In this chapter we identified how the atomic structure of plastics, metals, and ceramics determine their physical properties. We identified the six atom building blocks for all plastics and discovered how these six atoms are linked by covalent bonds, Van der Waal's force, and molecule complexity. We discovered that plastic materials are structures of super long string molecules entwined with each other and formed into two basic structures: random (amorphous) and ordered (crystalline) patterns.
Also we discovered that a plastic's micro structure is viscoelastic, exhibiting both properties of viscous flow and elastic solid. The amorphous areas of the micro structure determine viscous response. The crystalline areas exhibit properties of an elastic solid. The higher the crystallinity, the more stable the material. All but seven plastic materials have micro structures that are more than 80% crystalline and are consider crystalline materials.
The manufacturing process used with plastic materials is called polymerization. In the polymerization process billions of small molecules, called monomers are combined to form giant molecules called polymers. These new giant molecules form microstructure that are linear, branched, or cross linked. Linear molecules form into crystalline structures. Branched molecules form into amorphous structures. Cross linked molecules will not melt and create thermoset plastic materials.
