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SSP for Polyamides

In the area of PA, Buhler has been building drying and SSP plants since 1982, and in this time has built some 90 lines worldwide. Buhler supplies specialized equipment for the thermal handling of PA pellets without mechanical agitation. This includes process design to the building of turnkey plants as well as retrofitting existing plants.

Buhler has extensive experience with the thermal treatment of a wide range of polyamide types: from PA4,6 through to PA11 and 12, and in particular PA6,6 and PA6.

Solid state polycondensation (SSP) of polyamide can be used to further increase the molecular weight – measured as relative viscosity (RV) – after the melt phase.

History

Polyamide (PA) is considered the first engineering thermoplastic and is one of many heterochain thermoplastics that has atoms other than carbon in the chain. Polyamide was invented in 1928 by Wallace Carothers, of the DuPont company, in search of a “super-polyester” fiber with molecular weights greater than 10,000. The first commercial Polyamide, called nylon, came in 1938. Polyamide was created when a condensation reaction occurred between amino acids, dibasic acids, and diamines.

More Information

Polyamide SSP Polyamide Drying & Conditioning SAP Polyolefines Polycarbonate Bio-Polymers Polyoxymethylene Polybutylenterephthalate

Key Features

  • Fast heat-up in fluid bed for accurate control of the reaction temperature and therefore RV.
  • Excellent control over the final moisture content by accurate control of the gas dew point.
More about key features

Process Description

The SSP treatment of polyamide typically takes place at temperatures between 120-200°C under nitrogen. A column reactor is used with the nitrogen passing in a counter-current flow. A fluid bed is used to quickly heat or cool the material to and from the SSP temperature. The viscosity can be increased from 2.5 SAV (sulphuric acid viscosity) to values as high as 4.0 SAV.