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Experimental Investigation of Carbonization Processes in the Formation of Foam-Based Epoxy Resin Containing Carbon Nanoparticles
Published in Alexander V. Vakhrushev, Omari V. Mukbaniani, Heru Susanto, Chemical Technology and Informatics in Chemistry with Applications, 2019
S. G. Shuklin, D. S. Shuklin, A. V. Vakhrushev
When the sample is heated to the pyrolysis start temperature (533 K), phosphorus-containing substances are released to the surface of the sample (ammonium salts of polyphosphoric acid are formed). It should be noted that the temperature of the beginning of the decomposition of PFA is 463 K. Judging by the fact that the nitrogen line with a binding energy N1s 402.1 eV is preserved in the spectra up to a temperature of 573 K, the decomposition reaction has a more complex character. It is possible that complete deamination of PFA, and therefore its complete destruction into the polymer, is difficult, due to the high density of the polymer and its degradation products up to high temperatures. The obtained data are confirmed by determining the temperature dependence of the heat capacity of the studied materials.
Improving the performance of cold bituminous emulsion mixtures (CBEMs) incorporating waste materials
Published in S.E. Zoorob, A.C. Collop, S.F. Brown, Performance of Bituminous and Hydraulic Materials in Pavements, 2017
This material was obtained from Eggborough Power Station. PFA is used in many engineering works such as for fill works, grouting, partial replacement of cement in concrete mixtures, road-base and sub-base stabilization, light weight aggregates, land reclamation, bituminous mixtures, etc. (National Ash 2001). There are three types of PFA:Conditioned ash: PFA taken directly from the silos to which water had been added to assist with delivery and subsequent compaction on site. The particle size is in the range of 1 and 100 μm.Stockpiled ash: previously conditioned ash which has been placed temporarily on a stockpile before delivery to site.Lagoon ash: PFA which has been taken from the ash silos, pumped to storage lagoons and allowed to settle and drain prior to re-excavation and delivery to site. This material contains coarser particle sizes, i.e. 6 to 5000 μm (5.0mm), (national Ash, 2001).
Basic Materials Engineering
Published in David A. Hansen, Robert B. Puyear, Materials Selection for Hydrocarbon and Chemical Plants, 2017
David A. Hansen, Robert B. Puyear
Perfluoralkoxy (PFA). PFA, also sold under the trade name of Teflon, is very similar to FEP except that it has a higher continuous service temperature, 500°F (260°C). It is melt processible, with essentially the same universal chemical resistance as PTFE.
Applicability of a 100-mL Polyethylene Vial for Low-Level Tritium Measurement Using a Low-Background Liquid Scintillation Counter
Published in Fusion Science and Technology, 2020
Yoshinari Oshimi, Mayu Ohki, Misato Nagano, Takuyo Yasumatsu, Masanori Hara, Satoshi Akamaru, Masato Nakayama, Miki Shoji
We used a vial of 100 mL of perfluoroalkoxy alkane (PFA) for low-level tritium measurements using a low-background LSC. PFA is highly transparent, has high durability against chemical substances, and contains less radioactivity. Therefore, PFA vials have long been used as low-level tritium counting vials. However, PFA vials are expensive when compared to polyethylene (PE). Additionally, since PFA contains fluorine atoms, used vials cannot be incinerated. Polyethylene is free from halogen atoms, but the durability of PE against chemical substances is lower than that of PFA. The wall effects of vials must be considered when a plastic vial is used for LSC tritium measurements. The organic liquid scintillator can diffuse into the plastic wall of the vial. The vial wall containing liquid scintillator diffused emits scintillation photons when it is irradiated by the external standard gamma source in the LSC. In consequence, evaluation of the quenching index when using the external standard gamma source is distorted. In modern scintillators, which use diisopropylnaphthalene or linear alkylbenzene as the solvent, the wall effect can be overcome.5–7 Thus, PE bottles can be used as the counting vials for LSC tritium measurements. Various PE bottles are commercially available, but the applicability of 100-mL PE bottles as a tritium counting vial in a low-background LSC has not previously been demonstrated.
Exploration of polyvinylidene difluoride (PVDF) for improvement of weathering resistance of textile substrates
Published in The Journal of The Textile Institute, 2022
Bharathi Dasaradhan, Biswa Ranjan Das, Thako Hari Goswami, Namburi Eswara Prasad
In recent years, many polymer coatings are used for protection of textile substrate from natural hazardous factors. Miklecic et al. (2015) studied the stability of acrylate coating with TiO2 and ZnO, after accelerated exposure. Similar studies were also done for other polymeric coatings like polyvinyl chloride and polyurethane for making them weather durable (Gesenhues, 2000; Mirabedini et al., 2011). The main problem with these organic polymeric coating is photo-oxidation, which lead to many changes like flaking, chalking, cracking, strength loss, etc. over time (Allen et al., 2004; Feldman, 2002). Hence, there is need for use of polymer, which is highly resistant to these changes over out-door exposure. Fluoro polymers are one such class of polymers that are used as protective coatings for many years. Their unique performance is due to the high bond strength of Carbon-Fluorine elements, which makes flouro polymers highly stable to environmental and chemical degradation. Fluoro polymer based coatings are known to give protection for more than 20 years compared to other coatings and this was proved by work of Razak et al. (2004), in which they evaluated the change in performance characteristics of polyvinylchloride (PVC) and polytetrafluoroethylene (PTFE) coated fabrics after subjecting to natural weathering of two years and was observed no degradation in PTFE coated fabrics. Fluoro polymers also possess other desirable attributes of coating; excellent chemical resistance, high abrasion resistance, high thermal stability, flame resistance, very low permeation to moisture and gases and low surface tension (Gardiner, 2015; Henry et al., 2018; Wood et al., 2000). Different fluoro polymers that are used for this kind of specified purpose include PTFE, fluorinated ethylene propylene (FEP) and perfluoroalkoxy alkanes (PFA). Polyvinylidene difluoride (PVDF) is the best fluoro polymer resin that has excellent weather resistance among other fluoro polymers (Teng, 2012). PVDF is a highly non-reactive and pure thermoplastic flouro polymer, which has alternating -CF2- and -CH2- units in its structure. Landry and Blanchet (2012) explored the significance of compounding PVDF with other conventional coating material for improvement of service life of light sensitive substrates. They compared the weather resistance performance of two different coating systems (PVDF-acrylic coating and acrylic coating) applied on similar wood species. Their results confirmed the resistance of PVDF to UV degradation in terms of colour change, atomic concentration and surface degradation (Landry et al., 2013). The ease of process-ability of PVDF compared to other fluoro polymers, both by melt and solvent processing, makes it a suitable candidate to be used as coating for protection of substrates from weathering degradation. Silagy et al. (2000) discussed in detail about the different technologies of application of PVDF as protective top coat on thermoplastic polymer substrates. In addition to excellent weatherability, PVDF based coating also possess other desirable characteristics like colour & gloss retention, self-cleaning and water repellency (Kumar et al., 2016).