PP Plastic, also known as Polypropylene, is a widely used thermoplastic polymer. Its chemical name is polypropylene, and it is commonly abbreviated as PP. The specific gravity of PP is around 0.9 to 0.91 g/cm³, with a molding shrinkage rate between 1.0% and 2.5%. The ideal molding temperature range falls between 160°C and 220°C.
PP offers several advantages, including low density, good mechanical strength, stiffness, and hardness compared to low-density polyethylene. It can withstand temperatures up to about 100°C, making it suitable for various applications. Additionally, it has excellent electrical insulation properties, especially at high frequencies, which are not significantly affected by humidity. However, at low temperatures, PP tends to become brittle and lacks wear resistance. It is also prone to aging over time.
PP is commonly used in the production of general mechanical components, corrosion-resistant parts, and electrical insulators.
**Molding Characteristics:**
1. PP is a crystalline material with low moisture absorption. It melts easily but can degrade if exposed to hot metal surfaces for extended periods.
2. It has good flowability, but the shrinkage range is relatively large, which can lead to issues like shrinkage, sink marks, and warping.
3. The cooling process is fast, so the gating and cooling systems need to be designed carefully to ensure even heat dissipation. Controlling the mold and material temperature is crucial. At lower temperatures and higher pressures, the material may develop orientation, which can affect part quality. If the mold temperature is below 50°C, the plastic parts may appear rough or have poor weld lines. When the mold temperature exceeds 90°C, warping and deformation are more likely to occur.
4. To prevent defects such as short shots and stress concentration, the wall thickness of the plastic part should be kept uniform. Sharp corners should be avoided to reduce the risk of cracking during use.
By understanding these properties and characteristics, manufacturers can optimize the design and production process for better performance and durability.
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