Propylene ethylene random copolymer
DATE：2022/12/28 8:44:19 / READ： / SOURCE：This station
2.2.2 Propylene ethylene random copolymer
During propylene polymerization, a small amount of ethylene monomer is added in the polymerizer, and copolymerization is carried out in the polymerizer to obtain a copolymer with propylene and ethylene segments irregularly distributed in the main chain of the polymer, which is called propylene ethylene random copolymer, or random copolymer polypropylene. According to the national standard GB 2546-88, the abbreviation code of random copolymer polypropylene is PP-R, and the homopolymer polypropylene is PP-H.
Since the propylene ethylene random copolymer contains 1%~4% (mass) ethylene, propylene and ethylene segments are distributed irregularly in the molecular chain, so that the product's stereoregularity (isotacticity) is destroyed and copolymers with different crystallinity are obtained. The crystallinity of polypropylene decreases gradually with the increase of ethylene content. When the ethylene content exceeds 30%, the propylene ethylene random copolymer almost becomes an amorphous polymer.
(1) Performance characteristics
The performance characteristics of propylene ethylene random copolymer are: the transparency is obviously improved when the ethylene content is low, the stiffness and impact strength are also improved with the increase of ethylene content, the melting temperature range is wide during processing, and the molding processability is good. Its products are characterized by toughness, cold resistance, high impact strength and good transparency, but their melting point, embrittlement point, rigidity and crystallinity are low. At present, a new random copolymer polypropylene is developed, in which a small amount of α Olefin copolymerization (a-olefin is generally ethylene, but also butene, pentene and octene, with the content of 1% - 4%). Due to the application of metallocene catalysts, the random copolymerization of propylene becomes possible and easier.
(2) Forming method and application
The molding method of propylene ethylene random copolymer is the same as that of general thermoplastic molding products. Products can be molded by extruders, injection molding machines, blow molding, thermal molding, powder molding and secondary processing methods. At present, this material is mainly used to produce films and pipes in China.
The pipes formed by propylene ethylene random copolymer (PP-R) are relatively easy to produce molded products, with good recyclability of raw materials and heat resistance. They improve the low-temperature brittleness of homopolymer polypropylene (PP-H) pipes, can be used at higher temperatures (such as 60 ℃), and have good long-term water pressure resistance. This propylene ethylene random copolymerization polypropylene (PP-R) pipe is mainly used for cold and hot water pipes in construction projects. It is easy to install and connected by hot melting socket, with reliable performance and convenient maintenance.
The film formed by propylene ethylene random copolymer can be cast and extruded. The films can be ordinary packaging films, heat shrinkable packaging films and composite films. The film has the characteristics of high transparency, good smoothness and heat sealing, good toughness and impact resistance. It is mainly used for packing various articles.
During propylene polymerization, a small amount of ethylene monomer is added in the polymerizer, and copolymerization is carried out in the polymerizer to obtain a copolymer with propylene and ethylene segments irregularly distributed in the main chain of the polymer, which is called propylene ethylene random copolymer, or random copolymer polypropylene. According to the national standard GB 2546-88, the abbreviation code of random copolymer polypropylene is PP-R, and the homopolymer polypropylene is PP-H.
Since the propylene ethylene random copolymer contains 1%~4% (mass) ethylene, propylene and ethylene segments are distributed irregularly in the molecular chain, so that the product's stereoregularity (isotacticity) is destroyed and copolymers with different crystallinity are obtained. The crystallinity of polypropylene decreases gradually with the increase of ethylene content. When the ethylene content exceeds 30%, the propylene ethylene random copolymer almost becomes an amorphous polymer.
(1) Performance characteristics
The performance characteristics of propylene ethylene random copolymer are: the transparency is obviously improved when the ethylene content is low, the stiffness and impact strength are also improved with the increase of ethylene content, the melting temperature range is wide during processing, and the molding processability is good. Its products are characterized by toughness, cold resistance, high impact strength and good transparency, but their melting point, embrittlement point, rigidity and crystallinity are low. At present, a new random copolymer polypropylene is developed, in which a small amount of α Olefin copolymerization (a-olefin is generally ethylene, but also butene, pentene and octene, with the content of 1% - 4%). Due to the application of metallocene catalysts, the random copolymerization of propylene becomes possible and easier.
(2) Forming method and application
The molding method of propylene ethylene random copolymer is the same as that of general thermoplastic molding products. Products can be molded by extruders, injection molding machines, blow molding, thermal molding, powder molding and secondary processing methods. At present, this material is mainly used to produce films and pipes in China.
The pipes formed by propylene ethylene random copolymer (PP-R) are relatively easy to produce molded products, with good recyclability of raw materials and heat resistance. They improve the low-temperature brittleness of homopolymer polypropylene (PP-H) pipes, can be used at higher temperatures (such as 60 ℃), and have good long-term water pressure resistance. This propylene ethylene random copolymerization polypropylene (PP-R) pipe is mainly used for cold and hot water pipes in construction projects. It is easy to install and connected by hot melting socket, with reliable performance and convenient maintenance.
The film formed by propylene ethylene random copolymer can be cast and extruded. The films can be ordinary packaging films, heat shrinkable packaging films and composite films. The film has the characteristics of high transparency, good smoothness and heat sealing, good toughness and impact resistance. It is mainly used for packing various articles.
Author：admin