Novel polyurethane nanocomposites based on toluene diisocyanate, poly(propylene glycol), various hyperbranched polymers (HBPs), and layered silicate were synthesized with the aim of determining the effect of the layered silicate loading and the functionality of HBP on the structure and properties of polyurethane nanocomposites. The microstructure of the nanocomposites was investigated by X-ray diffraction analysis and high-resolution transmission electron microscopy. It was found that exfoliated morphology and good dispersion were obtained up to 8 phr clay loading for all of the nanocomposites. approximately 100% increment in tensile strength, approximately 2-fold increase in the lap shear strength, approximately 200% increment in the peel strength, and 120% increment in the storage modulus along with a dramatic improvement in thermal stability were observed with the addition of 8 phr clay, over the pristine polyurethane. The higher the level of functionality of the HBP, the higher is the property enhancement. These properties were correlated with the state of dispersion of the clay platelets in the polyurethane matrix, the structure of the matrix, and clay-polymer interaction.

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A novel flexible polyurethane was prepared using ionic liquid as crosslinker. It showed lower Tg, superelastomeric behavior with very high elongation, better tensile and oil resistance properties than a non-ionic crosslinked PU or a linear PU.

Elastomers and their composites are extensively used as a thermal insulation system in heat treatment, power generation, fire protection, and aerospace. Among different elastomers, low-density ethylene propylene diene terpolymer (EPDM) has interesting properties, such as excellent resistance to aging and oxidative degradation due to its saturated back bone. Furthermore, introduction of polyimide (PI) to the base elastomer increases its thermal stability. On the other hand, carbon nanofiber (CNF) reinforces the matrix to enhance the mechanical properties with an additional advantage of better char yield. To achieve better rubber-filler compatibilization, modification of EPDM was carried out by grafting with maleic anhydride (MAH). Morphological studies by scanning electron microscopy and high-resolution transmission electron microscopy exhibited uniform dispersion of nanofillers throughout MAH grafted EPDM matrix. Thermal properties of the EPDM/PI nanocomposites were characterized by thermogravimetric analysis and differential scanning calorimetry. Besides these, thermal conductivity, thermal diffusivity, and specific heat were also measured. PI- and CNF-filled maleated EPDM composites showed very good physical and thermomechanical properties for high-temperature insulation compound.

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Novel elastomeric miscible blend nanocomposites have been prepared by co-reacting isocyanate terminated liquid polyurethane pre-polymer with thiol terminated polysulfide together with chain extender, modified organic nanoclay, and curator. The studies report the influence of nanoclay loading on the morphology, mechanical and thermal properties of the nanocomposites. The morphology and state of dispersion of nanoclays in the nanocomposites were studied by high resolution transmission electron microscopy (HRTEM). It was seen that nanoclay particles were well dispersed in the blend at 1, 3, and 5 wt.% nanoclay loadings. The reactive miscibility of blend was confirmed by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR). The effect of clay loading on thermal stability of polysulfide PS/IPU blend and their nanocomposites was studied by thermogravimetric analysis (TGA). It was observed that thermal stability of nanocomposite progressively increased with increase in nanoclay loading. However, about 123% increment in adhesive strength, 78% increment in tensile strength were observed at 3 wt.% clay loaded nanocomposite when compared to control blend. This enhancement in thermal, adhesion and mechanical properties demonstrate that the resulting nanocomposites can be tailored as novel adhesive and coating materials for aerospace application.

Addition of nanoclay particles to a typical tertiary amine cured polysulfide modified epoxy adhesive leads to large increase in the single-lap shear strength of aluminum-aluminum joint. The nanoclay particles are very well dispersed (near fully exfoliated) in the polymer matrix even at 8 wt.% of nanoclay concentration. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies provide evidences for the excellent dispersion of the nanoclay platelets in the polymer matrix. The addition of nanoclay particle results in a significant increase in the elongation at break values along with the marginal increase in the tensile strength. The nanoclay provides good ductility to the epoxy-polysulfide adhesive by forming very flexible interface, which leads to less brittle composite having good strength. The increase in work to break (Wb) values by the addition of nanoclay represents the potential for dissipating a greater amount of energy during the bond rupture process of the lap shear test, and hence the adhesive strength increases. In addition, the increase in joint strength by the addition of nanoclay can also be attributed to the good interaction between the epoxy-polysulfide adhesive and the aluminum substrate in the presence of nanoclay.