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Overview of PP materials

Popularity:375Publication time:2017-08-15

First, PP Material Overview:

PP plastic, chemical name: polypropylene

English Name: Polypropylene (PP)

ZD: 0.9-0.91 g / cubic centimeter forming shrinkage: 1.0-2.5% Forming temperature: 160-220 ° C

PP is a crystalline highlighter, the most PP is lightened in common plastic, only 0.91 g / cm3 (smaller than water). In a general plastic, the heat resistance of PP is preferably, the thermal deformation temperature is 80-100 ° C, can be cooked in boiling water. PP has good stress cracking, with high bending fatigue life, commonly known as "100-fold glue". The comprehensive performance of PP is superior to PE. PP products are light, tough, and chemical resistance. Disadvantages of PP: low dimensional accuracy, lack of rigidity, poor weather resistance, is easy to generate "copper harm\\

In daily life, the commonly used preservation cassettes are made of PP materials.

Second, the formation characteristics:

1. Crystallization, small hygroscopicity, easy to break, long-term contact with hot metal.

2. Good fluidity, but the shrinkage range and shrinkage value are large, and a shrinkage hole is easily occurring. Ded, deformation.

3. Fast cooling, casting system and cooling system should slow heat, and pay attention to controlling the molding temperature. It is easy to orientation when the temperature is low, and the mold temperature is less than 50 degrees. More than 90 degrees, more warpage deformation

4. Plastic wall thickness must be uniform, avoiding lack, sharp corners to prevent stress.

Third, PP process characteristics

PP has better fluidity at the melting temperature, good molding performance, two features of PP on processing: One: The viscosity of the PP melt has a significant decrease in the increase of shear speed (smaller by temperature 2; 2: The degree of molecular orientation exhibits a large shrinkage.

The machining temperature of the PP is preferably from 200 to 300 ° C, it has good thermal stability (the decomposition temperature is 310 ° C), but at a high temperature (270-300 ° C), it will be degraded in the barrel for a long time. Due to the significant decrease in the viscosity of PP, improve the injection pressure and injection speed increase its liquidity, improve contraction deformation and depression. The molding temperature should be controlled in the range of 30-50 ° C. The PP melt can pass a narrow mold gap. PP During the melting process, PP is absorbed to absorb a large amount of melting heat (larger than hot), which is more hot after the product is drawn. When the PP material is processed, no drying is required, the shrinkage ratio of PP and the crystallinity are lower than PE.