Nanocomposites development shows the extreme possibilities of what’s possible with additives—specifically, the finely distributed nanoparticles that, at low loadings, create altogether new kinds of polymer-based materials. The SPE Polymer Nanocomposites 2014 conference in October at Lehigh University was a key event to attend to understand the progress in developing these materials for mainstream engineered applications—and even for use in 3-D printing/additive manufacturing.

Carbon nanoparticles were the focus of the first morning of the conference. Keynote speaker Prof. Lawrence Drzal of Michigan State University spoke on the potential of graphene nanoplatelets becoming “a low-cost additive for multifunctional materials,” given the electrical and thermal conductivity, mechanical and barrier properties, and other benefits they can bring to a composite.

Electrical conductivity using carbon black and nanotubes was the topic of Paul Brigandi of Dow Chemical. He explained that multiphase polymer blends—where one polymer is loaded with conductive carbon filler and “co-continuously” blended within a bulk polymer—can provide the percolation network required for conductivity. In this case, carbon nanotubes would only have be loaded into the polymer in which they can more easily be dispersed, rather than the entire bulk.

Topics on cellulose nanofibrils and nanocrystals (CNCs) made up the remainder of the conference’s first day. Speakers spoke on the challenges of bonding cellulose to polymers and dispersing and orienting the particles in the matrix. Dispersion was addressed by Greg Schueneman of the Forest Products Laboratory, who proposed low-temperature solid state shear pulverization as an effective way to break up CNC agglomerates and distribute CNCs in polyolefins.

In 3-D printing processes, nanocomposites could have an important role to play. Lehigh Prof. Raymond Pearson pointed out that well-dispersed nanoparticles impart high viscosities to nanocomposites; this can make them hard to process conventionally, but it’s not an issue for a layer-by-layer additive manufacturing process like selective laser sintering (SLS). With optimized settings, SLS can produce parts with multi-functional properties, using materials such as the silica/nylon-12 nanocomposites that Pearson’s team studies. Other developments will help bring additive manufacturing completely into mainstream manufacturing in the next 5-10 years, estimated speaker John Jaddou of Cabot Corp.

The 2015 Polymer Nanocomposites conference is scheduled for October, again at Lehigh in Bethlehem, Pennsylvania, USA, and again sponsored by the SPE Lehigh Valley Section.