Fiber reinforced polymeric composites with tailorable electrical resistivities and process for preparing the same

• US 9,017,580 B2
• Filed: 11/22/2010
• Issued: 04/28/2015
• Est. Priority Date: 11/24/2009
• Status: Active Grant

• Current Assignee: The Defence Research and Development Organisation (Republic of India)
• Original Assignee: The Defence Research and Development Organisation (Republic of India)
• Inventors: Sankaran, Sundaram, Dasgupta, Samudra, Kumar, Madishetty Narayana Rao Jagdish
• Primary Examiner(s): Kopec, Mark
• Assistant Examiner(s): Hammer, Katie L
• Application Number:
  US13/510,793
• Publication Number:
  US 20120261623A1
• Time in Patent Office: 1,618 Days
• Field of Search: None
• US Class Current: 252/511
• CPC Class Codes: B29C 70/025 with particular filler
• CPC Class Codes: B29C 70/882 partly or totally electrically conductive, e.g. for EMI shielding conductive floors or floor coverings H05F3/025; EMI shielding in general H05K9/00
• CPC Class Codes: B29K 2063/00 Use of EP, i.e. epoxy resins or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2105/165 Hollow fillers, e.g. microballoons or expanded particles
• CPC Class Codes: B29K 2105/167 Nanotubes
• CPC Class Codes: B29K 2309/08 Glass
• CPC Class Codes: B29K 2707/04 Carbon
• CPC Class Codes: B29K 2995/0005 Conductive
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/779 Possessing nanosized particles, powders, flakes, or clusters other than simple atomic impurity doping
• CPC Class Codes: Y10S 977/842 for carbon nanotubes or fullerenes

Abstract

The present invention relates to polymer composite materials, more particularly relates to composite materials with tailor made surface electrical resistivities in the range of 10⁹ to 10⁻¹ Ω/sq. and process of making the same. The process for preparing Fiber Reinforced Polymeric (FRP) Composite, said process comprising acts of homogeneously mixing 1-30% by weight of different electrically conducting fillers in matrix resin system to obtain resin mix; wetting dry preforms using the resin mix; compacting the wetted preforms to obtain green composite; curing the green composite; and post-curing the cured composite to prepare the FRP Composite.

Claims

1. Fiber Reinforced Polymeric (FRP) composite, the FRP composite comprising a dry preform, the dry preform comprising reinforcement fibers and the dry preform being laminated a resin mix comprising resin, hardener and electrical conductive fillers selected from one of:

carbon black, ranging from about 1% to about 10% by weight of the resin mix,

silver coated hollow glass microspheres, ranging from about 1% to about 30% by weight of the resin mix, and

carbon nanotubes, ranging from about 0.1% to about 4% by weight of the resin mix, wherein said FRP composite has density ranging from 0.9 g/cc to 2.0 g/cc, a surface electrical resistivity ranging from 10⁹ Ω

/sq. to 10<sup>−

1</sup> Ω

/sq., an ambient temperature storage modulus ranging from 4 GPa to 15 GPa, an Inter Lamellar Shear Strength (ILSS) ranging from 15 MPa to 50 MPa and is capable of withstanding a temperature up to 170°

C.

2. The FRP composites as claimed in claim 1, wherein the conductive carbon black has particle size ranging from 10 microns to 100 microns and bulk electrical resistivity of less than 100 Ω

-cm.

3. The FRP composites as claimed in claim 1, wherein the silver coated hollow glass microspheres have diameter ranging from 20 microns to 200 microns and silver content ranging from about 10% to about 50% of bulk weight of the microspheres.

4. The FRP composites as claimed in claim 1, wherein the carbon nanotubes are single or multi walled with outer diameter ranging from 2 nm to 100 nm, length ranging from 100 nm to 2000 nm, and are selected from a group comprising crude carbon nanotubes, purified carbon nanotubes, with purity varying from 30% to 100% by weight, non-functionalized carbon nanotubes and functionalized carbon nanotubes, wherein said functionalization is carried out using amine or hydroxyl termination.

5. The FRP composites as claimed in claim 1, wherein the reinforcement fibers are selected from a group comprising glass fibers, carbon fibers and aramid fibers in forms selected from a group of woven fabrics, unidirectional tapes, and chopped strand mats.

6. The FRP composites as claimed in claim 1, wherein said resin is a thermosetting resin selected from a group comprising novolac based epoxy and DGEBA based epoxy.

7. The FRP composite as claimed in claim 1, wherein the dry preform is laminated with 2 layers of the resin mix.

8. The FRP composite as claimed in claim 1, wherein said hardener for epoxy resins is selected from a group comprising diethyl triamine (DETA), triethylene tetramine (TETA), diamino diphenyl methane (DDM) and diamino diphenyl sulphone (DDS).

9. A process for preparing the Fibre Reinforced Polymeric (FRP) Composite of tailorable surface electrical resistivities as claimed in claim 1, said process comprising:

obtaining a resin mix by homogeneously mixing resin with hardener and electrically conducting fillers selected from one of

carbon black, ranging from about 1% to about 10% by weight of the resin mix,

silver coated hollow glass microspheres, ranging from about 0.1% to about 30% by weight of the resin mix, and

carbon nanotubes, ranging from about 1% to about 4% by weight of the resin mix;

laminating dry preforms using the resin mix;

compacting the laminated preforms to obtain a green composite;

curing the green composite; and

post-curing the cured composite to prepare the FRP Composite, wherein said FRP composite has surface electrical resistivities ranging from 10⁹ Ω

/sq. to about 10<sup>−

1</sup> Ω

/sq.

10. The process as claimed in claim 9, wherein the carbon black and the silver coated hollow glass microspheres are manually mixed in the resin mix.

11. The process as claimed in claim 9, wherein the carbon nanotubes are homogeneously mixed in the matrix resin by a process comprising at least one of ultrasonication, manual mixing and shear homogenization.

12. The process as claimed in claim 9, wherein the compacting of the laminated preforms are carried out using a process selected from a group comprising vacuum bagging, matched die molding, compression molding and autoclave molding.

13. The process as claimed in claim 9, wherein the curing of the green composite is carried out at room temperature for about 24 hours or at elevated temperature ranging from about 80°

C. to about 180°

C. for about 2 to 4 hours.

14. The process as claimed in claim 9, wherein the post-curing is carried out at temperature ranging from about 120°

C. to about 350°

C. for about 2-4 hours.

15. The process as claimed in claim 9, wherein the dry preform is laminated with 2 layers of the resin mix.