In this study, high-performance thermoset polymer composites are synthesized by using both long fibers and nanoclays. Epoxy and phenolic resins, the two most important thermoset polymers, are used as the polymer matrix. The hydrophobic epoxy resin is mixed with surface modified nanoclay, while the hydrophilic phenolic resin is mixed with unmodified raw nanoclay to form nanocomposites. Long carbon fibers are also added into the nanocomposites to produce hybrid composites. Mechanical and thermal properties of synthesized composites are compared with both long-fiber-reinforced composites and polymerlayered silicate composites. The optimal conditions of sample preparation and processing are also investigated to achieve the best properties of the hybrid composites. It is found that mechanical and thermal properties of epoxy and phenolic nanocomposites can be substantially improved.

In this article, a new manufacturing method was used to prepare the hybrid composite, wherein carbon nanofibers were sprayed and bonded onto continuous fiber mats instead of pre-mixing them in the polymer resin. The effect of carbon nanofibers on the mold filling characteristics in a vacuum assisted resin transfer molding system was investigated. A simple one-dimensional flow model was used to correlate the permeability and porosity to the mold filling time. It was found that the dispersion and loading of the carbon nanofibers affected the permeability and porosity of the reinforcement system, and hence the mold filling time.

In this study, the preparation, properties, and characterization of thin films or “nanopapers” of carbon nanofibers (CNFs) were studied. Specifically, a layer‐by‐layer nanopaper preparation method was used, which significantly improved the mechanical properties of nanopapers. The effect of CNF nanopaper on the cure kinetics of a low temperature epoxy resin was studied. A modified autocatalytic model was used to represent the reaction kinetics. It was found that the presence of CNF nanopaper substantially increased the resin reaction rate and final conversion. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polyaniline (PANI) ''nanograss'' was grown on carbon nanofibers (CNFs). The cure behavior of an epoxy resin with and without unmodified CNFs or PANI modified CNFs was studied by means of non-isothermal and isothermal differential scanning calorimetry (DSC). CNFs accelerated the reaction of epoxy and diamine. PANI surface modification further increased the reaction rate and the extent of reaction. An autocatalytic cure kinetic model was used to fit the reaction curves. It was found that activation energies of the epoxy reaction decreased in the presence of CNFs and PANI modified CNFs. The observed catalytic effect of CNF and PANI surface coating can be very useful for low temperature cure of large epoxy composite products.

In this study, a new approach was used to prepare polymer composites reinforced by both nanoparticles and continuous fibers. Carbon nanofibers were prebound onto glass fiber mats, and then unsaturated polyester composites were prepared by vacuum-assisted resin transfer molding. Mechanical and thermal properties of these composites were measured and compared with those of the composites synthesized by premixing carbon nanofibers with the polymer resin. Flexural strength and modulus of composites improved with the incorporation of nanoparticles. Specifically, the property improvement was higher in the case of the composites prepared by the new prebound method. It was also found that carbon nanofibers increased the glass transition temperature and reduced the thermal expansion coefficient of unsaturated polyester composites.