PVC, UPVC, CPVC, PP, PE, PB, PVDF plastic pipe performance and differences#pipe extrusion line#extrusion machine
PVC (PolyVinylChloride) is generally available in seven grades (SG1-SG7) according to its hardness and properties, with a density of about 1.4 g/cm³. Below SG4, it is generally a soft product, which requires a large amount of plasticizer when forming, and is mainly used for making artificial leather, wire and cable insulation, seals, etc. Above SG5, it is a hard product, mainly used for making various pipes, such as drainage, electrical, post and telecommunications pipes and fittings, various plates, sheets and profiles, etc. The shrinkage rate of PVC in forming is 0.6-1.5%, and it has good mechanical properties. PVC has a shrinkage rate of 0.6-1.5%, good mechanical properties, excellent electrical properties, self-extinguishing, strong acid and alkali resistance, good chemical stability and low prices. However, its development is hindered by its low use temperature, which is around 80°C at the highest.
The resin is produced by chlorination modification of polyvinyl chloride (PVC) resin and is a new type of engineering plastic. The product is a white or light yellow tasteless, odourless, non-toxic loose granule or powder. After the chlorination of PVC resin, the irregularity of the molecular bonds increases and the polarity increases, which increases the solubility of the resin and the chemical stability, thus improving the heat resistance of the material and the corrosion resistance of acids, alkalis, salts and oxidants. The mechanical properties of the thermal deformation temperature of the values are improved, the chlorine content is increased from 56.7% to 63-69% , the Vicat softening temperature is increased from 72-82 °C, (to 90-125 °C), the maximum use temperature can reach 110 °C and the long-term use temperature is 95 °C. Among them, CORZAN CPVC performance indicators are more excellent. Therefore, CPVC is a new type of engineering plastics with broad application prospects.
The UPVC pipe is made of PVC resin, which has excellent characteristics such as accurate temperature sensing, regular melting and rapid absorption of the effective ingredients of additives when the gravitational force between the resin molecular chains is weakened, and at the same time, the world famous calcium and zinc compound heat stabilizer is used, which can capture, inhibit and absorb the neutralization of hydrogen chloride during the process of high temperature and melting of the resin, and carry out double bond addition reaction with the polyene structure to replace the active and unstable chlorine atoms in the molecule. The double bond addition reaction with the polyene structure displaces the active and unstable chlorine atoms in the molecule. This effectively and scientifically controls the catalytic degradation and oxidative decomposition of the resin in the molten state.
PP pipe is a semi-crystalline material. It is stiffer and has a higher melting point than PE. As homopolymer PP is very brittle above 0°C, many commercial PP materials are irregular copolymers with 1-4% ethylene or higher rates of ethylene content in pincushion copolymers. The strength of PP increases with increasing ethylene content and has a Vicat softening temperature of 150°C. Due to its high crystallinity, the material has good surface stiffness and scratch resistance, and PP does not suffer from environmental stress cracking. PP is usually modified by adding glass fibres, metal additives or thermoplastic rubber. the flow rate MFR of PP ranges from 1 to 40. low MFR PP materials have better impact resistance but lower ductility. For the same MFR, the copolymer type has higher strength than the homopolymer type. Due to crystallisation, the shrinkage of PP is quite high, typically 1.8 to 2.5%. And the directional uniformity of shrinkage is much better than for materials such as PE-HD. The addition of a 30% glass additive can reduce shrinkage to 0.7%. Both homopolymer and copolymer types of PP material have excellent resistance to moisture absorption, acid and alkali corrosion, and solubility. However, it is not resistant to aromatic hydrocarbon (e.g. benzene) solvents, chlorinated hydrocarbon (carbon tetrachloride) solvents, etc. Nor does PP remain resistant to oxidation at high temperatures, as PE does.
PP is a crystalline polymer with a large shrinkage rate (1.0-1.5%) due to large volume changes and high molecular orientation when the melt is condensed. Therefore, during the molding process, the injection pressure and shear rate should be increased in order to improve the molding quality of the product.
Polyethylene is the most structurally simple polymeric organic compound and is the most widely used polymer material in the world today. It is polymerised from ethylene and is divided into high density polyethylene, medium density polyethylene and low density polyethylene according to its density. Low-density polyethylene is soft, more high-pressure polymerisation; high-density polyethylene has the characteristics of rigidity, hardness and mechanical strength, more low-pressure polymerisation. High-density polyethylene can be used for containers, pipes, and high-frequency electrical insulation materials, used for radar and television. Low density (high pressure) polyethylene is often used in large quantities. Polyethylene is waxy and has a wax-like smoothness. When not dyed, low-density polyethylene is transparent, while high-density polyethylene is opaque, and polyethylene is a highly polymeric chain made up of repeating -CH2-units connected by the addition and polymerisation of ethylene ( CH2=CH2 ). The properties of polyethylene depend on the way it is polymerised; high density polyethylene (HDPE) is produced by Ziegler-Natta polymerisation under moderate pressure (15-30 atm) catalytic conditions of organic compounds. The polyethylene molecules polymerised under these conditions are linear and have long molecular chains with molecular weights of several hundred thousand. In the case of free radical polymerisation under high pressure (100-300 MPa), high temperature (190-210 C) and peroxide catalysis, the result is low density polyethylene (LDPE), which is branched.
Polyethylene is insoluble in water and has very little water absorption, even for chemical solvents such as toluene and acetic acid, which are only slightly soluble at temperatures above 70°C. However, polyethylene in particulate form can melt or solidify at temperatures ranging from 15°C to 40°C. When the temperature rises, it melts and absorbs heat; when the temperature decreases, it solidifies and gives off heat. It is also a very good building material because it absorbs very little water, is not easily moistened and has insulating properties.
Polybutylene was developed and applied in the early 1970s and its material characteristics dictate high technical and equipment requirements for the production of profiles, with large investments in fixed assets.
Appearance is translucent or white powder or particles, the molecular chain is closely arranged, but also has a strong hydrogen bond, oxygen index of 46%, non-combustible, crystallinity 65% ~ 78%, density of 1.17 ~ 1.79g/cm3, melting point of 172 ℃, heat deflection temperature 112 ~ 145 ℃, long-term use temperature of -40 ~ 150 ℃.
PVDF resin is mainly refers to vinylidene fluoride homopolymer or vinylidene fluoride and a small amount of other fluorine vinyl monomer copolymer, PVDF resin both fluorine resin and general resin characteristics, in addition to good chemical resistance, high temperature resistance, oxidation resistance, weather resistance, radiation resistance, but also has piezoelectricity, dielectricity, thermoelectricity and other special properties, is currently the production of fluorine containing plastics ranked PVDF applications are mainly concentrated in the petrochemical, electrical and electronic and fluorocarbon coating fields. Its good chemical stability, electrical insulation properties, so that the production of equipment to meet the TOCS and flame retardant requirements, is widely used in the semiconductor industry on the storage and transport of high-purity chemicals, in recent years the use of PVDF resin made porous membrane, gel, diaphragm, etc., in the lithium secondary battery applications, the current use of PVDF has become one of the fastest growing market demand. PVDF is the most important fluorocarbon coatings PVDF is one of the most important raw materials, and fluorocarbon coatings prepared from it have been developed to the sixth generation. Due to the superb weather resistance of PVDF resin, it can be used outdoors for a long time without maintenance, and this type of coating is widely used in power stations, airports, highways, high-rise buildings, etc. In addition, PVDF resin can also be blended with other resins, such as PVDF and ABS resin blended to get composite materials, has been widely used in construction, automotive decoration, home appliance shell, etc.
PVC is a kind of plastic decoration material, PVC is the abbreviation of polyvinyl chloride material, is the main raw material of polyvinyl chloride resin, add the appropriate amount of anti-aging agent, modifier, etc., through the mixing, calendering, vacuum blister and other processes to make the material.
PVC materials are lightweight, heat insulation, heat preservation, moisture-proof, flame retardant and easy to construct. Specifications, colours and patterns.
It is one of the most widely used decorative materials among plastic materials.
The advantages of PVC fasteners are mainly the following:
1. light quality, heat insulation, heat preservation, moisture resistance, flame retardant, acid and alkali resistance, corrosion resistance.
2. Stability, good dielectricity, durability, anti-aging, easy to fuse and bond.
3. Strong bending strength and impact toughness, high elongation when broken.
4. Easy to process and shape through kneading, mixing, sheeting, cutting, extruding or die-casting processes, and can meet the needs of various profile specifications.
5. Smooth surface, bright colour, decorative, wide decorative applications.
6. The construction process is simple and the installation is convenient.
PE pipe is made of polyethylene material, PE pipe is suitable for concealed installation, open installation material is easy to age.
PP-R pipe has the advantages of light weight, good strength, corrosion resistance, no scale, long service life, etc., in addition to the following main features:
(1) Non-toxic, hygienic, green building materials, PP-R raw materials are polyolefin, its molecules are composed of carbon, hydrogen elements, non-toxic, excellent health performance;
(2) heat-resistant, heat preservation, energy-saving products, PP-R pipe Vicat softening temperature of 131.3 ℃, the highest use temperature of 95 ℃, long-term (50 years) use temperature up to 70 ℃. The thermal conductivity of the product is 0.24W/m℃, which is only 1/200 of the thermal conductivity of steel pipe, so it has excellent energy-saving effect for hot water pipe insulation;
(3) Easy to install, reliable, using hot fusion homogeneous connection, a few seconds to complete a joint connection, and metal pipe and water appliance connection using high-quality metal insert fittings, safe and reliable.
Application areas for PP-R hot and cold water pipes
Hot and cold water systems in buildings, including central heating systems;
Heating systems in buildings, including floor, wall panel heating and radiant heating systems;
Systems for the supply of pure water that can be used directly for drinking;
Central (centralised) air conditioning systems;
Agricultural, garden irrigation systems;
Swimming pool networks;
Pipe networks for solar installations;
PPR is generally used for small pipe diameters, and PPR is available for both open and concealed installations.
PB pipe is a polybutylene polymer material, which has been widely used in developed countries such as Europe and America, and has replaced copper as the preferred material for hot water supply pipes.
The main raw material of PEX pipe is HDPE, as well as initiator, cross-linking agent, catalyst and other additives, such as special requirements can also add other modifiers.
PEX pipes are manufactured using the world’s most advanced one-step (MONSOIL method) technology, using ordinary polyethylene raw materials to add silane grafting material, forming chemical covalent bonds between polymer macromolecular chains to replace the original van der Waals forces, thus forming a three-dimensional cross-linked network structure of cross-linked polyethylene, the degree of cross-linking up to 60% ~ 89%, so that it has excellent physical and chemical properties.
ABS is a styrene-butadiene-acrylonitrile-based terpolymer, with high impact toughness and good mechanical strength, heat resistance, oil resistance, etc.
Home laying of electrical wires are used PVC pipe, and should be the standard fire PVC pipe, there are also some re-laying of sewerage using PVC pipe, and commonly used PPR are used in the renovation of water lines, PPR is more suitable for water.
The essence of the difference is that the raw materials are different, ppr is random copolymer polypropylene, pvc is polyvinyl chloride. pvc can be used for drainage, ppr is mainly for water (used as drainage cost is too high). In fact, pvc is not as toxic as the medical infusion tubes and many plastic packaging are pvc, used for construction only added modifiers, plus ppr can be hot melt pvc can not.
PPR is produced from copolymer polypropylene material, PVC is produced from polyvinyl chloride material, the former high production costs, health grade is also better than PVC, and can go below 75 ℃ hot water, the disadvantage is easier to deformation. pvc is due to low production costs, is widely used in agricultural irrigation, the disadvantage is only go cold water.
PE water supply pipe low temperature embrittlement temperature is very low, can be used in the range of -40 ℃ to 60 ℃, winter installation and construction will not occur in the pipe brittle crack.
Polyethylene is an inert material, resistant to a variety of chemical media erosion, no anti-corrosion protection, chemical substances in the soil will not cause any degradation of the pipeline, will not occur decay, rust and corrosion phenomenon.
PE water supply pipe elongation at break exceeds 800%, local vibration will not cause all the pipe vibration, strong resistance to vibration. The winding nature of polyethylene allows PE water pipes to be coiled, reducing the need for a large number of connecting fittings and allowing the construction to bypass obstacles, reducing the difficulty of construction.
Due to the high crystallinity of HDPE, the strength and hardness increases. Fused tightly, it can withstand internal pressure and is commonly used for water supply and burning pressure pipes.
Hygienic and non-toxic, the pipe does not breed bacteria, will not cause secondary pollution of water quality, completely solve the defects of the pipeline pollution of water.
PE water supply pipe smooth inner wall, small coefficient of friction, small fluid resistance, small head loss, no scaling, reduce the pressure loss of the pipeline and water transmission energy consumption, the economic advantages are obvious.
PE water pipes are connected by hot and electric fusion, the strength of the interface is higher than the strength of the pipe itself, which can effectively resist the circumferential and axial forces generated by internal pressure. The sealing performance is so good that there is no need to worry about leakage due to distortion of the interface.