Accelerated UV Aging Research Articles

Effect of artificial weathering on the some surface properties of uv system parquet varnish applied to persian silk (Albizia julibrissin) wood

Her ağaç türüne ait ahşap malzemeyi doğru ve verimli kullanabilmek için farklı özelliklerini bilmek gerekmektedir. Bu çalışma, UV sistemli parke endüstrisinde gülibrişim (Albizia julibrissin) ahşabının değerlendirme olanaklarını araştırmak amacıyla yapılmıştır. UV sistemli parke vernikleri, endüstriyel uygulamalara göre bir parke fabrikasında 3 ve 5 kat gülibrişim ahşabına uygulanmıştır. Daha sonra elde edilen malzemeler 252 ve 504 saat UVA-340 lambaları kullanılarak hızlandırılmış, UV yaşlandırma işlemlerine tabi tutulmuştur. Yaşlandırma öncesi ve sonralarında renk parametreleri (L*, a* ve b*), parlaklık değerleri, könig sarkaç sertliği ve yüzey yapışma direnci (MPa) testleri yapılmıştır. Yaşlandırma ile bu testlerin değiştiği gözlenmiştir. Sonuç olarak, gülibrişim (Albizia julibrissin) ahşabı parke endüstrisinde kullanılabilir.

Analysis of Ageing Processes of Semi-Crystalline Materials

The article presents the influence of accelerated UV ageing on the structural properties of selected polymer materials. In this study, 3 types of materials from a group of thermoplastics known as PP30T, PE, POM were used. The test samples were prepared by injection moulding. In turn, an accelerated UV ageing process (600 h) was carried out in the UV Test chamber with fluorescent lamps characterized by a wavelength of 313 nm. Changes in the structure of the tested materials were observed by using an optical microscope. Measurements of gloss on the surface of primary samples that were exposed to UV rays were also taken. In addition, the structure of primary and aged samples was tested by differential scanning calorimetry (DSC). The conducted studies have demonstrated the impact of UV radiation on the changes in the surface layer of tested materials.

UV-0/HPC laminated coatings for protection of cellulosed-based cultural heritage against UV rays

Irradiation by light is considered to be one of the primary sources of damage to the cellulose matrix under environmental conditions. In this study, a laminated assembly method was used to coat 2, 4-dihydroxybenzophenone (UV-0) and hydroxypropyl cellulose (HPC) on the paper surface to form a light-shielding layer. The coating material was characterized by UV–vis and FTIR. The photostability of the coating treatment was further evaluated by comparing the measured values of UV–vis, infrared spectrum, degree of polymerization, tensile strength, folding endurance and chromaticity before and after accelerated aging for two kinds of paper samples. The results demonstrated that the coating treatment could significantly enhance the photodurability of cellulose-based materials with different pigments under accelerated UV aging conditions.

Investigation of PEG/mixed metal oxides as a new form-stable phase change material for thermoregulation and improved UV ageing resistance of bitumen.

The form-stable phase change material (PCM), polyethylene glycol (PEG)/ZnMgAl-mixed metal oxides (MMO), is prepared as a performance-enhancing additive of bitumen. In PEG/MMO PCM, PEG exhibits the phase-change function while ZnMgAl-MMO acts as the support carrier to prevent leakage of liquid PEG during phase transition. The properties of PEG/MMO PCM were analysed by XRD, SEM, FTIR, DSC, TG and UV-vis spectrophotometry. The results showed that the maximum PEG confined by MMO could be 65% and 65PEG/MMO PCM exhibited good thermal and chemical stability, sufficient phase change enthalpy and excellent UV absorption properties. Furthermore, the temperature regulation and UV ageing resistance of PEG/MMO PCM modified bitumen was evaluated by the thermal storage and release test and accelerated UV aging test. As a new type of performance-enhancing additive, PEG/MMO PCM is expected to be effective in regulating extreme temperature and resisting UV aging of bitumen and thus significantly extending the service life of bitumen pavement.

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.

Use of rapid prototyping technology in complex plastic structures. Part II. Impact of operating conditions on functional properties of polymer harmonic drives

The influence of operating conditions on physical and mechanical properties of tooth surface in the flexspline of a harmonic drive was investigated. 3D printed test models were made from poly(acrylonitrile--co-butadiene-co-styrene) (ABS) copolymer and from poly(lactic acid) (PLA) and subjected to the accelerated UV aging test and to bench tests. Measurements of hardness, Vicat softening point and atomic force microscopy (AFM) analysis were performed in order to determine the properties of the teeth surface in the gear wheels. Furthermore, the degree of degradation of the plastics was determined with IR spectroscopy. It was found, that the ambient conditions and exploitation of harmonic drives do not affect the value of softening point and hardness. On the other hand, the AFM analysis indicated that the sides of teeth were smoother as a result of their cooperation. The values of Ra parameter in the areas examined decreased from 110.0 to 54.6 nm and from 23.9 to 17.0 nm for the gear wheels made of ABS and PLA, respectively. Furthermore, the Derjaguin--Muller-Toporov modulus (DMT) of surfaces was also decreased from 10.0 to 3.0 GPa and from 4.5 to 2.2 GPa in the gear wheels made of ABS and PLA, respectively. The AFM imaging provide evidence for destructive effects of UV radiation and elevated humidity, confirmed by IR spectroscopy.

New organic-inorganic hybrids as multifunctional additives to improve ethylene-norbornene (EN) composite stability

In this study, new multifunctional organic-inorganic pigments were synthesized by the complexation of carboxlic azo dyes (D1, D2) with aluminum-magnesium hydroxycarbonate (LH) and were applied as colorants in ethylene-norbornene copolymer (EN). The structures of the hybrid pigments were analyzed by X-ray diffraction (XRD), secondary ion mass spectrometry (TOF-SIMS), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). X-ray diffraction revealed that the hybrid pigments had developed new crystalline structures and showed the presence of additional peaks on their diffraction patterns. Moreover, TOF-SIMS confirmed that the modification had been successful, with the formation of dye-metal complexes embedded in the LH structure. The EN composites with hybrid pigments were subjected to accelerated UV aging. Alterations were monitored by Fourier transform infrared spectroscopy (FT-IR), spectrophotometry, differential scanning calorimetry (DSC) and mechanical tests. It was found that the EN composites containing hybrid pigments showed approximately 4 times higher tensile strength than both EN and an EN sample with unmodified LH under 250 h of UV irradiation. Adding 2 wt% of the multifunctional hybrid pigments to EN copolymer significantly enhanced the aging resistance and thermal stability of the resulting composites.

The Effect of UV Aging on Antimicrobial and Mechanical Properties of PLA Films with Incorporated Zinc Oxide Nanoparticles.

The aim of this study was to examine the influence of accelerated UV-aging on the activity against chosen microorganisms and the mechanical properties of poly-lactic acid (PLA) films enhanced with ZnO nanoparticles. The pure PLA films and tri-layered PLAZnO1%/PLA/PLAZnO1% films of 150 µm thickness were extruded. The samples were treated with UV-A and Q-SUN irradiation. After irradiation the antimicrobial activity and mechanical properties of the films were analyzed. The results of the study demonstrated that PLA films did not inhibit the growth of Staphylococcus aureus, Bacillus cereus, Escherichia coli, Bacillus atrophaeus, and Candida albicans cells. PLA films with incorporated zinc oxide nanoparticles decreased the number of analyzed microorganisms. Accelerated UV aging had no negative effect on the activity of the film containing nano-ZnO against Gram-positive bacteria, but it influenced the activity against Gram-negative cells and C. albicans. Q-SUN irradiation decreased the antimicrobial effect of films with incorporated nanoparticles against B. cereus. UV-A and Q-UV irradiation did not influence the mechanical properties of PLA films containing incorporated ZnO nanoparticles.

Fluorinated Polyacrylic Resins for the Protection of Cultural Heritages: The Effect of Fluorine on Hydrophobic Properties and Photochemical Stability

Two new water-repellent methyl methacrylate-based resins were synthesized changing the fluorinated pendant chain length of the co-monomers adopted, 2,2,2-trifluoroethyl acrylate and 1H,1H,2H,2H-perfluorooctyl methacrylate. The macromolecular and hydrophobic properties of the resultant polymers were investigated and their photochemical stability was estimated via an accelerated UV aging test. This work demonstrates that a polymeric protective prepared from a co-monomer bearing a short fluorinated pendant chain is characterized by more satisfactory hydrophobic and durability features than those of long fluorinated pendant chain-based polymers.

Influence of Ageing with UV Radiation on Physicochemical Properties of Acrylic-Polyurethane Coatings

Investigated systems of acrylic-polyurethane coatings consisted of three kinds of coatings: base coat (acrylic), intermediate (polyurethane) and top coat (acrylic); each made up of two layers. Mean thickness of the coating system was equal (145 ± 1) μm. In time of accelerated UV ageing, electromagnetic radiation was emitted of wave length in the range (300 - 400) nm which was progressively inducing a destruction of coatings chemical structure, especially photooxidation and photolysis of coating material. Carried out X-ray investigations revealed increased contents of oxygen in aged coatings due to their photooxidation which resulted in increased tendency of coating microfragments to chip off from surface layer with the ageing time flow. The hardness increase of UV aged coatings was also observed which intensified their surface layer brittleness. This contributed to their thickness decrease by more than 10% after 2016 h of ageing. Photodestruction of UV aged coatings was documented as well by characteristics obtained during investigations carried out with DMA method use. A noticeable physical destruction of the coatings was observed in the form of silver cracks, etchings and grooves in surface layer as well as craters extending also into interlayer. Processes of physical and chemical destruction undergoing in aged coatings influenced roughness profile change and coatings surface topography shaping. After 2016 h of UV ageing, the roughness parameters (Ra, Rz, Rt) increased several times. Long-lasting UV radiation influence on the surface of investigated acrylic-polyurethane coating systems contributed to their decorativeness loss. Microscopic examinations revealed colour change (yellowing) of blue pigment contained in polyurethane interlayer. Decline in coating gloss was also observed as the result of surface roughness increase.

Determination of the color changes against accelerated UV aging of used water based layers on some heat-treated (ThermoWood) wood species

Aim of study: The objective of this study is to investigate the accelerated UV resistance of water-based varnish layers, applied on heat-treated wood (ThermoWood) surfaces. Area of study: Determination of the relationship between heat-treated, water based varnish, aging and color. Material and Methods: Wood specimens prepared from Scotch pine ( Pinus sylvestris L.), Oak ( Quercus petreae L.) and Oriental beech ( Fagus orientalis L.) were heat-treated according to ThermoWood method at 190 o C for 2 hours, and at 212 o C for 1 hour and 2 hours. Following the heat treatment, one and two component water-based varnishes were applied to similar layer thicknesses. The finished specimens were exposed to UV-A 340 nm fluorescent lamp in a “QUV accelerated weathering tester” for 144, 288 and 432 hours (ASTM G 154-06, 2006). At the end of each exposure period, red color tone, yellow color tone, lightness and total color difference values were determined according to ASTM-D 2244-3. Main results: Lightness and total color difference values of the water-based single and double component varnishes increased after the UV aging. Research highlights: All color parameters had changed due to aging.

Influence of clay nanofillers on properties of ethylene‐octene copolymers

The article deals with preparation, properties and usage of ethylene‐octene copolymers/clay films. Different properties of two types of ethylene‐octene copolymers (Engage 8540 and Engage 8842) with 17 and 45 wt% of octene (EOC‐17 and EOC‐45) were compared in nanocomposites with two types of clays—Cloisite 93A and Dellite 67. The aim was to evaluate the influence of (nano)filler type on ethylene‐octene nanocomposites properties. Mechanical and thermal properties, morphology, and UV radiation degradation were observed. Furthermore, permeability of three different gasses was determined. EOC nanocomposites perform a higher elongation at break, especially EOC‐45. Dynamic Mechanical Analysis (DMA) showed an increase of E′ modulus of all nanocomposites in a wide range of temperatures compared to pure EOC. Intercalation of nanofillers was studied by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). It has been proved that EOC‐45 has a better dispersion EOC‐17. DSC analysis showed a shift in a crystallization temperature for EOC‐17, where the nanofiller acted as a nucleation agent due to the worse dispersion. Barrier properties were improved by almost 100% by addition of organoclay for all measured gasses; they were best for EOC‐17 nanocomposites due to a higher crystallinity. XRD together with transmission electron microscopy (TEM) showed much better dispersion for EOC‐45 nanocomposites. Fourier transform infrared spectroscopy (FTIR) and accelerated UV aging showed CO peaks for EOC nanocomposites. POLYM. COMPOS., 39:4581–4593, 2018. © 2017 Society of Plastics Engineers

Fly-ash contribution to Nd:YAG laser yellowing and its mitigation using UV-B light

Abstract Nd:YAG Q-Switched laser cleaning of soiled stone at 1064 nm can sometimes result in yellower appearances than other conventional cleaning techniques. The yellowing effect is known to be at least partially due to the laser beam interaction with soiling matter, especially with infra-red absorbing components such as iron oxides, carbonaceous particles or fly-ash. In this study, pure plaster plates were artificially soiled with natural black crust and fly-ash powders. The morphology and crystalline structure of the soiling materials was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Soiled plaster plates were then treated by Nd:YAG QS laser light at 1064 nm. The laser irradiation led to the appearance of a yellow tone in all cases, highlighting the fly-ash contribution to the yellowing effect. Afterwards, the irradiated plaster plates were exposed to UV-B light (313 nm) for a few dozen hours using an accelerated UV ageing chamber. This treatment resulted in a significant attenuation of the yellow colour for all the samples. Colour measurements revealed that this photo-bleaching effect was essentially due to brightness L* and saturation C* variations and not to hue h* variation towards less yellow shades. As hue variation is often related to chemical transformations of chromophores, this result tends to indicate that the yellowing reduction was mainly due to scattering effects.

Self-Organized Fullerene Interfacial Layer for Efficient and Low-Temperature Processed Planar Perovskite Solar Cells with High UV-Light Stability.

In this Communication, a self‐organization method of [6,6]‐phenyl‐C61‐butyric acid 2‐((2‐(dimethylamino)‐ethyl) (methyl)amino)ethyl ester (PCBDAN) interlayer in between 6,6‐phenyl C61‐butyric acid methyl ester (PCBM) and indium tin oxide (ITO) has been proposed to improve the performance of N–I–P perovskite solar cells (PSCs). The introduction of self‐organized PCBDAN interlayer can effectively reduce the work function of ITO and therefore eliminate the interface barrier between electron transport layer and electrode. It is beneficial for enhancing the charge extraction and decreasing the recombination loss at the interface. By employing this strategy, a highest power conversion efficiency of 18.1% has been obtained with almost free hysteresis. Furthermore, the N–I–P PSCs have excellent stability under UV‐light soaking, which can maintain 85% of its original highest value after 240 h accelerated UV aging. This self‐organization method for the formation of interlayer can not only simplify the fabrication process of low‐cost PSCs, but also be compatible with the roll‐to‐roll device processing on flexible substrates.

Properties of Polystyrene Clay Nanocomposites Prepared Using Two New Imidazolium Surfactants

Montmorillonite/polystyrene nanocomposites were prepared by in situ photopolymerization of styrene in the presence of 2% by weight of clay organomodified by two new imidazolium surfactants having in their structure an alkyl chain with 20 or 22 carbon atoms, respectively. Thermogravimetry showed that the new surfactants are more thermally stable than conventional alkylammonium surfactants. The properties of the obtained nanocomposites were compared with those of pristine polystyrene, with those of a microcomposite obtained by in situ polymerization of styrene in the presence of unmodified clay, and with those of a nanocomposite obtained starting from an organomodified clay with a short alkyl chain (12 carbon atoms) imidazolium surfactant. XRD, TEM, and rheological analysis showed that the clay/PS nanocomposites have a mixture of intercalated and partially exfoliated structure layers, where the higher the surfactant alkyl chain length, the higher the exfoliation degree. Kinetics curve of accelerated UV aging, obtained by following through infrared spectroscopy the increase of carbonyl functions during aging, showed that the rate of photooxidation of clay containing samples is higher than neat polystyrene. The rate is higher as a function of the degree of dispersion of the filler in the polymer matrix.

Effects of Ageing on the Color and Surface Chemistry of Paulownia Wood (P. elongata) from Fast Growing Crops

The behavior of paulownia wood (Paulownia elongata) was investigated using three different ageing tests: simulated natural ageing under the influence of light under indoor conditions, temperature-induced ageing in the dark, and UV-induced ageing. Ageing effects were evaluated by color measurements in the CIE Lab system. Simulated natural ageing of wood in indoor conditions (6 months) and UV-accelerated ageing (72 h) are complex and dynamic processes, which resulted mostly in yellowing of the samples due to photo-degradation. Temperature-induced ageing (288 h at 100 C) resulted mostly in a rapid and visible darkening of the paulownia wood. Comparative in-time evolution of color changes during accelerated UV ageing testing and simulated natural ageing testing under indoor conditions allowed the estimation of an acceleration index of about 50X. Fourier transform infrared spectroscopy (FTIR) was used to examine specific chemistry changes occurring during these ageing tests. UV light from natural or artificial sources caused primarily lignin degradation followed by oxidative processes leading to carbonyl-containing chromophores. Temperature-induced partial degradation of hemicelluloses and oxidative processes resulted in the formation of chromophores containing mostly conjugated carbonyl groups. This research highlighted that paulownia wood (P. elongata) is quite sensitive to ageing under the action of light and temperature, which cause notable color and surface chemistry changes.

Ethylene-Octene Copolymers/Organoclay Nanocomposites: Preparation and Properties

Two ethylene-octene copolymers with 17 and 45 wt.% of octene (EOC-17 and EOC-45) were compared in nanocomposites with Cloisite 93A. EOC-45 nanocomposites have a higher elongation at break. Dynamical mechanical analysis (DMA) showed a decrease oftan⁡δwith frequency for EOC-17 nanocomposites, but decrease is followed by an increase for EOC-45 nanocomposites; DMA showed also increased modulus for all nanocomposites compared to pure copolymers over a wide temperature range. Barrier properties were improved about 100% by addition of organoclay; they were better for EOC-17 nanocomposites due to higher crystallinity. X-ray diffraction (XRD) together with transmission electron microscopy (TEM) showed some intercalation for EOC-17 but much better dispersion for EOC-45 nanocomposites. Differential scanning calorimetry (DSC) showed increased crystallization temperatureTcfor EOC-17 nanocomposite (aggregates acted as nucleation agents) but decreaseTcfor EOC-45 nanocomposite together with greatly influenced melting peak. Accelerated UV aging showed smaller C=O peak for EOC-45 nanocomposites.

The protective effects and aging process of the topcoat of intumescent fire-retardant coatings applied to steel structures

The protective effects of a topcoat on an intumescent fire-retardant coating were studied under hydrochloric acid solution corrosion, accelerated UV aging and natural weathering. The protective effects were determined to be appreciable under all the aging conditions. During hydrochloric acid corrosion testing, the coating sample without the topcoat exhibited no fire resistance after immersion for 48 h. When a topcoat was used, the acid solution could not directly corrode the fire-retardant coating. However, the solution was observed to seep into the coating layer from the edges, demonstrating that special attention must be paid to the edges and corners to avoid the pollution source corroding the coating and substrate. Under the accelerated UV aging conditions, the fire-resistant properties of the unprotected coating deteriorated significantly after 20 days of aging due to the hydrolysis and photooxidation of the components. However, the coating with a topcoat exhibited better fire-proof properties, even after 40 days of aging. During the natural weathering process, the fire resistance of the coating without a topcoat significantly decreased after being exposed to the high levels of precipitation and UV radiation that occur during summer. The fire-resistant properties were completely lost after 1 year of aging exposure. However, the protected sample exhibited no distinct changes in the duration of fire resistance. The results of this study remind engineering personnel to pay attention to the deterioration of the coating properties and to take protection measures. Despite slightly decreasing the fire resistance performance and increasing the cost, the protective effect of the topcoat was remarkable. Therefore, a compatible topcoat is considered indispensable for fire-retardant coatings used outdoors to ensure the best long-term fire resistance performance.

Accelerated UV ageing studies of acrylic, alkyd, and polyvinyl acetate paints: Influence of inorganic pigments

The stability of two types of acrylic binding media, alkyd and polyvinyl acetate (PVAc), four widely used synthetic binders in modern and contemporary art, to UV light also including the UV-B range (315–280nm, middle UV) for simulating sunlight outdoor conditions was studied and compared by double-shot and single-shot Py-GC/MS, FTIR-ATR, and colour measurements. Thermally assisted hydrolysis and methylation (THM-GC/MS) analyses were used for the alkyd. Additionally, the influence of inorganic pigments on the photo-oxidative stability of the binding media was also considered. For this purpose, the binders in their pure form as well as mixed with eight different inorganic pigments (titanium white—anatase and rutile, cadmium yellow, cadmium red, hydrated chromium oxide green, ultramarine blue, raw umber Cyprus, and ivory black) were exposed to the accelerating artificial UV ageing for different periods of time and analysed before and after UV exposure. After UV ageing, the double-shot Py-GC/MS detected the effect of photo-oxidative processes of the binders in a much more detailed way than by the single shot. For instance, photo-oxidation of the acrylics resulted in a production of oligomers even during the thermal desorption step of double-shot Py-GC/MS and in a decrease of the EA and nBA main monomers in the pyrolysis second step. Contrarily, the aged alkyd samples were mostly characterised by a decrease of unsaturated fatty acids and especially by the increase of free ortho-phtalic acid detected by double-shot Py-GC/MS and THM-GC/MS, which is also reflected in the FTIR-ATR results. On the other hand, an increase of free acetic acid was observed for the aged polyvinyl acetate by double-shot Py-GC/MS. Colour measurements recorded a greater sensitivity of the alkyd paints, shown by to the bigger shift of L*, a*, and b* coordinates and change of E* values. Of additional interest was the higher sensitivity to the UV light for synthetic binding media in combination with pigments.

Identification of copper phthalocyanine blue polymorphs in unaged and aged paint systems by means of micro-Raman spectroscopy and Random Forest

Copper phthalocyanine (CuPc) blues (PB15) are largely used in art and industry as pigments. In these fields mainly three different polymorphic modifications of PB15 are employed: alpha, beta and epsilon. Differentiating among these CuPc forms can give important information for developing conservation strategy and can help in relative dating, since each form was introduced in the market in different time periods. This study focuses on the classification of Raman spectra measured using 532nm excitation wavelength on: (i) dry pigment powders, (ii) unaged mock-ups of self-made paints, (iii) unaged commercial paints, and (iv) paints subjected to accelerated UV ageing. The ratios among integrated Raman bands are taken in consideration as features to perform Random Forest (RF). Features selection based on Gini Contrast score was carried out on the measured dataset to determine the Raman bands ratios with higher predictive power. These were used as polymorphic markers, in order to establish an easy and accessible method for the identification. Three different ratios and the presence of a characteristic vibrational band allowed the identification of the crystal modification in pigments powder as well as in unaged and aged paint films.