Today's KNOWLEDGE Share : POLYAMIDE-IMIDE (PAI)

Today's KNOWLEDGE Share

POLYAMIDE-IMIDE (PAI)

Polyamide-imide (PAI) is an amorphous, opaque thermoplastic that can be melt processed using conventional injection molding, extrusion or compression molding techniques.

PAI or polyamide-imide is one of the most resistant polymers on the market today. It draws its notoriety from its resistance. Without additives, polyamide-imide has the ability to withstand extreme temperatures. This material remains unchanged even when exposed to a temperature of 270°C.

Furthermore, PAI is a very durable plastic, has low frictional resistance and is resistant to UV, gamma and X-rays.

SPECIFIC GRAVITY :1.41

TENSILE STRENGTH 21,000 psi

FLEXURAL STRENGTH  33,000 psi

FLEXURAL MODULUS  600,000 psi

COEFFICIENT OF LINEAR THERMAL EXPANSION :1.7 (D696)

WATER ABSORPTION (Immersion 24 hours):0.30 (ASTM D570)

GLASS TRANSITION TEMPERATURE :280 °C

MAX CONTINUOUS SERVICE TEMPERATURE IN AIR :500 °F

HEAT DEFLECTION TEMPERATURE @ 264 psi :532 °F

DIELECTRIC STRENGTH:600 (D194)

When PAI is melt-processed, its high glass transition temperature, non-Newtonian flow over a wide processing shear range and its amorphous morphology pose many significant challenges. Among the most challenging are:

*Narrow processing window with processing temperatures greater than 600 F

*Melt viscosity that is highly temperature and shear rate sensitive

*As a polycondensation polymer, PAI is highly moisture sensitive and must be thoroughly dried and maintained during melt processing to prevent molecular weight and thermal-mechanical property degradation

*Thermal cure for 20 or more days at 500 F to optimize properties after melt processing.

To achieve optimum properties, PAI must be processed under closely controlled conditions and then thermally cured to advance its molecular weight through a staged heat cycle up to 500 F. The curing process completes the imidization process and builds molecular weight via polycondensation. Water is the condensation by-product which must be removed in order to advance the MW and Tg. Since polycondensation is a two-way reaction, it is critical to remove water to advance the reaction. If water is present at temperatures at or above the glass transition temperature, hydrolysis and property loss can occur.

Polyamide-imide / PAI is used for manufacturing of:

Moving parts, track rollers, bearings, gears, bearing washers.

Bushings, vanes, seals, jacks and panels, electrical components and bushings, gears, plugs,connectors, parts of pumps, seals, valves,items furnaces conveyors, hydraulic valves, air grilles, security features

clutch seals bearing and sliding bearing portion.

PAI - polyamide-imide is used for runners, guide rollers in printers, copiers.

PAI available in Unfilled Grade,Graphite filled,glass filled,carbon filled PAI grades are available in the global market to meet the end application requirements.

Major Brands:Tecator, Torlon, Duratron, Kermel

source:solvay/brakeplastics/ptonline.com