Home > News > Daily News > PP Material


PP Material

  • Author:naky
  • Source:www.diecastingpartsupplier.com
  • Release on:2014-11-17
The physical properties of PP feature editor

Polypropylene is non-toxic , odorless, tasteless milky highly crystalline polymers, density of only 0. 90 -. "0 91g / rm, is one of the lightest of all varieties of plastic it particularly stable water . the water absorption of only 0. O1%, in case of a molecular weight of about 8 150 000 . moldability is
good, but the shrinkage rate ( 1% to 2.5% ) . walled products easy to depressions , the size of some of the high precision parts, but also difficult to meet the requirements, the product surface gloss, easy coloring . Mechanical Properties.

High crystallinity polypropylene , regular structure , which has excellent mechanical properties . The absolute value of the mechanical properties of polypropylene than polyethylene , but still in the plastic material of the species belonging to the low tensile strength of 30 MPa can be achieved , or only slightly higher level. Larger isotactic polypropylene has a high tensile index .

Strength , but increases with isotactic index , the impact strength of the material has declined, but then decreased to a certain value does not change.

Great influence of temperature and loading rate for polypropylene toughness. When the temperature is higher than the glass transition temperature , fracture toughness, impact damage was below the glass transition temperature of brittle fracture and impact strength values ??dropped significantly. Increase the loading rate , can rise to the temperature fracture toughness of brittle fracture transition . Polypropylene has excellent resistance to bending fatigue resistance, and its products can be bent at room temperature 106 times without damage.

However, at room temperature and at low temperature, regular molecular structure itself is high , so the impact strength is poor . The most prominent properties of polypropylene is resistant to bending fatigue resistance , commonly known as pleated plastic . Thermal Performance.

Polypropylene has good heat resistance , the product can be sterilized at temperatures above 100 ℃ , without being subject to external conditions , 150 ℃ not deformed . Brittle transition temperature of -35 ℃, at less than -35 ℃ embrittlement occurs , cold resistance than polyethylene. For the reported value of the glass transition temperature of polypropylene has a 18qC, OqC, 5 ℃ , etc. This is because people with different samples , which contained different proportions of crystalline phase and the amorphous phase , so that the amorphous part of the molecular chains of different chain lengths due. The melting temperature of the polypropylene to increase to about 40 to 50% than polyethylene , about 164 a 170 ℃, 100% of isotactic polypropylene.

Mp 176 ℃