Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins

Definitions

• CNTs have the potential to be useful in multiple areas of technology. CNTs are the strongest materials known at this time in terms of tensile strength and elastic modulus, suggesting a role in mechanical reinforcements for lightweight composite materials. SWCNTs have a tensile strength 50-100 GPa and a modulus of 1-2 TPa, five and ten times greater than steel, respectively, while one-sixth of the weight. See Baughman, R. H et al. Science 2002, 297, 787. They can withstand pressure up to 24 GPa, surpassing even diamonds.
• Dispersion of CNTs within a matrix and CNT interaction with the matrix determine whether the properties of CNTs are integrated well into the polymeric matrix. Difficulties in uniformly dispersing CNTs within a matrix are caused by the strong van der Waals interactions amongst the tubes. Aggregation of CNTs within a matrix causes defects in the composite material. Enough aggregation can cause the composite material to fail. Other problems associated with incorporating CNTs into other materials occur because of the lack of interfacial interactions between the matrix and the CNTs. Failure of CNTs to interact with the matrix leads to low or no material reinforcement from lack of load transfer efficiency from the matrix to the CNTs. See Huang, Y.Y. and E. M.
• CNT-polymer composites are highly important polymer composites.
• CNT-epoxy composites promise new composite materials that are stronger, more flexible yet less dense, thus less heavy, than current materials.
• a need remains for a method for dispersion of non-functionalized CNTs or non-covalently functionalized CNTs in aqueous or non-aqueous solutions, where the desired properties of the CNTs remain intact, little to no aggregation of the CNTs occurs in solution and interfacing between the CNTs and a matrix occurs at a level to transfer the unique properties of the CNTs to the matrix. Furthermore, a need remains for a method to create a stable non-functionalized CNT or non-covalently functionalized CNT dispersion where the dispersion remains stable for significant lengths of time, such as weeks or months.
• the present invention is directed to methods of dispersal of CNTs into one or more solvents with or without carrier compounds and the dispersion containing CNTs is then integrated with a polymer and to the CNT -polymer composites produced by such methods. Integration of CNTs with one or more polymers is augmented through improved dispersal of the CNTs, with or without covalent bonding with the molecules of the polymer matrix during the curing process.
• Another embodiment of the present invention is directed towards a method of dispersion where the CNTs are added to an alcohol, such as isopropyl alcohol, in the presence of a carrier compound, such as a titanate, zirconate or glycol ester.
• a carrier compound such as a titanate, zirconate or glycol ester.
• the CNT dispersion is further combined with an alkaline carbonate to achieve a stable dispersion of CNTs.
• the present invention includes a method of dispersion of CNTs in a hydrocarbon solvent, such as toluene, Dowanol PMA (propylene glycol methyl ether acetate), Dowanol EPh (ethylene glycol phenyl ether) or Dowanol PPh (propylene glycol phenyl ether), in the presence of a carrier compound.
• a hydrocarbon solvent such as toluene, Dowanol PMA (propylene glycol methyl ether acetate), Dowanol EPh (ethylene glycol phenyl ether) or Dowanol PPh (propylene glycol phenyl ether)
• the final CNT dispersed mixture is added to a polymer matrix, such as an epoxy resin.
• a polymer matrix such as an epoxy resin.
• the solvents and carrier compounds are removed from the CNT dispersed mixture plus polymer matrix either before or after the addition of a curing agent, thus leaving the dispersed CNTs in the polymer plus curing agent matrix. Removal of the solvents and carrier compounds is accomplished by vacuum distillation, fine filtration or organic solvent nano-filtration using an Evonik Duramem membrane, defined here as "OSN.”
• OSN Evonik Duramem membrane
• the CNTs are separated based on a characteristic inherent in a CNT, such as, but not limited to, chirality, electrical conductivity, thermal conductivity, diameter, length, number of nested tubes, and combinations thereof.
• the CNTs are purified using techniques that include, but are not limited to, Chiang et al, J. Phys. Chem, B, 2001, 105, 1157-1161 and 8297-8301. The terms "CNT,” "CNTs,” and
• nanotube(s) are used synonymously herein.
• Polymers of the present invention include epoxies and polymer resins, such as an alkyd resin, a polyester resin, vinyl resin (epoxy resin combined with an unsaturated monocarboxylic acid) or a silicone resin.
• Epoxies of the present invention are cross-linked polymeric species, where the cross-linking is between epoxy resin species comprising epoxide groups and a curing agent. Curing is defined as the process of cross-linking of the epoxy resin species and the curing agent.
• Suitable epoxy resins include, but are not limited to, diglycidyl ether of bis-phenol-A, Nov lac epoxy, cyloaliphatic epoxy, brominated epoxy, aliphatic amines, aromatic amines, and combinations thereof.
• Epoxies may further comprise additives such as, but not limited to, plastisizers, anti-degradation agents, diluents, toughening agents, pigments, clay fillers and combinations thereof.
• the general step of dispersal of the CNTs in a solvent can require selection of a suitable solvent for dispersing the CNTs with a particular group.
• Dispersal can include mixing, agitation, and sonication for assistance in dispersal.
• the level of homogeneity of the mixture can be variable initially or varied in subsequent processing steps.
• the removal can be an evaporative process, a vacuum removal process or other enhanced evaporative removal process or a filtration process.
• dispersion-resin mixture process was adding the epoxy resin to the dispersion mixture and stirring the solution for at least 10 min. and up to and including 30 min. in a low powered ultrasonic bath. Removal of the solvent from the dispersion-resin mixture was completed by organic solvent nano-filtration ("OSN"). White, L.J. Membrane Science, 2006, 286, 26.
• OSN organic solvent nano-filtration
• This Example illustrates dispersion of SWCNTs in an alkaline carbonate in the presence of a titanate compound.
• SWCNTs of 95% or greater purity with a diameter of 8-15 nm and a length of 10-50 ⁇ were obtained by a variety of sources.
• a titanate compound (Neoalkoxy Titanate LICA- 09) was added to propylene carbonate via the carrier solvent dimethyl sulfide.
• Concentration of CNTs added to the titanate-containing solvent was 0.01% up to and including 5.5% by weight and the titanate ranged from 0.2% up to and including 20% weight percent of the weight of the CNT concentration.
• the CNT-solvent mixture was mixed by sonication.
• the sonication process used a 3/16 inch diameter tapered ultrasonic probe coupled to a Sonics and Materials VCX 750 Sonicator, where the Sonicator was at 25%o power.
• the sonication process consisted of repeated cycle of 5 sec. on and 5 sec. off for a total of 15 minutes. Dispersion of SWCNTs remained stable at least 3 months.
• This Example illustrates dispersion of MWCNTs in an alkaline carbonate in the presence of a titanate compound.
• MWCNTs of 95% or greater purity with a diameter of 8-15 nm and a length of 50-80 ⁇ were obtained by a variety of sources.
• a titanate compound (Neoalkoxy Titanate LICA- 09) was added to propylene carbonate via the carrier solvent dimethyl sulfide.
• Concentration of CNTs added to the titanate-containing solvent was 0.01% up to and including 5.5% by weight and the titanate ranged from 0.2% up to and including 20% weight percent of the weight of the CNT concentration.
• the CNT-solvent mixture was mixed by sonication.
• the sonication process used a 3/16 inch diameter tapered ultrasonic probe coupled to a Sonics and Materials VCX 750 Sonicator, where the Sonicator was at 25% power.
• the sonication process consisted of repeated cycle of 5 sec. on and 5 sec. off for a total of 15 minutes. Dispersion of SWCNTs remained stable for at least 3 months.
• This Example illustrates dispersion of MWCNTs in an alkaline carbonate in the presence of a titanate compound.
• MWCNTs of 95% or greater purity with a diameter of 8-15 nm and a length of 50-80 ⁇ were obtained by a variety of sources.
• a titanate compound (Neoalkoxy Titanate LICA- 09), concentration of titanate ranging from 0.2% up to and including 20% as weight percent of the weight of the MWCNTs, was added to isopropyl alcohol.
• Concentration of CNTs added to the titanate-containing solvent ranged from 0.01% up to and including 5.5% by weight and the titanate ranged from 0.2% up to and including 20% weight percent of the weight of the CNT concentration.
• the CNT-solvent mixture was mixed by sonication.

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• 2013
  • 2013-05-08 WO PCT/US2013/040226 patent/WO2013169960A2/fr not_active Ceased

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