Preparation, processing and analysis of physical properties of calcium ferrite-CNTs/PET nano-composite

The present work is focused on the preparation of composites based on Poly(ethylene terephthalate) (PET) and novel nano-hybrid filler composed of Calcium Ferrite (CF)-Carbon Nanotubes (CNTs), obtained by direct growth of CNTs on CF based iron catalysts. The carbon content in the hybrid filler was 76 wt%. Composites loaded with 1.0, 1.5, 2.0, 3.0 wt% of filler were obtained by melt compounding and processed by thin-wall injection molding. Unfilled Poly(ethylene terephthalate) was processed using the same techniques. Structural characterization and physical properties (thermal, mechanical and electrical) were analyzed and correlated to the hybrid filler loading, and to the percentage of carbon nanotubes

Synthetic strategies for the enhancement of Mg(OH)2 thermochemical performances as heat storage material

Abstract This work deals with the study of influence of multi walled carbon nanotubes (CNTs) characteristics on thermochemical performance of hybrid materials based on Mg(OH) 2 (M) as heat storage medium. Two different functionalized CNTs samples are investigated, separated curly tubes (SN) and bundles of straight nanotubes (BN). Hybrids were synthesized by reverse deposition precipitation method and their structure was characterized by X-ray analysis and scanning electron microscopy. The heat storage performance was studied through a thermogravimetric apparatus, simulating heat storage/release cycles. It is demonstrated that separated CNTs owning mainly carboxylic groups increase the interaction with precipitated magnesium hydroxide, improving the reacted fraction during dehydration/hydration cycle. In terms of dehydration/hydration conversion the samples' rank is SN-M>Mg(OH) 2 >BN-M. SN-M exhibits higher heat storage/output capacity (~1250 kJ/kg Mg(OH)2 , ~350 MJ/m 3 )

Influence of the Cobalt Phase on the Highly Efficient Growth of MWNTs

In this work, the influence of the cobalt phase on the growth of carbon nanotubes by the catalytic chemical vapour deposition of CH4 with catalysts containing Co, Mo and Mg is investigated. To this end, the catalytic behaviour of physically mixed CoO/MgO+MgMoO4 and CoMoO4+MgMoO4 is studied. The results obtained show that CoMoO4+MgMoO4 allows for the attainment of the highest CNT yield (2407 wt % against 1296 wt %). Its higher activity is ascribed to the greater formation of active sites that, in light of current assessments, are constituted by metallic cobalt adjacent to Mo2C, and the huge exfoliation of the catalyst, which contributes towards enhancing their exposure

Morphological and Structural Evaluation of Hydration/Dehydration Stages of MgSO4 Filled Composite Silicone Foam for Thermal Energy Storage Applications

Salt hydrates, such as MgSO4·7H2O, are considered attractive materials for thermal energy storage, thanks to their high theoretical storage density. However, pure salt hydrates present some challenges in real application due to agglomeration, corrosion and swelling problems during hydration/dehydration cycles. In order to overcome these limitations, a composite material based on silicone vapor-permeable foam filled with the salt hydrate is here presented. For its characterization, a real-time in situ environmental scanning electron microscopy (ESEM) investigation was carried out in controlled temperature and humidity conditions. The specific set-up was proposed as an innovative method in order to evaluate the morphological evolution of the composite material during the hydrating and dehydrating stages of the salt. The results evidenced an effective micro-thermal stability of the material. Furthermore, dehydration thermogravimetric/differential scanning calorimetric (TG/DSC) analysis confirmed the improved reactivity of the realized composite foam compared to pure MgSO4·7H2O.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31). This work was partially supported by ICREA under the ICREA Academia program

Definition of an Experimental Set-up for Studying the Safety of Hydrogen Transport Systems

The required energy transition, unavoidable for the decarbonisation of industrial processes and economic sectors, is increasing the attention in Europe and around the world towards hydrogen. Hydrogen is an energy carrier, globally trusted to meet climate challenges, as it can store and deliver large amounts of energy per unit mass, reducing CO2 emissions. Hydrogen can be used as a feedstock, a fuel or an energy carrier and storage and it has many possible applications in the industrial, transport, energy and construction sectors. These properties make hydrogen essential to support the EU's commitment to achieve carbon neutrality by 2050 and for the global effort to implement the Paris Agreement while working towards zero pollution. For the purpose of facilitate this process, it is necessary to have a network capable of making this resource usable in a capillary, efficient and safe way. Gas pipelines, used to transport natural gas, can be exploited for the transport of pure or mixed hydrogen. It is therefore necessary to understand how hydrogen can affect the integrity and safety of gas pipelines, in order to establish whether the hydrogen/natural gas mixture is a viable and safe solution and within what ratios. Hydrogen embrittlement manifests in a loss of mechanical properties such as decreased ductility and toughness, increasing failure likelihood and gas releases, which are very dangerous, due to hydrogen ability to catch fire very easily and to the explosion hazard. The purpose of this work is the design and demonstration of a test setup for pipeline steel in a high-pressure gaseous hydrogen environment, by means of miniature hollow pipe-like specimen working at high-pressure hydrogen, in a safe and easily accessible manner with the basic laboratory equipment

On the CVD Growth of C Nanotubes Over Fe-Loaded Montmorillonite Catalysts

The synthesis of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) of isobutane (i‐C4H10) over sodium‐exchanged K10‐montmorillonite based iron‐ catalysts is investigated. By studying the influence of iron‐addition (5–25wt%) on the catalyst performances, at 700 °C, an empirical relationship is derived relating the mass of CNTs synthesized with the exposed surface of loaded iron, as resulting from simultaneous change of number, size and dispersion of Fe‐nanoparticles available for the growth

Engineering of chitosan-hydroxyapatite-magnetite hierarchical scaffolds for guided bone growth

Bioabsorbable materials have received increasing attention as innovative systems for the development of osteoconductive biomaterials for bone tissue engineering. In this paper, chitosan-based composites were synthesized adding hydroxyapatite and/or magnetite in a chitosan matrix by in situ precipitation technique. Composites were characterized by optical and electron microscopy, thermogravimetric analyses (TGA), x-ray diffraction (XRD), and in vitro cell culture studies. Hydroxyapatite and magnetite were found to be homogeneously dispersed in the chitosan matrix and the composites showed superior biocompatibility and the ability to support cell attachment and proliferation; in particular, the chitosan/hydroxyapatite/magnetite composite (CS/HA/MGN) demonstrated superior bioactivity with respect to pure chitosan (CS) and to the chitosan/hydroxyapatite (CS/HA) scaffolds

Synthesis of Me Doped Mg(OH)2 Materials for Thermochemical Heat Storage

In order to investigate the influence of metal (Me) doping in Mg(OH)2 synthesis on its thermochemical behavior, Ca2+, Co2+ and Ni2+ ions were inserted in Mg(OH)2 matrix and the resulting materials were investigated for structural, morphological and thermochemical characterization. The densification of the material accompanied by the loss in porosity significantly influenced the hydration process, diminishing the conversion percentage and the kinetics. On the other hand, it increased the volumetric stored/released heat capacity (between 400 and 725 MJ/m3), reaching almost three times the un-doped Mg(OH)2 value

Thermo-Physical Characterization of Carbon Nanotube Composite Foam for Oil Recovery Applications

To meet the increasing demands for effective cleanup technologies to deal with the oil spill accidents that significantly affect the ecological and environmental systems, promising composite materials based on carbon nanotubes containing silicone foams were investigated. Pump oil, kerosene, and virgin naphtha had been used to assess, during sorption tests, foams behavior. Test results highlighted the advantage of the hydrophobic and oleophilic behavior of carbon nanotubes, and their high mechanical strength for oil spill recovery application was studied. In order to better relate the property-structure relationship for this class of materials, the role and influence of functionalized nanotubes on thermo-physical and morphological characteristics of the foams had been evaluated. The results showed how the pristine nanotubes fillers, despite functionalized ones, led to optimal composite foam performances with high hydrophobic (62 mg g−1) and oleophilic (6830 mg g−1 in kerosene oil) characteristics. The evidenced high oil selectivity was a relevant key point in order to consider the suitable material for oil spill recovery applications. Eventually, the proposed configuration exhibited the best thermo-physical performances and high reusability, leading to the optimal cost-benefits option