PP – Polypropylene, PP homopolymer, PP copolymer
Information about PP thermoplastic
Application: Approx.. 25% of all thermoplastics is constituted by PP. Used for food packaging, foil and bowls for microwave, “Bumpers”, “Fibertex materials”. Packaging for paint. Piping . what, containers and the like, which is welded of plates. PP is widely used in the chemical industry. Binder, suitcases, parts for cars, interior parts for washing machines in order to increase the strength used kacherede PP plates often reinforced with glass reinforced polyester – GUP as “lining” in containers. PP is used in the food industry include. , because it is resistant to liquids and solvents and the chemicals, one usually uses in such companies. PP is used for clothing, doors, containers, filtered, pumpedele og autoklaveplader. PP modified with EPDM used for items with high demands on impact strength.
Bending: Suitable for bending of heating wire / infrared heater at smaller thicknesses. Plates can also varmbukkes when heated with a heat gun el. or similar. The plate is heated, until it softens, and then be bent over an edge, a tube or otherwise, having the desired shape. The plate is held in this position, until it has cooled. Bending with welding bucks sword at greater thicknesses. Cold forming of the sheet is possible, if the cut is retained in shape. Otherwise, they will eventually straighten out. The internal tensions, usually give no problems.
Features mechanical: PP homopolymer – PP-H – er et materiale, losing much of the stiffness with increasing temperature. Det er dog HD-end stack.
Kærvslagstyrken er mindre end PE. Impact-resistant Modified PPCs (copolymer) or PP / EPDM can get very high kærvslagstyrker. Polypropylene has good flexibility, which can be exploited by hinges – thin material can withstand bending back and forth countless times.
PP has as PE tend cold filling at moderate loads. The allowable deformation is great though (that. 2,5%). Reinforced types have better measurement stability.
Features electric: The electrical characteristics are almost the PE’s; there is a good electrical insulator. Problems with static electricity may occur.
Colors: Normally, the PP-H semi-finished dyed gray-beige.
Physiological properties: PP is odor- and smagsneutralt, and it is friendly to the skin. It is suitable for use in the food industry.
Can be approved by BGA (Germany) and FDA (USA).
History: Isotactic polypropylene was discovered in 1954 of the Italian Kemist Guilio Natta and his assistant Paulo Chini, cooperating countries with the Italian company Montecatini. Polypropylene was described in the years up to 1956 by several manufacturers, for example, DuPont and Phillips. I 1957 starter Hercules (USA) production of bottles for pastureringsbrug. I 1961 there were already at least 9 North American producers.
Identification fire test: Burns with a clear, not sooting flame, blue at the bottom, yellow at the top, shoots a wave of molten material in front of the flame. Drips, smells such as oil or wax (do not self-extinguishing). . The ignition temperature is 345 ° C. PP added flame retardant called PPs.
Trade names: PPDWU, PPDWST
Category: Semi-crystalline material with variable stiffness and varying clarity.
Chemical resistance: PP is as PE highly resistant to chemicals. Aqueous solutions of the salts, acids and bases (inorganic) as well as alcohol and some oils tolerated. Vaskelud over 100 ° C is tolerated well. It is not resistant to oxidizing fluids. Gasoline and benzene and several other hydrocarbons gives swelling. If they contain halogens, enhanced attack.
The crystallinity is essential for chemical resistance. Stress corrosion can
occur with certain acid mixtures (chrome) and copper salt solutions (stabilization).
Chemical structure: as polyethylene, men med en CH3 group instead of each 4. brintatom
It is very common, PP adjusted, copolymer or blended with other polymers.
Delivery: Plates pipe rods welding wire.
Bonding: Difficult. Due to the good chemical resistance and a high surface resistance (upolaritet) can not be directly lime PP. One must before gluing process make a pretreatment to achieve a reasonable strength in the adhesive joint. Joining with glue are rarely used because of the relatively low strength and the cumbersome pretreatment.
Environment:Considered one of the most environmentally friendly plastics. Causes no significant impacts to the environment resulting from incomplete combustion only emission of CO2 and water.
Topics can not react with substances in the body, However, one should not inhale dust.
Polypropylene is chemically stable up to temperatures where the plastic is broken. Can 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: varying clarity. PPH is because of the crystallites opal, opaque, and the visible light can not pass.
Surface treatment: Difficult. It is possible to print and apply color after prior treatment
Cleaning: Resistant to most cleaning products.
Assembly (mechanical): Avoid threading and countersunk screws. Upon collection of other materials e.g.. ., please note that the plastic has large coefficient of expansion.
Injection molding: Widely used
Cutting: PP is like most plastics fairly easy to process. Cool shavings can cause problems. The tool must be very sharp. punching, punching and cutting of thin sheets is possible with close setting of the blades. Tapping into the material should be avoided and instead take advantage of genvindbøsninger of metal. Self-tapping screws should also avoid.
Welding: Hot gas welding 280-320OC.
The mass to the extruder temperature 200-230 ° C and an air temperature of 250-300 ° C
For hot air welding found welding wire in bars or on the inductor. For extruder is welding wire on the spool.
Friction welding 100-300 m/min.
Stuksvejsetemperatur with varmespejl 210 ° C +/- 10°C
Female / mandrel welding 250-270 ° C .
Thermal Properties: Becomes brittle at temperatures below approximately. -5°C. PP Khan autoklaveres. PPH has a scope, Located at higher temperatures than PE-HD. It should not normally be used below 0 ° C, because the impact strength is not adequate.
PP can be applied to about. 110°C, if the load is moderate.
Crystalline melting point: that. 165°C. Above this one can shape the material thermoplastic elastic. Withstands dampsterilisation and hot vand application.
UV- Stability: The material is not UV stable, but thick-walled parts with coloring damage usually only in the surface.
It is possible to heat mold plates, but it requires a special technique. You can use both negative- and forming positive. The material must be by hot forming on both sides is heated to a temperature of about. 180°C. At a temperature between 150-160 ° C it is possible to influence or pressure profiling in PP.