Artificial Aging Test Research Articles

Influence of handheld nonthermal plasma on shear bond strength of polyaryletherketone to resin-matrix cement

Background/purposeChallenges exist regarding the bonding efficiency of polyaryletherketone (PAEK), a high-performance thermoplastic, attributed to its chemical inertness and hydrophobic surface, hindering effective bonding with resin-matrix cement. This research explored the impact of handheld nonthermal plasma (HNP), under varying operational parameters, on PAEK surface wettability and changes in bonding performance with cement. Materials and methodsThree types of disc-shaped PEAK specimens were prepared, with surface treatments categorized as grinding, airborne-particle abrasion (APB), and HNP. Surface wettability was analyzed using a contact angle analyzer (n = 10). Specimens were bonded with resin cement and subjected to artificial aging tests: distilled water bath (NA), thermocycling, and highly accelerated stress tests (n = 10 for each test). Shear bond strength (SBS) was measured, failure modes were analyzed, and statistical analyses were conducted. ResultsThe HNP markedly improved PAEK surface wettability, achieving superhydrophilicity (P < 0.05). This effect intensified with extended operation times (30 or 60 s) and reduced elapsed times (<30 s). HNP-treated PAEK exhibited higher SBS than APB (P < 0.05) and maintained bonding durability after artificial aging, particularly in ketone-enriched variants. Failure analysis revealed predominantly adhesive failure under APB–NA treatment, mixture failures under HNP–NA treatment and postaging, but no cohesive failure. ConclusionThe HNP device benefits dental settings by transforming the PAEK surface into superhydrophilic properties, thereby improving PAEK–cement bonding. It significantly enhances bond durability within 30 s of operation and after a 30 s elapsed period. It is noteworthy that ketone-enriched PAEK demonstrates markedly improved bonding performance.

Molecular dynamics supported thermal-moisture aging effects on properties of silicone rubber

Silicone rubber materials are widely used as protective coatings in multiple fields. In this work, accelerated artificial aging tests of silicone rubber under different thermal and hygrothermal conditions were performed to better understand how temperature and humidity affected aging behavior and mechanism. It was noticed that due to the presence of oxygen molecules, the main chain of silicone rubber broke and produced free radicals, while water molecules brought hydrolysis reactions and produced silicone hydroxyl structures. Furthermore, computer aided molecular simulation was carried out to better understand the diffusion of small particles in silicone rubber materials, as well as to study how they affect the chain structure, providing support for the mechanism of aging. Finally, two lifespan prediction models were proposed respectively to determine the usage life of silicone rubber under certain temperature and humidity conditions, which provides guidance value for the use of silicone rubber.

Evaluating the Atypical Aging Potential Development in Sparkling Wines Can Be Achieved by Assessing the Base Wines at the End of the Alcoholic Fermentation.

Traditional sparkling wine production is a lengthy and costly process, involving a double fermentation step and a period of aging sur lie; thus, monitoring quality during the key manufacturing stages is crucial. The effects of the second fermentation on the development of 2-aminoacetophenone (AAP), the main marker of the atypical aging (ATA) defect, were investigated on 55 base wines (BWs) and corresponding sparkling wines (SWs) produced in an experimental winery. While the AAP content of the SWs was observed to be higher than the BWs, it was found that an artificial aging test carried out on the BWs could be a good predictor of ATA development in SWs. Further, the antioxidant capacity of the SWs was noticed to correlate well with the potential AAP formed during accelerated aging. Finally, an analysis of covariance (ANCOVA) model of linearization capable of predicting AAP formation in SWs using the data obtained from the corresponding BWs was created.

Influence of Long-Term Storage and UV Light Exposure on Characteristics of Polyurethane Foams for Cryogenic Insulation.

Rigid polyurethane (PUR) foams have been the most effective insulation material used in space launchers since the beginning of cryogenic fuel use, due to their outstanding thermal and mechanical properties. In this study, spray-applied PUR foams using different ratios of amine-based catalysts were produced. Due to climate change, several restrictions have been made regarding the usage of blowing agents used for PUR foam production. Lately, hydrofluoroolefins (HFOs) have been suggested as an alternative for PUR foam production due to their low global warming potential (GWP) and ozone depletion potential (ODP), replacing the hydrofluorocarbons (HFCs) so far used. This change in blowing agents naturally altered the usage of catalysts. Reactive amine-based catalysts are less hazardous because of their low volatility and ability to react successfully with isocyanate or polyols. Spray-applied PUR foams with a potential application for cryogenic insulation were produced and tested for long-term storage, analyzing parameters such as the pH value of polyol composition, foaming kinetics (trise, tcream), etc. Athermal analysis (TG, DSC) was also applied to developed materials, as well as artificial ageing by exposing samples to UV light. It was discovered that PUR foams obtained using reactive amine-based catalysts, such as Polycat 203 and 218, have a higher integral heat capacity, but polyol mixtures containing these catalysts cannot exceed a storage time of more than 4 months. It was also observed from artificial ageing tests of PUR cryogenic insulation by exposure to UV light that the thickness of the degraded layer reached 0.8 mm (after 1000 h), but no significant destruction of cellular structure deeper in the material was observed.

Artificial aging test method for the assessment of changes in properties of architectural membranes and membrane connections

In order to determine changes in the functional properties of architectural membranes due to weathering and forecast their durability, it is very essential that the accelerated aging test simulates conditions that are maximally close to the natural operating conditions of these materials in tensile structures. This paper introduces the development of an artificial weathering test for the investigation of changes in the properties of architectural membranes and connections from this material by incorporating climatic factors characteristic of the continental climate zone of mid-latitude in the aging model. The duration, intensity, and sequence of cyclic impact under which artificial aging has to be performed were based on the analysis of the environmental conditions of this zone. 1000 h impact consisting of 520 h of radiation with UVA-340 lamps and 480 h of cyclic immersion in acidic pH water, freezing (−18 °C) and heating (60 °C) are the main stages of the aging model. The developed aging model was experimentally verified by testing the PES/PVC coated material that is used in tensioned membrane structures and its connections of three types (overlap, pocket and laced). The results indicate that the model is useful both for determining changes in the properties of membranes and connections and may serve as a potential tool for forecasting the aging of architectural membranes.

Effect of CeO2 NPs on stability of regenerated silk fibroin against UV‐aging

AbstractRegenerated silk fibroin (RSF) fibers have great application prospects in medicine, textiles, optoelectronics, and other fields. However, under the synergistic action of ultraviolet, oxygen, and water, RSF will inevitably become brittle, which will greatly shorten the service life of RSF. Therefore, it is urgent to find some methods to protect RSF from aging damage. Cerium dioxide nanoparticles have a strong ultraviolet absorption and antioxidant capacity and have been used as an anti‐aging component for other biomaterials. Thus, the RSF/CeO2 NPs hybrid fibers were successfully prepared, and a series of artificial aging tests were carried out. Mechanical property is an important index to measure the aging degree. After aging, compared with RSF, the stress of RSF/CeO2 NPs hybrid fibers was increased by 130.47 ± 4.78 MPa, and the strain of RSF/CeO2 NPs hybrid fibers was increased by 69.89% ± 1.37%. The results of Fourier transform infrared spectroscopy, UV–Vis, sodium dodecyl sulfate polyacrylamide gel electrophoresis discussed the protective mechanism of CeO2 NPs, which prevent the transition from β‐sheet to α‐helix/random coil and the disorder of structure. Furthermore, RSF/CeO2 NPs hybrid fibers have an excellent antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria; the antioxidant activity of RSF/CeO2 NPs hybrid fibers is gradually enhanced in the presence of UV‐light.

Evaluation of Long-Term Boiling Water Immersion as Artificial Aging Test of Silicone Rubber Insulators

Our country IRAN have long coastal area with length of more than 1830 km. Utility companies with 30 years of experience in using polymeric insulators in this very heavy polluted area. Operational history in these areas indicates many insulating problems. With the advancement of polymer insulation technology, the utilities want to select the longest life insulators for these areas. Laboratory studies accelerated testing of polymer insulators is the only available method to investigate the trend of insulator degradation during the aging process, because it takes a long time for noticeable changes and signs of aging to appear on insulators in the power grid. Different methods such as salt-fog, UV and boiling water are used to test artificial aging, each method has advantages and disadvantages. In our experience, boiling water is used as a low-cost method in compared to the other methods especially salt fog test. The aim of this research was to determine a shorter method for evaluation of SR insulators. In this paper, the accelerated aging of polymer insulators using salt-fog and boiling water immersion tests are investigated. During and after the aging test, the polymer insulator's electrical quality is analysed using leakage current measurement tools, partial discharge, and hydrophobicity. Surface changes are also analysed by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), Thermo Gravimetrical Analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR) both qualitatively and quantitatively.

Safeguarding outdoor cultural heritage materials in an ever-changing troposphere: Challenges and new guidelines for artificial ageing test

Safeguarding outdoor cultural heritage materials in an ever-changing troposphere: Challenges and new guidelines for artificial ageing test

Advanced decay of the Fontvieille porous limestone used in the construction of Pouillon’s housing estates in Algiers (Algeria)

Numerous residential complexes were designed and built on the coastline of Algeria during the 1950 s by the renowned architect Fernand Pouillon using the Fontvieille soft porous limestone (Provençal Molasse) belonging to the Miocene deposits (French quarries). An important part of this architectural heritage is prematurely affected by visible decay phenomena of the building stone such as disintegration, differential erosion, encrustation, and biological colonization, and orange patina. The Climat de France estate located in an urban maritime area that has a typical Mediterranean climate, and considered to be one of the most important and populous in Algiers, is a distinctive example. The primary research objective was to describe the major decay patterns observed and the related processes and mechanisms affecting the Fontvieille porous limestone. The mineralogical, chemical, and petrographical analysis, combined with petrophysical and mechanical tests, were performed using analytical techniques (X-ray diffraction (XRD), X-ray fluorescence (XRF) spectrometer, scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX)), and other standard methods on samples of this limestone coming from the buildings’ façades. The alteration degree quantification was performed using an artificial aging test and revealed severe damage. The results proved that the stone is highly affected by physical–chemical deterioration mechanisms, which induced the reduction of its mechanical properties. This stone is vulnerable to salt crystallization effects through wet-dry cycles resulting from macro- and micro-climatic changes, in addition to permanent sea spray exposure. The storage and transfer properties of the limestone are closely linked to emergence of the decay patterns in a relatively short time due to these particular coastal North African climatic conditions.

A Model Iron Gall Ink: An In-Depth Study of Ageing Processes Involving Gallic Acid

Iron gall inks have been among the most used writing materials after carbon black, thus representing an important element of the historical and artistic heritage of our society. Crucially, the preservation of manuscripts and drawings is influenced by the presence of these inks, leading to conservation issues related to paper degradation and text fading. Besides all the advances obtained in paper conservation, the study of iron gall ink's behaviour and ageing is still an important topic, which requires investigation through an accurate molecular characterisation to produce reliable models. In the present work a micro-destructive method based on liquid chromatography techniques (HPLC-DAD and HPLC-ESI-Q-ToF) has been optimised starting from a model gallic acid-based ink. An in-depth study of the behaviour of the ink in time was performed by natural and artificial ageing tests, monitored by colorimetry, showing the autoxidation of gallic acid to ellagic acid in the prepared mock-ups. The effect of relative humidity on ageing processes was also evaluated, allowing us to determine different intermediates depending on the environmental conditions. Finally, the analytical method developed was then successfully applied for investigating 19th-20th century historical ink samples, where one of the identified ageing markers was detected, besides the expected gallic and ellagic acids.

Detection of maize seed germination rate based on improved locally linear embedding

Locally linear embedding (LLE) is a nonlinear dimensionality reduction method, which has great advantages over linear dimensionality reduction methods. However, the traditional LLE takes the Euclidean distance as the distance measure, which is difficult to accurately reflect the spatial position relationship between the high-dimensional data of the near-infrared spectrum, resulting in a poor modeling effect. This paper tries to improve the LLE with different distance metric methods and proposes a rapid detection method for maize seed germination rate based on improved local linear embedding and near-infrared spectroscopy. In this paper, a total of 315 samples from 7 different types of maize seeds, purchased from the seed market, were adopted as the research object. We performed artificial aging tests with 8 different gradients (from 0d to 7d with interval of 1d) on them and completed the germination rate test after collecting the near-infrared spectral data for each sample. The Monte Carlo cross-validation (MCCV) algorithm, combined with PLSR and SVM, was used to remove abnormal samples from the spectral and germination rate data. And then, for comparison, we used several different improvement strategies for LLE (traditional Euclidean distance, Manhattan distance, Chebyshev distance, Correlation coefficient, and Cosine similarity) to reduce the spectral data dimension and established PLS and SVM germination rate prediction models. We compared the prediction effects of different models to explore the optimal improvement strategy of LLE dimension reduction distance measurement. The results showed that the cosine similarity was the best improvement strategy under the same modeling method. The R2 of the LLE_ cos-PLS model's test set can reach 0.8384, and the R2 of the LLE_cos-SVM model's test set can reach 0.8765. The results showed that the cosine similarity could better reflect the spatial distribution in the spectral data of aged maize seeds, and the precision of the model was higher after LLE_cos dimensionality reduction. Compared with the linear modeling method PLS, the nonlinear modeling method SVM is more suitable for predicting the germination rate of maize seeds. This study can provide a reference method for the quality inspection of other agricultural products.

Effect of Artificial Freeze/Thaw and Thermal Shock Ageing, Combined or Not with Salt Crystallisation on the Colour of Zamora Building Stones (Spain)

After subjecting Zamora building stones to accelerated ageing tests, colour changes were studied, namely: (a) freezing/thawing and thermal shock (gelifraction and thermoclasty), and (b) combination of freezing/thawing plus thermal shock and salt crystallisation (sulphates or phosphates) (gelifraction, thermoclasty and haloclasty). Zamora building stones are silicified conglomerates (silcretes) from the Cretaceous that show marked colour changes due to the remobilisation of iron oxyhydroxides. In this work, four varieties were: white stone; ochreous stone; white and red stone; and purple stone Their micromorphological characterization (skeleton, weathering plasma and porosity/cutan) is formed of grains and fragments of quartz and quartzite as well as by accesory minerals muscovite and feldspar (more or less altered), and some opaque. Quartz, feldspar and illite/mica were part of the skeleton; kaolinite, iron oxyhydroxides, and CT opal were part of the weathering plasma or cutans; their porosity were 11.7–8.7%. Their chromatic data have been statistically analysed (MANOVA-Biplot). They showed higher variations in ΔE*, ΔL*, Δa* and Δb*on combined freezing/thawing plus thermal shock and sulphates crystallisation leading to rapid alteration of the building stones. Chromatic differences between the other two artificial ageing tests were less evident and were not detected in all samples. The global effect of ageing on the Zamora building stones darkened them and reduced their yellowing. The ochreous stone suffered the least variation and the purple stone the most. This study of the colour by statistical analyse may be of interest for the evaluation and monitoring of stone decay, which is an inexpensive, simple, easy and non-destructive technique.

PA-12-Zirconia-Alumina-Cenospheres 3D Printed Composites: Accelerated Ageing and Role of the Sterilisation Process for Physicochemical Properties.

The aim of this study was to conduct artificial ageing tests on polymer-ceramic composites prepared from polyamide PA-12 polymer matrix for medical applications and three different variants of ceramic fillers: zirconia, alumina and cenospheres. Before ageing, the samples were subjected to ethyl oxide sterilization. The composite variants were prepared for 3D printing using the fused deposition modeling method. The control group consisted of unsterilized samples. Samples were subjected to artificial ageing in a high-pressure autoclave. Ageing conditions were calculated from the modified Hammerlich Arrhenius kinetic equation. Ageing was carried out in artificial saliva. After ageing the composites were subjected to mechanical (tensile strength, hardness, surface roughness) testing, chemical and structural (MS, FTIR) analysis, electron microscopy observations (SEM/EDS) and absorbability measurements.

How to accelerate natural weathering of polymeric photovoltaic backsheets – A comparison with standardized artificial aging

The weathering performance of polymeric backsheets is most accurately assessed by outdoor exposure to natural weathering and examination of their performance characteristics by observing changes in properties. The main drawback of natural weathering is the long exposure time. Therefore, also existing qualification tests for photovoltaic (PV) components suggest accelerated artificial aging tests. This should lead to similar materials degradation as long-term outdoor exposures cause. However, it is necessary to establish connections between field performance of polymer products and accelerated materials durability testing in order to better predict the service life of a polymer product. Therefore, the main focus of this work was to evaluate the effect of natural and artificial aging on multilayer backsheet films for PV modules. For this reason, different backsheet films were naturally and artificially aged. Subsequently the optical, chemical, mechanical and thermal properties were characterized. In general, only some changes in properties after up to 3000 h of accelerated aging can be correlated with natural weathering for 2.5 years. The degradation mechanism of the polymeric part during natural weathering has to be considered when trying to simulate natural aging conditions in order to choose the right parameters for artificial aging. Thus, the right test design for artificial aging tests is highly important, as well as the consideration of the degradation mechanisms when trying to simulate natural aging conditions. • Xenon aging didn't provoke same changes in optical properties as natural weathering. • UV-fluorescence aging with standardized parameters was the most harmful test. • The used artificial aging tests (ISO4892) only partially simulate natural aging. • Different microclimatic conditions were found for outdoor and indoor weathering.

Effect of Artificial Aging Test on PEEK CAD/CAM Fabricated Orthodontic Fixed Lingual Retainer

Background: The purpose of this study was to evaluate the effect of in vitro long-term simulation of oral conditions on the bond strength of PEEK CAD/CAM lingual retainers. Material and methods: The sample consisted of 12 PEEK CAD/CAM retainers each composed of 2 centrally perforated 3x4mm pads joined by a connector. They were treated by 98% sulfuric acid for 1 minute and then conditioned with Single Bond Universal and bonded to the lingual surface of premolar teeth by 3M Transbond TM System. Half of the retainers were artificially aged using a 30-day water storage and 5000 thermocycling protocol before bond strength testing to compare with the non-aged specimens. Results: The artificially aged retainers showed a marginally lower bond strength than the non-aged retainers. However, independent sample t-test indicated that this difference was statistically not significant. Conclusion: The durability of the PEEK lingual retainer adhesive system has been confirmed using the well-known oral simulating artificial aging protocol of water storage and thermocycling.

The effect of traditional amur cork tree bark extract dyes on thermal stability of paper by accelerating ageing

Extracts from amur cork tree barks contain some of the most important traditional natural dyes used, especially for functional production in ancient Chinese papers, due to religious reasons and their aesthetic aspects and antibacterial properties. Some ancient paper artefacts, dyed with this colourant and scattered around the world, are currently preserved to different extents. This study aims to characterize the thermal degradation process of amur cork tree bark extracts dyed papers to improve the knowledge and effectiveness of restoration practices. The properties of extracts dyed papers treated under dry-heat accelerating ageing conditions were investigated via optical observation and scanning electron microscopy as well as with pH, tensile strength and folding endurance analyses. The results showed that the main components from extracted dyes played important roles in affecting the properties of dyed paper. The changes in surface colour, pH, morphology and mechanical properties after the artificial dry-heat ageing tests revealed the most suitable concentration of extract dyes for maintaining the long-term thermal stability of the paper.

Wood Surface Modification with Hybrid Materials Based on Multi-Walled Carbon Nanotubes.

In this work, new treatments based on multi-walled carbon nanotubes (MWCNTs), MWCNTs decorated with zinc oxide (ZnO), MWCNTs decorated with hydroxyapatite (HAp) and MWCNTs decorated with silver (Ag) nanoparticles dispersed in PHBHV solution are proposed for improving sound oak wood properties. We hypothesize that the solutions containing decorated MWCNTs will be more efficient as wood consolidants, not only because of the improved mechanical properties of the treated wood but also because of the hydrophobic layer created on the wood surface. In order to test these hypotheses, the treatments’ potential was investigated by a number of complex methods, such as colorimetric parameter measurements, water absorption tests, mechanical tests, artificial aging and antifungal tests. The data confirm that the treated wood materials have moderate stability, and the color differences are not perceived with the naked eye. A significant improvement of the treated samples was observed by water absorption, humidity and mechanical tests compared to untreated wood. The best results were obtained for samples treated by brushing with solutions based on decorated CNTs, which confirms that a uniform and thicker layer is needed on the surface to ensure better protection. The wood behavior with accelerated aging revealed that the control sample degraded faster compared to the other treated samples. Antifungal tests showed that higher growth inhibition was obtained for samples treated with 0.2% MWCNTs_ZnO + PHBHV. Considering all of the obtained results, it can be concluded that the most effective treatment was MWCNTs_ZnO + PHBHV at a nanocomposite concentration of 0.2%, applied by brushing. Thus, wood protection against mold and fungi will be achieved, simultaneously ensuring improved mechanical strength and water barrier properties and therefore maintaining the structural integrity of sound oak wood over time.

Application of resin-TiO2 nanoparticle hybrid coatings on travertine stones to investigate their durability under artificial aging tests

Three different stone coating products including industrial resin, resin-anatase nanoparticles and resin-rutile nanoparticles (NPs) were used to evaluate their stone surface protection effect against thermal shock and salt crystallization on three types of porous travertine stones. The results showed that the use of nanoparticles of both TiO2 polymorphs (rutile and anatase) dispersedly in resin, significantly increased durability of the stones surfaces during the aging tests. No color change in the sample surfaces is another advantage of the resin-TiO2 NPs hybrid coating. Product with anatase nanoparticles shows by far the best performance in protecting the stone surfaces. In both aging tests, samples coated by resin-anatase NPs had the lowest mass changes and the highest surface hardness compared to samples coated by the other coatings. Mineralogy, porosity and microbial activity textural features controlled the durability of the studied stones. Mono-mineral composition and macro porosity of studied samples explain their significant durability against the thermal shock process. On the other hand, the growth of salt crystals in the pore space of the stones in some cases induced macroscopic cracks, particularly in Abarkooh sample with high porosity and microbial textural features Scanning electron microscopy observation confirms that the samples underwent microcracking processes related mainly to salt crystallization pressures. Finally it can be concluded that the resin-TiO2 NPs hybrid coating had a good compatibility with the stone substrate and could be very promising to protect the porous stone façades against natural aging processes.

Spectroscopic Stability Studies of Pressure Sensitive Labels Facestock Made from Recycled Post-Consumer Waste and Agro-Industrial By-Products

To support circular economy and sustainability, the use of synthetic polymers should be minimized due to their excessive accumulation in the environment and low biodegradation rate which leads to a global waste problem. Thus, the quota of natural resources should be increased, as well as the use of agriculture and industrial waste or by-products as raw materials in industrial processes. Agro-industrial wastes were found to have high cellulose fiber potential which makes them an excellent resource for paper production. This study investigates the influence of artificial aging test on the stability of commercially available fiber based self-adhesive pressure sensitive labels (PSL), in which the facestock is made of 15% agro-industrial byproducts, 40% post-consumer recycled paper and 45% virgin wood pulp and compared to ones made of biobased polyethylene. The results showed that optical brighteners are present in the composition of fiber based PSL. Moreover, the fluorescence and UV-Visible spectroscopy results indicated that by the action of UV irradiation and temperature. The oxidation of cellulose was not found by FTIR spectroscopy, indicating its high stability.

Water-Based Aerosol for Book Deacidification: Experimental Apparatus and Theoretical Interpretation of Results.

One of the major problems in book conservation is the long-term deconstructive effect of acidity introduced into the paper by several additives, which, in the presence of humidity, generates a hydrogen cation with a strong catalytic role in cellulose depolymerization. Many types of treatment have been used in the past, but up to now, research for less-invasive, fast and cheap methods is still vividly ongoing. In this study, an approach to book deacidification is presented, where alkaline water solutions are administered to bound books in the form of micrometer-sized aerosol droplets, without using vacuum apparatus accessories. Alkaline clouds treatments were alternated with gentle air fluxes of drying steps. Few cycles are required to achieve uniform deacidification of books. The treatment could be conducted with proper apparatus on large volumes, resulting in rapid treatment time and low cost. The titration curve reporting the variation of book pH, with respect to the amount of absorbed alkaline aerosol, was built and interpreted in terms of a chemical model for the neutralization process. FTIR, PXRD and XRF spectroscopies were used to characterize the book chemistry. The effects of the treatment on the book were evaluated by measuring the degree of polymerization (DP) of the paper and the colorimetric coordinates of the paper and ink. Artificial aging tests revealed a general increase in the aging stability of the deacidified paper samples with respect to the untreated samples. Finally, the alkaline reserve data are discussed.