CLTE Co-efficient of linear thermal expansion Eg: pvc .000035 per inch per degree of temperature
change from ambient F.
DUROMETER Hardness of plastic measured by the resistance of indentation. Shore A for softer plastic
Shore D for harder plastic.
MELT INDEX An ease of flow measurement for a thermoplastic defined as the mass of plastic in grams
flowing in 10 minutes through a specific size orifice.
IMPACT A physical property and measurement of the relative impact strength of different materials
STRENGTH using a drop dart impact tester.
PLASTICIZER A substance added to plastic materials to increase softness or flexibility
DIE LINES Horizontal or longitudinal lines or marks on the extruded surface
FLEXURAL The physical property and measurement of a materials relative stiffness to deflection under
MODULUS pressure or tension.
DRAW DOWN Pulling the extrusion from the die at a linear speed higher than that at which the material
is naturally emerging from the die. This brings the extrusion into the correct dimension.
ELONGATION The stretching of plastic material which changes dimensions.
THERMOPLASTIC Materials that become soft when heated and solid when cooled over and over again.
THERMOSET Materials that experience a chemical change during processing that become solid and stay
solid even if heated again.
ELASTOMER Flexible materials that can be stretched up to twice their length at room temperature and
return to their original length when released.
CRYSTALLINE Stronger and stiffer materials that process at a higher temperature with a narrow window
from solid to liquid. Eg: polyethylene and nylon. Can’t be melted again.
AMORPHOUS Disorganized polymer chains that melt at lower temperatures gradually. Eg: pvc and abs.
Not as strong and stiff as crystalline plastics. Can be melted and solidified many times.