This paper presents an investigation into the durability of geopolymer materials manufactured using class F fly ash and alkaline activators when exposed to a sulfate environment. Three tests were ...used to determine resistance of geopolymer materials. The tests involved immersions for a period of 5 months into 5% solutions of sodium sulfate and magnesium sulfate, and a solution of 5% sodium sulfate+5% magnesium sulfate. The evolution of weight, compressive strength, products of degradation and microstructural changes were studied.
In the sodium sulfate solution, significant fluctuations of strength occurred with strength reduction 18% in the 8FASS material prepared with sodium silicate and 65% in the 8FAK material prepared with a mixture of sodium hydroxide and potassium hydroxide as activators, while 4% strength increase was measured in the 8FA specimens activated by sodium hydroxide. In the magnesium sulfate solution, 12% and 35% strength increase was measured in the 8FA and 8FAK specimens, respectively; and 24% strength decline was measured in the 8FASS samples. The most significant deterioration was observed in the sodium sulfate solution and it appeared to be connected to migration of alkalies into solution. In the magnesium sulfate solution, migration of alkalies into the solution and diffusion of magnesium and calcium to the subsurface areas was observed in the specimens prepared using sodium silicate and a mixture of sodium and potassium hydroxides as activators. The least strength changes were found in the solution of 5% sodium sulfate+5% magnesium sulfate. The material prepared using sodium hydroxide had the best performance, which was attributed to its stable cross-linked aluminosilicate polymer structure.
•LECA and NA, leads to density adjustment while improving compressive strength, DF, wet/dry durability index.•Low ER of mixtures increased probability of rebar corrosion of mixtures.•EAFS and LECA ...had positive and adverse effects on salt-scaling resistance respectively.•All of mixtures exhibited high abrasion resistance.
This article reports the results of an experimental investigation on novel concrete mixtures containing electric arc furnace slag aggregates (EAFS) and lightweight expanded clay aggregates (LECA), focusing on the durability properties. Six concrete mixtures consist of EAFS-natural-LECA (M-Group) and five mixtures of EAFS-LECA (N-Group) compared with 100% EAFS as reference. Workability and density of the mixtures were studied as fresh properties and compressive strength, as well as durability indexes including the electrical resistivity (RCPT and four-point Wenner test), salt-scaling under freeze and thaw cycles, abrasion resistance (abrasive groove length and wear depth), durability under wet and dry cycles, and durability factor under freeze/thaw cycles. Results showed that application of both LECA and natural aggregates, by maintaining the structural-level strength, leads to density adjustment while increasing the freeze/thaw durability factor, improving dimensional stability and controlling the level of cyclic wet/dry-stains. An average increase of durability factor of M-Group and N-Group comparing to the reference were observed up to about 124% and 63% respectively. The results indicated the positive effects of using natural aggregate and LECA on modifications of reference mixture. Measured abrasive groove length ranged between 20 and 23 mm and the depth of wear ranging from 0.1 to 0.3 mm confirming the improving effects of physical structure of EAFS aggregates. The studied mixtures, namely M6 and N5 with 0.744 kg/m2 and 1.204 kg/m2 exhibited the lowest salt-scaling mass-loss with 31% and 112% increase compared with the reference.
•A two-step procedure is proposed for the development of superhydrophobic surfaces.•The superhydrophobic surfaces show excellent superhydrophobicity.•The method improved the mechanical stability ...anddurability of surfaces.•The prepared superhydrophobic surfaces exhibited superior low ice adhesion property.
Superhydrophobic surfaces have showngreat potential anti-icing applications because of their low energy input, light weight and simplestructure, which attract considerable attentions of researchers. The mechanical stability and chemical durability are the essential aspects that limit their practical application. In this paper, the femtosecond laser technology was applied to process the surface of titanium alloy and then the surface was functionalized by a dual-layers coating to obtain lotus leaf-like superhydrophobic surfaces. Through the treatment of femtosecond laser, periodic microstructures were created on the surface of the titanium alloy. After that, a dual-layers coating was produced and sprayed on the surface, which was used to form nanostructure and low surface energy layer. The superhydrophobic surface shows excellent superhydrophobicity with a higher contact angle of 165° and lower sliding angle of 1.2°. Furthermore, the testing results on adhesion strength, water resistance, heat resistance and aviation kerosene resistance of the dual-layers coating exhibited remarkable mechanical stability and chemical durability. Moreover, ice adhesion on untreated smooth surfaces (US-S), sprayed dual-layers coating surface (SN-S) and combined femtosecond laser with dual-layers coating treated surface (MN-S) were investigated in simulated application environment. The MN-S could effectively minimize the ice adhesion, which can reduce the tensile forces and shear forces by up to 26.09%, 44.12% compared to the sample SN-S and 52.78%, 58.24% than that of the sample US-S. The present study provided a chemical-assisted ultrafast femtosecond laser processing technique that could be applied to large-scale preparation of low ice adhesion superhydrophobic surface, presenting broad application prospects.
Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic ...circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.
The incorporation of Pt nanoparticles into a highly stable and porous amine-functionalized MIL-101(Cr) was performed for construction of a visible light driven H2 evolution system with high activity ...and strong stability.
The role of plastic packaging in protecting food is quite appreciable, but the problems like non-biodegradable nature, recycling issues, and leaching of harmful chemicals to food and soil create ...serious concerns for human health and the environment. The global packaging protocols and awareness about plastic packaging also necessitate to develop new packaging material focusing on the environment, food quality and safety. Thus, urgent attention is required for alternatives of non-biodegradable food packaging materials from bio-sourced polymers.
This paper highlights the different plastic packaging substitutes, opportunities, and challenges associated with biodegradable environment-friendly packaging. The paper also summarized different bio-sourced polymers with the application, biodegradability, and prospects for commercial applications in food packaging.
Bio-sourced packaging materials are an emerging alternative to conventional polymers. Natural feedstocks rooted biopolymers are economically competing with conventional ones due to their wide availability, easy processing, biodegradable, compostable nature, good mechanical and barrier properties. Bio-based polyesters produce diverse alternatives from stiff to soft material with properties ranging from partially to fully biodegradable. However, bio-based primitive drop-in plastics are yet the market leader because of their excellent physical properties, cost-effectiveness and durability.
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•Conventional food packaging material adversely affect the ecosystem & human health.•Bio-sourced feedstock helps in developing eco-friendly food packaging alternatives.•Natural biopolymer & primitive drop-in plastics proxies conventional polymer.•High cost, low barrier properties and durability are the key challenges with bio-sourced plastic.
The biological durability of ten wood species was determined on the basis of results from laboratory agar block tests. The experiment utilised two specimen formats: standard EN 113-2 specimens (15 × ...25 × 50 mm) and mini-blocks (5 × 10 × 30 mm) exposed to two fungi (Coniophora puteana and Trametes versicolor) for varying incubation periods. Mini-block tests yield dissimilar outcomes compared to the European standard test at six, eight, ten or 16 weeks of incubation. This discrepancy extended to both durability classifications based on median percentage mass loss and those based on relative mass loss (x-values). It was therefore concluded that laboratory tests with miniaturised specimens are not advisable as a substitute for conventional durability classification assessments.
Nowadays, state-of-the-art for optical data storage (ODS) have emerged as a leader in the competition of data storage technologies. However, the development of optical storage technology based on ...optically stimulated luminescence (OSL) encounter the serious problems, of single storage mode and easily decoding. In this study, a series of Ba2SiO4 (denoted as BS): Eu2+, Ln3+ (Ln = Dy, Ho) phosphors with adjustable trap distributions (trap depths of 0.6–0.8 eV) have been developed by high-temperature solid-phase method and exhibit intense green emission peak located at 504 nm under excitation of 360 nm. Typically, BS: 0.02Eu2+, 0.02Ho3+ phosphor owns a shallow trap depth of 0.696 eV and BS: 0.02Eu2+, 0.02Dy3+ phosphor shows a deep trap depth of 0.81 eV. Interestingly, the flexible optical information storage film prepared by BS: 0.02Eu2+, 0.02Ho3+ phosphor through spin-coating technique can storage the “National Water Conservation Logo” pattern under NUV irradiation and reappear even after more than 60 days at 75 °C. Subsequently, multimodal anti-counterfeiting strategy is proposed by BS: Eu2+, Ln3+ (Ln = Dy, Ho) phosphors with adjustable trap depths and the flexible information coding device with high transmittance has been developed, in which encrypted message of “HELLO” and “86068” can be recognized at 75 °C and 130 °C, respectively. This work not only lays the foundation for realizing the durability of optical information storage, but also provides high security with multiple levels of retrievability.
Abstract
Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat ...dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.
Anti-biofouling materials that combat microorganism attachment have been intensively studied due to the ever-growing demand on smart and durable coatings. Although various hydrophilic polymer ...surfaces demonstrated superior anti-biofouling properties, their practical application was hampered by the undesired mechanical vulnerability and complicated fabrication process. In this review, we summarized the mechanically and chemically robust anti-biofouling coatings into six strategies namely (i) 3D-grafted coatings, (ii) hierarchical spheres-based coatings, (iii) inorganic nanomaterials-reinforced coatings, (iv) hydrolysis-based coating, (v) semi-interpenetrating structure-based coatings, and (vi) layer-by-layer (LbL) assembled coatings. The anti-biofouling efficacy and durability of these coatings over a series of challenges were also comprehensively presented. The purpose of this review is to inspire researchers to develop novel anti-biofouling coatings for future practical applications.
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•A snapshot of the evolvement of anti-microbial and anti-biofouling materials as well as the significance of hydrophilic polymers-based coatings are presented.•Standard methods to evaluate mechanical, chemical, and thermal stabilities of anti-biofouling coatings are provided.•Commonly used techniques to assess anti-biofouling property are outlined.•Six strategies to increase long-term durability of bio-fouling coatings are summarized and compared.
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