Plastics Polymer Terms and Definitions - Engineers Edge

Plastics Design Resources
Injection Molding Manufacturing and Services

Definitions realted to plastics industry, materials and manufacturing.

Alloys - is a way to create custom variations in plastics. I general alloys are combinations of polymers that are physically mixed.

Brittleness - is the lack of a material to with stand impact. Typically, brittle materials have lower impact and higher stiffness properties.

Density - of any material is a measure of the mass per unit volume.

Ductility - is the ability of a material to be stretched, pulled, or rolled into shape with destroying the integrity of the material.

Elasticity - is the ability of a material to return to its original size and shape after being deformed. Most plastic materials have limited elasticity.

Elastomers - A material which at selected temperatures stretches under low stress and returns back to the original length upon release of stress.

Notch Sensitivity - is a measure of the ease with which a crack propagates through a material from a pre-existing notch, crack or sharp corner.

Plasticity - is the inverse of elasticity. A material that tends to stay in the shape or size to which it is deformed has high plasticity.

Specific Gravity - is the ratio of the mass of a given volume of material compared to the mass of the same volume of water, as measured at 23 degrees centigrade.

Thermosets - are plastics that undergo chemical change during processing to become permanently insoluble and infusible. Thermoset material will undergo or has undergone a chemical reaction by the action of heat, catalysts, ultra-violet light, etc., leading to a relatively infusible state. Typical of the plastics in the thermosetting family are the aminos (melamine and urea), most polyesters, alkyds, epoxies, andphenolics.

Thermoplastics - are resins that repeatedly soften when heated and harden when cooled. This characteristic facilitates the forming of the material into desired shape when the thermoplastic is placed within a die or fixture of the desired final geometry. This process is referred to as Thermoforming .

Water Absorption - is the materials tendency or lack of to absorb water.