PES Resin in Injection Molding: What to Note?

Injection molding is a widely used method in plastic processing, and has developed rapidly in these years. Polyethersulfone resin can be used to make Various plastic items by injection molding. What things should be noted when PES resin is used in the injection molding?

 

Working Principle

The principle of injection molding is to heat the PES resin in the barrel of the injection machine and subject it to shearing force to melt and plasticize into a viscous fluid state. Then pressure it with a plunger or screw. At a faster speed, allow the molten melt to pass through a narrow nozzle at the front of the barrel. Then quickly put it into a closed mold with a certain temperature.  After a period of cooling and solidification, open the mold and take out of the product. 

 

 

Requirements

Polyethersulfone PES resin has higher viscous flow temperature and higher melt viscosity. Thus, the molding injection machine generally requires high temperature and high pressure, the temperature of the barrel can be heated to 400 ℃, and the larger injection pressure should be able to reach 180 MPa. When performing injection molding, the processing temperature must be strictly controlled because long-term exposure to excessively high temperature conditions will aggravate the degradation of PES materials.

 

Therefore, according to empirical values, in the temperature range that meets the molding requirements, it is suggested to use a lower barrel temperature and die temperature. During the processing, the mold temperature must be even, and a mold temperature control machine is recommended. Due to the high melt viscosity of polyethersulfone, the part design has the highest requirements on the basis of general plastic design.

 

 

Processing Properties of PES

1. The small amount of water in PES resin means quite unfavorable to the molding process. Therefore, the polyethersulfone material should be fully dried before processing. The temperature of drying conditions should be controlled at 120-160%, and the time of heat preservation should be 3-6h to make the water content is less than 0.12%.

 

2. The melting temperature range of PES resin  is narrow, which is from 315 to 335t, but the melt cooling rate is faster. Therefore, a higher injection rate should be used to send the melt into the mold cavity to avoid insufficient mold filling.

 

3. The melt of PES resin is a pseudoplastic, and its apparent viscosity increases with a decreasing shear rate, but the decrease is not large.

 

4. PES resin can have melt thickening when it is processed for a long time or for multiple times within the normal processing range. Therefore, when processing PES resin , the residence time of its melt in the equipment should be strictly controlled not to exceed 40 minutes.

 

5. Injection molding is used to process engineering parts. It is recommended to use screw injection, mainly with equal-moment gradual screw. The screw groove of the homogenization section should be deeper than the general screw to avoid excessive shear friction heat of the melt. The nozzle should be a straight-through type, and the welding mark should be avoided when designing the mold.

 

6. PES resinhas higher heat resistance. Its free volume decreases after being heated, so the whole molecular structure is tighter.

 

7. Generally, PES resin forms an amorphous structure during molding. Thus, the expansion rate is relatively low during the extrusion and the shrinkage rate is also low during the injection. However, if a small amount of nucleating agent is applied, a crystal structure can also be formed.

 

Why Choose Us?

Polima is a top manufacturer of polyethersulfone, offering high-quality PES resin granule, PES resin powder, modified PES resin, etc. If you want to buy superior raw materials, welcome to contact us at office@polima.com.cn. We can talk more details about the polyethersulfone material.