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Nucleation

Nucleation Imerys talcs for optimum performance and productivity in semi-crystalline polymers

Imerys talcs are effective nucleating agents in semi-crystalline polymers such as polypropylene, polyamides, polyesters, POM, PET and PBT where they increase crystallization rate and temperature improving productivity.

Talc’s unique crystalline structure provides an optimum surface for the nucleation of semi-crystalline polymers.

The use of talc as an efficient and highly cost-effective nucleating agent for polypropylene (PP) is well known and has been explained by the strong affinity of the neutral basal plane of the talc crystalline structure with the non-polar polypropylene.

Talc has also proved to be an effective nucleating agent for polar resins such as polyamides and polyester including polylactic acid (PLA). 

Crystalc / PP matrix
Talc crystalline structure provides a unique surface for nucleation of polymers

Talc nucleation modifies the morphology of crystalline polymers during crystallization by increasing the number of nuclei in the polymer melt and reducing the size of crystallites formed in the final nucleated products.

This increases flexural modulus and heat deflection temperature and can improve impact resistance at low talc loading levels.

The most significant effect of talc nucleation is in increasing the crystallization temperature of polymers, which could reduce cycle time in injection molding and increase throughput of thermoforming and other polymer processes.

PP crystallization
Talc increases the number of nuclei in the polymer melt. Example in PP

In Polypropylene

The crystallization of PP is fast enough that even non-nucleated neat PP reaches maximum crystallization during injection molding.

Imerys talc does not affect degree of crystallinity, but it does allow crystallization to start earlier when PP solidifies from a molten state. This results in higher crystallization temperature, which can increase throughput of industrial polymer processes, for example by reducing injection molding cycle times.

Nucleation with Imerys Talc also significantly improves the morphology of PP by reducing the size of spherulites, resulting in higher stiffness, HDT, and impact performance at loading levels of 0.25-1.0 weight percent.

Effect of minerals on crystallization temperature of a high impact PP copolymer

For PP nucleation, we recommend our Crys-Talc®, which also provides the best optical properties.

In Polyamide 6

The crystallization of PA6 is also fast enough to allow the resin to reach maximum crystallization without a nucleating agent.

However, nucleation with Imerys talc increases the crystallization temperature of PA6, allowing the melt to solidify faster improving the throughput of industrial processes by reducing injection molding cycle times.

Effect of minerals on the crystallization temperature of PA6

Graph showing effect of minerals on PA6 crystallization temperature

For PA6 nucleation, we recommend our Crys-Talc®, Cimpact® or Jetfine® products.

In Biopolymers

Used in biopolymers, such as polylactic acid (PLA) and polyhydroxyalkanoate (PHA), Imerys talcs:

  • Speed up crystallization
  • Improve HDT
  • Increase stiffness
  • Improve dimensional stability in terms of shrinkage and thermal expansion
  • Reduce brittleness
  • Improve barrier properties
  • Reduce molding times
  • Reduce formulation costs

For PLA nucleation, we recommend our Crys-Talc® or Jetfine® products.

 

We offer a full range of bespoke formulation and technical and process support services to help you match the right mineral grade to your application requirement.

Please contact us, we will be only too happy to help

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Plastics