BIMODAL CELLULAR THERMOPLASTIC MATERIALS

• US 20080280123A1
• Filed: 03/12/2008
• Published: 11/13/2008
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Washington University In St Louis
• Original Assignee: Washington University In St Louis
• Inventors: Kumar, Vipin, Miller, Dustin
• Granted Patent: US 7,923,104 B2
• Time in Patent Office: Days
• US Class Current: 428/315.7
• CPC Class Codes: B29C 44/10 Applying counter-pressure during expanding
• CPC Class Codes: B29C 44/3453 Feeding the blowing agent to solid plastic material
• CPC Class Codes: B29C 44/5609 Purging of residual gas, e.g. noxious or explosive blowing agents
• CPC Class Codes: B29C 44/588 with means for venting, e.g. releasing foaming gas
• CPC Class Codes: B29K 2079/085 Thermoplastic polyimides, e.g. polyesterimides, PEI, i.e. polyetherimides, or polyamideimides; Derivatives thereof
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29K 2995/0039 Amorphous
• CPC Class Codes: B29K 2995/004 Semi-crystalline
• CPC Class Codes: C08J 2201/032 Impregnation of a formed object with a gas expandable particles, e.g. polystyrene beads C08J9/18
• CPC Class Codes: C08J 9/00 Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof mechanical aspects of shaping of plastics or substances in a plastic state for the production of porous or cellular articles B29C
• CPC Class Codes: Y10T 428/249978 Voids specified as micro
• CPC Class Codes: Y10T 428/249979 Specified thickness of void-containing component [absolute or relative] or numerical cell dimension

Abstract

Methods for reducing the density of thermoplastic materials and the articles made therefrom having similar or improved mechanical properties to the solid or noncellular material. Also disclosed are improvements to foaming methods and the cellular structures of the foams made therefrom, and methods for altering the impact strength of solid or noncellular thermoplastic materials and the shaping of the materials into useful articles.

Claims

1. A cellular thermoplastic material, comprising:

micro-sized cells having an average cell size of greater than 1.0 μ

m to 100 μ

m,

wherein the micro-sized cells comprise cell walls; and

nano-sized features in the cell walls of the micro-sized cells, wherein the nano-sized features have an average size of 0.1 nm to 500 nm.

2. The cellular thermoplastic material of claim 1, wherein the thermoplastic material is an amorphous or semi-crystalline polymer.

3. The cellular thermoplastic material of claim 1, wherein the average is 20 nm to 40 nm n.

4. The cellular thermoplastic material of claim 1, wherein the nano-sized features provide open connectivity between adjacent micro-sized cells.

5. The cellular thermoplastic material of claim 1, comprising an intrabimodal cellular structure.

6. A cellular thermoplastic material, comprising:

a primary structure comprising nano-sized cells having an average size of less than 1 μ

m; and

secondary micro-sized cells having an average size of 2 μ

m to 3 μ

m interspersed among the primary structure.

7. The cellular thermoplastic material of claim 6, wherein the primary structure comprises the majority of the cellular thermoplastic material.

8. The cellular thermoplastic material of claim 6, comprising an interbimodal cellular structure.

9. A cellular thermoplastic material, comprising:

a primary structure comprising cells having an average size of 1 μ

m to 2 μ

m; and

secondary micro-sized cells having an average size of 10 μ

m to 15 μ

m interspersed among the primary structure.

10. The cellular thermoplastic material of claim 9, wherein the primary structure comprises the majority of the cellular thermoplastic material.

11. The cellular thermoplastic material of claim 9, comprising an interbimodal cellular structure.

12. A cellular thermoplastic material, comprising:

a primary structure comprising nano-sized cells having an average size of 0.1 nm to 100 nm; and

secondary micro-sized cells having an average size of greater than 0.1 μ

m to 100 μ

m interspersed among the primary structure.

13. The cellular thermoplastic material of claim 12, wherein the primary structure comprises the majority of the cellular thermoplastic material.

14. The cellular thermoplastic material of claim 12, comprising an interbimodal cellular structure.

15. A cellular thermoplastic material, comprising:

a primary structure comprising cells having an average size of less than 2 μ

m; and

secondary micro-sized cells having an average size of 2 μ

m to 100 μ

m interspersed among the primary structure.

16. The cellular thermoplastic material of claim 15, wherein the primary structure comprises the majority of the cellular thermoplastic material.

17. The cellular thermoplastic material of claim 15, comprising an interbimodal cellular structure.