PP plastic     Chemical name: Polypropylene

English Name: polypropylene (PP)     Specific gravity: 0.9-0.91 g / cm3 molding shrinkage: 1.0-2.5% molding temperature: 160-220 ℃

 

Features: non toxic, tasteless, low hardness, rigidity, heat resistance are better than low-voltage polyethylene, can be used at about 100 degrees. It has good electrical properties and high-frequency insulation, not affected by humidity, but brittle at low temperature, not wear-resistant, easy to aging. It is suitable for making general mechanical parts, corrosion-resistant parts and insulation parts. The common acid and alkali organic solvents have little effect on it and can be used in tableware.

Molding characteristics:

1. the crystallite has small moisture absorption, easy to break down the melt, and it is easy to decompose in contact with hot metal for a long time.

2. Good fluidity, but large shrinkage range and value, easy to produce shrinkage cavity, dent and deformation.

3. The cooling speed is fast, the pouring system and cooling system should dissipate heat slowly, and attention should be paid to control the molding temperature. When the material temperature is low temperature and high pressure, it is easy to orient. When the mold temperature is lower than 50 ℃, the plastic parts are not smooth, which is easy to produce poor fusion, flow marks, and warpage above 90 ℃.

4. The thickness of plastic wall should be uniform to avoid lack of glue and sharp corner to prevent stress concentration.