Ultrafine talcs not only increase the stiffness or flexural modulus of polypropylenes and thermoplastic olefins (TPOs) used in automotive composites but also help to maintain impact strength to produce the overall needed balance of these properties.

The Specialty Minerals Inc.’s (SMI’s) talcs used in this example are MicroTuff^® AG609 and AG191 talcs, 0.8 and 1.9 micron appearance grade talcs manufactured in Barretts, Montana.

This study was carried out in a TPO compound based on a 20 melt index polypropylene homopolymer with a constant ethylene octene elastomer concentration of 25 percent based on the total weight of the formulation. Each talc was used at a 10 and 20 percent reinforcement level.

Talc samples were compounded into the TPO resin on a 34 mm counter rotating twin screw extruder. Test pieces were molded on an 84 ton-Arburg injection molder at a melt temperature of 200^oC. Performance data were measured adhering to the following ASTM procedures:

• ASTM D790 for Flexural Modulus
• ASTM D256 for Impact Testing

Both of the talcs examined in this study are highly effective at increasing the flexural modulus or stiffness of the TPO formulation by approximately the same order of magnitude. The stiffness of the TPO formulation increases with increasing talc concentration. Both talcs improve the impact properties (Notched Izod) of the TPO formulation compared to the unfilled system. At the 20 percent loading level, the benefit of the finer, 0.8 micron Microtuff^® AG 609 talc becomes evident by the additional improvement in Izod impact strength.

Another performance example using a SMI ultrafine talc can be seen by clicking here.

Click here for more information on how high-aspect ratio minerals such as talc can improve the flexural modulus of plastic composites and click here for more information on the fundamentals of impact strength.

Learn more:

• SMI products for plastics
• SMI Products for reinforced polyolefins
• SMI Minerals for automotive polyolefins
• SMI Minerals for appliance polyolefins
  
  
• Performance of fine talcs in under-the-hood thermoplastic olefin (TPO)
• Performance of fine calcium carbonate in polypropylenes
  
  
• Talc in plastics
• What is Talc?  A minerals introductory web page
  
  
• Fundamentals of  Flexural Modulus / Stiffness
• Fundamentals of Impact
• Fundamentals of Nucleation
  
  
• SMI Products Used in Automotive Parts. See the parts of your car that are made with Specialty Minerals products.
  
  
• Download technical data sheets for Specialty Minerals products
• Request a sample