PPA

Polyphtalamide (PPA) denotes a series of nylon types with enhanced temperature resistance. They are capable of withstanding continuous temperatures of up to approximately 180°C and in terms of their price/performance ratio they are extremely attractive. PPA is used a lot in the automotive and electronic industries, also because of their chemical resistance and excellent mechanical and tribological specifications. Examples of applications include bearing boxes, connectors, casings, reflectors, ignition coils and plastic parts under vehicle bonnets. Use in combination with higher electrical voltages is also possible, for example in fuse holders.

Depending on the load, PPA is usable at temperatures of up to 180°C, with transient outliers up to 280°C. The moisture absorption is 2.5% at 23°C/50% RH and 8% after saturation in water, but these values are attained only after a very long time. In practice, the moisture absorption of glass fibre-strengthened PPA is less then 0.3% after 24 hours at 23°C.

Resistance to most organic solutions like alcohol, ketones, halogenated hydrocarbons and aliphatic and aromatic hydrocarbons is excellent, and the same applies to watery solutions of acids, alkaline substances, oils, greases and lubricants. Contact with strong acids and phenols must be avoided.

PPA is less sensitive to UV compared with PA6.6, but the addition of black carbon provides a significant improvement. The material is easily capable of withstanding cold deformation and stands out for its unrivalled combination of rigidity and strength, about 30% better than PA6.6.