Page 239 - Engineering Plastics Handbook

Polyphenylene Ether (PPE) Blends and Alloys 205

designed for use in exterior automotive parts, i.e., an injection-moldable
thermoplastic with both the strength and rigidity needed for large panels
and the high heat resistance for in-line or online painting. PPE/PA
alloys offer a unique balance of properties, which is not available in a
single resin. These include

■ Good low-temperature impact
■ High heat resistance
■ Short-term thermal capability over 400°F (200°C)
■ Online paint capability
■ Lower moisture absorption and lower moisture growth over polyamide
■ Higher properties at elevated temperatures
■ Better dimensional stability over nylon
■ Chemical resistance (automotive fluids)
■ Lower density
■ Surface appearance (Class A)
PPE/PA resins are available as unfilled and reinforced grades, a flame-
retardant grade, and conductive grades. In addition, there are PPE/PA
grades that can be processed by injection molding, extrusion, and blow
molding. The performance advantages of long glass-fiber-reinforced
PPE/PA66 materials have been studied [27].
PPA/PA resins exhibit broad environmental resistance to commonly
used automotive fuels, greases, and oils. In addition, these resins are
resistant to detergents, alcohols, aliphatic and aromatic hydrocarbons,
and alkaline chemicals. Where an application requires exposure to, or
immersion in, these or other harsh environments, the acceptable chemi-
cal compatibility of a plastic in an application can only be determined by
exposure to or immersion of prototypes or suitably stressed samples in this
type of environment under actual operating conditions [21].
The versatility of PPE/PA resins has resulted in an extensive variety of
automotive and nonautomotive applications. These include automotive
wheel covers, automotive exterior vertical body panels, automotive elec-
trical connectors, fluid engineering, office furniture, and lighting.

PPE/Polyamide Grades
Unfilled PPE/PA grades. These offer enhanced dimensional stability,
chemical resistance, and in most cases paintability. These grades are
made with polyamide 66. Representative properties of PPE/PA66 grades
appear in Table 9.9. Grades and key features include