Manipulating modulus

Metals

Relatively strong bonds

Dense

Many bonds per unit volume

Moderate-high modulus

Ceramics

Many atoms per unit volume

Stronger bonds

Very high modulus

Great specific stiffness

Polymers

Largely hydrocarbon chains

Strongly bonded along chain- not between

lower modulus

Thermo plastic

Not cross-linked

Melts when heated

Amorphous

Thermoset

Cross-linked

Degrade when heated

Amorphous

Elastomers

Lower modulus

Huge elastic strains

Foams

Less dense since air bubbles

Greatly reduced modulus

Composites

Combine with ceramics to increase modulus

Stiffness is intermediate between the two combined materials

How do you modify modulus?

Add alloying elements to METALS

how are composites used?

Reinforcement for the material that resists loads

Surrounds the reinforce, en and protects from the environment