form the “backbones” to which other atoms attach

Carbon Compounds and Polymers Pg 307 Carbon Compounds and Polymers Polymers form when chemical bonds link large numbers of monomers in a repeating pattern A polymer may consist of hundreds or even thousands of monomers

Pg 308 Natural Polymers Cellulose: strong flexible polymer found in plant cell walls Made in plants when sugar molecules are joined into long strands Humans cannot digest cellulose Starches: formed from sugar molecules that are connected in a different way than cellulose Found in pastas, breads, and many veggies Humans can digest starch

Polymers made by animals Silk: fibers of the cocoons spun by silkworms Wool: made from sheep’s wool Protein: a polymer is made of the amino acid monomers Depending on how they are used and in what order they form different things like fingernails, muscles and hemoglobin Pg 308

Pg 309 Synthetic Polymers Many common polymers are synthesized or made from simpler materials The base for many is coal or oil Plastic, carpet, clothing, glue, chewing gum are synthetic polymers

Pg 310 Comparing Polymers Synthetic polymers are often used in place of natural materials that are too expensive or wear out too quickly Polyester and nylon are used in place of wool, silk and cotton in clothes Laminated countertops and vinyl floors replace wood Synthetic polymers are also in CDs, computer parts, artificial heart valves and bike tires

Pg 310 Composites Composite: combination of two or more substances in a new material with different properties The combining of substances allows for a better stronger material to be made Many composites include one or more polymers A common natural composite is wood Made of long fibers of cellulose held together by lignin Cellulose is flexible but weak and lignin is brittle, but the combination of these two polymers makes wood strong

Pg 312 Uses of Composites Fiberglass composites are composed of glass fibers woven together and strengthened with a liquid plastic Strong and easy to mold material that is used for boat hulls, snow boards and bath tubs Fiberglass will not rust like metal does

Pg 313 Recycling Plastics It is often cheaper to throw plastics away and make new ones than it is to reuse them This leads to increased volume of trash Plastics last so long b/c they do not react very easily with other substances so they do not break down or degrade You can help reduce the amount of plastic waste by recycling

Chapter 8 section 3 Homework – pg 313

1A. What are polymers made of?

1B. What properties enable carbon atoms to form polymers and so many other compounds?

1C. How do the two kinds of polymers modeled in Figure 16 differ?

2A. Distinguish between natural polymers, synthetic polymers, and composites.

2B. Make a list of polymers you can find in your home 2B. Make a list of polymers you can find in your home. Classify them as natural or sythetic.

2C. Why are composites often more useful than the individual materials from which they are made?

3A. List two benefits and two problems associated with the use of synthetic polymers

3B. What happens to waste plastics when they are recycled?

3C. Think of something plastic that you have used today 3C. Think of something plastic that you have used today. Is there some other material that would be better than plastic for this use?