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Epoxy composites were prepared with different contents of hydrophobic silica aerogel particles to investigate their mechanical, thermal, and hydrophobic properties. The composites, particularly the one containing 1 wt % silica aerogel, showed remarkable toughness and yielding behaviors compared to neat epoxy, with its brittle behavior. As the content of silica aerogel increased, the thermal properties of the composites (e.g., thermal conductivity and thermal stability) improved. This was due to the very low thermal conductivity and high thermal stability of the silica aerogel particles. Moreover, the use of the hydrophobic silica aerogel led to the development of composites with hydrophobic properties. To examine the hydrophobicity more deeply, a series of water‐uptake tests were performed, and the results show that the composite with 3 wt % silica aerogel absorbed 50% less water than the neat epoxy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45706.

The properties of silica-aerogel/UPVC composites have been investigated with emphasis on sound and heat insulation. UPVC is a material of construction for window profiles and drainage pipes. Hydrophobic silica aerogels were synthesized using silicate sodium as a precursor through a two-step sol-gel process. The physical and textural properties of the synthesized silica aerogels such as density, surface area, and particle size were analyzed using SEM and BET analysis. Then, the synthesized aerogels were mixed with Unplastisized Polyvinyl Chloride (UPVC) compound at five different weight ratios in an internal mixer to find out the effects of silica aerogels on the thermal, mechanical, and acoustical characteristics. The prepared UPVC/aerogel composites were characterized for tensile properties, impact strength, hardness, Vicat softening temperature, thermal conductivity, sound absorption, and sound transmission loss. The results revealed that adding silica aerogel in to the matrix of UPVC increases its hardness and softening temperature while decreases impact strength. The thermal conductivity of UPVC was decreased by up to 50% using silica aerogel. The sound absorption property of UPVC was increased up to three times by using silica aerogels due to its high porosity. Silica aerogel increased the maximum sound transmission loss of UPVC in the low frequency range. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 134, 44685.

In the present study, epoxy samples containing nanoporous graphene (NPG) were synthesized and analyzed in terms of mechanical, morphological, thermal, adhesion, and anticorrosion properties. To this end, the employed curing agents (hardeners) were synthesized and NPG content was varied from 0 to 1 wt %. By using a hardener with aliphatic side chains, the toughness of the nanocomposite was improved without a decrease in the modulus. Adding 1 wt % NPG increased the modulus of the nanocomposite by about 30%. The dynamic mechanical results showed an increment in the glass transition of the samples containing 1 wt % NPG. Field emission scanning electron microscopy images were used to observe the fracture surface of the nanocomposites. The thermogravimetric analysis analysis also confirmed that using synthetic hardener and NPG as the nanofiller enhanced the thermal resistance of the samples. The images of the protected metal panel surfaces and their coatings were used to study adhesion and anticorrosion properties. These results indicated that the hardener synthesized in this work along with NPG improved the mechanical, thermal, adhesion, and anticorrosion properties of the epoxy nanocomposites effectively. The specific characteristic of the synthetic hardener was its chemical structure including both aliphatic and cyclic polyamines as the side groups. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46201.

In this investigation, silica aerogel (SA)/Rigid Polyurethane (PUR) foam composites and silica aerogel/Polyurethane (PU) composites were prepared by dry mixing of granular and grinded silica aerogels with polyol part. They were then combined with diisocyanate part. Three different types of PUR foams and an elastomeric coating grade of PU were studied as well. Results show that thermal conductivity of foams did not decrease by adding silica aerogel. It even increased for some grades which is assumed to be due to the change in cell configuration of these foams. It was also found that sound insulation performance of these cellular composites did not improve significantly. Unlike foam composites, addition of silica aerogel into elastomeric PU improved its thermal and acoustic insulation properties. Because of the more promising properties of elastomeric PU composites, further examinations including measurements of compression strength and water contact angle of silica aerogel/PU composites were also taken. Final results showed a significant improvement in general properties of PU coatings by adding little amounts of silica aerogel (1-4 wt %). V C 2016Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44521.

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