High-performance polyamides: PPA, PA 4.6 and PARA

Materials › High-performance polyamides: PPA, PA 4.6 and PARA

PPA, PA 4.6 and PARA — polyphthalamide, polyamide 4.6 and polyarylamide — are distinct families, considered when specific combinations of thermal, mechanical and dimensional performance are needed. They are not interchangeable: the choice calls for comparing grades under the intended service conditions, because within each family stabilisation and reinforcement weigh more than the acronym. In our archive they exist only reinforced: an unfilled grade would make no economic sense.

The bars compare reinforcement levels, not families: within each level different chemistries sit side by side, and the GF50 below rests largely on PARA grades, the stiffest of the three. The same figures therefore cannot be applied indiscriminately to a PPA, a PA 4.6 and a PARA: to size a part you need the datasheet of the chosen grade. Under each card it is stated which families the sample is made of, and the composition is unbalanced: the GF30 rests mainly on PA 4.6 grades, the GF50 mainly on PARA grades. These are also expensive, demanding materials: hot mould, thoroughly dried resin, narrow process window. The comparison with a heat-stabilised conventional polyamide has to be made on the grade’s heat-ageing data, under the intended conditions: service life, load, environment, properties to be retained.

Each row is the median of a selection of manufacturers’ datasheets held in our archive, with the property, the standard and the number of grades stated next to the value. These figures describe the sample: they serve to compare the levels with one another, not to size a part, and they are not a guaranteed material specification. For that you need the datasheet of the chosen grade, which we supply on request.

Where a level shows no value, the documented sample was not sufficient: we prefer to remove the figure rather than publish one that does not hold. HDT and impact strength are deliberately absent, because datasheets often do not state the test condition — whether HDT is at 1.8 or 0.45 MPa, whether the impact specimen is notched — and values collected under different conditions cannot be compared.