PP Characteristics And Composition Structure
PP plastic, chemical name: polypropylene
English name: Polypropylene (PP)
Weight: 0.9 to 0.91 grams per cubic centimeter Molding shrinkage rate: 1.0- 2.5% molding temperature: 160-220 ℃.
PP for crystalline polymer, commonly used plastic PP in the light, only 0.91 g/cm3 density (smaller than water). In general plastic, PP had better heat resistance, its thermal deformation temperature is 80-80 ℃, and can be in the boiling water.PP has good resistance to stress cracking resistance, high bending fatigue life, commonly known as the "hundred fold glue".The comprehensive performance of PP is better than that of PE material.PP products light weight, good toughness, good chemical resistance.PP disadvantages: low dimensional accuracy, insufficient rigidity, weather resistance is poor, after it has shrinkage, after demoulding, easy to aging, crisp, easy to deformation.
1.Crystalline material, hygroscopicity, prone to melting body burst, long-term contact with the hot metal is easy to decompose.
2. Good liquidity, but the scope and contraction value is big, prone to shrinkage cavity. Dent, deformation.
3. The cooling speed, gating system and cooling system should slow cooling, and pay attention to control the molding temperature. Easy orientation when low temperature temperature high pressure, mold temperature is lower than 50 degrees, the plastic parts is not smooth, easy to cause weld adverse, flow mark, 90 degrees or more prone to buckling deformation
4. Plastic wall thickness should be uniform, to avoid the lack of glue, sharp corners, to prevent stress concentration.
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