Accelerated Aging Method Research Articles

Development of an accelerated aging method for Brandy

Brandy de Jerez plays a very important role in the economy of its production area. Currently, there are many wineries interested in innovating and diversifying their products, demanding a method which would allow them to age the spirits in a quick and simple way, enabling the testing of different variables in its elaboration.In this paper, a study of the accelerated aging on a laboratory scale of a Brandy de Jerez, employing oak chips and ultrasound as extraction method, has been carried out.The samples obtained by accelerated aging have been analytically and sensorially analyzed, comparing them with those of reference brandies which had been aged in the traditional way.After 30 days, the proposed method allows us to obtain a Brandy with similar analytical and sensorial characteristics to those which have been aged in the traditional way for an average term of between 6 and 18 months.

Accelerated ageing of an EAF black slag by carbonation and percolation for long-term behaviour assessment

The efficient reuse of industrial by-products, such as the electric arc furnace (EAF) black slag, is still hindered by concern over their long-term behaviour in outdoor environments. The aim of this study was to develop an accelerated ageing method to simulate the long-term natural carbonation of EAF slag exposed to the elements. The degree of carbonation achieved in a freshly produced slag after accelerated ageing and in a slag used on a fifteen-year-old unpaved road was very similar. The influence of particle size on accelerated carbonation was assessed, with it being concluded that the slag sample with a particle size bigger than 5–6 mm underwent slight carbonation over time when it was exposed to CO2. The accelerated ageing procedure based on percolating a previously carbonated water solution through the slag column allowed gradual leaching with simulated acid rain, as well as providing information about the gradual and total chemical release from the slag. Three classification groups were established according to the release rate of the determined elements. The joint use of the accelerated carbonation method and the percolation test is proposed as a useful tool for environmental risk assessment concerning the long-term air exposure of EAF black slag.

High Antioxidative Performance of Layered Double Hydroxides/Polypropylene Composite with Intercalation of Low-Molecular-Weight Phenolic Antioxidant

It is of increasing interest to develop high-performance antioxidants for polypropylene (PP). Here, we have developed an organic–inorganic hybrid antioxidant by direct intercalation of low-molecular-weight hindered phenolic antioxidant (AO) into the interlayer region of layered double hydroxides (LDH), prepared the AO-LDH/PP composites following a simple solvent washing method, and investigated the thermal stability of the AO-LDH/PP composites by an accelerated aging method at 150 °C under air atmosphere. The results show that the one-step synthesis method is available to produce the AO-LDH with a basal spacing of 2.8 nm and that the addition of AO-LDH does not influence the crystallization behavior of PP. Furthermore, the radical-scavenging ability of AO-LDH is similar to that of the AO species. The AO-LDH significantly improves the long-term thermal stability of PP related to the CO3-LDH. The AO-LDH exhibits excellent antioxidative performance with promising applications in the field of polymers.

Soiling of building envelope surfaces and its effect on solar reflectance – Part II: Development of an accelerated aging method for roofing materials

Highly reflective roofs can decrease the energy required for building air conditioning, help mitigate the urban heat island effect, and slow global warming. However, these benefits are diminished by soiling and weathering processes that reduce the solar reflectance of most roofing materials. Soiling results from the deposition of atmospheric particulate matter and the growth of microorganisms, each of which absorb sunlight. Weathering of materials occurs with exposure to water, sunlight, and high temperatures. This study developed an accelerated aging method that incorporates features of soiling and weathering. The method sprays a calibrated aqueous soiling mixture of dust minerals, black carbon, humic acid, and salts onto preconditioned coupons of roofing materials, then subjects the soiled coupons to cycles of ultraviolet radiation, heat and water in a commercial weatherometer. Three soiling mixtures were optimized to reproduce the site-specific solar spectral reflectance features of roofing products exposed for 3 years in a hot and humid climate (Miami, Florida); a hot and dry climate (Phoenix, Arizona); and a polluted atmosphere in a temperate climate (Cleveland, Ohio). A fourth mixture was designed to reproduce the three-site average values of solar reflectance and thermal emittance attained after 3 years of natural exposure, which the Cool Roof Rating Council (CRRC) uses to rate roofing products sold in the US. This accelerated aging method was applied to 25 products–single ply membranes, factory and field applied coatings, tiles, modified bitumen cap sheets, and asphalt shingles–and reproduced in 3 days the CRRC's 3-year aged values of solar reflectance. This accelerated aging method can be used to speed the evaluation and rating of new cool roofing materials.

A Comparative Analysis of the Performance of PVC Film Aging by Ultraviolet and Thermal Methods

In this article, the changes of the polyvinyl chloride (PVC) film properties and its law are analyzed during the ultraviolet and thermal aging. Using accelerated aging methods in laboratory,it was found that the tensile strength by ultraviolet aging fell down, on the contrary, it raised by thermal aging. This result indicate that PVC film was not aged to reduce the tensile strength at 50°C for 120h.We found the air permeability curves rose firstly then to decline, and the moisture permeability of PVC film curves declined by the two aging methods. The effects of the ultraviolet aging on the air and moisture permeability were a marked decrease.

Role of thermoxidation and depolymerisation in the ageing of systems paper/gum arabic/historical ink

AbstractThe aim of this study was to assess the role and proportional representation of depolymerisation and thermoxidation reaction paths in the systems paper/gum arabic (GA)/historical ink during various accelerated ageing methods. The historical inks under study are iron-gall, bistre, and sepia. The results indicate that thermoxidation represents only a minor reaction path in the ageing of paper/GA/ink systems except for the iron-gall ink and the light-thermal method of accelerated ageing. The iron-gall ink accelerates both reaction paths of ageing, i.e. thermoxidation and depolymerisation; in this case, thermoxidation might become the prevailing degradation reaction path. For the sepia ink, an anti-depolymerisation stabilising effect in thermal methods of ageing has been detected. Considering the thermoxidation reaction path, the results even suggest that a compound preventing thermoxidation is formed during the thermally accelerated ageing in air and in 100 mg L−1 of NO2. In the light-thermal ageing, the most stable sample is the Whatman paper (W)/GA/bistre ink.

Research on the Bending Properties of the Bamboo-Wood Container Flooring

In this paper, the bending properties of bamboo-wood container flooring and bamboo curtain-OSB container flooring were tested and the six-cycle artificial accelerated aging method of ASTM D1037 was conducted to evaluate the aging performance of two kinds of bamboo-wood container floorings. The modulus of rupture (MOR) and modulus of elasticity (MOE) were tested in the longitudinal and transverse directions before and after aging. The results showed that both the bending strength and MOE decreased after aging. The retention ratios of MOR of the bamboo-wood container flooring and bamboo curtain-OSB container flooring were respectively 43.5%, 72.0%, and the retention ratios of MOE were 54.6%, 76.3%. In general, the effect of aging on the bamboo-wood container flooring was larger than that on the bamboo curtain-OSB container flooring.

Investigation of Aging of Asphalt Concrete Reservoir Facing With Time

AbstractThe objective of this work was to study the aging of asphalt concrete facings with time based on the test results from field and laboratory specimens. The mechanical behavior of samples drilled out at three different locations of the Tianhuangping asphalt facing, which had performed for 13 years, was tested, and the properties of the bitumen extracted from the samples were investigated. Test results show that hot production caused most of the aging of the bitumen, and the most severe aging in the field occurred in the most exposed location, but only “skin deep” (0–10 mm) in the asphalt facing. To predict the aging of asphalt facings with time, an accelerated aging method was developed in the laboratory, and a relationship was established between the laboratory-accelerated aging in hours and the field aging in years. Laboratory-accelerated aging test results show that bending strain at failure of asphalt concrete reduced 37 % because of hot production, 25 % in the first 20 years of service, and 6 % in another 30 years of service.

Characterization and prediction of fracture properties in hygrothermally degraded adhesive joints: an open-faced approach

One of the challenges in the application of structural adhesive joints is the prediction of their long-term durability. During the service life, moisture diffuses into the adhesive layer and eventually degrades its fracture properties. Environmental degradation should thus be taken into consideration in the design and analysis of adhesive joints. This work first provides an overview, summarizing the recent efforts regarding the hygrothermal exposure of adhesive joints, accelerated aging methods, water diffusion modeling, and characterization of fracture properties in adhesively bonded joints. The second part presents a recent degradation methodology by which the fracture toughness evolution of adhesive joints can be predicted using fracture test data obtained using the accelerated open-faced degradation method.

风电叶片复合材料的湿热老化性能研究

采用加速老化仿真腐蚀实验，以风电叶片复合材料为研究对象，研究了去离子水和3.5 wt% NaCl溶液两种介质对复合材料力学性能的影响。研究结果表明，复合材料的吸湿率在去离子水中比在NaCl溶液中的大，导致其力学性能的下降也比在3.5% NaCl溶液中浸泡下降的大。通过试样表面和断口形貌分析说明了吸湿特征的产生和力学性能下降的原因。 The mechanical properties of composites immersed in distilled water and 3.5 wt% NaCl solution were studied by an accelerated aging method using wind turbine blades as the research object. The results show that the absorption rate of the composite materials immersed in distilled is higher than that immersed in 3.5 wt% NaCl solution, resulting in the decline of the mechanical properties of the composites immersed in distilled is higher than that in 3.5 wt% NaCl solution. The reasons for the mixture absorption characteristics and the decline of the mechanical properties were explained by SEM analysis of the surface and fracture morphology of the samples.

A method for screening the relative long‐term stability of biochar

AbstractBiochar is being actively explored as a tool for long‐term soil carbon sequestration. However, in order for this to be effective the long‐term environmental stability of biochar must be assured. Here, we define and test an accelerated ageing method that seeks to reflect the oxidative nature of biochar degradation in soil. The method was applied to a systematic set of biochar samples produced from sugarcane bagasse, and a set of biochar samples produced from four different biomass sources. The stability of carbon in these samples was found to range between 41.6% and 76.1%, loosely correlating with biochar O : C ratio (r = 0.73). Increasing intensity of oxidative treatment eliminated more carbon. It also increased surface O : C ratio in a manner reported for naturally aged charcoal samples. The method effectively discriminated biochar produced under contrasting pyrolysis conditions and could be used as a proxy for environmental ageing of approximately 100 years under temperate conditions.

Evaluation of the micro-mechanical strength of resin bonded–dentin interfaces submitted to short-term degradation strategies

The aim of this study was to evaluate the microtensile bond strength (μTBS) and confocal micropermeability of resin bonded–dentin specimens created using two representative two-step/self-etch adhesives submitted to short-term period degradation strategies such as simulated pulpal pressure, thermo- or mechanical-cycling challenges. Clearfil SE Bond (CSE) and Silorane adhesive (SIL) were bonded to flat deep dentin from seventy extracted human molars and light-cured for 10s. Composite build-ups were constructed using with Filtek Z350 XT and Filtek P90 respectively. The specimens of each adhesive group were subjected to three different accelerated aging methods: (1) thermo-cycling challenge (5000 cycles); (2) mechanical-cycling load (200,000 cycles); (3) experiment and (4) conventional method for simulated pulpal pressure (20cm H2O). Control resin-bonded specimens were stored in distilled water for 24h. μTBS and confocal microscopy (CLSM) micropermeability evaluation were performed and the results were analyzed using Two-way ANOVA and Tukey's tests (α=0.05). The CLSM evaluation revealed micro-cracks within the Silorane-bonded dentin subsequent to mechanical-cycling load, whereas, the simulated pulpal pressure induced evident micropermeability in both bonding agents. Mechanical loading provides discernible bonding degradation in a short-term period in resin–bonded dentin created using two-step/self-etch adhesives. However, simulated pulpal pressure may reduce the sealing ability of self-etch adhesives causing greater water uptake within the resin–dentin interface.

Tensile properties degradation of glass fiber-reinforced polymer bars embedded in concrete under severe laboratory and field environmental conditions

This paper presents the test results of an experimental study to investigate the durability of newly developed glass fiber-reinforced polymer bars. The main objective of this study is to investigate any degradation in the tensile properties of the glass fiber-reinforced polymer bars using accelerated aging methods. Glass fiber-reinforced polymer bars were embedded in concrete prisms and exposed to several environmental conditions for 6, 12, and 18 months. The environments included exposure to tap water and seawater at two temperatures (room temperature and 50°C), seawater dry/wet cycles and alkaline solution at 50°C. In addition, two typical field conditions of the Kingdom of Saudi Arabia (Gulf area and Riyadh area) were included. The performance of the glass fiber-reinforced polymer bars was evaluated by conducting tensile tests on the bars extracted out from the concrete prisms after exposure to different conditions. In addition, scanning electron microscope was used to investigate the degradation mechanism of the bars. After 18 months of exposure, test results showed that both the tap water at 50°C and the alkaline solution at 50°C had the maximum harmful effect on the tensile strength of glass fiber-reinforced polymer bars. The two field conditions showed almost no degradation in the tensile properties of the tested bars.

Dynamic vacuum stability test method and investigation on vacuum thermal decomposition of HMX and CL-20

Dynamic Vacuum Stability Test (DVST) method monitoring the reaction process continuously and directly was used to investigate the thermal decomposition of HMX and CL-20. DVST employs the built-in pressure and temperature mini-sensors combined with the data acquisition-processing unit to achieve the dynamic and real-time measurement. The eligible thermal stability of HMX and CL-20 is determined by the very little amount of evolved gas. The non-isothermal reaction model of HMX varies with experimental temperature, while that of CL-20 adheres only to one. The isothermal reaction rate constants of the two samples both increase exponentially with the rise of temperature. It may be due to the accelerating autocatalysis in the solid-state thermal decomposition. DVST as an accelerated aging method was also applied to predict the storage life of materials. DVST can replace the traditional VST method in application of thermal analysis of chemicals especially energetic materials.

Long-term durability prediction models for GFRP bars in concrete environment

This article presents a durability study of glass fiber reinforced polymer (GFRP) bars within concrete environment and provides recommendations for effective accelerated ageing methods, data reduction and validation, and formulation of master curves for long-term predictions. Concrete beams reinforced with GFRP bars were immersed in tap water inside temperature-controlled tanks. Sustained load was applied to beam samples, and elevated temperatures were used to accelerate the ageing of GFRP bars. After exposure, GFRP bars were tested for residual tensile strength, which was considered as a measure of the durability performance of the specimens. Scanning electron microscopy (SEM) images were used to evaluate the microstructural changes of conditioned specimens. Short-term (up to 270 days) results showed that compared to alkalinity and low sustained load, moisture and elevated temperature played much more important roles in accelerating environmental attack to GFRP bars. Based on the short-term test results, the dominant degradation mechanism for GFRP bars in concrete was found as the deterioration of fiber/matrix interface. A degradation model based on Arrhenius concept and prediction procedures are given, and correlations with other studies and field data are provided. The tensile strength retentions for GFRP bars in saturated concrete subjected to sustained load were predicted. It was found that degradation rates decreased rapidly, but tensile strength retentions at different exposure temperatures converge to a constant value with the increase of exposure time. Beyond fiber-matrix debonding, there is a possibility that other degradation mechanisms such as fiber corrosion may start to dominate the deterioration process of GFRP bars with time.

Effect of <i>In Situ</i> Surface Modificated Nano-Zinc Oxide on the Curing Structure and Property of Natural Rubber Conventional Vulcanization

In-situ surface modificated nano-zinc oxide was prepared in sol-gel method and the microscopic structure of the zinc oxide particles was analyzed by transmission electron microscopy (TEM). The influence of the nano-zinc oxide on the physical properties of NR vulcanizates was investigated, and the vulcanizates heat-resistant oxygen aging property was studied by the hot air accelerated aging method. Therefore, not only can the strength and elongation properties of vulcanizates greatly be improved, but aslo the heat oxygen aging property of vulcanizate rubber was extremely promoted.

Comparative oxidative stability of α‐tocopherol blended and diffused UHMWPEs at 3 years of real‐time aging

Vitamin E (α-tocopherol) is a free-radical stabilizing antioxidant used to maintain oxidative stability in radiation cross-linked ultra-high molecular weight polyethylene (UHMWPE) used in total joint replacements. We investigated the oxidative resistance of vitamin E-stabilized UHMWPE in (i) postirradiation vitamin E-diffused UHMWPE, (ii) vitamin E blended and irradiated UHMWPE, and (iii) unstabilized, irradiated UHMWPE after accelerated aging and real-time aging in an aqueous environment at 40°C for 36 months. Unstabilized samples exhibited substantial oxidation throughout the surface and bulk with both types of aging. While vitamin E-stabilized, radiation cross-linked UHMWPEs were all superior to unstabilized samples, irradiated blends showed surface oxidation and subsurface oxidation potential beginning at ten months in real-time aging. In contrast, postirradiation vitamin E-diffused UHMWPEs showed no detectable oxidation and no increase in oxidation potential despite elution of some vitamin E. We also showed that current thermal accelerated aging methods were unable to differentiate among the oxidative stability of vitamin E-stabilized, radiation cross-linked UHMWPEs prepared by different processes.

Influence of Flexural Loading on Permeablility of Chloride Ion and Diffusion Coefficients in RC Beams

The permeability of chloride ion in concrete can be studied using the accelerated aging method in a short period, but the influence of loading characteristic on chloride ion permeability and diffusion coefficients is not considered generally. Three RC beam (120 mm×240 mm×2400 mm) specimens with different flexural loading state are exposed in an artificial corrosion container filled with salt-fog of 5.0 % sodium chloride for 40 days, the chloride ion concentration in different depths of compressive and tensile region are measured, diffusion coefficients of different region concrete are fitted on the basis of Fick’s second law, the effect of flexural loading on chloride ion concentration and diffusion coefficients of concrete are analyzed. The results show that the effect of the flexural load influences permeability of chloride ion and diffusion coefficients of concrete, content of chloride and diffusion coefficients of concrete are controlled by loading level, and the bending load is one of the important factors that can not be ignored in the study of concrete durability.

Analysis of Aging-Related Problems of Wood Residues Composite

The anti-aging property of wood residues composite is an important indicator for measuring the service performance of products. And the aging problems of these composite materials have attracted more and more attention from people. So we had a research on such problems. By means of experiments, this paper analyzed the reasons for the aging of wood residues composite. Through contrast experimental methods, we analyzed the way to accelerate the aging of them. At last, we adopted the 6-cycle accelerated aging method of ASTM D1037and the aging instrument detecting method according to their characteristics and available experimental conditions. Based on actual conditions, we analyzed the aging factors of wood residues composite such as temperature, humidity, specimen size ,surface decoration and so on.

Teste de envelhecimento acelerado para avaliação do potencial fisiológico de sementes de grama-bermuda

A utilização de sementes para formação de gramados esportivos e ornamentais tem assumido grande importância no Brasil, principalmente pelo baixo custo em relação à formação por placas de tapetes naturais. As "bermudas" [Cynodon dactylon (L.) Pers] são as principais gramas utilizadas na formação de campos esportivos e, dentre os problemas enfrentados, destaca-se a dificuldade de estabelecimento adequado da cultura, fato que exige a utilização de sementes de alto potencial fisiológico, de modo a permitir rápida emergência e desenvolvimento das plantas. Assim, estudaram-se procedimentos para a condução do teste de envelhecimento acelerado para determinar o potencial fisiológico de sementes dessa espécie, incluindo a avaliação da eficiência do uso de solução saturada de NaCl como alternativa para a realização do teste. Para tanto, cinco lotes de sementes foram submetidos aos testes de germinação, emergência de plântulas e envelhecimento acelerado (períodos de 48, 72 e 96 h, a 41 e 45 ºC, com e sem o uso de solução saturada de NaCl). O experimento foi conduzido em delineamento inteiramente casualizado. O envelhecimento acelerado com o uso de solução saturada de NaCl, dentre os procedimentos estudados, é o método mais adequado para avaliação do potencial fisiológico de sementes de grama-bermuda, sendo que a combinação 45 ºC/48 h é eficiente para a classificação dos lotes em diferentes níveis de vigor.