VICTREX PEEK 450G is defined as a standard melt viscosity (MV) PEEK grade, with a medium molecular weight.  Other VICTREX PEEK grades are available with higher and lower melt viscosities and higher or lower molecular weights respectively.  VICTREX PEEK 150G is a higher flow, lower molecular weight, lower MV grade of PEEK compared to 450G.  [A lower melt viscosity, measured in Pa.s, equates to a higher Melt Flow Rate (MFR)].  As a result, 150G may be more suitable for applications where lower viscosity in the melt during processing is desirable, for example, when injection moulding thin-walled parts or long, thin sections with intricate geometries; impregnating carbon or glass fibres for composite prepregs; or adding high levels of solid fibrous or particulate fillers and reinforcements to make compounds.  However, the lower molecular weight also changes the bulk properties of the polymer:  lower molecular weight PAEKs have higher stiffness and strength combined with reduced toughness, ductility and impact resistance.  This is a consequence of the shorter polymer chains, which are less entangled, crystallise more readily and to a greater overall extent.  Some of the properties of 450G and 150G are compared in the table below to illustrate these differences.