Polypropylene is a thermoplastic propene polymer. It is produced using propylene polymerization technology using metal complex catalysts. The parameters for obtaining this material are similar to those for which low-pressure polyethylene is made .
Depending on which catalyst is used, it is possible to obtain a polymer of any type 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 whose bulk density varies to 0.5 g / cm³. The described material may be colored, stabilized or unpainted.
Specifications: molecular structure
According to the molecular structure, polypropylene is divided into several main varieties, among them:
- isotactic;
- atactic;
- syndiotactic.
The stereoisomers of the material differ in physical, mechanical and chemical characteristics. For example, atactic polypropylene has the form of a rubber-like material, which is characterized by high fluidity. In this case, the melting point of polypropylene for extrusion is approximately 80 ° C, while the density can reach 850 kg / m³.
This material dissolves very well in diethyl ether. Isotactic polypropylene differs in properties 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 chemicals.
Physical and mechanical properties
Today, the use of polypropylene is very common. The melting point of this material is different for some species. Quite often it is 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 tolerates the effects of temperatures.
The level of its softening begins at around 140 ° C, while the melting temperature reaches 175 ° C. The material does not undergo corrosion cracking. 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 various areas of industry today, many varieties of polypropylene are used. The melting point of this material expands the scope. The elongation at break in percentage can vary from 200 to 800%. The tensile yield strength is equal to the limit of 250 to 350 kgf / cm². The notch impact strength varies from 33 to 80 kgf · cm / cm², while the Brinell hardness is equal to the limit of 6 to 6.5 kgf / mm².
Basic chemical properties
If you plan to purchase any products made of polypropylene, the melting point of this material should be known to you. It is discussed in the article. From it you can learn 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 the material will dissolve in aromatic hydrocarbons. In this case, we are talking about toluene and benzene.
Due to the fact that polypropylene contains tertiary carbon atoms, it is resistant to oxygen when exposed to ultraviolet radiation and elevated temperatures. This leads to a tendency to aging compared to polyethylene. Under the influence of aggressive environments, polypropylene is not as strong as polyethylene, it undergoes cracking. It is able to undergo cracking tests even under stress.
Melting point of polypropylene pipes
Quite often, the modern consumer is interested in the melting point of polypropylene. Pipes, this applies if you plan to implement the installation of a heating system. When exposed to a temperature of 140 ° C, the material becomes soft, while it loses its shape. Whereas if the temperature rises to a mark of 170 ° C, then the melting stage will begin. At the same time, it will cease to be solid and lose the ability to maintain its technical characteristics and shape.
Heating systems are not designed for such a temperature level, therefore polypropylene pipes are suitable for supplying water to the system. Typically, manufacturers declare that the maximum possible temperature of polypropylene pipes is 95 ° C. Products are able to withstand a higher level of temperature, but for a short time. If the pipes are used for a long time at a temperature of more than 100 ° C, then their service life will decrease.
With temperature extremes, polypropylene will change in size. When heated, it will expand, and when cooled, it will contract. Under the influence of high temperatures, pipes may begin to sag between the fasteners, and in the outer layer you will notice bloating.
The nuances of using polypropylene pipes
You can also use polypropylene products. The melting point of such pipes may be different. This must be taken into account if you have PN20 brand products. In this case, we are talking about a pipe whose working temperature reaches 60 ° C. But if we are talking about the product PN25, then this indicates that it will be able to withstand temperatures up to 95 ° C.
Conclusion
With exact certainty, we can say that polypropylene can be installed near smoke mines. The melting point of polypropylene, however, does not indicate that pipes should not be protected. Experts recommend purchasing reinforced products that are less prone to deformation when exposed to high temperatures. Therefore, pipes must be further protected by insulation and have an internal fiberglass or aluminum layer. This will protect the pipes from expansion and extend their life.