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Glass fiber replacement

Glass fiber replacement Imerys minerals make excellent glass fiber extenders in polyamides

Imerys minerals such as wollastonite, calcined kaolin and  mica can be used in partial replacement of chopped glass fiber in polyamide compounds to reduce warpage and improve surface appearance, rheology and isotropy of mechanical properties.


High aspect ratio wollastonite products improve thermo-mechanical properties in plastics, especially polyamides, and are excellent extenders for chopped glass fiber.  

High aspect ratio wollastonite can be used to replace one third of chopped glass fiber in polyamide formulations where it: 

  • Maintains or even improves thermal and mechanical properties
  • Improves surface aesthetics due to less splay during injection molding 
  • Reduces equipment abrasion, hence maintenance costs
  • Increases brightness and gloss
  • Maintains weldline strength (especially surface treated wollastonite) 

Wollastonite for fire retardant applications

Imerys wollastonites are cost-effective replacements for milled and chopped glass fibers in polyamides and other engineering alloys which need to meet UL-94 flame retardant (FR) properties. 

We recommend our Nyglos® wollastonite for these applications.

Calcined kaolin for glass fiber extension

Imerys silane-modified calcined kaolin is used in Engineering Thermoplastics (ETPs) to enhance key performance requirements including reinforcement and reducing warpage and shrinkage of the molding. 

Used in in combination with glass fibers in polyamide 6 and polyamide 6,6, silane-modified calcined kaolin significantly improves:

  • Elongation at break
  • Falling weight impact strength
  • Unnotched Charpy strength
  • Toughness

We recommend our Polarite grades where impact strength is a critical performance requirement in combination with low shrinkage and warpage.


Highly delaminated Imerys mica products are good reinforcing additives that can be used in partial replacement of glass fiber to maximize stiffness and improve isotropy while maintaining strength and toughness properties inherent to glass-fiber reinforcement. 

Partial replacement of chopped glass fiber with mica in polyamides: 

  • Improves flexural/tensile modulus
  • Maintains heat deflection temperature 
  • Improves melt rheology
  • Reduces cross-flow shrinkage and anisotropy inherent in glass fiber filled formulations


We recommend our high aspect ratio Suzorite® mica products for the extension of chopped glass fiber in polyamide 6, polyamide 6,6, or recycled polyamide applications.  


We offer a full range of custom 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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