Polypropylene melting point: characteristics and properties

Polypropylene is a thermoplastic polymer of propene. It is obtained by the technology of polymerization of propylene using metal complex catalysts. The parameters for obtaining this material are similar to those for which low-density polyethylene is manufactured .

Depending on which catalyst is used, it is possible to obtain any type of polymer or a mixture thereof. The melting point of polypropylene is one of the important characteristics of this material. It has the appearance of a white powder or granules, the bulk density of which varies to 0. 5 g / cm³. The material described can be colored, stabilized or unpainted.

Technical characteristics: molecular structure

According to the molecular structure, polypropylene is divided into several main varieties, among them:

• Isotactic;
• Atactic;
• Syndiotactic.

Stereoisomers of the material differ in physical, mechanical and chemical characteristics. For example, atactic polypropylene has the appearance of a rubbery material, which is characterized by high fluidity. The melting point of polypropylene for extrusion in this case is about 80 ° C, while the density can reach 850 kg / m3.

In diethyl ether, this material dissolves very well. By properties isotactic polypropylene differs from the above and has a high modulus of elasticity, its density reaches 910 kg / m³, while the melting temperature varies from 165 to 170 ° C. In this variety, polypropylene is characterized by excellent resistance to chemical reagents.

Physical and mechanical properties

Today, the use of polypropylene is very common. The melting point of this material differs in certain species. It is often compared with polyethylene, but polypropylene does not have such a high density, it is 0.91 g / cm³. In addition, polypropylene is harder, resistant to abrasion and well tolerates the effects of temperatures.

The level of its softening begins at 140 ° C, while the melting point reaches 175 ° C. Corrosive cracking material is not exposed. It is resistant to oxygen and light, but this sensitivity is reduced if stabilizers are added to the ingredients in the manufacture of polypropylene.

In many areas of industry today, many varieties of polypropylene are used. The melting point of this material expands the field of application. The relative elongation at break in percent can vary from 200 to 800%. The tensile yield stress is equal to the limit from 250 to 350 kgf / cm². The notched impact strength varies from 33 to 80 kgf · cm / cm², while the Brinell hardness is between 6 and 6.5 kgf / mm².

Basic chemical properties

If you plan to purchase any products from polypropylene, the melting point of this material should be known to you. About it is discussed in the article. From it you can learn and other chemical properties. For example, the material is chemically stable, and in organic solvents it only slightly swells. If the temperature rises to 100 ° C, then in the aromatic hydrocarbons the material will dissolve. In this case we are talking about toluene and benzene.

For the reason that polypropylene contains tertiary carbon atoms, it is resistant to the effects of oxygen when exposed to ultraviolet radiation and elevated temperatures. This causes an inclination to aging in comparison with polyethylene. Under the influence of aggressive media polypropylene is not as strong as polyethylene, cracked. It is able to undergo stress cracking tests.

Melting temperature of polypropylene pipes

Quite often a modern consumer is interested in the melting point of polypropylene. Pipes this applies if you plan to arrange the heating system. When exposed to a temperature of 140 ° C, the material becomes soft, and it loses its shape. While if the temperature rises to a mark of 170 ° C, then the melting stage will come. At the same time, it will cease to be solid and will lose the ability to maintain its technical characteristics and form.

Heating systems at this temperature level are not calculated, therefore polypropylene pipes are suitable for supplying water to the system. Typically, manufacturers state that the maximum possible temperature of polypropylene pipes is 95 ° C. Products are able to withstand a higher temperature level, but for a short time. If the pipes are used for a long time at a temperature of more than 100 ° C, the life of their pipes will decrease.

When temperature drops, polypropylene will change in size. When heated, it will expand, and when cooled, it will contract. Under the influence of high temperatures, the pipes may begin to sag between the attachments, and in the outer layer you will notice a swelling.

Nuances of using polypropylene pipes

You can also use products made of polypropylene. The melting temperature of such pipes can be different. This must be taken into account if you have PN20 products in front of you. In this case we are talking about a pipe whose operating temperature reaches 60 ° C. But if we are talking about the product PN25, then this indicates that it will be able to withstand the temperature to 95 ° C.

Conclusion

With exact certainty it can be said that polypropylene is installed near the smoke shafts. The melting point of polypropylene, however, does not indicate that the pipes should not be protected. Experts recommend buying reinforced products, which are less susceptible to deformation when exposed to high temperatures. Therefore, the pipes should be additionally protected by insulation and have an inner fiberglass or aluminum layer. This will protect the pipes from expansion and extend their life.