PPS-based compounds are among the most widely used in metal replacement applications destined for highly chemically challenging environments, as in situations characterised by permanent contact with hydrocarbons and solvents, or in the presence of strong inorganic aggressive agents, for example.
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Indeed, few other polymers are able to offer the same level of resistance to such a wide range of chemical substances, even at high temperatures.
Another recognised advantage of PPS (polyphenylene sulphide) is that it can be used successfully even at operating temperatures touching 200°C, a circumstance that can arise both in the working environment as a whole and locally (e.g. parts situated close to electric motors, or in the automotive and industrial applications).
Moulded items in reinforced PPS, as opposed to other semicrystalline polymers, offer remarkable, even unique, dimensional stability, thanks to a very limited differential shrinking, and consequently minimal deformations, similar to those typical of amorphous plastics.
Exceptional mechanical strength and resistance to creep and fatigue are the other key properties of this engineering polymer, which remains reliable even when subjected to strong and repeated stresses over time.
PPS is thus the perfect candidate for use in the production of mechanical parts that need to be dimensionally very precise, but also robust, resistant, stable and reliable, even in the most extreme applications.
We are talking about parts like the VP Plast moulded vanes installed on the rotors of rotary pumps built by the French company Mouvex, part of the PSG group and a leader in the construction of compressors and pumps for the handling of liquids.
In rotary vacuum pumps, the vanes are the heart of the entire device and the performance of the system depends largely on how well they work. Their precise function is to take up and force forward the fluid needing to be moved, and they have to guarantee a tight seal between the rotor and the internal jacket, so as to prevent fluid leaking into the pump chamber and causing a loss of pressure. Since they must also slide radially along the rotor without wearing the metal, the surface hardness and finish are crucial.
For all the above reasons, which allow its rotary pumps to handle fluids of all kinds — hydrocarbons, bitumen, mixtures, suspensions and solutions, chemicals, corrosive and abrasive high-viscosity liquids — Mouvex now uses LARTON G/40, a 40% glass fibre-reinforced PPS compound supplied by LATI, in addition to stainless steel and PEEK.
PPS-based LARTON compounds by LATI are also available in versions with mineral fillers conferring maximum dimensional stability, and in a carbon fibre-reinforced version for ATEX-approved antistatic applications.
