Lexicon of Materials - P

Our dictionary of materials consists of technical terms, which are explained in detail using easily understood language. Please click on a letter of your choice to reach the relevant material.
 

Synthetic fiber made from polyacrylonitrile (PAN). PAN precursor is the raw material used in the production of high-performance carbon fiber.

Oxidized, thermally stabilized polyacrylonitrile (PAN) fiber that will not burn, melt, soften or drip.
The excellent textile processing properties of PANOX® open up wide range of application from fire-protective apparel to fire-retardant furniture and machine, automotive, and aircraft components.

See also: Carbon fiber

SGL Group's tradename for high performance PTFE products. Manufactured as round shaped liners in proprietary paste-extrusion process or as sheets for large size and weldable linings. Also available as antistatic (conductive) material. POLYFLURON® greatly extends the service life of components used in demanding corrosive applications.Continuous quality assurance measures ensure that our products are of consistently high quality.

Polytetrafluoroethylene (PTFE) is the fully fluorinated polymer of tetrafluoroethylene monomers with a very high molecular weight.  It is produced as powder in either a suspension (S-PTFE) or an emulsion (E-PTFE) technology. Due to the extremely long molecular chains, it is processed into a semifinished product by compression with a following sintering step that melts the micro particles together. PTFE composes only of carbon and fluorine with an extremely strong bonding. This gives the polymer a unique stability versus heat aging and chemical attack.  

Owing to its almost universal chemical resistance at usage temperatures up to 260 °C, PTFE is a preferred construction and lining material for the heavy-duty corrosion protection of equipment, pipework, and fittings used in the chemical industry. Furthermore it offers excellent dielectric properties and very high flexural fatigue resistance, which makes it suitable for flexible parts like expansion joints, flexible hoses, and tubes as well as electrical insulators.

Preforms are three-dimensional fabrics of high-quality fibers impregnated
with curable resins. Preforms are the base materials for the manufacture of fiber composite materials.

Prepregs stand for textile reinforcing materials made from high-quality carbon, glass, and aramid fibers impregnated with different resin systems.

Graphite has been employed in chemical process equipment engineering for more than 70 years. In this sector, its applications are determined in the first place by its chemical and physical properties and in the second place by its suitability as a construction material for equipment and pressure vessels.

Production process for semi-finished graphite products

The production process for graphite requires an extensive amount of time and energy.

Mixing and forming

The raw materials (low-iron petroleum cokes and pitch binders) are mixed at a moderate temperature, forming a homogeneous compound. Forming by ram extrusion

Continuous process

  • Forming into solid material or tubes
  • Forming by vibration molding

Discontinuous process

  • Graphite properties non-directional (isotropy)
  • Forming by isostatic pressing
  • Baking, impregnation and rebaking.

The baking process converts the binder pitch to coke, removes most of the volatiles at 1200°C, and leaves a solid, non-deformable carbon body (amorphous carbon). Baking is followed by pitch impregnation and subsequent rebaking to improve density and other properties.

Graphitization

This production step heats the carbon material to a temperature of approx. 3000°C by electricity, inducing the formation of the crystalline graphite structure. Synthetic resin impregnation by a vacuum-pressure process fills the pores within the graphite, making the material impermeable.

Pyrolytic graphite is an impervious material with anisotropic properties, deposited as a thin coating on the graphite by chemical vapor deposition (CVD).