Mechanical Properties of SUMIKAEXCEL PES

Long Term Deformation

Creep

When designing products of the appropriate strength required for actual usage, it is not adequate to rely solely upon the values derived from standard testing (i.e., 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 1 depicts the tensile creep properties of natural grade 4800G at temperatures of both 20 deg C and 150 deg C. As indicated in Figure 2, it can be seen that SUMIKAEXCEL PES possesses excellent creep resistance. The natural grades of SUMIKAEXCEL PES sustained a creep deformation of only 1% after 3 years, under a load of 20 MPa and at a temperature of 20 deg C. At a temperature of 150 deg C, the creep deformation after 3 years remained at only 1%, even though a load of 10 MPa had been applied.

Figure 1
Tensile Creep Properties of Natural SUMIKAEXCEL PES (4800G)
 
Figure 1 Tensile Creep Properties of Natural PES (4800G)
Figure 2
Flexural Creep Properties of Glass Fiber Reinforced SUMIKAEXCEL PES (3601GL30 and 4101GL30)
Figure 2 Fexural Creep Properties of Glass Fiber Reinforced PES (3601GL30 and 4101GL30)

Impact Strength

SUMIKAEXCEL PES is tough resin that possesses outstanding impact resistance.Figure 3 depicts the comparison of the Izod impact strength with unnotched of SUMIKAEXCEL PES with several high heat resistant plastics. It shows that natural grade of SUMIKAEXCEL PES keeps higher impact property compared with glass fiber reinforced grade, which is very similar with other plastics.
SUMIKAEXCEL PES, however, is susceptible to notch shape. Figure 4 and 5 describe radius dependence of notch tip for Izod impact properties. The tooling design requires attention, if product by SUMIKAEXCEL PES has sharp corners or screw threads. As well, cutting sprue and gates cleanly, and smoothing mold surfaces will prevent stress concentration, thus ensuring the original strength of SUMIKAEXCEL PES.

Figure 3 Impact Resistance

Figure 3 Impact Resistance
Figure 4
Notch Tip Radius Dependence of Impact Strength
 
Figure 4 Notch Tip Radius Dependence of Impact Strength
at a Temperature of 20 deg C (PES 4800G)
Figure 5
Temperature Dependence of Impact Strength (PES 4800G)
Figure 5 Temperature Dependence of Impact Strength
(PES 4800G)

Weld Strength

General Feature

When injection molding is performed, the temperature of weld areas (resin junctions) will be lower than that of non-weld areas. The strength of weld areas of glass fiber reinforced grades decreases with the glass fiber content. Figure 6 depicts a comparison between the strengths of non-weld and weld areas. Table 1 shows the tensile strengths of weld areas for SUMIKAEXCEL PES grades.

Figure 6 Flexural Strengths of Weld and Non-weld Areas

Figure 6 Flexural Strengths of Weld and Non-weld Areas

Table 1 Tensile Strength of Weld Areas

Grade Non weld Weld area
4100G 84 81
4800G 84 81
3601GL20 124 67
4101GL20 124 68
4101GL30 140 61

From the above figure and table, it is apparent that SUMIKAEXCEL PES possesses far greater weld strength than that of other resins. In particular, natural grades experience only minimal degradation of weld strength and maintain similar strength to that of non-weld areas.

Weld Strength of 4100G

image of Weld Strength of 4100G

Table 2 Weld Strength

Resin Flexural strength
(MPa)
Izod impact strength (J/m)
Without notch 0.25OR notch
Non weld Weld area Non weld Weld area Non weld Weld area
SUMIKAEXCEL PES 4100G 140* 140* >1960* 2156 68 68
4101GL20 190 110 411 117 68 29
4101GL30 180 110 362 98 68 29
PPS(GF40%) 170 70 166 29 49 19

Figure Marked with * = did not rupture

Note 1)
Molding Machine : Neomat N47 / 28, manufactured by
Sumitomo Heavy Industries, Ltd.
Injection Pressure : 130 MPa
Injection Speed : 60%
Cylinder Temperature : 340 deg C(4100G)
50 deg C(4101GL20・4104GL30)
Injection Time : 10秒
Cooling Time : 20秒

Weld Strength of Thin-walled Moldings

Figure 7 Relationship Between Wall Thicknesses of Moldings and Weld Area Tensile Strength

Figure 7 Relationship Between Wall Thicknesses of Moldings and Weld Area 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
    Weld areas of glass fiber reinforced grades can be improved by 15 - 20% through annealing treatment at a temperature range of 150 - 180 deg C. The appropriate annealing conditions are as follows: 150 deg C x 20 minutes for moldings having a wall thickness of 0.5 - 1.5 mmt ; and 180 deg C x 180 minutes for moldings having a wall thickness of 2 mmt.

Table 3 Improvement of Weld Tensile Strength in Glass Fiber Reinforced Grades Through Annealing

(Units: MPa)

Grade Before
Anniealing
50 deg C 180 deg 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 strength before annealing as 100%.

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

Mold Shrinkage

Non-reinforced grades of SUMIKAEXCEL PES have low mold shrinkage (0.6%) and no anisotropy. However, glass fiber reinforced grades possess anisotropic shrinkage, at 0.2% for MD and 0.4% for TD due to the orientation of GF.

Figure 8 Mold Shrinkage Comparison

Figure 8 Mold Shrinkage Comparison
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