& oren e. petel in the present work, nanocomposites based on the partially silane-terminated polyurethanes reinforced with sulfuric acid-treated halloysite nanotubes were synthesized and evaluated as a potential candidate for transparent blast resistant configurations. The polyurethane must present high tensile ductility at high strain rates to be able to contain fragments and increase the survivability of the system. Gas-gun spall experiments were conducted to measure the dynamic tensile strength (spall strength) and fracture toughness of the nanocomposite and neat polyurethane. the nanocomposite presented a 35% higher spall strength and 21% higher fracture toughness compared to the neat polyurethane while maintaining transparency. the recovered samples following the spall tests were analysed via scanning electron microscope fractographies. the nanocomposite and neat polyurethane samples were chemically characterized via fourier transform infrared spectroscopy and melting behaviour via differential scanning calorimetry. The improved properties can be attributed, in large part, to the presence of more rigid spherulitic structures, and a rougher fracture surface constituting of several micro-cracks within the nanocomposite. Transparent armour systems must protect against blast and ballistic threats while maintaining structural integrity and optical transparency. Generally, transparent armour systems are composed of laminated glasses sheets bonded together by thin adhesive interlayers of polyvinyl butyral, polyurethane, and/or ethylene-vinyl acetate films, normally combined with polycarbonate as a backing layer. To achieve ballistic protection requirements; the glass layers are generally much thicker than the polymeric layers, which leads to thick and heavy armour solutions 1,2. Material improvements that allow weight reductions among transparent armour systems are of great interest for personal and vehicular applications. Polymers are extensively used in armour applications. Stretched polymers fibers (e.g., Aramids) are widely used in the ballistic fabrics integrated into soft armour and spall liner applications 3. Transparent polymers have historically seen broad use in transparent armour applications, and while they continue to be used as costeffective solutions in some visor and ballistic eyewear applications, their primary role in more robust armour solutions has been relegated to interlayer or backing support for transparent ceramics 1,4. Figure 1a shows an illustrative representation of a typical transparent armour structure. Polyurethanes (PU) are commonly adopted as interlayers in ceramic laminated systems due to their high-tensile ductility and adhesive properties, which provides the containment of armour fragments and increases the spall resistance of the ceramic layers 5. Figure 1b presents a relative transparency comparison between a 9.5-mm-thick polycarbonate plate with and without a halloysite/polyurethane nanocomposite adhesive backing layer. The adhesive layer consisted of a 1.5-mm-thick layer of s...

In this work, hybrid polypropylene (PP)-based composites reinforced with graphene nanoplatelets (GnPs) and glass fiber (GF) were fabricated by injection molding to elucidate how the hybrid approach can produce synergistic effects capable of achieving properties and functionalities not possible in biphasic composites. Synergism between the reinforcements translated to improved mechanical performance, which was attributed to the chemically and/or electrostatically assembled hierarchical structure that facilitates load transfer at the interface while simultaneously tailoring the crystalline microstructure of the matrix by inducing transcrystallization and β-crystal formation. It was demonstrated that there exists an optimal concentration of 0.5 wt % GnP, producing the greatest mechanical properties and synergistic effect, corresponding to the highest degree of crystallinity (∼6% greater than Neat PP) and peak formation of β-crystals within the PP matrix. The greatest synergistic effect was found to be ∼52 and ∼39% for the specific tensile strength and flexural strength, respectively. The same optimal concentration of GnPs was found to produce the highest synergistic effect for thermal conductivity of ∼68% due to the volume exclusion effect induced by the GFs combined with the higher crystallinity of the microstructure, promoting the formation of thermally conductive pathways. Ultimately, the mechanisms contributing to the synergistic effect presented in this work can be used to maximize the performance of hybrid composite systems, giving them the potential to be tailored for a variety of high-performance industrial applications to meet the rising demands for ultra-strong, thermally conductive, and lightweight materials.

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