3D-Printed Conductive Compositions Anticipating or Indicating Structural Damage

Abstract

The present invention provides an article comprising a body and at least one segment of 3D printable conductive composite in mechanical communication with the body. The body includes a first material, and at least one conductive composite segment includes a matrix material, a plurality of carbon nanotubes, and a conductive additive. The conductive additive includes a plurality of metal particles, a plurality of graphite particles, or a combination thereof.

Description

technical field

[0001] The present disclosure relates to smart articles comprising conductive compositions that can be used to indicate structural damage or potential structural damage. Background technique

[0002] Additive manufacturing (also known as three-dimensional printing) as practiced in industry has so far mainly involved printing structural features. There is a need for materials and processes that integrate functional properties, such as electronic features, into additive manufacturing. Recently, polymer composite compositions of potentially useful conductive materials in additive manufacturing have been commercialized, but their conductivities are generally low, in the range of ~10 -3 S / cm to ~2.0 S / cm or more. Commercially available materials, especially conductive materials such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) generally have limited mechanical properties (e.g., are not flexible and / or are rather brittle), which Use as a fun...

Examples

example 1

[0066] By extruding a polymer substrate (polycaprolactone; "PCL") with 10% by weight of multi-walled carbon nanotubes (MWNT) together with 30% by weight of silver (Ag) flakes on a Haake twin-screw extruder Conductive composite segments were prepared by melt mixing at 30 rpm for 30 minutes. The resulting material was cryogenically ground and the ground compound was extruded into filaments using a melt flow indexer (MFI) and a modified die. Extrusion conditions on the MFI included a 1.8 mm hole and a 16.96 kg weight in order to produce the final filament. The final filament has a diameter of about 1.75 mm.

example 2

[0068] A 10 cm cross-section of the extruded filament of Example 1 with the tip coated with silver paint was used to measure electrical resistance in order to calculate bulk conductivity. Resistance measurements are done using a digital multimeter. The bulk conductivity was calculated using Equation 1 above.

example 3

[0070] A composite similar to that of Example 1 was prepared, but using 30% by weight of Ag nanoparticles instead of Ag flakes.

technical field

[0001] The present disclosure relates to smart articles comprising conductive compositions that can be used to indicate structural damage or potential structural damage. Background technique

[0002] Additive manufacturing (also known as three-dimensional printing) as practiced in industry has so far mainly involved printing structural features. There is a need for materials and processes that integrate functional properties, such as electronic features, into additive manufacturing. Recently, polymer composite compositions of potentially useful conductive materials in additive manufacturing have been commercialized, but their conductivities are generally low, in the range of ~10 -3 S / cm to ~2.0 S / cm or more. Commercially available materials, especially conductive materials such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) generally have limited mechanical properties (e.g., are not flexible and / or are rather brittle), which Use as a fun...

Examples

example 1

[0066] By extruding a polymer substrate (polycaprolactone; "PCL") with 10% by weight of multi-walled carbon nanotubes (MWNT) together with 30% by weight of silver (Ag) flakes on a Haake twin-screw extruder Conductive composite segments were prepared by melt mixing at 30 rpm for 30 minutes. The resulting material was cryogenically ground and the ground compound was extruded into filaments using a melt flow indexer (MFI) and a modified die. Extrusion conditions on the MFI included a 1.8 mm hole and a 16.96 kg weight in order to produce the final filament. The final filament has a diameter of about 1.75 mm.

example 2

[0068] A 10 cm cross-section of the extruded filament of Example 1 with the tip coated with silver paint was used to measure electrical resistance in order to calculate bulk conductivity. Resistance measurements are done using a digital multimeter. The bulk conductivity was calculated using Equation 1 above.

example 3

[0070] A composite similar to that of Example 1 was prepared, but using 30% by weight of Ag nanoparticles instead of Ag flakes.

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