low density

low melting point (large molecular weight increases bonding and melting point)

low corrosion

low thermal and electrical conductivity (C-C bonds are covalent, pi bond increase electron mobility)

• mix two materials
• matrix phase surrounded dispersed phase
• process seperately and bond together

• fiber-reinforced
• tissue -- cells dispersed in extracellular matrix
• shell -- mineral matrix with organic particles
• crystalline (load bearing) -- collagen
• amorphous (elastic bonding) -- elastin

nature and quantity of material

shape and size

bonding between components

parallel along fibers:

composite modulus = volume percent (a) x modulus (a) + (1 - volume percent (b)) x modulus (b)
= V1E1 + (1 - V1) x E2

perpendicular to fibers

E = [V1/E1 + (1 - V1)/E2]^(-1)

1. least soluble protein
2. 3D cross-linked network
3. elastic
4. difficult to process

1. compact fiber (good strength)
2. function: skin, tendon, bone, cartilage, blood vessel wall, basement membrane
3. structure: porous (cell migration, suck blood)