Polypropylene (PP) is a semi-crystalline thermoplastic and belongs to the group of polyolefins. PP is odorless and skin compatible, it is suitable for applications in the food industry as well as pharmaceutics, and is physiologically entirely harmless. It can be processed via injection molding, extradition, blow molding, hot shaping, welding, deep drawing and machining. Additionally, it is used to produce foam. PP can be filled with mineral fillers such as talcum, chalk or glass fibers. This significantly widens the spectrum of mechanical properties (stiffness, operating temperatures etc.). Polypropylene at room temperature is resistant to greases and almost all organic solvents, apart from powerful oxidizers.
Surface energy and contact angle
Due to its low surface energy, polypropylene is hard to glue or print. Because of that a plasma treatment is neccessary to get a good result.
The following table shows the effect of plasma treatment with the plasma system plasmabrush PB3 on PP.
|Material: Polypropylene||Surface energy||Contact angle H2O|
|5 minutes after plasma treatment||48,0 mN/m||65,0°|
|1 hour after plasma treatment||50,5 mN/m||60,0°|
|2 hours after plasma treatment||51,0 mN/m||62,0°|
|4 hours after plasma treatment||52,0 mN/m||58,0°|
PP is used in machine and vehicle manufacturing for the interior of cars, instrument panels, battery cases and crash-absorber elements, as well as for child seats and bicycle helmets.
In electronic engineering, it is used for transformer housings, insulating foils, wire sheathings and cable sheathings. BBOP-oriented polypropylene foil is especially important as a dielectric of plastic film capacitors and power capacitors.
In the building industry, it is used for armatures, fittings and piping; in ventilation and air-conditioning technology, it is used in conditions favorable for corrosion, and for the extraction of corrosive gases, mostly in the form of PP-s (s=low flammability). Furhtermore in medical technology, the food industry, in households and in packaging technology, many products containing PP are used: tubs for dairy products, bottle caps, inner parts of dishwashers, reusable containers and so on.