Accelerated Light Aging Research Articles

The Coloristic Properties of Biodegradable Fibers

This work aims to present the results of evaluating the coloristic properties of polylactic acid (PLA) fibers. PLA is common nowadays in much research, as it is a biodegradable plastic from renewable sources. However, little research is devoted to PLA fibers, and even less to applied research of colored fibers. The prepared color masterbatches, created using inorganic pigments, such as titanium dioxide and carbon black, were subsequently used to prepare dyed PLA fibers in mass. The fibers were drawn to the maximum drawn ratio. The properties of the pure and dyed fibers were investigated before and after accelerated light aging using Q-SUN equipment. The changes were recorded by Fourier Transform Infrared (FTIR) spectroscopy and colorimetric properties were recorded using a device spectrometer from TECHKON SpectroDens. We also evaluated thermal properties from the first heating via differential scanning calorimetry (DSC). The measurements were taken before and after the aging of the PLA fibers, in order to see the effect of aging on the supermolecular structure, excluding the influence of the preparation process and the influence of the kind of PLA. Using inorganic pigments showed sufficient color stability even after accelerated light aging, which is beneficial for using colored fibers in practice.

An investigation of the photostability of 19th century artists’ cochineal lake pigments using MFT and conventional accelerated ageing tests

ABSTRACT Red lake pigments are known for their high light-sensitivity generally when exposed to museum environments. In the cultural heritage field, the colour loss experienced by organic pigments is of special concern as the appearance of objects may be significantly altered after uncontrolled exposure to light. The present work focuses on the use of microfading testing (MFT) to study the light sensitivity of 19th century cochineal paints. MFT is a technique that combines visible reflectance spectroscopy with accelerated light ageing testing and was developed to perform in situ investigations of the light-sensitivity of cultural heritage materials in a relatively short amount of time. Reconstructions of these pigments following the manufacturing processes used by 19th century Winsor & Newton workers, as well as historic samples of cochineal pigments, were prepared using gum arabic and poly(vinylacetate). Purple cochineal paints showed a moderate sensitivity to light, while Carmine, Crimson and Scarlet paints were classified as high-sensitive materials. Overall, the carmine references turned out to be the most lightfast when mixed with gum-arabic while the scarlet pigment with poly(vinyl acetate) showed a slightly smaller colour change when compared with the almost complete loss of colour of the other poly(vinyl acetate) paints. Finally, advantages and drawbacks of the MFT method are addressed.

Application of Accelerated Light Aging Test in the Quality Evaluation of Automotive Coatings

Application of Accelerated Light Aging Test in the Quality Evaluation of Automotive Coatings

Comparison of Colour Properties of Polypropylene and Poly-(Lactic) Acid Fibres Dyed With Photoluminescent Dye

Abstract Every manufacturer wants to protect their textile products and their brand. A possible solution is, for example, the insertion of fibres with special pigments visible under irradiation by UV light into the final product. The paper focused on the study of the structure and colourimetric properties of polypropylene (PP) and poly-(lactic) acid (PLA) fibres modified with photoluminescent dye and halloysite (HNT) modified with photoluminescent dye. The photoluminescent dye and HNT modified with photoluminescent dye affected the structure of PP and PLA fibres differently. Increasing the HNT content up to 0.15 % increased the orientation of the PP fibres. In the case of PLA fibres, the increased content of photoluminescent dye in PLA fibres increased their orientation in the observed concentration area. PLA-based knitted fabrics showed better light stability, where there was no visible degradation of the knitted fabric, only its darkening. Likewise, PLA-based knitted fabric showed luminescence in UV light even after accelerated light aging.

Nano–Titanium Dioxide Coating of Chinese Fir Treated by High-Temperature Steam to Improve the Anticorrosion and Surface Hydrophobicity

Abstract The organic material of wood treated with inorganic nanoparticles has gained significant improvements in its stability against ultraviolet (UV) light and moisture degradation. Here, a new method was proposed to modify Chinese fir (Cunninghamia lancellata), which was treated by high-temperature steam and coated with titanium dioxide (TiO2) nanoparticles. Due to the synergistic effect, the treated Chinese fir can obtain the properties of surface hydrophobicity and photoaging resistance that can prevent the invasion of moisture and the damage of UV light from sunlight. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction were used to characterize the morphology, structure, chemical composition, hydrophobicity, and light-aging resistance of the treated Chinese fir. By means of comparative experiments, the Chinese fir was treated with 5 percent nano-TiO2 solution and annealed at 300°C. The surface water contact angle reached to about 130°, indicating the strong hydrophobicity. In addition, the total color difference (ΔE*) after accelerated light aging for 120 hours was only 45 percent of the control sample.

Highly stretchable, breathable and negative resistance variation textile strain sensor with excellent mechanical stability for wearable electronics

In recent years, wearable and stretchable electronic devices have attracted great research interest and effort due to their promising applications in electronic skin, wearable health monitoring, human–machine interactions and so on. However, it still remains a great challenge to fabricate highly stretchable and wearable devices with excellent breathability, mechanical robustness and laundering durability. Herein, we fabricated a highly stretchable and breathable textile strain sensor based on conductive polyester fabric (CPF) with weft-knitted structure by chemically growing conductive and transparent Al-doped ZnO (AZO) element via atomic layer deposition (ALD). The CPF strain sensor demonstrates captivating performance, including high stretchability (up to 130%) and long-term stability (3000 cycles), as well as a distinct negative resistance variation with increasing strain owing to its weft-knitted structure. Most importantly, due to the formation of chemical interactions between textiles and AZO films during ALD process, the CPF strain sensor exhibits excellent mechanical robustness and laundering durability under reciprocating rubbing (50 kPa load pressure, 30 cycles), washing (500 r/min for 10 cycles, 200 min) and light fastness (accelerated light aging test for 7 days), thus allowing the fabrication of breathable and comfortable wearable sensor without elastomer encapsulation. Based on its admirable performances, the CPF strain sensor can be easily knitted or sewed on garments or attached on human skin directly for tracking both large and subtle human motions, revealing its numerous prospects in wearable electronics, intelligent robotics and other fields.

Plasma treatment of gelatin photography

Abstract Plasma pre-treatment represents the key enabler technology for microfine cleaning, surface activation and plasma coating of almost all types of materials — from plastics, metals and glasses to textiles, composites and photographs. More and more conventional industrial treatment methods are being replaced by plasma technology in order to make processes more effective and environmentally friendly. This study is oriented on the characterization of a photographic image on two types of photographic paper (glossy and matt photographic paper with a barite layer), and monitoring the effects induced by the Atmospheric Discharge with Runaway Electrons (ADRE) plasma in air atmosphere on the photographic image layers. To evaluate their long-term stability before/after plasma treatment, degradation of black and white gelatin photographic components upon accelerated light aging using Q-SUN was investigated and the photoinduced changes were recorded by FTIR spectroscopy, densitometry and colorimetry. The results obtained demonstrated that the plasma discharge had no significant destructive effect on the photographic image as only negligible changes in the structure of the gelatin were detected due to plasma processing. Consequently, it can be concluded that low-temperature ADRE plasma in air atmosphere has the potential for successful applications in microbial decontamination and purification of damaged gelatin photographs.

Change is permanent: thoughts on the fading of cochineal-based watercolor pigments

BackgroundColor change in artworks has been commented on for centuries. Fading of watercolor pigments is a notable alteration. Pigments based on carminic acid are among those particularly prone to color loss, but the mechanism and factors are not well understood.ResultsWe painted out three pigments prepared from the aqueous extract of carminic acid (CA) from Dactylopius coccus: the uncomplexed, and aluminium- and tin-complexed lakes. These were applied in a 2% gum Arabic solution to papers that were acidic, neutral or alkaline pH and exposed to accelerated light aging in a weatherometer. The comparative rate of fading was dependent on the complexation and on the pH of the substrate. On alkaline paper, the Al complex was least light stable, on neutral paper the three colorants responded similarly, and on acidic paper the tin complex was the least light stable. This is discussed in light of the published information on reactions and mechanism of color loss of CA.Graphical abstractCochineal-based pigments fade on exposure to light. In watercolor paints, the rate depends not only on the complexation of the ligand but also the pH of the paper substrate

Antimicrobial properties of silver nanoparticles misting on cotton fabrics

The purpose of this research was to investigate whether silver nanoparticles (AgNPs) misting could be an effective disinfection and protection method for cotton fabric. The study showed that the disinfection resulted in the reduction of microorganism number by 32–100%, depending on the strain. Fabric humidity of not less than 84% ensures high effectiveness of the process. It was proved that vegetative cells are more susceptible to nanoparticles than spores. The antimicrobial protection of cotton fabric results in the 33–93% reduction of microorganism number. The application of AgNPs does not influence significantly the optical and mechanical parameters of cotton fabric, even after accelerated light ageing. The AgNPs misting is safe for personnel. The AgNPs misting can be considered as an alternative for currently used disinfection methods of ancient textiles.

Effect of light aging on silicone-resin bond strength in maxillofacial prostheses.

The aim of this study was to investigate the effect of accelerated light aging on bond strength of a silicone elastomer to three types of denture resin. A total of 60 single lap joint specimens were fabricated with auto-, heat-, and photopolymerized (n = 20) resins. An addition-type silicone elastomer (Episil-E) was bonded to resins treated with the same primer (A330-G). Thirty specimens served as controls and were tested after 24 hours, and the remaining were aged under accelerated exposure to daylight for 546 hours (irradiance 765 W/m(2) ). Lap shear joint tests were performed to evaluate bond strength at 50 mm/min crosshead speed. Two-way ANOVA and Tukey's test were carried out to detect statistical significance (p < 0.05). ANOVA showed that the main effect of light aging was the most important factor determining the shear bond strength. The mean bond strength values ranged from 0.096 to 0.136 MPa. The highest values were recorded for auto- (0.131 MPa) and photopolymerized (0.136 MPa) resins after aging. Accelerated light aging for 546 hours affects the bond strength of an addition-type silicone elastomer to three different denture resins. The bond strength significantly increased after aging for photo- and autopolymerized resins. All the bonds failed adhesively.

Surface investigations of old book paper treated with hydroxyapatite nanoparticles

Today, modern chemicals, as nanomaterials, are essential to preserve the world's artistic and cultural heritage.A new restoration method for old book paper restoration, based on a special hydroalcoholic suspension of hydroxyapatite nanoparticles, have been presented and discussed in this paper. This new method is based on the nanoparticles properties to penetrate into the materials network, to adhere to them, covering the damaged area and consolidating the damaged region. Several methods of instrumental chemical analysis have been employed: DLS, in order to determine the size of the synthesized nanoparticles and SEM, AFM spectral techniques to study the nanoparticles interaction with the paper support. Also, pH and change in yellowness of the restored surface have been evaluated, too.The influence of accelerated light aging has also been evaluated and discussed in this study, taking into acount that the aging of the document paper is an unavoidable process, difficult to study.

Micro-fading spectrometry: A tool for real-time assessment of the light-fastness of dye/textile systems

Micro-fading spectrometry is a technique that combines visible reflectance spectroscopy and accelerated light aging testing. Therefore, it is a useful tool for determining the light-stability of dyes applied on textile substrates in a relatively short amount of time. Traditional accelerated light aging methods usually require controlling many variables such as time and intensity of illumination, correct positioning of the sample during irradiation, and reproducible spot selection for each subsequent spectrocolorimetric measurement. The use of micro-fade testing as an alternative way of conducting light-fastness assessments of dye/textile systems has been explored. The results indicate that the technique is suitable for testing the color stability of cultural heritage materials and industrially manufactured textiles since it is a direct and non-contact method that takes into account the aforementioned experimental variables.

Ageing of vinyl emulsion paints—an atomic force microscopy study

AbstractThis paper presents a morphological study of poly(vinyl acetate) (PVAc) based films, either cast from polymer solutions or aqueous emulsions, which are widely used in modern and contemporary art, namely as binding media. Different vinyl films were prepared: single polymer, unpigmented and TiO2‐pigmented emulsion films, and subjected to accelerated light ageing. The evaluation of the surface changes of these films, over 3500 hours irradiation under a Xenon lamp (λ≥ 300 nm), was characterized by atomic force microscopy (AFM). The samples studied have suffered minor surface changes and revealed pronounced photostability. The AFM results obtained indicate that the most relevant morphological changes that occurred over time were primarily related to the exudation of surfactants, present in the vinyl emulsions. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Phytochemical analysis of young fustic (Cotinus coggygria heartwood) and identification of isolated colourants in historical textiles

Young fustic (Cotinus coggygria Scop.; Anacardiaceae) has been used as a dyestuff since antiquity. Phytochemical investigation of the methanol extract of the heartwood has led to the isolation and structure elucidation by nuclear magnetic resonance and mass spectrometry (MS) of 3',4',6-trihydroxyaurone (sulfuretin) and 3',4',7-trihydroxyflavonol (fisetin) as well as 3',4',7-trihydroxyflavanol (fustin), 3',4',5,7-tetrahydroxyflavonol (quercetin), 3',4',5,7-tetrahydroxyflavanol (taxifolin), 4',7-dihydroxyflavanol, 3',4',7-trihydroxyflavanone (butin), 4',7-dihydroxyflavanone (liquiritigenin), trans-2',3,4,4'-tetrahydroxychalcone (butein), 4',5,7-trihydroxyflavanone and trans-2',4,4'-trihydroxychalcone (isoliquiritigenin). The isolated compounds were used as reference materials for the development of a high-performance liquid chromatography-diode array detector-MS method, which was then applied to analyse (1) fresh silk samples dyed with young fustic, (2) dyed silk subjected to artificially accelerated light ageing and (3) historical silk micro-samples, extracted from ecclesiastical post-Byzantine garments (fifteenth to eighteenth century), which belong to monasteries of Mount Athos. Sulfuretin and fisetin, which are usually used as markers for the identification of the yellow dye and, for the first time, some of the aforementioned flavonoid components of young fustic were identified in the historical extracts. Furthermore, preliminary experiments suggested that although the amounts of the dye components decrease with light ageing, the relative ratio of fisetin and sulfuretin, after a first step of ageing, seems to be almost unaffected by such degradation processes raised by light. The effect of the latter on the morphology of the dyed silk fibres is briefly investigated by scanning electron microscopy.

Metal soaps of wool wax acids as stabilizers for plasticized polyvinyl chloride

AbstractCopper, magnesium, lead, nickel, cobalt, manganese, iron, chromium, cadmium, and barium soaps of the wool wax acid fraction have been tested as stabilizers for plasticized polyvinyl chloride polymers. Barium, cadmium, and lead soaps performed well in the light stability evaluations. In the heat aging tests barium, magnesium, lead, and nickel soaps were superior while cadmium, and manganese soaps performed poorly. The copper, cobalt, iron, and chromium soaps were ineffective.Two tests for stability were employed: an accelerated light aging test and an accelerated heat aging test. Combinations of barium and cadmium soaps were tested for synergistic effects and found to be more effective as stabilizers than the individual soaps. Soaps made from fractions of acids by partitioning the whole wool wax acid fraction were also tested. Neither the hydroxy nor the non‐hydroxy acid fraction soaps had as goad stabilizing properties for PVC as those of the whole acid fraction.

Digest of Cooperative Test Program on Accelerated Light Aging of Rubber

Abstract The Eveready unit without filters and the Atlas Twin-arc Weatherometer effect a more rapid deterioration of vulcanized rubber on exposure than does ourdoor exposure in summer. The degree of acceleration varies with the particular compound tested. In these tests it was found that from 0.6 to 3.0 hours' exposure in the machines, depending on the compound, was equivalent to 1 day of outdoor summer exposure. The procedure followed in making Eveready tests is not sufficiently standardized to obtain satisfactorily comparable results in several laboratories, with a wide variety of compounds. The Atlas single-arc equipment shows little acceleration in aging rate compared with the Atlas twin-arc and Eveready equipment used in these tests. No broad conclusions can be drawn from the results of tests in the Atlas twin-arc equipment, since results were reported for only one of these machines. It is suggested that measurements of the total radiation may be of greater significance than measurements in the ultraviolet region alone. Further' standardization in connection with ventilation and maintenance of a constant uniform temperature around the exposed specimens appears desirable. Further work is required to determine the effect of the thickness of the exposed sample on the rate of deterioration. If exposure periods are to be for time periods such as were used in these tests, it may be desirable to use thicker specimens.

Sunlight and Accelerated Light Aging of Synthetic Rubbers

Abstract Recently Werkenthin, Richardson, Thornley and Morris reported on the sunlight and accelerated light aging of various natural and synthetic rubber stocks, and proposed a method for standardizing the accelerated light aging test. The purpose of the present paper is to provide data on the correlation of sunlight aging with accelerated light aging for various synthetic rubber stocks loaded with mineral pigments. FORMULAS AND CURES The formulas and cures for the synthetic rubber stocks are given in Table I. These stocks have a loading corresponding to a good quality, 40 per cent wire insulation compound. Most of the prominent types of synthetic rubber manufactured in this country and one foreign synthetic rubber were included in this study. It was necessary to blend Vistanex Medium with natural rubber, inasmuch as this synthetic rubber cannot be vulcanized.