What is processing condition of PPE injection molding?

PPE performance characteristics:

PPE is a thermoplastic engineering plastic with excellent overall performance, outstanding in electrical insulation and water resistance, and good standard stability. Dielectric function ranks first among engineering plastics: There is no strong polar group in the molecular design of PPE resin, the electrical function is stable, and it can maintain excellent electrical function within a wide range of temperature and frequency ranges. Its dielectric constant and dielectric loss tangent are the smallest among engineering plastics, and are almost unaffected by temperature, humidity and frequency.

Its volume resistivity is the highest among engineering plastics. PPE's excellent electrical properties make it widely used in the production of electrical products, especially high-voltage resistant parts, such as the line output transformer (FBT) of color TVs. Excellent mechanical and thermal properties: PPE subchains are rich in aromatic ring structures, and the molecular chain is relatively rational. The resin has high mechanical strength, excellent creep resistance, and little effect of temperature changes. PPE has high heat resistance, with a glass transition temperature of up to 211°C and a melting point of 268°C.

Performance of PPE injection molding:

PPE can be processed by either plunger or screw injection molding machines. Generally, screw injection molding machines are used, requiring a length-to-diameter ratio greater than 15:1 and a compression ratio of 1.7 to 4.0 (generally 2.5 to 3.5); Extrusion: PPE can be processed into tubes, sheets, rods, blocks, etc. on the extruder. It is better to use a venting type extruder with a large aspect ratio, with a screw aspect ratio of 24:1, a compression ratio of 2.5-3.5, a sudden change type, equidistant and unequal depth, and a proper depth in the metering section.

Compression molding: Glass cloth soaked in a benzene solution of 10%-18% PPE can be controlled according to the lamination process conditions of thermosetting plastics. The glue content of the glass cloth is controlled at 35%±5%, and the drying temperature is 70-110℃; Molding process: When the mold temperature rises to 250℃, maintain the temperature for 5min, the pressure is 6MPa, and the temperature is continuously raised to 300℃, kept warm for 1h, and then naturally cooled to 180℃, and cooled to room temperature by cold water for demoulding. PPE can also be film-formed and processed secondary;

PPE performance has excellent physical and mechanical properties, heat resistance and electrical insulation, low hygroscopicity, high strength, and standard stability. It needs to be processed at a high temperature of 300℃.

For this reason, the PPE resin is modified by the "alloying" method of blending polystyrene or impact polystyrene. Most of the useful functions of this modified resin are preserved. Almost all the products sold on the market are alloyed products.

Because PPE alloy overcomes the disadvantage of stress cracking of PPE itself, improves the processing function of PPE, and has excellent thermal, electrical and mechanical functions. This modified polystyrene or impact polystyrene polyphenylene ether has a low glass transition temperature, is easier to process, and has no degradation. Of course, the heat resistance has dropped, but most of the useful functions of PPE resin are retained.