About Custom Injection Molding - Plastics
Common Thermoplastics Defined
Thermoplastic Molecular Arrangements
Filler Contributions to Plastic
Compound Design- Rubber
Rubber Material Design

About Plastics

With the boundless flexibility of polymers, copolymers and resins, today’s plastic designer has countless ways of designing a custom plastic molding. There are over 50 plastic types, which translate to over 30,000 different materials that can be derived from these primary plastics.

Plastics are commonly differentiated by the terms thermoplastics and thermosets. Thermoset plastic takes its physical form only upon chemical transformation and cannot be remelted or have its shape altered after this conversion. Thermoplastics, by contrast, can be ground, melted and reshaped given sufficient temperature (and assuming the temperature is not so high as to cause vaporization of chemical breakdown). Due in part to this convenience, thermoplastics are found more readily, and with a wider range of colors and characteristics than thermosets.

Plastics defined by an organized, densely-arranged set of molecules that recur in predictable and specific points are termed Crystalline Plastics. Crystalline Plastics are notable in that they have the tendency to move from solid to liquid state abruptly at their melting temperature. Notable features of Crystalline Plastics are high shrinkage, strong chemical resistance, a greater tendency to warp, a sharp melting point and fast cycling.

A more random arrangement of these molecules found in such common plastics as Polypropylene are known as Semi-Crystalline.

An entirely random set of molecules would define an Amorphous plastic. These plastics are unique in that their characteristics are entirely related to their molecular flexibility. Unlike Crystalline Plastics, the tend to move more slowly from a solid to liquid state. Notable features of Amorphous Plastics are low shrinkage, weak chemical resistance, physical stability, slow cooling and gradual softening.