plastic terms



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.