What is pp material, detailed

PP has unusual resistance to chemical solvents, acids and alkalis. It can produce high purity PP, which is used in the semiconductor industry. It is also resistant to bacterial production, suitable for disposable syringes and medical devices. It can be used for injection molding or machining and welding. It can be used for tubing, filter material, horn cylinders and other plastic products that require higher quality than polyethylene products. Banknotes are made from biaxially oriented polypropylene (BOPP), which has improved durability. Polypropylene was discovered by Italian chemist Giulio Natta in the early 1950s. In modern science, something can be invented at the same time by people in different locations. Polypropylene is such an extreme example, having been invented independently about nine times. It was the kind of drama that patent attorneys dream of, and the litigation didn't end until 1989. Polypropylene has tried to continue the legal drama, and two American chemists, J. Paul Hogan and Robert Banks, who worked for Phillips Petroleum, are now considered the "official" inventors of the material. Like its cousin polyethylene, polypropylene is cheap and plentiful. It is used in products ranging from plastic bottles to carpeting, plastic furniture, and in large quantities in the automotive industry. Polypropylene is a highly rigid material and is a polyolefin, along with PE. The homopolymer density is as low as 0.90, and can be reinforced with glass fibers and minerals such as calcium carbonate.PP is not suitable for use below 0oC. If it is to be used at sub-zero temperatures, it must be ***polymerized with butadiene, which gives rise to ***polymerized PP. homopolymerized PP operates at a temperature of 90oC, and has very good resistance to chemicals (acids and alkalis). Parts made from homopolymer PP have very low hygroscopicity, but shrinkage during injection molding is high. The electrical properties are very good, but the UV resistance and resistance to other penetration properties are poor. The common methods of chemical modification: one is to take the modified resin monomer as one element and the modified monomer as the other element, and carry out grafting***polymerization and obtain new ****polymer in the reaction kettle; the second method is to use the modified resin as the main raw material, and carry out effective modification of the resin molecule by increasing the polar elements in it. Polypropylene is widely used in the production of plastic pipes, but PP is a material with poor aging resistance. in order to improve the performance of PP, PP-B and PP-R resins were invented through chemical modification methods. the PP-B resin is a block ****polymer of propylene and ethylene. Synthesis of propylene - ethylene block **** polymer to use two polymerization reactor. One for monomer propylene polymerization into homopolymer polypropylene, the other is the first reactor produced by the introduction of homopolymerization of PP ethylene to form propylene - ethylene block **** polymer, that is, the formation of ethylene - propylene elastic segment.PP-B resin is essentially homopolymerization of PP and ethylene *** polymerization modification. Modified PP-B resin has the performance advantages of both PE and PP. PP-R is a random polypropylene based on **** poly PP modified with ethylene. The smallest molecular weight of random PP is only a few tens of thousands, small cohesion, low melting point, poor mechanical properties. Only through the ethylene modified random PP has practical application value. The modification process is to gasify propylene and feed it into the reactor by gas phase method, and use the airlock system to send the material from the first reactor to the second reactor, and add ethylene in the second reactor. Using high activity, high selectivity of propylene catalyst, added to the upper part of the reactor, by stirring it evenly dispersed to the powder layer, by controlling the proportion of ethylene and propylene to form a random **** polymer. This polymer changes the configuration of the PP molecular chain, so that ethylene is randomly and uniformly polymerized on the molecular chain of PP. Compared with ordinary PP, PP-R material stress cracking resistance has been greatly improved, in the temperature and internal and external pressure, its performance decay is very slow, is currently used as one of the most ideal materials for the production of transporting hot and cold water pipes. Chemical modification creates new materials Chemical modification can not only change the performance of a resin, but also create new resin materials. Some of the most commonly used resins are modified, such as ultra-high molecular weight polyethylene (UHMPE), which is a product of chemical modification. This UHMPE greatly improves the mechanical properties of HDPE materials. Its wear resistance and self-lubricating more than other engineering plastics, mechanical properties and corrosion resistance is no less than polytetrafluoroethylene (PTFE).LLDPE is also through chemical modification. It is in the polymerization of ethylene introduced butene, hexene, octene and a small number of a-olefin monomers and the formation of **** polymer. It has a similar molecular configuration to HDPE, but with reduced density and crystallinity.LLDPE has good resistance to environmental stress cracking, and its mechanical properties are also superior to those of LDPE, so its range of applications has expanded accordingly. And chlorinated polyethylene (CPE) is also a product of chemical modification. It is the product of HDPE through chlorination. Chlorine (CL) partially replaces the hydrogen (H) in the HDPE molecule, causing the molecule to suffer crystalline damage, thus making it softer and more flexible. It can not only be processed into CPE products by extrusion or injection molding, which are widely used in construction, electrical appliances, etc., but also CPE itself becomes an excellent modifier, which can be used to improve the flame retardancy of PE materials and the impact resistance of PVC materials by physical ****mixing. Physical modification *** mixing modification of the resin and other one or more materials through mechanical means *** mixing to achieve some special requirements, this way is *** mixing physical modification. The *** mixing modification can not change the molecular configuration, but can give the material new properties.PE's *** mixing modification is more difficult, the reason is that the compatibility of PE resin is poor. In order to improve the compatibility of the two phases, usually need to introduce another intermediate substance. Such as HDPE and PP is not compatible, to make the two resins **** mixing, the introduction of intermediate substances such as ethylene-propylene rubber (ethylene and propylene **** polymer, also known as binary ethylene-propylene rubber) in order to improve its compatibility. PP-H resin for plastic pipe production is also modified by ****blending. It is based on homopolymerized PP resin, the introduction of a certain amount of toughening modifier, such as PP resin and polybutadiene and other rubber substances **** blend, or PP resin and EVA **** blend. The amount of toughening agent added can vary from 5%-20% to obtain different characteristics. In actual production, as the modification of the material is usually added to a variety of additives, so the order of addition in the process of *** mixing modification is also very important, otherwise the mixing can not achieve the desired effect.