polymers and composites

Question 1

polymer definition

Answer 1

a substance with very long molecules. has identical groups of atoms, repeated many times.

Question 2

examples of polymers

Answer 2

wool, cotton, rubber

Question 3

natural polymers definition

Answer 3

polymers that come from plants and animals. eg. rubber trees make rubber

Question 4

wool;

Answer 4

traps heat because wool fibres trap air between them, useful for jumpers and socks

Question 5

cotton is;

Answer 5

strong and durable. it absorbs sweat, useful for T-shirts

Question 6

Rubber is;

Answer 6

flexible, waterproof, and durable. suitable for tyres

Question 7

synthetic polymers definition

Answer 7

they do not occur naturally, they are made in chemical reactions. there are hundreds of synthetic polymers, and they each have their own properties

Question 8

poly(ethene)

Answer 8

is a scientific name for polythene. there are two types, neither type breaks down and decays naturally.

Question 9

LDPE

Answer 9

low-density poly(ethene). the molecules slide over each other, making it flexible but strong. used in carrier bags.

Question 10

HDPE

Answer 10

High-density poly(ethene). also strong and flexible. harder than LDPE, the surface can be very smooth. used in artificial knee joints that include metals like titanium.

Question 11

PVC

Answer 11

Poly(vinyl chloride) is waterproof, flexible, and does not conduct electricity. is suitable for waterproof clothing and insulating electric cables.

Question 12

composites definition;

Answer 12

a mixture of materials. a combination of material properties. eg. reinforced concrete is made up of steel bars coated with concrete; concrete is strong, but can break when stretched, with steel, however, it does not break as easily.

Question 13

CFRP

Answer 13

carbon-fibre-reinforced plastic has low density, does not rust, is very strong, and can be moulded into any shape.

Question 14

CFRP composites

Answer 14

carbon fibres ( thin tubes of carbon ) woven into a fabric and a gluelike polymer to mould it into different shapes. CFRP can be used to make bicycles, but they are often expensive and are badly damaged when crashed.

Question 15

the airplane A380

Answer 15

is the largest passenger airplane. contains approximately 20% composite materials including;
-thin layers of aluminium
-layers of glass fibre
-a gluelike polymer to join the layers