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Do you know the physical properties of pp nonwovens
- Aug 17, 2018 -

Do you know the physical properties of pp nonwovens?

Polypropylene is a non-toxic, odorless, odorless, milky white, highly crystalline polymer with a density of only 0.90--"0. 91g/rm. It is one of the lightest varieties of all plastics today. It is unchanged for water. The water absorption rate in water is only 0. O1%, the molecular weight is about 80,100,000. The formability is good, but the shortening rate is large (1% to 2.5%). The thick-walled products are easy to be sunken, and some dimensional precision is better. High parts, it is difficult to reach the request, the product profile is good gloss and easy to color.[4]

Mechanical properties

Polypropylene has high crystallinity and regular structure, and it has excellent mechanical properties. The absolute value of the mechanical properties of polypropylene is higher than that of polyethylene, but it is still a low grade in plastic materials, and its tensile strength can only reach 30 MPa or slightly higher. Polypropylene with a larger isotactic index has higher elongation

Strength, but with the advancement of the isotactic index, the impact strength of the material has dropped, but it does not change after falling to a certain value.

Temperature and loading speed have a great influence on the toughness of polypropylene. When the temperature is higher than the glass transition temperature, the impact damage is ductile fracture, brittle fracture below the glass transition temperature, and the impact strength value drops greatly. The forward loading speed increases the temperature at which the ductile fracture transitions to the brittle fracture. Polypropylene has excellent anti-corrugation properties, and its products can be bent 106 times at normal temperature without damage.

However, at room temperature and low temperature, the impact strength is poor due to the high molecular structure of the person. The most outstanding performance of polypropylene is the anti-corrugation property, commonly known as the 100-fold adhesive. [5]

Thermal performance

Polypropylene has excellent heat resistance, and the product can be sterilized and sterilized at a temperature of 100 ° C or higher. Under the condition of no external force, it is not deformed at 150 ° C. The embrittlement temperature is -35 ° C, and embrittlement occurs below -35 ° C, and the cold resistance is not as good as polyethylene. The reported values of the glass transition temperature of polypropylene have 18qC, OqC, 5°C, etc., which is also because people use divergent samples, in which the ratio of crystal phase to amorphous phase is different, so that the chain length of the amorphous part in the molecular chain is divergent. And to. The melting temperature of polypropylene is about 40-50% higher than that of polyethylene, about 164-170 ° C, 100% isotactic polypropylene

The melting point is 176 ° C. [5]

Chemical invariance

The chemical invariance of polypropylene is very good. In addition to being attacked by concentrated sulfuric acid and concentrated nitric acid, it can keep the same for other chemical reagents. However, low molecular weight aliphatic hydrocarbons, aromatic hydrocarbons and chlorinated hydrocarbons can make polypropylene. Softening and swelling, while its chemical invariability has progressed with the increase of crystallinity, so polypropylene is suitable for the construction of various chemical pipelines and fittings, anti-erosion and brilliant.

Electrical performance

It has a high dielectric constant and can be used to build heated electrical insulation products as temperature rises. Its breakdown voltage is also very high, and it is used as an electrical accessory. It has good resistance to voltage and arc resistance, but it has high static electricity and is easy to age with copper.

Weather resistance

Polypropylene is very sensitive to ultraviolet light, and it can improve its aging resistance by inserting zinc oxide, sec-valerate, carbaryl or similar white filler.

Hydrophobic parameter comparison reference value (XlogP): 3.32, number of hydrogen bond donors: 03, number of hydrogen bond acceptors: 34, number of changeable bond numbers: 15, number of tautomers: 6, topological molecular polarity profile Product (TPSA): 29.5 Prevent strong oxidants, chlorine, potassium permanganate sealed, kept in a cool dry place to ensure a good ventilation.

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