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Block copolymers are of both theoretical and practical importance because of their ability to self-assemble in nano-ordered structures. The self-assembly processes in these materials, are a consequence of the intermolecular micro phase separation between the dissimilar chains covalently linked together. Another important property of block copolymers is that, in solution with a selective solvent, they aggregate to form physical gels. Their technological importance is due to their ability to form elastic solids via self-assembly, with midblocks bridging aggregated end-block micelles. In our study poly(styrene-b-butadiene-b-styrene) (SBS), form, by its dissolution in a mid-block-selective solvent (THF) physical gels. So the morphology and the rheological behavior of the thermoreversible gels have been studied and characterized. Moreover, the gel behavior was also studied when Ag nanoparticles were added to the SBS matrix. The results of this study show that the gel stability is not affected by the presence of Ag nanoparticles. [ABSTRACT FROM AUTHOR]

Due to the low density and insulation capability, EPDM rubber, reinforced with aramid or phenolic fibers, represents the state of the art of Elastomeric Heat Shielding Materials (EHSMs). However, these composites, used as ablatives, tend to exhibit a limited ablation resistance especially in severe hyperthermal environments such as the combustion chamber of rocket motors: here the propellant combustion byproducts cause the thermo-oxidation and mechanical erosion of the ablatives used as protection of the rocket case. In order to increase char retention, the thermo-oxidation resistance and insulation capabilities, boron based fillers can be added in the material formulation. In this work the effect of three different boron containing fillers embedded in EPDM/phenolic pulp composites was evaluated. [ABSTRACT FROM AUTHOR]

EPDM/aramid fibers ablatives represent the state of the art of Elastomeric Heat Shielding Materials (EHSMs) for Solid Rocket Motors (SRMs). EPDM exhibits the lowest density among elastomers maximizing the payload of a SRM. Due to necessity to further maximize the payload of a rocket, density reducer fillers, such as glass or phenolic microballoons, can be considered in the material formulation of the SRM insulation liner. However, the open literature on EPDM based EHSMs combined with these density reducers is extremely limited because these formulations are generally proprietary of companies manufacturing SRMs. In our paper we studied the heat capacity, thermal and dimensional stability, mechanical properties, and ablation resistance of EPDM based EHSMs combined with glass microspheres at different percentages. Moreover, Perlite, an affordable density reducer additive commonly used in concrete applications, was also evaluated and compared with glass microballoons. [ABSTRACT FROM AUTHOR]

In this paper, we report the development of a glass fiber reinforced composite based on a MWNT-doped epoxy matrix. The intrinsic electrical conductivity of carbon nanotubes has allowed the production of a nanocomposite with enhanced electrical properties, respect the neat matrix. Due to the high aspect ratio of carbon nanotubes, very small amounts of these particles were enough for modifying the electrical properties of the obtained glass fiber composites. A low-velocity impact was created on the surface of the laminate, in order to produce a damage, which not involved the catastrophic failure of the sample. In order to evaluate the damage level, a mechanical characterization was performed on pristine samples, on one hand, and impacted The measurement of the electrical resistance, before and after the impact, was exploited as a way for detecting the presence of the damage produced. The results have shown that it is possible to associate the increase in electrical resistance of the composite with the formation of a damage due to an impact. [ABSTRACT FROM AUTHOR]