Artificial Accelerated Aging Test Research Articles

Light-Induced Colour Changes in Wood Surfaces in Indoor Conditions Determined by an Artificial Accelerated Test: Influence of Wood Species and Coating Materials

Stabilising the natural colour of wood species exposed to light in indoor conditions is a challenge that could be better addressed based on a deeper understanding of the occurring phenomena and influencing factors. This paper investigates comparatively the light-induced colour changes for three hardwood species, namely, European maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.) and European walnut (Juglans regia L.), as well as the influence of finishing with three types of clear, colourless waterborne lacquers: acrylic-polyurethane (F1), acrylic (F2) and polyurethane (F3) on their colour stability. Colour measurements in the CIELab system in conjunction with an artificial accelerated ageing test under the action of UV-VIS radiation, simulating natural light passing through window glass, and two types of test samples were employed to highlight the influence and contributions of the wood substrate and of the coating films to the global colour modifications. Coating films applied on 1 mm clear glass slides were employed as a sort of “detachable” finish for this purpose. Direct exposure to UV-VIS light caused visible colour changes for both uncoated and coated wood surfaces, the values of the calculated colour differences (ΔE) after a 72 h exposure being dependant on both the wood species and the coating material. Excepting two situations for walnut, statistically significantly higher colour differences were obtained for the uncoated samples: maple (9.36 units), ash (8.39 units), walnut (6.20 units), compared to the coated ones: maple (4.92–5.71 units), ash (2.25–3.94 units), walnut (4.74–7.70 units). The wood substrates underlying the coating films were found to bring the maximum contribution to the overall colour changes in the clear coated surfaces, while the coating films employed in this research demonstrated a fairly good colour stability to UV-VIS light exposure, with maximum colour changes (∆E) up to only 1.30 units. Overall, the wood species and the type of coating were found as influencing factors in interaction with the light-induced colour changes in wood surfaces in indoor conditions.

Mechanical properties of aged glue laminated bamboo for structural members

This research experimentally investigates the mechanical properties of aged unidirectional engineered bamboo (EB) laminate, pivotal in constructing glued laminated bamboo (glubam) structures. Investigations encompassed both outdoor exposure and artificial accelerated aging tests. In particular, outdoor exposure spanning three six-month intervals from July 2019 to December 2020. Complementarily, the Boil-Test (BT) method, as per the BS EN1087–1 standard, was employed for accelerated aging. The research examined tension, compression, bending, and shear mechanical characteristics of the aged bamboo samples. Notably, failure modes were predominantly influenced by fiber, matrix, and interfacial lamination layers. Findings revealed the superior anti-aging capacity of bamboo fibers compared with than that of bamboo matrix and lamination layer. Bamboo fibers maintaining over 75% of their original tensile strength. The BT accelerated aging method gave conservative estimations compared to outdoor exposure tests. Conclusively, the research yielded a novel tri-linear stress-strain model for analyzing the bending performance of glubam structures under varying aging conditions. This model incorporated strength reduction factors derived from the experimental data obtained from the corresponding compression and tension tests.

A Novel Silicone Rubber for Situation Awareness

An insulator plays an important role in the external insulation of power grid. The antifouling flashover coating on the insulator’s surface can effectively reduce the incidence of pollution flashover accidents. Local overheating, local arc, lightning and other damage lead to the deterioration of the antifouling flashover coating, resulting in pollution flashover accidents. In order to realize the on-line identification of electric arc on the surface of antifouling flashover coating, various functional nanoparticles were prepared and added into the silicone rubber to prepare functional antifouling flashover coating. The colour deviation of the coating heated at different temperatures was measured by a spectrophotometer, and the trace of arcs on the sample surface was observed. The results show that the functional nanoparticles can slightly improve the tensile strength and AC breakdown strength of silicone rubber composites. The composites change colour in 2 min at 250°C or 1s at 500°C, showing obvious indication traces after an electric arc passes the surface of an insulator in a short period. Still, the composites possess excellent functional properties after 1000h artificial accelerated aging test.

A method for the treatment of black tea waste: Converting it into liquid mulching film and solid mulching film

AbstractThis work was aim to prepare biodegradable mulching film from biomass materials to reduce the environmental pollution caused by plastics. Black tea waste was divided into two parts and combined with degradable materials such as polyvinyl alcohol and cellulose to prepare two degradable mulching films: liquid mulching film (LMF) and solid mulching film (SMF). The optimum formula was developed after studying the effects of various components of degradable mulching film on mechanical properties in both dry and wet circumstances. The properties of LMF and SMF were characterized and tested by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), light transmittance test, contact angle test, water resistance test, artificial accelerated aging test, and degradation performance test. The results demonstrated that LMF and SMF had good mechanical properties, resistance to ultraviolet light, water resistance, aging resistance, and biodegradation. Using tea waste to prepare mulching film material has the advantages of no pollution, easy biodegradation, and good biocompatibility.

An R2R3-Type Transcription Factor OsMYBAS1 Regulates Seed Germination under Artificial Accelerated Aging in Transgenic Rice (Oryza sativa L.)

MYB-type transcription factors play an essential regulatory role in seed germination and the response to seedling establishment stress. This study isolated a rice R2R3-MYB transcription factor, OsMYBAS1, and functionally characterized its role in seed germination. There was no significant difference in the germination rate of each transgenic line in the standard germination test. However, compared to the germination rate of the wild type (WT) measured in the artificial accelerated aging test, the germination rates of the overexpression lines OE-OsMYBAS1-1 and OE-OsMYBAS1-2 were significantly increased by 25.0% and 21.7%, respectively. In contrast, the germination rates of the knockout mutants osmybas1-1 and osmybas1-2 were decreased by 21.7% and 33.3%, respectively. Additionally, the above data indicated that OsMYBAS1 possibly plays a positive role in rice seed germination. Moreover, the antioxidant enzyme activities of OsMYBAS1-overexpressing plants were enhanced by 38.5% to 151.0% while the superoxide dismutase (SOD) enzyme activity of osmybas1 mutants was decreased by 27.5%, and the malondialdehyde (MDA) content was increased by 24.7% on average. Interestingly, the expression of the antioxidation-related genes OsALDH3, OsAPX3, and OsCATC was enhanced in the OsMYBAS1 overexpression lines, which is consistent with the above results. Furthermore, transcriptome sequencing determined 284 differentially expressed genes (DEGs), which were mainly involved in the carbohydrate metabolic process, glycerolipid metabolism, and glycerophospholipid metabolism. Therefore, these findings provide valuable insight into the breeding of new rice varieties with high seed germination.

Impact Resistance of Rendering Mortars with Natural and Textile-Acrylic Waste Fibres

Renders should have an adequate resistance to impacts, since they must protect the substrate. The use of fibres may enhance the energy absorbed when the mortars are submitted to an impact load, which contributes to postpone the first crack, and control its propagation and width. In this study, the impact strength was measured by a falling mass from different heights. The cracking pattern and the impact energy for the appearance of the first crack and until failure were evaluated. An artificial accelerated ageing test was also performed, and the impact resistance was analysed before and after ageing. In order to analyse the effects of recycled fibres, wool, coir, flax and textile-acrylic waste fibres were used as reinforcement in cement and cement-lime mortars. The results indicated that the fibres’ addition significantly improved the impact energy of the rendering mortars in comparison with the reference mortars. Concerning the crack patterns, the recycled fibres prevented the opening or the growth of the cracks, before and after ageing. This effect is mainly due to the fibre’s bridge mechanism, due to crossing the open cracks and hindering their propagation. The fibres’ type, length and volume fraction have influenced the mortars’ performance in terms of impact resistance. Textile-acrylic fibres waste presented the best performance by comparison with the natural fibres used.

Artificial and Natural Aging of Polypropylene Used in Passenger Vehicle Bumpers

Polypropylene (PP) has a wide range of applications in the automobile bumpers due to its many excellent properties. Mechanical properties of PP for automobile bumpers are investigated through an artificial accelerated aging test. The aging rules after different years of normal use and the artificial accelerated aging test are analyzed. The correlation between natural and artificially accelerated aging is also explored. It provides a reference for the study of the aging properties of polymers for automotive applications. Results show that the UV aging test can effectively simulate changes in tensile and bending strengths after natural aging and can be used to evaluate the weathering resistance of PP materials used in automotive bumpers. The tensile and bending strengths of these materials remain good during aging, and elongation is sensitive to aging. The short-term artificial accelerated aging test does not exert a significant influence on the impact strength of materials, and artificial accelerated aging does not completely reproduce the aging process of the material.

Incorporation of Natural Fibres in Rendering Mortars for the Durability of Walls

One of the main functions of renders, together with the overall aesthetic appearance of the building, is the protection of the walls against external aggressive actions, such as water, salts solutions, erosion, and mechanical impacts. However, some anomalies of renders may drastically hinder their protection ability. In fact, cracking, high water permeability, and loss of adherence to the substrate of renders limit their barrier effect and favour the exposure of the substrate to external actions. The incorporation of fibres in mortars is commonly pointed out to reduce their cracking susceptibility, due to the probable enhancement in tensile strength and ductility of the composite. The use of lime in substitution of the part of the cement binder is seen as a method to reduce the modulus of elasticity and therefore enhance the resistance to cracking due to drying shrinkage. Therefore, this study investigates the wall protection-related properties of natural fibre-reinforced renders with cement-lime as a binary binder at 1:1:6 volumetric ratio. With this purpose, wool, coir, and flax fibres are used at 20% by total mortar volume and the water behaviour, cracking susceptibility, and adherence to the substrate of the mortars are assessed. Specifically, the water absorption by capillarity, drying rates, permeability to water under pressure, adherence strength, and shrinkage are evaluated. In order to evaluate the renders’ durability and therefore the durability of the protection to the walls, an artificial accelerated ageing test is performed based on heating-freezing and humidification-freezing cycles. The results indicate that the fibres’ addition reduced the shrinkage and modulus of elasticity of the mortars, which suggests lower susceptibility to cracking. The addition of fibres in mortars seemed to slightly affect their water performance and only at early ages. From the results, it was concluded that the adherence strength is not affected by the fibres’ incorporation. The fibres seem also to reduce the impacts of the ageing cycles on the mortar and the improvements provided by the fibres’ addition to the mortars’ performance remained after ageing when compared to the mortars without fibres, thus being a potential alternative to increase their durability. These aspects are particularly important for buildings, since they can extend their service life and promote their sustainability.

Rapid and non-destructive detection method for water status and water distribution of rice seeds with different vigor

In this study, newly harvested and aged rice seeds were analyzed to determine their aging process, identify the difference between artificially and naturally aged seeds, and to develop a rapid, accurate, and non-destructive detection method for water status and water distribution of rice seed with different vigor. To this end, an artificially accelerated aging test was conducted on the newly harvested rice seeds. Then, low-field nuclear magnetic resonance (LF-NMR) technology was applied to test the new (Shennong No. 9816, 2018), old (Shennong No. 9816, 2017), and artificially aged seeds (Shennong No. 9816, 2018). A standard germination test was conducted for three types of seeds. Finally, the differences of water status and distribution between rice seeds of different vigor were analyzed based on the standard germination test results and wave spectrometry information collected using LF-NMR. The results indicated that new seeds, old seeds, and the artificially accelerated aging rice seeds all exhibited two water phases, and the vigor of rice seeds after the artificial accelerated aging test was lower than that of new seeds. There were significant differences between the frequencies of bound water at the time of the peak and the time at the end of the peak for the three types of seeds. The two times showed an increasing trend for rice seeds with poor vigor, indicating that the ability of the water in the rice seeds having poor vigor to combine with other substances was weakened. There were significant differences between the distributions of free water peak end time for the three types of seeds. All the rice seeds with poor vigor exhibited a decreasing trend at this time, indicating that the freedom of free water inside the rice seed samples with poor vigor was weakened. The total water content of the artificially aged seeds and the aged seeds was higher than that of the new seeds, but the free water content increased from artificially aged seeds to new seeds to aged seeds. This indicates that LF-NMR technology is an effective detection method that can simply compare the differences in seed vitality with respect to water distribution as well as differentiate the seed internal water content of artificially aged and naturally aged seeds. Keywords: low-field nuclear magnetic resonance, rice seed, water status detection, water distribution detection, seed vigor DOI: 10.25165/j.ijabe.20211402.5780 Citation: Song P, Kim G, Song P, yang T, Yue X, Gu Y. Rapid and non-destructive detection method for water status and water distribution of rice seeds with different vigor. Int J Agric & Biol Eng, 2021; 14(2): 231–238.

Weathering modification of acrylic emulsion by introducing UV absorbing groups

AbstractA new kind of UV‐absorbing silicon‐fluorinated acrylic emulsion was prepared by emulsion polymerization with 4‐allyloxy‐2‐hydroxybenzophenone, 3‐methacryloxypropyltrimethoxysilane (MPS) and hexafluorobutyl methacrylate (HFMA) as functional monomers. The emulsion and its coating were characterized by transmission electron microscope, Fourier transform infrared spectrum (FTIR), X‐ray photoelectron spectroscopy, ultraviolet absorption spectrum，thermo‐gravimetric analysis, water contact angle (CA), and artificial accelerated aging test. The results indicated that the emulsion with core‐shell structure was synthesized and showed prominent absorption peaks at 320 and 350 nm. The water CA of the coating was increased from 70.2° to 86.7° because of the incorporated HFMAs and MPSs. Both of the initial and final decomposition temperatures of the coating were increased by more than 20°C compared with those of the unmodified coating. After 10 days of accelerated aging, the color difference (ΔE) and rate of loss of gloss (ΔG) were only 2.78% and 5.22%, while those of the unmodified coating were as high as 22.94% and 78.57%, respectively. Because of the UV absorbers were incorporated by chemical reaction, the new coating had a more durable and effective anti‐ultraviolet performance compared with the coatings the UV absorbers were introduced by physical blending.

Concrete-Based and Mixed Waste Aggregates in Rendering Mortars.

This paper presents a study of incorporation of two types of construction and demolition waste (CDW) in rendering mortars, as aggregates at 0%, 20%, 50% and 100% (by volume). Recycled concrete aggregate (RCA) and mixed recycled aggregate (MRA) were used. The former is mainly composed of cementitious waste and the latter consists of a mixture of non-segregated wastes. The performance of the cement mortars with recycled aggregates was evaluated through an extensive experimental programme. The analysis comprised workability, mechanical strength, water absorption, shrinkage, open porosity and the evaluation of durability by permeability to water under pressure after an artificial accelerated ageing test. The results are considered positive, although as the incorporation of recycled aggregates (both MRA and RCA) increased the mechanical strength, the modulus of elasticity and bulk density decreased, which leads to the production of lighter mortars that are less susceptible to cracking. The modified mortar with 20% of MRA presented the best performance, in terms of mechanical behaviour.

Experimental Study on the Influence Factors of Durability of Composite Geomembrane

The durability of composite geomembrane materials may decrease under the long-term influence of natural environment such as light and temperature. In order to study the influence of different factors on the durability of composite geomembrane, the durability of composite geomembrane with different aging time was tested by artificial accelerated aging test. The experimental results show that the longitudinal tensile strength of composite geomembrane material decreases slightly with the increase of time. Additionally, the longitudinal elongation of composite geomembrane materials is proved to be located in a reasonable range, and there is no obvious upward or downward trend. The permeability coefficient of composite geomembrane material varies with the aging time, however, the test result remains in the same order of magnitude. The longitudinal tensile strength of composite geomembrane in dry state is larger than that in immersed state. The strength of the welded joint of geomembrane is larger than that of the bonded joint. The yield strength and breaking strength of geomembrane materials increase slightly with time, and there exists no significant changes in terms of the yield elongation and breaking elongation.

A comparative study on the artificial UV and natural ageing of beeswax and Chinese wax and influence of wax finishing on the ageing of Chinese Ash (Fraxinus mandshurica) wood surfaces

This study investigated and compared the behaviour of two types of natural waxes, beeswax and Chinese wax, by means of two different ageing tests: an artificial accelerated ageing test using UV light and a simulated natural ageing test (indoors conditions) based on the action of natural, window-filtered light. The same tests were employed to evaluate the influence of wax finishing on the ageing behaviour of Chinese Ash (Fraxinus mandshurica) wood surfaces. Ageing effects were evaluated by direct and microscopic observation, colour measurements in the CIELab system and FTIR investigations. The results yielded by both accelerated UV ageing (72 h) and simulated indoors natural ageing (6 months) indicate that the waxes under analysis here are materials with a good ageing resistance. FTIR investigation revealed only minor chemical changes following ageing, more evident with beeswax than with Chinese wax. Finishing Chinese Ash wood surfaces with the two types of waxes influenced their ageing behaviour in terms of colour and surface chemistry changes. For both UV and natural ageing the maximum colour differences occurred for the samples finished with Chinese wax. The colour differences ΔE after 72 h accelerated UV ageing were in all the cases higher than those occurring after 6 months of indoors simulated natural ageing. Acceleration indexes for UV exposure compared to exposure to natural window-filtered sunlight, of about 40X-60X, were calculated. Both UV accelerated ageing and natural simulated ageing resulted in significant surface chemistry changes for the unfinished Chinese ash wood samples, consisting mostly in lignin degradation and formation of carbonyl containing chromophores. FTIR investigation of wax finish wood samples revealed only very minor chemical changes of the top wax layers, although chemical changes occurring beneath the coating layer on the wood surface are highly probable. Overall, the experiments presented in this paper indicate that Chinese wax seems slightly more resistant to ageing than beeswax.

Functional triazine ultraviolet absorbers for sunlight protection of polymer materials surface

Most of the polymer coatings are directly exposed to sunlight, leading to serious degradation on their surfaces. Functional triazine ultraviolet absorber (FT-UVA) with surface enrichment property was synthesized. The surface enrichment property of FT-UVA in coating surfaces was investigated using X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier-transform infrared spectrometry (ATR-IR). Contact angle measurements suggest that the enrichment of FT-UVAs on coating surface yielded a hydrophobic film. The effective protection of FT-UVA for PVC coating was investigated by artificial accelerated aging test. The calculation of dynamic process was conducted to gain insights into the surface enrichment mechanism of FT-UVA in coating.

Degradation Behavior of Nitrile Rubber O-rings in Hydraulic Oil

The degradation behaviors of nitrile rubber O-rings immersed in hydraulic oil were investigated by adopting the artificial accelerated aging test. The chemical structures and mechanical properties of the aged samples under different conditions were evaluated by measuring the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, crosslinking density, weight loss, mechanical properties and fracture morphology. The ATR-FTIR results indicate that the amide groups and the hydroxyl groups were formed in the surface of the aged samples. The changes in the crosslinking density of the samples attributed to the competition between crosslinking and chain scission. The mechanical test results show that the tensile strength of samples immersion in oil changed remarkably for the different temperatures. In addition, the fracture morphology results demonstrate that the formation of the defects also led to the decrease in properties of the aged samples.

Study of Tensile Bond Strength for Structural Silicone Sealants after Artificial Accelerated Aging

Tensile bond strength is one of the most significant properties for structural silicone sealants used in the glass curtain walls. During the service process, aging of the silicone sealants shall be involved in comprehensive actions of environment factors, e.g. temperature, humidity, and ultraviolet light etc. In this study, artificial accelerated aging test was conducted to make clear the development of tensile bond strength, Shore hardness and elongation. The test results show that: (i) the specimens under damp-heat test have more degeneration than specimens under humidity-freeze test; (ii) the environment of high temperature and high humidity leads to the change of tensile bond, Shore hardness, elongation, and results in interfacial failure of samples.

Synthesis and characterization of UV-absorbing fluorine-silicone acrylic resin polymer

A series of UV-absorbing fluorine-silicone acrylic resin polymers containing different amount of UV-absorbent were successfully prepared by solution polymerization, with 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate (BHEM), vinyltrimethoxysilane (VTMS) and hexafluorobutyl methacrylate (HFMA) as modifying monomers. The acrylic polymers and the coatings thereof were characterized by Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) absorption spectrum, thermogravimetric analysis (TGA), water contact angle (CA) and Xenon lamp artificial accelerated aging tests. Results indicated that the resin exhibited high UV absorption performance as well as good thermal stability. The hydrophobicity of the coatings was of great improvement because of the bonded fluorine and silicone. Meanwhile, the weather-resistance was promoted through preferably colligating the protective effects of BHEM, organic fluorine and silicone. Also, a fitting formula about the weatherability with the BMHE content was tentatively proposed.

Multifunctional TiO2-based hybrid coatings on limestone: Initial performances and durability over time

In the present work, the photocatalytic activity of different coatings containing titanium dioxide nanoparticles, both pure and in conjunction with metallic nanoparticles (silver and copper) to improve their photocatalysis and biocidal efficiency, was monitored over time. The nanoproducts were applied on travertine – a porous limestone – through spray-coating. An artificial accelerated ageing test – based on the prolonged exposure to ultraviolet light and the repeated application of stains – was used to simulate the extended use of the coatings on outdoor surfaces. Microscopical, aesthetical and physical macroscopic features, as well as self-cleaning and biocidal efficiencies of the coating-substrate system, were analysed assessing possible changes over time. The outcome of the research pointed out a good aesthetic compatibility with stone substrate (showing limited visual alteration) and high photocatalytic efficiency before ageing. Durability of self-cleaning and biocidal effects was also very clear while wettability of treated surfaces – especially without metallic nanoparticles – was the most altered characteristic of the coatings at the end of the ageing.

Multiscale analysis of the radiooxidative degradation of EVA/EPDM composites. ATH filler and dose rate effect

This study is focused on the radiooxidative degradation of polymeric insulation of electric cables used in Nuclear Power Plants (NPPs). In order to investigate the degradation mechanisms of the insulation, model composites with ATH (Aluminium TriHydrate) filler and blends (without filler) based on a cross-linked mixture of EVA (Ethylene Vinyl Acetate) and EPDM (Ethylene Propylene Diene Monomer) were submitted to gamma-rays. In normal operating conditions of a NPP, the dose rate which electric cables are exposed to is around 0.1Gyh−1. In this work, artificial accelerated ageing test process has been applied at a relatively low dose rate of 7Gyh−1. Gamma-irradiations at higher dose rates typically used to accelerate the ageing, in the range 0.2–1kGyh−1, were also carried out.The first part of the study is focused on irradiations performed at relatively low dose rate and is devoted to the highlighting of the radiooxidative degradation mechanisms of EVA/EPDM blend with and without ATH filler. Correlations between the evolutions of the chemical, morphological and mechanical/electrical properties of the materials occurring after the ageing process are presented. It is shown that the degradation process is governed by radical oxidation mechanism involving chain scissions leading to the formation of carboxylic acids as end-groups. One of the main effects of the ATH filler is the progressive loss of the mechanical properties of the composite upon radiooxidation whereas they are maintained in the case of the unfilled sample. Despite the oxidation of the polymer, no change in the electrical properties of the blend and of the composite could be observed.The second part of the study focuses on the dose rate effect. It is shown that one of the main consequences of an increase of the dose rate from 7Gyh−1 to 0.2–1 kGy h−1 is a reduction of the chain scission process yield by a factor of about 20. Therefore, an important and consistent finding is that there are some limits that must not be exceeded in terms of dose rate to ensure a global satisfactorily representativeness of the accelerated ageing process.

Bentonite as a natural additive for lime and lime–metakaolin mortars used for restoration of adobe buildings

This work estimates the behaviour of mortars based on lime, seeking their application as renders of adobe walls. Mortars with binder:aggregate 1:3 volumetric ratio were prepared as is traditionally used in old buildings in central parts of Portugal.Due to specificity of the support, two clays, natural clay bentonite (5wt.%) and artificial clay metakaolin (20wt.%) were used as additives to lime mortar to prepare 3 types of blended mortars, besides the air lime reference mortar. Mortar prisms 4×4×16cm were analysed to assess mechanical properties and salt resistance. Moreover, the mortars were placed in three ways on old adobes taken from demolished houses and their behaviour was verified by artificial accelerated ageing test. Lastly, mortars were applied on a wall made from traditional adobes, where panels were monitored and trials with adhesion strength and Karsten tubes have been conducted. The results obtained by comparison of the characteristics from all the experimental procedures reveal that mortar containing air lime and 5wt.% of bentonite fulfils in the best way the requirements in its use as render of adobe buildings.