Nucleation efficiency of talc in the foaming behaviour and cellular structure of polymer-based foams

1. A polymer-based foam composition comprising:

a polymer, wherein the polymer is a polypropylene polymer or a polystyrene polymer; and

from 0.5 wt. % to 1.7 wt. % talc particles, based on the total weight of the composition, wherein the talc particles comprise microcrystalline talc;

wherein the polymer-based foam composition has an average cell size of φ=150 μm or less in at least one of a vertical direction (φ VD ) and a width direction (φ WD ).

2. The polymer-based foam composition according to claim 1 , wherein the polypropylene polymer is a polypropylene homopolymer.

3. The polymer-based foam composition according to claim 1 , wherein the polymer is the major component of the composition.

4. The polymer-based foam composition according to claim 1 , wherein the microcrystalline talc has an average particle size d 50 by Sedigraph of 0.5 to 10 μm.

5. The polymer-based foam composition according to claim 1 , wherein the microcrystalline talc has an aspect ratio according to Jennings theory of between 9 and 15.

6. The polymer-based foam composition according to claim 1 , wherein the microcrystalline talc has a surface BET area of 5 to 25 m 2 /g.

7. The polymer-based foam composition according to claim 1 , wherein the polymer-based foam composition has a ratio φ VD /φ WD of the average cell size in the vertical direction φ VD to the average cell size in the width direction φ WD of 0.7 or more.

8. The polymer-based foam composition according to claim 1 , wherein the polymer-based foam composition contains N f =10 5 or more cells per cm 3 .

9. The polymer-based foam composition according to claim 1 , produced by a two-step extrusion-mixing and foaming process.

10. The polymer-based foam composition according to claim 1 , produced by a single-step injection-moulding foaming process.

11. A product comprising the polymer-based foam composition according to claim 1 .

12. A method of formation of the polymer-based foam composition as defined in claim 1 , the method comprising:

providing a polymer composition, wherein the polymer composition is a polypropylene polymer composition or a polystyrene polymer composition;

providing a microcrystalline talc product in an amount of 0.5 wt. % to 1.7 wt. % based on the total weight of the composition;

introducing the microcrystalline talc product into the polymer composition in an extrusion-mixing process; and

foaming the polymer composition using a gas comprising at least one of CO 2 , nitrogen, and a noble gas; wherein the polymer-based foam composition has an average cell size of φ=150 μm or less in at least one of a vertical direction (φ VD ) and a width direction (φ WD ).

13. A method of formation of the polymer-based foam composition as defined in claim 1 , the method comprising:

providing a polymer composition wherein the polymer composition is a polypropylene polymer composition or a polystyrene polymer composition;

providing a microcrystalline talc product in an amount of 0.5 wt. % to 1.7 wt. % based on the total weight of the composition; and

introducing the microcrystalline talc product into the polymer composition; and

foaming the composition using a single-step injection moulding foaming process; wherein the polymer-based foam composition has an average cell size of φ=150 μm or less in at least one of a vertical direction (φ VD ) and a width direction (φ WD ).

14. The product of claim 11 , wherein the product is at least one of a packaging, a food packaging product, a plastic part for automotive vehicles, a thermal and/or noise insulation foam, a pipe, a consumer good, or an appliance.