HDPE‐Fly Ash/Nano Fly Ash Composites

Fly ash (FA) based polymer composites are assuming increasing importance because of its potentiality, fine particle size and plenty availability of FA. FA is mainly a mixture of inorganic metal oxides such as SiO₂, Al₂O₃, Fe₂O₃, CaO, MgO, Na₂O, TiO₂, and so forth. This article highlights the results of the various modifications onto the HDPE‐FA/nano structured FA (NFA) composites. When FA and NFA are melt blended with HDPE it gives rise to improved flexural properties only. Further modifications, that is, Maleic anhydride (MA) grafting of the matrix, electron beam irradiation of the composite and irradiation of the FA/NFA studied separately to find their impact on the detail properties of the composite. Of the three modifications implemented the electron beam irradiation of HDPE‐FA/NFA composite yielded excellent physico‐mechanical, thermal and dynamic mechanical properties. Fracture surface analysis of the HDPE, unmodified and modified FA/NFA composites studied employing SEM correlated well with the physico‐mechanical properties. The results prove that FA is valuable reinforcing filler for HDPE and its size reduction to nano level is a more effective criterion for its future use. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4558–4567, 2013     

Mechanism of the formation of M23C6 plates around undissolved NbC particles in a stabilized austenitic stainless steel

The plate-like morphology of M23C6 carbide precipitated around undissolved NbC particles in a stabilized austenitic stainless steel has been studied by transmission electron microscopy. This precipitation occurred during high temperature ageing of the specimens which had previously been quenched in water from 1550 K. These carbide plates that are characterized by {111}- and {101}-type interfaces have a cube-cube orientation relationship with austenite and lie on {110} austenite planes. Such precipitation was not commonly observed in specimens that were deformed prior to ageing. The possible mechanisms for the nucleation and growth of these precipitates are discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

Thermodynamic analysis of growth of iron oxide films by MOCVD using tris(<Emphasis Type="Italic">t</Emphasis>-butyl-3-oxo-butanoato)iron(III) as precursor

Thermodynamic calculations, using the criterion of minimization of total Gibbs free energy of the system, have been carried out for the metalorganic chemical vapour deposition (MOCVD) process involving the β-ketoesterate complex of iron [tris(t-butyl-3-oxo-butanoato)iron(III) or Fe(tbob)₃] and molecular oxygen. The calculations predict, under different CVD conditions such as temperature and pressure, the deposition of carbon-free pure Fe₃O₄, mixtures of different proportions of Fe₃O₄ and Fe₂O₃, and pure Fe₂O₃. The regimes of these thermodynamic CVD parameters required for the deposition of these pure and mixed phases have been depicted in a ‘CVD phase stability diagram’. In attempts at verification of the thermodynamic calculations, it has been found by XRD and SEM analysis that, under different conditions, MOCVD results in the deposition of films comprising pure and mixed phases of iron oxide, with no carbonaceous impurities. This is consistent with the calculations.     

Mechanical,dynamic mechanical,and thermal characterization of fly ash and nanostructured fly ash‐waste polyethylene/high‐density polyethylene blend composites

Disposal of polyethylene used as carry bags is the greatest challenge increasing day by day. Composite materials were prepared by mixing Fly ash (FA) and nanostructured fly ash (NFA) from thermal power station as filler and blends of Waste polyethylene (WPE)(carry bags) collected from municipal solid waste (MSW) with virgin high‐density polyethylene (HDPE) as matrix. Different modifications were induced to improve the overall properties of these composites. At first, the WPE/HDPE blend matrix was modified by grafting with maleic anhydride (MA) and the composite prepared with FA/NFA. Then, the WPE/HDPE‐FA/NFA composite as a whole was treated with electron beam irradiation at 250 kGy radiation dose and finally the FA/NFA filler was treated with radiation dose of 250 kGy and the composite prepared. Significant enhancement in tensile strength, flexural strength, flexural modulus, and hardness are observed for MA modified and irradiated composites, the increase being more prominent in irradiated composites. Furthermore, an increase in storage/loss moduli with enhanced thermal stability was observed with the addition of FA/NFA and upon modifications. The analysis of the tensile fractured surfaces by scanning electron microscopy was in well correlation with the mechanical properties obtained. In summary, after analyzing the effects of the three different modifications on mechanical, dynamic mechanical and thermal properties, the irradiation on to the WPE/HDPE‐FA/NFA composites investigated was selected as the most appropriate for future applications. POLYM. COMPOS., 37:3256–3268, 2016. © 2015 Society of Plastics Engineers     

Effects of nucleating agents on crystallization and microstructure of fluorophlogopite mica-containing glass–ceramics

The alteration of crystallization behavior, microstructure, and thermal properties of fluorophlogopite mica-containing glass–ceramics by nucleating agent is systematically studied. TiO₂, TiO₂ + ZrO₂, and ZrO₂ have been doped as the nucleating agents in the SiO₂–MgO–Al₂O₃–B₂O₃–K₂O–MgF₂ (BMAPS) glass system and prepared by the melt-quench technique. The glass without nucleating agent is also prepared to ascertain the influence of nucleating agent. Addition of nucleating agents effectively increases the softening as well as glass transition temperatures. From the DSC study, it is found that the fluorophlogopite mica crystallization exotherm exhibited in the temperature range 800–850 °C and the activation energy varies in the range 167–182 kJ/mol. The opaque mica glass–ceramics are derived from these BMAPS glasses by a controlled heat treatment process and heat treatment at 1050 °C is found to be optimum. The mica crystals were identified as fluorophlogopite for all the four BMAPS glasses by X-ray powder diffraction (XRD) and subsequently confirmed by FTIR spectroscopy. Excellent matching with fluorophlogopite crystal was obtained in Zirconia-containing glass–ceramic as perceived from the XRD and FTIR studies. The microstructure of interlocked card-like mica flake crystals is found to form as seen from scanning electron microscopy, and such microstructure is obtained when ZrO₂ has been used as nucleating agent. Glass–ceramic without nucleating agent possesses Vickers hardness value 4.58 Gpa and it is increased with addition of the nucleating agent (5.67–6.56 GPa), ZrO₂-containing glass–ceramic possess lower hardness (5.67 GPa) and better machinability. Therefore, ZrO₂ is the most efficient nucleating agent to generate fluorophlogopite mica in these glass–ceramics useable for SOFC applications.     

Destabilization of LiBH4 by nanoconfinement in PMMA–co–BM polymer matrix for reversible hydrogen storage

Destabilization of LiBH₄ by nanoconfinement in poly (methyl methacrylate)–co–butyl methacrylate (PMMA–co–BM), denoted as nano LiBH₄–PMMA–co–BM, is proposed for reversible hydrogen storage. The onset dehydrogenation temperature of nano LiBH₄–PMMA–co–BM is reduced to ∼80 °C (ΔT = 340 and 170 °C as compared with milled LiBH₄ and nanoconfined LiBH₄ in carbon aerogel, respectively). At 120 °C under vacuum, nano LiBH₄–PMMA–co–BM releases 8.8 wt.% H₂ with respect to LiBH₄ content within 4 h during the 1st dehydrogenation, while milled LiBH₄ performs no dehydrogenation at the same temperature and pressure condition. Moreover, nano LiBH₄–PMMA–co–BM can be rehydrogenated at the mildest condition (140 °C under 50 bar H₂ for 12 h) among other modified LiBH₄ reported in the previous literature. Due to the hydrophobicity of PMMA–co–BM host, deterioration of LiBH₄ by oxygen and humidity in ambient condition is avoided after nanoconfinement. Although the interaction between LiBH₄ and the pendant group of PMMA–co–BM leads to a reduced hydrogen storage capacity, significant destabilization of LiBH₄ is accomplished.     

Environmentally Benign Fouling-Resistant Marine Coatings: A Review

The undesirable accumulation of marine organisms on any surfaces immersed in seawater is termed as marine fouling. This natural phenomenon contributes a major economic concern for marine industries, e.g. for ships, vessels, oil, wind-turbine sea-platforms, pipelines, water valves and filters by limiting the performances of the devices and materials. In the last decades, several efforts have been employed in the development of efficient antifouling (AF) coatings by following the recent trend in materials science. The current review presents the research and development made in AF strategies for coatings based on two main approaches, detachment of biofoulants or preventing biofoulants attachment.     

Mechanical and barrier properties of polyvinyl chloride plasticized with dioctyl phthalate,epoxidized soybean oil,and epoxidized cardanol

Plasticized polyvinyl chloride (PVC) films were prepared by melt compounding and compression molding using epoxidized cardanol (EC), a biobased plasticizer and its plasticization effect was compared with epoxidized soybean oil (ESBO) and dioctyl phthalate (DOP). The mechanical, migration, thermal, and barrier properties of the plasticized films were compared. The effect of replacing DOP with EC on the properties of PVC films was also investigated. The tensile strength, elongation at break, tensile modulus and impact strength values of PVC/EC films were higher in comparison to PVC/DOP and PVC/ESBO films at a fixed plasticizer loading of 40 wt.%. Also, the films prepared with a mixture of DOP + EC showed higher tensile strength and elongation at break compared to that of films prepared with only DOP. The PVC/EC films showed good thermal stability and reduced oxygen transmission rate (OTR) compared to PVC/DOP films. The addition of graphene and nanoclay in the PVC/plasticizer system exhibited an increase in oxygen transmission. However, the oxygen barrier property of nano filler incorporated PVC/EC films was better than PVC/DOP films. All the films showed negligible water vapor transmission rate (WVTR).