New Prototyping and Production Capabilities for Design, Development and Supply of NanocompositesBrad Thomas - NanoSperse LLC
NanoSperse had its origins within the University of Dayton Research Institute, where in the early 2000s work was conducted to develop ways of achieving uniform dispersion of highly crystalline graphite nanoparticles into resin systems. In 2009 NanoSperse constructed its own facility with the intention designing and supplying well dispersed nanocomposite resin system to meet an emerging industrial need. They have immediate scale-up capability to meet the demand of dispersion technologies they develop.
Nanoparticles of graphite have inherently high electrical and thermal conductivity as well as strengthening potential; however, early attempts at using them in composite systems were largely disappointing because the particles were clumping in the binders, and not providing the contact channels to achieve any of their potential properties. Funded by AFRL's-Mantech, the UDRI conducted research along three directions to overcome this obstacle focusing on Direct Digital Manufacturing, Molding Materials, and Multi-Function Structures.
It is an very high priority goal at NanoSperse to be a beta test site for "safe handling" of the nanoparticles. A concept of "cleanspace within cleanroom" and extensive worker protection equipment is utilized to prevent airborne releases and exposure.
NanoSperse utilizes a Haynes pusher furnace (with heating capability to 2500C) as well as a fluidized bed reactor to accomplish much of its dispersion technology. It has successfully scaled up production of "exfoliated graphite" a flake like form that is highly crystalline and excellent for uniform dispersion.
With good dispersion it has been demonstrated that some mechanical property improvement as well as electrical and thermal conduction can be achieved in composite systems.
NanoSperse has developed processes to bond nano-tubes into resins which is referred to as "functionalization". In 45/45 tension tests functionalization is proven to dramatically reduce pull-out of the graphite from the resin due to very thin very long tubes and excellent uniformity of dispersion.
One of the first commercial products is a nano-graphite enhanced epoxy coating on an inlet guide vane. This coating has proved to last 5 time longer than pervious protection for the vane. The cost is significantly higher than urethane coating but that coating chunks out rapidly in service, while the NanoSperse coating remains uniform and wear away gradually over a long time span.
Currently NanoSperse is developing uniformly dispersed nano fiber containing resin concentrates which can be diluted in regular dough blenders while maintaining the dispersion uniformity.
Multifunctional Properties such as conductive adhesives are a project being pursued.
Direct Digital Manufacturing is an outgrowth of the SLS process of fast prototyping using laser to melt material onto itself, building a part layer by layer. 3D printing is an application suited to fused thread dispersions. Aluminum metal parts have been difficult to replace with composites in some application because of the high di-electic property of the composites. Properly dispersed nanocomposites come much closer to simulating the metal due to the internal electrical conductivity of the material. This is particularly important where EMI shielding is a requirement for the component being converted from metal to composite.
In the area of glass-epoxy composites, the addition of well dispersed nanoparticles has shown to dramatically reduce delamination on the backside of the composite when subjected to ballistic impact testing. This is because the nano particle enhancement absorbs shock.
During Q & A Brad revealed that NanoSperse purchases all of its nano particles, but as purchased they tend to have varying degrees of impurity, and are not suitable for uniform dispersion due to clumping and bundling. NanoSperse functionalizes the particles in a gaseous phase process. Typically addition of nanoparticles to composites are measured by weight % and are in the vicinity of 7%. Functionalized additions can go to higher percentages. If such additions were measured in volume % the additions would be very high (> 50%).