Composite Materials Research Progress

Major Trends in Polymeric Composites Technology 113
benefit of a new supply chain for highly capable structural fibers. New generations
of continuous carbon fibers are also being developed both on the micro and nano
scales with improved performance and functionality.
IV. Processing Technologies: the autoclave has been the mainstay for many years, but
growing trends toward lean manufacturing make this a roadblock to improved
efficiency. Continuous and inexpensive processing is making the curing step a part
of the overall lean philosophy in composite manufacturing. A growing trend is the
move away from prepregs to the family of materials and processing called resin
infusion (RI). This includes Resin Transfer Molding (RTM), Vacuum-Assisted
Resin Transfer Molding (VARTM), Resin Film Infusion (RFI), and the development
of new continuous processes. All this is based on low-cost material forms of neat
resin and fiber preforms that allow the manufacturer to put the two together in
proprietary and efficient ways.
V. Other trends include a new generation of thermoplastics being developed to serve the
growing automation of TP parts, smart materials and structures which can de-couple
requirements and reduce weight, low-cost carbon fibers from bio sources, and others.
1. Nanocomposites and Multifunctional Materials
The definition of nanocomposites covers a variety of systems such as one-dimensional, twodimensional
and, three-dimensional materials made of distinctly dissimilar components and
mixed at the nanometer scale for achieving drastically enhanced properties. To obtain multifunctionality
in nanocomposites, nanoparticles with high aspect ratio have been successfully
employed. This denotes being functional in one property while either achieving new
properties that are unknown in the individual components or improving and maintaining other
intrinsic properties.
Nanocomposites can be used as matrices for nano/macro-composites, or traditional
composites when micro-scale fibers are included. Nano constituent composites have also been
made into nanoscale fibers through spinning methods. To date, the creation of such new
materials has resulted in:
• Enhanced mechanical properties: strength, stiffness; toughness, impact resistance,
structural durability, etc.
• Improved electrical conductivity
• Improved thermal conductivity and thermal management
• Improved flame resistance, thermal stability and increased service temperatures
• Enhanced acoustic damping
• Improved dimensional stability (low or tailored coefficient of thermal expansion)
• Enhanced tribological properties (wear, abrasion resistance, hardness)
• Improved barrier properties and environmental controls
• Decreased permeability
• Reduced shrinkage