Exfoliation of montmorillonite and related properties of clay/polymer nanocomposites

Inhibitori korozije se dodaju u malim kolicinama u korozivnu sredinu te se uglavnom koriste u zatvorenim sustavima. Zbog njihove siroke primjene u industrijskim procesima, nužno je da su ti spojevi netoksicni za covjeka i njegov okolis. Među ekoloski prihvatljivim inhibitorima korozije isticu se razliciti derivati imidazola. Molekula imidazola sadrži dva atoma dusika kao i  -elektrone aromatske molekule koji omogucuju dobru adsorpciju (a time i dobru inhibiciju korozijskog procesa) na razlicite metale. U ovome radu bit ce dan pregled inhibitorskog djelovanja homolognog niza derivata imidazola na koroziju bakra u kiselim i neutralnim elektrolitima. Ispitivanja djelotvornosti ovih spojeva u zastiti bakra provedena su elektrokemijskim metodama, a struktura zastitnog inhibitorskog sloja ispitana je modernim metodama analize povrsine (SEM, AFM). Dobiveni rezultati ukazuju na znatan utjecaj strukture molekule inhibitora na njegovu inhibitorsku djelotvornost.

Copper Corrosion Inhibitors

https://repository.up.ac.za/bitstream/handle/2263/15875/Ilunga_Effect%282011%29.pdf?sequence=1

The effect of Si–Bi2O3 on the ignition of the Al–CuO thermite

In this article, thermal degradation behavior of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based plastic-bonded explosives (PBXs) bonded with a different fluoropolymer matrices namely indigenous poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM), FK 800, fluoroplastic F-32L and fluororubber SKF 32 was investigated through non-isothermal thermogravimetric analysis (TG) technique under nitrogen atmosphere. It was observed that the mass loss of PBXs containing FKM and FK 800 matrices occurred in three steps. The mass loss of PBXs containing fluoroplastic F-32L and fluororubber SKF 32 occurred in two steps. Kinetics were investigated through non-isothermal TG at different heating rates for the first step of degradation by means of model-free Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods. The activation energies calculated by applying FWO method are in good agreement and very close to those obtained by KAS method. The results revealed that the effect of the polymer matrices on the thermal degradation reaction of TATB was significantly observed especially different outcomes of kinetic parameters. The reaction models for degradation were also studied by Criado method. The reaction models are probably best described by the power law and diffusion models.

Thermal degradation kinetics and reaction models of 1,3,5-triamino-2,4,6-trinitrobenzene-based plastic-bonded explosives containing fluoropolymer matrices

Financial support from the THRIP programme of the Department
of Trade and Industry and the National Research Foundation
as well as African Explosives Limited is gratefully acknowledged

/pdf/manganese-as-fuel-in-slow-burning-pyrotechnic-time-delay-4akvm3q5hw.pdf

Manganese as Fuel in Slow‐Burning Pyrotechnic Time Delay Compositions

Lead and its compounds in detonator time delays are being phased out owing to environmental and health concerns. It was found that changing from the conventional rolled lead elements to rigid aluminium tubes caused a significant decrease in the burn rate. It also impaired ignitability, especially of slow burning compositions such as SiBaSO4. Consequently, potential alternatives for the latter and also the fast burning SiPb3O4 system were sought. Bi2O3, prepared by thermal decomposition of bismuth subcarbonate, gave fast burning compositions with silicon as fuel (155 mm s−1 with 20% Si). This system was ignitable by the spit of a shock tube. The SiSb6O13 system required an initiating composition and yielded slow burning compositions. The lowest sustainable and reproducible burn rate in lead tubes, in the absence of additives, was 4.8 mm s−1. In lead tubes, it was possible to reduce the burn rate further by adding fumed silica: A composition obtained by adding 10% fumed silica (add-on basis) to a 10% Si–90% Sb6O13 composition still burned reliably at a burn rate of 2.3 mm s−1.

Sb6O13 and Bi2O3 as Oxidants for Si in Pyrotechnic Time Delay Compositions

Aqueous silicon dispersions are used to produce pyrotechnic time delay compositions. The propensity of the silicon to react with water and to produce hazardous hydrogen gas must be suppressed. To this end, the effect of air heat treatment temperature on the rate of corrosion of silicon was investigated. It was found that four hour heat treatments at temperatures below 350°C provided significant passivation. This is attributed to the removal of the hydroxyl groups present on the SiO2 surface scale layer. It was found that thickening the silica layer, by heat treatment at higher temperatures, causes a further reduction in the amount of hydrogen released. However, differential thermal analysis (DTA) studies showed that excessive silicon surface oxidation increased the ignition temperature and reduced the heat release of a near-stoichiometric Si-lead chromate pyrotechnic composition.

/pdf/suppressing-hydrogen-evolution-by-aqueous-silicon-powder-55ibs0plz9.pdf

Suppressing Hydrogen Evolution by Aqueous Silicon Powder Dispersions by Controlled Silicon Surface Oxidation

Supported in part by AEL Mining Service and by the National Research Foundation of South Africa (Grant 83874).

/pdf/calcium-sulfate-as-a-possible-oxidant-in-green-silicon-based-nrsqp2dibi.pdf

Calcium Sulfate as a Possible Oxidant in “Green” Silicon‐based Pyrotechnic Time Delay Compositions

Slow-burning Si-BaSO4 pyrotechnic delay compositions are employed commercially for intermediate to long-time delays. However, there is very little information on this composition available in open literature. The reactivity of this composition was therefore characterized and compared to that of Si-CaSO4. The Si-BaSO4 composition supported combustion in the range of 20–60 wt% Si in the bomb calorimeter. However, burning was only sustained between 20 and 40 wt% Si in rigid aluminum tubes, with burning rates of between 8.4 and 16 mm s−1. These values are comparable to those for the Si-CaSO4 system (6.9–12.5 mm s−1). However, the CaSO4-based formulations tended to have higher energy output and produced more transient pressure compared to the barium sulfate compositions. Both formulations were insensitive to impact, friction, and electrostatic discharge stimuli. The reaction products were a complex mixture that contained crystalline phases in addition to an amorphous phase. Although barium sulfate is insoluble...

/pdf/a-comparative-study-of-si-baso4-and-si-caso4-pyrotechnic-5c93o350ad.pdf

Olinto Del Fabbro

Papers

Manganese as Fuel in Slow‐Burning Pyrotechnic Time Delay Compositions

Sb6O13 and Bi2O3 as Oxidants for Si in Pyrotechnic Time Delay Compositions

Suppressing Hydrogen Evolution by Aqueous Silicon Powder Dispersions by Controlled Silicon Surface Oxidation

Calcium Sulfate as a Possible Oxidant in “Green” Silicon‐based Pyrotechnic Time Delay Compositions

A Comparative Study of Si-BaSO4 and Si-CaSO4 Pyrotechnic Time-Delay Compositions