PA6.6: Polyamide 6.6

General Properties

Short Name:

Name:

PA6.6

Polyamide 6.6

Along with PA6, PA6.6 is one of the most frequently used polyamides and belongs to standard plastics. As already mentioned for other polyamides, PA6.6 can absorb humidity (e.g., air humidity). This allows for a higher flexibility and toughness, but, at the same time, reduces hardness and strength. It can also result in volume changes in the material. Polyamide 6.6 (PA6.6) is produced by a polycondensation reaction between hexamethylene diamine and adipic acid. F

Structural Formula

Properties

Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.Glass Transition Temperature	65 to 90°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Temperature	225 to 265°C
Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).Melting Enthalpy	185 J/g
Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. Decomposition Temperature	430 to 473°C
Young's Modulus	3000 MPa
Coefficient of Linear Thermal Expansion (CLTE/CTE) The coefficient of linear thermal expansion (CLTE) describes the length change of a material as a function of the temperature.Coefficient of Linear Thermal Expansion	35 to 45 *10^-6/K
Specific Heat Capacity	1.67 to 1.70 J/(g*K)
Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.Thermal Conductivity	0.24 to 0.33 W/(m*K)
DensityThe mass density is defined as the ratio between mass and volume. Density	1.13 to 1.16 g/cm³
Morphology	Semi-crystalline thermoplastic
General properties	Good mechanical strength. High impact strength. Good damping behavior. Good abrasion resistance
Processing	Injection molding
Applications	Mechanical, automotive and apparatus engineering, e.g., for plain gearings, gear wheels, sliding plates

NETZSCH Measurement

Instrument	DSC 204 `F1` `Phoenix^®`
Sample Mass	10.15 mg
IsothermalTests at controlled and constant temperature are called isothermal.Isothermal Phase	5 min
Heating/Colling Rates	10 K/min
Crucible	Al, pierced lid
Atmosphere	N₂ (50 ml/min)

Evaluation

As a semi-crystalline thermoplastic, PA6.6 showed a Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition at 68°C (midpoint) in the 2^nd heating (red) and an endothermal melting range from approx. 200°C to 270°C. As is often the case for PA6.6, a second melting transition at 250°C can be observed as a pre-peak (or shoulder) prior to the actual main melting effect with a peak temperature of 261°C. In the 1^st heating (blue), Post Crystallization (Cold Crystallization)The post crystallization of semi-crystalline plastics occurs primarily at elevated temperatures and increased molecular mobility above the glass transition.post-crystallization (ExothermicA sample transition or a reaction is exothermic if heat is generated.exothermal eff ect at 237°C) occurred prior to the melting peak. The corresponding Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition temperature in the 1^st heating at 54°C (midpoint) is lower than the T_g at 68°C in the 2nd heating due to the presence of a small amount of water, as evidenced by the shallow evaporation peak between 100°C and 200°C (blue curve).