Mechanical Properties

Short-term deformation

Tensile strength

The stress-strain curve (hereinafter referred to as S-S curve) from the tension test for SUMIKAEXCEL PES is shown. Stress and strain are proportional until the stress reaches a certain level. When designing PES strength, it is important to remember that there are portions where the stress and strain are not proportional.

Figure 3-2-1 S-S Curve of Tensile Strength of 4100G

Figure 3-2-1 S-S Curve of Tensile Strength of 4100G

Figure 3-2-2 S-S Curve of Tensile Strength of 4101GL30

Figure 3-2-2 S-S Curve of Tensile Strength of 4101GL30

Temperature Dependence of Flexural Modulus

The heat deformation temperature is 200 to 220°C, and the continuous operating temperature is certified as 180 to 190°C by the UL temperature index. The modulus of elasticity shows almost no change in the temperature range of -100 to 200°C. It has the highest level among all thermoplastic resins, especially above 100°C.

Figure 3-2-3 Temperature Dependence of Flexural Modulus

Figure 3-2-3 Temperature Dependence of Flexural Modulus

Impact strength

SUMIKAEXCEL PES has excellent impact resistance. Izod impact strength is shown in comparison with other heat resistant resins. The unnotched non-reinforced grade does not break. Figure 3-2-6 shows the temperature dependence of the impact strength. SUMIKAEXCEL PES has sufficient impact strength even at temperatures below 0°C such as -100°C.

Figure 3-2-4 Impact Resistance of SUMIKAEXCEL PES

Figure 3-2-4 Impact Resistance of SUMIKAEXCEL PES Izod impact strength (3.2mm thickness, unnotched) (J/m)

Figure 3-2-5 Notch Sensitivity of Impact Strength at 20°C (4800G)

Figure 3-2-5 Notch Sensitivity of Impact Strength at 20°C (4800G)

Figure 3-2-6 Temperature Dependence of Impact Strength (4800G)

Figure 3-2-6 Temperature Dependence of Impact Strength (4800G)

Weld strength

With injection molding, the strength of welded areas (resin junction) becomes lower than that of the non-welded areas. The strength of the welded areas of the glass fiber reinforced grade decreases according to the amount of glass fiber. Figure 3-2-7 shows a comparison between the strength of non-welded areas and the strength of welded areas, and Table 3-2-1 shows the tensile strength of welded areas with SUMIKAEXCEL PES. SUMIKAEXCEL PES has extremely high weld strength compared to other resins. The non-reinforced grade in particular shows almost no decrease in reinforcement of welded areas and has the same strength as non-welded areas.

Weld tensile strength

Figure 3-2-7 Tensile Strength

Figure 3-2-7 Tensile Strength

Table 3-2-1 Tensile Strength of Welded Area

(Unit : MPa)

Grade Non-welded area Welded area
4100G 84 81
4800G 84 82
3601GL20 124 67
4101GL20 124 68
4101GL30 140 61

Weld flexural strength

Figure 3-2-8 Shape of Moldings for Weld Evaluation

Figure 3-2-8 Shape of Moldings for Weld Evaluation

Table 3-2-2 Flexural Strength and Izod Impact Strength of Welded and Non-Welded Areas

Grade Flexural strength (MPa) Izod impact strength (J/m)
Unnotched 0.25 notch
Non-
welded area		 Welded area Non-
welded area		 Welded area Non-
welded area		 Welded area
4100G 140* 140* > 1960* 2156 68 49
4101GL20 190 110 411 117 68 29
4101GL30 180 110 362 98 68 29
PPS-GF40% 170 70 166 29 49 19

Values with * mark : Do not break

Molding machine : Sumitomo Heavy Industries' Neomat N47/28
Injection pressure : 130MPa
Injection speed : 60%
Cylinder temperature : 340°C (4100G)
  350°C (4101GL20, 4101GL30)
Injection time : 10 seconds
Cooling time : 20 seconds

Weld strength of thin-walled moldings

Figure 3-2-9 Wall Thicknesses Dependence of Weld Tensile Strength

Figure 3-2-9 Wall Thicknesses Dependence of Weld Tensile Strength

Improvement of Weld Strength

If the degradation of weld strength proves to be a problem during actual usage, weld strength can be improved through the methods introduced below.

  • Improvement by Annealing
    The strength of the welded areas of the glass fiber reinforced grade can be improved by 15 to 20% through annealing treatment at a temperature range of 150 to 180°C. The appropriate annealing conditions are as follows: 150°C × 20 minutes for moldings having a wall thickness of 0.5 to 1.5mm thickness ; and 180°C x 180 minutes for moldings having a wall thickness of 2mm thickness.

Table 3-2-3 Improvement of Weld Tensile Strength in Glass Fiber Reinforced Grades through Annealing

(Unit : MPa)

Grade Initial 150°C 180°C
20min 20min 180min
3601GL20 68 76 (113%) 76 (113%) 77 (114%)
4101GL20
3601GL30 61 75 (123%) 75 (121%) 75 (121%)
4101GL30

Percentage in parentheses indicates the comparison with the initial strength as 100%.

  • Improvement Through Increased Mold Temperatures
    Greater weld strength can be achieved if the mold temperature is increased during the molding process. Therefore, set the mold temperature to 160 to 180°C and then observe any strength changes.

Long-Term Deformation

Creep properties

When designing parts of the appropriate strength required for actual usage, it is not adequate to rely solely upon the values derived from standard testing (e.g., ASTM) for mechanical strength and flexural modulus.
In order to determine the most appropriate design values, all potential changes that may occur in the dimensions and mechanical strength of moldings must be considered under actual operating conditions, based upon creep properties and temperature-induced changes.
Figure 3-2-10 depicts the tensile creep properties of the non-reinforced grade 4800G at temperatures of both 20°C and 150°C. The non-reinforced grades of PES sustained a creep deformation of only 1% after 3 years, under a load of 20MPa at a temperature of 20°C. At 150°C, the creep deformation after 3 years remained at only 1%, under a load of 10MPa. Figure 3-2-11 shows the flexural creep properties at 150°C for glass fiber reinforced grades (3601GL30 and 4101GL30). SUMIKAEXCEL PES shows excellent creep properties compared to crystalline PPS (40% glass fiber reinforced grade).

Figure 3-2-10 Tensile Creep Properties of Non-Reinforced Grade (4800G)

Figure 3-2-10 Tensile Creep Properties of Non-Reinforced Grade (4800G)

Figure 3-2-11 Flexural Creep Properties of Glass Fiber Reinforced Grades (3601GL30, 4101GL30)

Figure 3-2-11 Flexural Creep Properties of Glass Fiber Reinforced Grades (3601GL30, 4101GL30)

Figure 3-2-12 Tensile Creep Properties of Non-Reinforced Grade (4100G)

Figure 3-2-12 Tensile Creep Properties of Non-Reinforced Grade (4100G)

Figure 3-2-13 Tensile Creep Properties of Glass Fiber Reinforced Grade (4101GL30)

Figure 3-2-13 Tensile Creep Properties of Glass Fiber Reinforced Grade (4101GL30)

Figure 3-2-14 Flexural Creep Properties

Figure 3-2-14 Flexural Creep Properties

Fatigue Properties

Materials under loads that fluctuate over a long period of time experience fatigue fractures. The stress-life curve from a tensile fatigue test is shown. At 23±1°C with 60±5% RH, fatigue failure does not occur up to about 1.0 × 107 times even with a repeated load of 30MPa.

Figure 3-2-15 Stress-Life Curve of SUMIKAEXCEL Non-Reinforced Grades (3600G, 4100G, 4800G)

Figure 3-2-15 Stress-Life Curve of SUMIKAEXCEL Non-Reinforced Grades (3600G, 4100G, 4800G)

Figure 3-2-16 Stress-Life Curve of SUMIKAEXCEL Glass Reinforced Grades (3601GL20, 4101GL30)

Figure 3-2-16 Stress-Life Curve of SUMIKAEXCEL Glass Reinforced Grades (3601GL20, 4101GL30)

The symbol with a right arrow (→) indicates that the test piece has not been broken at that number of repetitions.

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