Mold shrinkage

Non-reinforced grades of 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 3-3-1 Comparison of Mold Shrinkage

CLTE (Coefficient of linear thermal expansion)

SUMIKAEXCEL PES has a small CLTE (Coefficient of linear thermal expansion) and a small temperature dependence. Figure 3-3-2 shows the temperature dependence of the CLTE. The CLTE of crystalline PPS-GF40% increases as the temperature rises, but amorphous SUMIKAEXCEL PES shows a constant value up to 200°C regardless of the temperature. Glass fiber reinforced 4101GL30 has a low CLTE of 2.0 × 10^-5(/°C) similar to that of aluminum, making it an ideal material for precision molding.

Figure 3-3-2 Comparison of the CLTE of SUMIKAEXCEL PES with That of Other Resins

PVT characteristics

The specific volume of thermoplastic resin, including SUMIKAEXCEL PES, changes according to the pressure regardless of whether it is in a solid or melted state. The compressibility of this resin is expressed as the relationship (PVT characteristics) between Pressure, Specific Volume and Temperature. PPS is a crystalline resin, so there is large amount of shrinkage due to crystallization. However, PES is an amorphous resin, so the amount of shrinkage is small, and it is excellent for dimensional accuracy and warpage.

Dimensional Change due to Water Absorption

Although SUMIKAEXCEL PES has a small moisture absorption property, the dimensional change due to moisture absorption of parts immediately after molding is small, at 0.15% at saturation (1.1%).

Figure 3-3-5 Dependence of Dimensional Change on Moisture and Water Absorption

Figure 3-3-6 Moisture Absorption Curve of SUMIKAEXCEL PES