PE – Polyethylene – PEL – PEM – HDPE
Information about the thermoplastic PE
Application: PE used for water pipes, sewer pipes, drainage pipes, gas pipes and cable ducts, cable insulation, plastic bags. Film for packaging, trash bags, shrink film, film for frozen food mm bags made of polyethylene are characterized by having a high cold flexibility in that the material is not brittle at temperatures below minus 100 ° C. The material is suitable in the sliding features due to the low friction and wear resistance . Used for fittings and fixtures, and HDPE sheets for Welding of vessels, containers and galvanotromler. PEHD 500 or HDPE 1000 is used for gears, chain guides, wear strips, etc. In conveyors for bulk materials, eg. coal, grain or gravel used PEHD 1000 to wear plates lining of silos and similar applications where the goods have a sliding movement across the plate materials. In the food industry PEHD are used in particular for cutting sheets, molds, foods, partition the cabinets, etc. Kitchen Things, chemical tanks, coating of slurry tanks, foil industrial / agricultural / household.
The picture shows a so-called HHRT Phantom used for calibration and control of PET – scanner.
The phantom is made of PE HD and includes a Ge68 solution in water.
Bending: Suitable for bending of heating wire / infrared heater at smaller thicknesses. PE plates can also be hot bent when heated with a heat gun. or similar. The PE sheet is heated, until it softens, and then be bent over an edge, a tube or otherwise, that has the desired shape. The plate is held in this position, until it has cooled. Bending with welding bucks sword at greater thicknesses. by PEHD 500 and 1000 are hot bending possible, but inconvenient. The material can embark on cooling, and it may therefore be necessary to keep the shaped article in a fixture, where it can be cooled from all sides. HDPE can be cold bent in the bending machines for steel. Cold forming of the HDPE sheet is possible, if the cut is retained in shape. Otherwise, they will eventually straighten out. The internal tensions, usually give no problems.
Features: Good abrasion resistance of bulk commodities, such as grain, coal or gravel.
High impact strength even at low temperatures. Large varmeudvidelseskoefficient and tend koldflydning. low friction. Good chemical resistance Low weight Resistant little mechanical loads compared to PA, POM and PETP. PE can withstand high impact soil and is very Vibration. Films have poor barrier properties against flavors, Oxygen and carbon dioxide.
Electrical properties: One of the best insulating plastic materials for electrical effects. It diselektriske tab is low. Static electricity can cause problems. Master batch can be added antistatic agent that increases the surface conductivity, reducing overcharging.
Colors: PE-foil transparent er. In semi-finished products are of color opal white. Supplied dyed in various colors. Difficult to paint and press.
Moisture absorption: Very small, less than 0,01%.
Physiological: For use in direct contact with food. Meets requirements for BGA and FDA. Commodity Types can meet US and European demands for hospital equipment.
Trade names: Bar®, Cestitech®, Cestitech®, PE-UHMW, PE-HML.
History: Discovered by scientists at chemistry experiments in the UK from ICI in 1932, production in 1939 (PE-LD).
used bla.a. to radarkablers isolation during 2 . World.
Karl Ziegler invented PEHD in 1953 . He was born November 1898 near Kassel in Germany and died August 1973 i Mülheim, west Germany.
consumption 2005 was in Western Europe : LDPE 5.000.000 tons. LLDPE 2.800.000 tons. HDPE 5.300.000 tons.
Identification fire test: Burns with a clear, not sooting flame, blue at the bottom, yellow at the top, drips and smells like candles (do not self-extinguishing). Can be found added flame retardant. Ignition: 340°C.
Category: Delkrystallinsk material of variable crystallinity (rigidity).
EP thermoplastic er en delkrystallinsk, which appears in white in an undyed state. The type of plastics is one of the most widely used plastic materials and produced in several varieties, which most commonly encountered PELLD (linear low density). – FLYING (low density) – PEHD (high density). PELD is soft and flexible – HDPE is tougher and stiffer. PEHD is present in multiple densities, bl.a. HD 300 – HD 500 – HD 1000.
Chemical resistance: Are identifiable by an excellent resistance to many chemicals. Does not absorb water and has a high water vapor density. Aqueous solutions of the salts, acids and bases do not attack. An exception is highly oxidizing chemicals such as nitric acid, olium and halogens. Below 60 ° C, almost all organic solvents harmless.
Chemical structure: Long chains of carbon with 2 brintatomer pr. carbon atom
Polyethylene prepared by polymerization of ethylene and the hydrocarbon is built up exclusively of the elements carbon and hydrogen. Polyethylene is converted by combustion to carbon dioxide and water, but are not biodegradable. The commercially available PE-types can be divided into three categories:
LDPE (Low-Density PE) 910-930 kg / m³. Prepared by the high pressure process 3000 bar and 300 °C.
HDPE (High-Density PE) 940-965 kg / m³ . Prepared as the low-pressure process, by 1 atm and 170 °C.
LLDPE (Linear Low-Density-PE)910-935 kg / m³. Prepared as the low-pressure process, by 1 atm and 170 °C. LLDPE always contain a co-monomer.
MDPE is made by mixing LD and HD.
Delivery: Foil sheets tubes rods.
Bonding: Difficult. Due to the good chemical resistance and a high surface resistance (upolaritet) can not be directly lime polyethylene. One must before gluing process make a pretreatment to achieve a reasonable strength in the adhesive lining. Joining with glue are rarely used because of the relatively low strength and the cumbersome pretreatment.
Environment: Considered one of the most environmentally friendly types of plastic and causes no significant impacts to the environment and leads to the complete combustion only emission of CO2 and water.
Topics can not react with substances in the body, However, one should not inhale dust.
Polyethylene is chemically stable up to temperatures where the plastic is broken. Polyethylene may be melted and solidify many times without being degraded.
When welding and heat bending , Work with temperatures far below the decomposition temperature of the plastic.
Optical properties: Folie er transparent men lysspredene.
Surface treatment: Difficult. It is possible to print and apply color on PEHD after a prior treatment
Taken: Among the cheapest plastics.
Cleaning: Resistant to most cleaning products.
Assembly (mechanical): Avoid threading and countersunk screws. Upon collection of other materials e.g.. ., please note that PE plastic has large coefficient of expansion.
Injection molding: Widely used . shrinkage between 1-2,5% depending on the particular. a. thickness .
Cutting: Use sharp tools.
Welding: Welding: Heat Mirror, hot air welding 300-340OC, and friction welding 100-300 m/min.
PE80 Stuksvejsetemperatur: 200° C 220 ° C til Stuksvejsetemperatur PE100: 220°C (quick changeover)
Stuksvejsetemperatur PE100 Uponor profit-RØR: 240°C +5 -2°C (quick changeover)
Ekstrudersvejsning PE-HD – massetemperatur 200-230 ° C – air temperature 250-300 ° C.
Ultrasonic welding is useful, but high frequency is not possible.
PEHD 500 and especially PEHD 1000 are difficult to weld.
The addition of release agents, anti-slip agents and antistatic agent in blends can complicate welding.
Thermal Properties: Can anvendes in the temperature range -50 to 80°C. PE-HD 1000 may be used down to -260 ° C. The crystalline melting point is: PE-LD as. 110°C, PE-LLD as. 125°C. PE-HD as. 130°C. By thermoplastic processing must be above this temperature. Glasovergangstemperatur as. -120°C. PE plastic has great varmeudvidelseskoefficient.
UV- Stability: Not resistant to UV light particularly well.
Coloured in black, the material can be used outdoors. Master batch can be added UV stabilizers.
Thermoforming (Termoformning): Thermoforming is a widely used processing method. You can thermoform and blow topics in PE.
Density: 0,91 – 0,96