1. The crystalline material has low humidity and is prone to melt fracture, and it is easy to decompose in long-term contact with hot metal.
2. The fluidity is good, but the shrinkage range and shrinkage value are large, and shrinkage holes are prone to occur. It will also dent and deform.
3. The cooling rate of PP injection molding is fast, and the casting system and cooling system should slowly dissipate heat. And pay attention to control the molding temperature, the temperature of the material is low and easy to be oriented under high pressure. When the mold temperature is lower than 50 degrees, the plastic part is not smooth, which is easy to produce poor welding and flow marks. Warping deformation is prone to occur above 90 degrees, so the temperature should be controlled at 80 degrees.
4. The plastic wall thickness must be uniform to avoid lack of glue and sharp corners to prevent stress concentration.
Polypropylene has high crystallinity and regular structure, so it has excellent mechanical properties. Products made by PP plastic injection molding have good heat resistance. The products can be sterilized at a temperature above 100°C, and will not deform at 150°C without external force.
The chemical stability of polypropylene is very good, so polypropylene is suitable for making various chemical pipelines and fittings, and has a good anti-corrosion effect. Polypropylene injection molding products have high-frequency insulation and excellent performance. Because it hardly absorbs water, the insulation performance is not affected by humidity. Its breakdown voltage is also very high, suitable for use as electrical accessories. Polypropylene has good voltage resistance and arc resistance, but it has a high degree of static electricity and is easy to age when it comes in contact with copper.
Polypropylene injection molding products are very sensitive to ultraviolet rays. Adding zinc oxide, dilauryl thiodipropionate, carbon black or similar milky white fillers can improve its aging resistance.
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