top of page

The polymer chain length in PET determines the molecular weight of the material & with it the physical properties that make PET such useful packaging material.

Intrinsic Viscosity (IV) is a measure of the polymers molecular weight. Therefore, it reflects the material’s melting point, crystallinity & tensile strength. The IV is used as part of the specification to select the right grade of PET for a particular application. It is measured at various points of the supply chain.


Taprath® offers a unique additive, TapStar IV Mod, for improving the intrinsic viscosity of condensation polymers. It has poly functionality that can link with a carboxylic acid, an amine, or a hydroxyl group. Thus, the end groups of the linear polymers get connected to each other & extend the chains. The product is uniformly acceptable for polyesters, polyamides & other condensation polymers.


Appearance: Powder/ granules
Colour: White
Solubility: Insoluble in water
Stability: Stable at ambient temperature under normal conditions

  • Effective at low concentrations

  • Ideal for low-cost applications

  • Compatible with most substrates

  • Non-toxic

  • RoHS Compliant


Condensation polymers tend to hydrolyze with small quantities of water that are adsorbed on the polymer. The water hydrolyses the polymer bond, generally randomly, causing the polymer chain to cleave in two unequal parts. The result is a reduction in molecular weight and consequently intrinsic viscosity.

To restore, the intrinsic viscosity, the end groups need to be reconnected. Depending on the intrinsic viscosity of the polymer (polyester or polyamides) and the expected increase in intrinsic viscosity, the dose needs to be adjusted.


Increases intrinsic viscosity of polyesters for bottle grade polyesters, molding and extrusion grade polyamide resins (Polyamide 6, 66, 11, 6 10, 9 10, 11, 12, etc.)

bottom of page