Nanomaterials

Brent AugustineSTS 201

1/25/05

Questions to be answered…

! Nanomaterials…..

! What are they?

! What makes them unique?

! How do they work?

! What are some applications?

! Where is it headed?

What are Nanomaterials?

! Nanomaterials are anybulk material thatcontain embeddednano-sized particlesthat are no larger than100 nm in any onedirection.

COURTESY OF STEVEKENIATH, MICHIGANMOLECULAR INSTITUTE

What makes them unique?

! When combined with nanoparticles,nanomaterials gain a slew of propertyenhancements such as…! Improved strength

! Increased hardness

! Improved ductility

! Improved tensile properties

! Resistance to tear

! And many other material enhancementproperties

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What makes nanomaterials unique?

! Nanomaterials behavethe way they dobecause when thenanoparticle grainsoverlap and reinforcethe material, many ofthe qualities of thenanoparticles areinherited by thematerial causing theadditional propertyenhancements.

Applications of how they work…

! The Hall-Petch model:

! Inverse relationship between grain size and yieldstrength

! Theorized with microparticles, proven to hold withnanoparticles as well

! Nanocrystalline Fe powder grain size reduced from33nm-8nm

! Showed increase in hardness and decrease in fracturestress

http://www.matsci.ucdavis.edu/MatSciLT/EMS-174L/Files/HallPetch.pdf

Carbon Black

! Carbon Black in tires:! Carbon Black,

produced by thepartial combustion ofnatural gas, has longbeen used as areinforcement inrubber tires

! Improved strengthand tensileproperties, tear andabrasion resistance,and increasedhardness

www.cf.ac.uk/engin/ staff/pjb/subpages/pfc.html

Carbon Black cont…

! Absolute strength ofnanocomposite notlinear

! Initially increaseswith the addition ofcarbon because ofthe reinforcementfrom carbon grains

! Then decreasesdue to the dillusioneffect when toomuch carbon blackis present

www.konimpex.com.pl/ phtml/sadza_techniczna.php

Courtesy of Bridgestone

Metal Nanocomposites

! Metals can be made intonanocrystalline materials that performbetter than regular metals.

! Roll copper at the temperature of liquidnitrogen

! Then, heat to around 450 K

! Results in ‘bimodal’ structure with micro-meter sized grains and nanocrystallinegrains

! Increases strength and hardness ofmetal because of the nanocrystallinegrains

! Shows high ductility as well, largergrains stabilize tensile deformation ofmaterial

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Reinforced Polymers

! One particular area of research has been the reinforcement ofpolymers coupled with Polyhedral Oligomeric Silsesquioxanes(POSS)

! Allows for greater mechanicals due to the entrainment with thepolymer chains

! Connections with polymer chains:

Current Industrial Applications

! Carbon black rubber filler in tires

! $4 billion industry

! Hummer H2

! Nanocomposites line the bed of the truck

GM’s 2005 Hummer H2cargo bed uses about 7 lbof molded-in-color TPOnanocomposite parts.

www.plasticstechnology.com/.../ 200411fa2.html

Industrial Applications

! Wilson Company

! Have added nano-sized silicon dioxidecrystals to rackets toincrease their power

! Also, coated tennisballs with a butyl-based nanoparticlethat cuts airpermeation in half andmakes them lastlonger

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Solar converting polymers

! Polymers embedded with copper basednanocrystals (copper indium diselenide)

! When exposed to energy source (photons orphonons):! Free charges of particles are generated and

transported along the polymer to electrodes

! Effectiveness due to ability of the carriers toarrive to the electrodes without recombiningwith oppositely charged particles

! Efficient because nanocrystals are able toconvert both photons and phonons

Future of nanomaterials

! Major influence on currentindustries

! Must ensure risk factorsare eliminated whendealing with the unknown

! TechnologicalSomnambulism cnn.com