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There have been given the study results of grain color characteristics of winter durum wheat varieties and lines (Triticum durum Desf.). There has been studied the effect of factors (‘variety’, ‘year’ and their correlation) on the expression of the main breeding-valuable traits that affect the quality of the final product. The purpose of the current study was to determine the variability of phenotypic characteristics of grain associated with the number of yellow pigments in grain, the color of semolina and finished pasta, to study the correlation between indicators and to identify the most promising ones for further work. Field trials were carried out in the scientific crop rotation laboratory of breeding and seed production of winter durum wheat of the FSBSI “ARC “Donskoy”. Laboratory and analytical study was carried out in the laboratory of biochemical, technological and agrochemical estimation in accordance with generally accepted methods and GOST. As a result of the study, there has been established that the main effect on such characteristics of grain quality of winter durum wheat as ‘general hardiness’, ‘mass fraction of protein in grain’ and ‘grain color index b’ was produced by the factor ‘year of study’ by 67.0 %, 48 .2 % and 65.4 % respectively. The ‘cereal color index b’, ‘dry pasta color index b’ and visual estimation of dry pasta were mainly influenced by the factor ‘genotype’ by 62.3 %, 82.5 % and 48.3 %, respectively. The severity of the trait ‘content of carotenoid pigments’ depended on all factors. Over the years of the study, the winter durum wheat varieties and lines developed by the FSBSI “ARC “Donskoy” according to color characteristics met the international requirements for durum wheat grain. As a result, the varieties ‘Grafit’ and ‘Karotinka’ stood out according to several studied characteristics in connection with which we recommend expanding the production crops of these varieties. There can be recommended to use promising lines 1147/19 and 971/19 and the variety ‘Solntsedar’ in the breeding process as sources with high color characteristics of grain and pasta.

Despite the increasing importance of recycling, the medical sector is hardy engaged at this time due to regulatory issues. The aim of this study was to evaluate the influence of γ‐radiation sterilization (48–52 kGy) on the repetitive injection molding of a polypropylene copolymer for medical applications. For this purpose, the material was analyzed after injection molding and irradiation. To evaluate the irradiation and reprocessing influence, optical, rheological, and mechanical properties were investigated in addition to chromatography. The latter comprised the quantitative determination of Irgafos 168 and the qualitative comparison of volatile degradation products formed, including the radiolysis product 1,3‐di‐tert‐butylbenzene. The influence of irradiation on the content of Irgafos 168, volatile organic compounds, and 1,3‐di‐tert‐butylbenzene was greatest after the first irradiation, with a decrease of Irgafos 168 content by 40%. The yellowness index and melting enthalpy were influenced by irradiation and processing, but showed no direct relationship to the individual process steps. The zero viscosity correlated directly with gas chromatography–mass spectrometry results and decreased by 80% after the first irradiation. In addition, the elongation at break was reduced by 95% after the second irradiation. The influence of irradiation on the studied characteristics was high, whereas the influence of repetitive processing did not show any measurable differences [ABSTRACT FROM AUTHOR]

In order to analysis the effect of temperature on thermal oxidative aging behavior of latex sponge. The morphology and structural changes of latex sponge after aging directly affect its product use value, and its aging behavior is closely related to temperature. This study is not limited to mechanical properties. By measuring the changes of whiteness index, yellowness index, crosslink density, and indentation hardness of latex sponge at 70 ℃ and 120 ℃, the thermal oxidative aging behavior of materials under different temperature conditions was analyzed. The experimental results show that the peak of the yellowness index is reached at 86 hours at 120 ℃, the pore structure disappears and residue powder is formed on the surface. The crosslinking density is initially increased first and subsequently decreased, and the indentation hardness is sharply increased in a short time. Under the condition of 70 ℃, a slow decrease in the whiteness index of the material is noted. The other indexes display a slow upward trend, and the complete pore structure is retained. It is concluded that the change procedure and final shape of the latex sponge morphology and structure during the aging process under the condition of 120 ℃ are significantly different from those under the relatively low temperature condition. The product value is rapidly lost due to thermal oxidative aging behavior, and the thermal oxygen aging resistance of 80NR latex sponge needs improvement. [ABSTRACT FROM AUTHOR]

Data-driven models including principal component regression (PCR), partial least square regression (PLSR), and least square support vector regression (LSSVR) have been widely applied as predictive models in various applications. However, studies employing regression models to estimate the yellowness index (YI) are scarce in the literature. This study, therefore, focuses on developing non-destructive YI measurements using regression models. The collected RGB calculated XYZ and obtained CIE LAB values were set as the input variables. Meanwhile, the YI value was denoted as the output variable. Results indicated that the LSSVR model outperforms PCR and PLSR models in predicting YI in which the root means square errors of LSSVR for the training and testing datasets were found to be 261,406% to 294,218% and 725% to 772% lower than PLSR and PCR, respectively. LSSVR is also attributed to higher coefficients of determination (R²) that are superior to PLSR and PCR, whose R² values are very close to 1. Nonetheless, the computational times of training and testing datasets for LSSVR are much longer than those of PLSR and PCR. Consequently, a highly accurate LSSVR model-based YI sensor shows promising applications particularly if the computational load can be further minimized. [ABSTRACT FROM AUTHOR]

Rubber latex foam (RLF) is widely used in daily life and its characteristics are active areas of research. However, the thermo‐oxidative aging behaviors of RLF at high temperatures have not been elucidated in detail. Herein this study, the aging degree and characteristics of five types of RLF materials with various ratios of natural rubber latex and synthetic rubber latex are investigated by using the yellowness index (YI), whiteness index, cross‐linking density, indentation density, and infrared spectrum. It is indicated in the results that the structural failure degree, YI, and cross‐linking density of the sample increased linearly with increasing natural‐to‐synthetic ratio (N/R ratio). It is observed that all RLF samples with various N/R ratios undergo aging reactions during the aging process, but the aging degree and aging rate of the samples differ. Furthermore, a lifetime prediction model is calculated by the standard method and the variable activation energy method, and the YI of RLF is used as an index to evaluate the service life, which serves as a useful tool for the quality evaluation of RLF. [ABSTRACT FROM AUTHOR]

Two kinds of latex sponge (80 NR and 0 NR) with different natural latex contents were exposed to 100 ℃ by accelerated hot air aging method. Their thermal-oxidative aging behavior was investigated by using yellowness index, whiteness index, crosslinking density and indentation hardness, and the hot air aging rule of the materials was discussed. The results showed that the yellowness index of 80 NR was always higher than that of 0 NR, while the whiteness index was always lower than the latter. The crosslinking density of 80 NR was always bigger than that of 0 NR, so the latex sponge of 80 NR was more prone to molecular chain breakage and crosslinking reaction. The indentation hardness of 80 NR was affected obviously by aging time, and would increase sharply in a short time. The indentation hardness of 0 NR was linearly correlated with aging time and had a small increase. The aging resistance of 0 NR was better than that of 80 NR.

The present research study has been made to identify the effect of the okra plant lifespan upon the optical appearance of the yielded fibers. 90 ± 10 days, 120 ± 10 days, and 160 ± 10 days matured crop waste were subjected to two different retting conditions. For this study, stagnant water retting conditions and running water retting conditions were approached. Optical properties such as whiteness index, yellowness index, and brightness index of yielded okra fibers were measured by spectrophotometer. The study revealed that for both the retting conditions, the whiteness and the brightness index increased with the retting period up to a certain level, i.e., approximately 5–15% improvement for the whiteness index while approximately 10–40% improvement for the brightness index. While the yellowness index mostly showed a reverse effect with the retting period. The reduction in the yellowness index was approximately 2–7%. However, the effect of the retting period got saturated after a certain retting period, i.e., in between 17 and 25 days. Okra fiber yielded from both 90 ± 10 days and 120 ± 10 days matured okra plants showed similar optical properties, but better whiteness index than fiber yielded from 160 ± 10 days matured okra plants. In this research study, similar optical properties were observed for the fibers yielded from both the retting conditions.

The purpose of the current work was to develop and introduce into production a spring durum wheat variety adapted to the climatic conditions of the Lower Volga region, which meets the modern requirements of the raw material market for pasta producers to productivity and grain quality. Grain quality is the most important criterion by which durum wheat is evaluated. For modern pasta production, there is a great need in grain with a grain unit of at least 770 g/l; with kernel hardness of at least 80.0%; with high quality of gluten (gluten index of at least 80 u.); with carotenoid pigments of 7.0–8.0 mg/kg, where the yellowness index (semolina color) is not less than 22.0 c.u. The new spring durum wheat variety ‘Tamara’ meets all the requirements. The variety was developed by the method of complex hybridization between the best varieties and lines of the laboratory for spring durum wheat breeding and seed production of the “FARC of South-East” and selected samples from the collections of the breeding centers of the Russian Federation, VIR, and ICARDA. The variety is middle-maturing, with 50 days from a germination to heading stage, with plant height of 96 cm. On average, through three years (2019–2021), the productivity of the variety exceeded that of the standard variety ‘Krasnokutka 13’ on 0.3 t/ha, and the variety ‘Saratovskaya zolotistaya’ on 0.5 t/ha. In 2020 in the production sowing of the Krasavskoye OPH the maximum productivity was 3.14 t/ha. The variety is characterized by a high percentage of carotenoid pigments, gluten elasticity and strength, an amber-yellow shade of spaghetti, their low digestibility, delicious taste and nutritional value. The new spring durum wheat variety ‘Tamara’ has been included in the State List of Breeding Achievements since 2022. The variety has been recommended for cultivation in the 8th region of the Russian Federation.

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The present research study has been made to identify the effect of the okra plant lifespan upon the optical appearance of the yielded fibers. 90 ± 10 days, 120 ± 10 days, and 160 ± 10 days matured crop waste were subjected to two different retting conditions. For this study, stagnant water retting conditions and running water retting conditions were approached. Optical properties such as whiteness index, yellowness index, and brightness index of yielded okra fibers were measured by spectrophotometer. The study revealed that for both the retting conditions, the whiteness and the brightness index increased with the retting period up to a certain level, i.e., approximately 5–15% improvement for the whiteness index while approximately 10–40% improvement for the brightness index. While the yellowness index mostly showed a reverse effect with the retting period. The reduction in the yellowness index was approximately 2–7%. However, the effect of the retting period got saturated after a certain retting period, i.e., in between 17 and 25 days. Okra fiber yielded from both 90 ± 10 days and 120 ± 10 days matured okra plants showed similar optical properties, but better whiteness index than fiber yielded from 160 ± 10 days matured okra plants. In this research study, similar optical properties were observed for the fibers yielded from both the retting conditions. [ABSTRACT FROM AUTHOR]

The weathering of plastics is always accompanied by a change in surface properties, especially wettability in the case of water. For plastics weathering in an aquatic environment, wettability plays an important role in transport, sedimentation, and dispersion in the water body. To quantify wettability, contact angle measurement is a fast and convenient method that requires little experimental effort. This technique was used with the aim of systematically discussing how measured values of contact angles can contribute to the assessment of the weathering state. Using polyethylene terephthalate (PET), wetting was analyzed on samples from artificial weathering and from controlled, natural weathering. Surface analytical methods were used (Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), ultraviolet and visible light spectroscopy (UV/VIS)) to analyze the parameters affecting the contact angle: (i) chemical bond breaking and formation, (ii) eco-corona formation and biofilm growth, and (iii) change in surface structure and roughness. It was found that wettability with water increased during weathering in all cases. The reasons for this varied and depended on the method of weathering. The improved wettability during artificial weathering was due to changes in the polymer surface chemistry. In natural weathering, however, the formation of eco-corona and biofilm was responsible for the changes. [ABSTRACT FROM AUTHOR]

Five kinds of rubber latex foams with different natural rubber latex content were studied by the accelerated hot air aging method, and the aging degree and aging rate were characterized by aging kinetic model and several performance parameters, such as yellowness index, whiteness index, cross-linking density.In addition, the hot air aging beha-viors of rubber latex foams were explored.The results showed that yellowness index increased and whiteness index decreased with the increase in the aging time during the aging process.The cross-linking density increased at a faster rate in the early and middle stages of the aging process, and increased at a relatively slower rate in the later stage of the aging process.The analysis of kinetic model of the rubber latex foams indicated that the aging reaction rate of the rubber latex foams with natural rubber latex mass fraction of 80% was the largest during the aging process, and the aging reaction rates of the rubber latex foams with natural rubber latex mass fraction of 50%, 40% and 0 were relatively close, which demonstrated that the rubber latex foams with low natural rubber latex content had better hot air aging performance.

Marine microplastics (MPs) are exposed to environmental factors, which produce aging, weathering, surface cracking, yellowing, fragmentation and degradation, thereby changing the structure and behavior of the plastic. This degradation also has an influence on the adsorption of persistent organic pollutants over the microplastic surface, leading to increased concentration with aging. The degradation state affects the microplastic color over time; this is called yellowing, which can be quantified using the Yellowness Index (YI). Weathering and surface cracking is also related with the microplastic yellowing, which can be identified by Fourier transform infrared spectroscopy (FTIR). In this study, the degradation state of marine microplastic polyethylene pellets with different aging stages is evaluated and quantified with YI determination and the analysis of FTIR spectrums. A color palette, which relates to the microplastic color and YI, was developed to obtain a visual percentage of this index. The relation with the adsorption rate of persistent organic pollutant over the microplastic surface was also determined. [ABSTRACT FROM AUTHOR]

Fried food products are very popular due to their unique characteristics such as color, smell, taste and desirable texture. Controlling frying conditions and using edible hydrocolloid coatings (gums) is one of the best ways in reduction of oil uptake, moisture retention and improving the appearance properties of fried foods. In this study, different concentrations of wild sage seed gum (0, 0.5, 1 and 1.5%) were used to coating of zucchini slices during deep frying at 155, 170 and 185°C and the relationship between process parameters and the quality of final product were modeled by genetic algorithm-artificial neural network method. The results of this study showed that coating with wild sage seed gum reduced the oil uptake of the final product and in terms of appearance characteristics, the coated samples were lighter. Coating pretreatment maintained the final product moisture and the size of the samples coated with 1.5% gum was larger than the other samples (lower surface changes percent). This process was modeled by genetic algorithm-artificial neural network method with 2 inputs include wild sage seed gum concentration and frying temperature and 7 outputs include oil percentage, moisture content, yellowness index (b* ), redness index (a* ), lightness index (L* ), color changes intensity (ΔE) and surface changes. The results of modeling showed that a network with 5 neurons in a hidden layer and using the sigmoid activation function can predict the physicochemical properties of fried zucchini slices. Sensitivity analysis results showed that the changes in the concentration of wild sage seed gum had the highest effect on the yellowness index and then on the surface color changes intensity index of fried zucchini slices. Also, the change of frying temperature has the highest effects on the color changes intensity and lightness indexes of fried samples. [ABSTRACT FROM AUTHOR]

Abstract Spectral images were captured of paper samples varnished with two water-soluble materials: gum arabic and egg white. The samples were submitted to degradation processes that partially or totally eliminated the varnish from the substrate (water immersion and ageing). The spectral information was used to obtain average color data and to characterize the spatial and color inhomogeneity across pixels, showing that the pixel spectral data are critical for an accurate characterization of the degradation process of the varnishes. Since the varnishes typically become yellower with ageing, this study introduces two novel and simple-to-compute yellowness indices based on the spectral information, which are validated against a standard colorimetric index (ASTM-E313 2015). The potential uses of spectral information are demonstrated with several pieces of a real antique map sample by comparing the spectral information measured before and after cleaning the sample. To sum up, the main contributions of this study are the characterization of the spatial homogeneity through pixel-based spectral and color information and the proposal of spectral-based yellowing indices for two critical applications (ageing process follow-up and effect of cleaning), as demonstrated with synthetic and historical samples of varnished paper respectively.

Marine microplastics (MPs) are exposed to environmental factors, which produce aging, weathering, surface cracking, yellowing, fragmentation and degradation, thereby changing the structure and behavior of the plastic. This degradation also has an influence on the adsorption of persistent organic pollutants over the microplastic surface, leading to increased concentration with aging. The degradation state affects the microplastic color over time; this is called yellowing, which can be quantified using the Yellowness Index (YI). Weathering and surface cracking is also related with the microplastic yellowing, which can be identified by Fourier transform infrared spectroscopy (FTIR). In this study, the degradation state of marine microplastic polyethylene pellets with different aging stages is evaluated and quantified with YI determination and the analysis of FTIR spectrums. A color palette, which relates to the microplastic color and YI, was developed to obtain a visual percentage of this index. The relation with the adsorption rate of persistent organic pollutant over the microplastic surface was also determined.

Since the earliest discovery and subsequent developments in the world of polymers associated problems and increasing applications have resulted in the rapidly expanding field of "additives." In this context, the term additive is very generalized in that it encompasses many facets associated with ever growing needs. Of the most important are antioxidants (primary and secondary), light stabilizers, processing aids, metal deactivators, flame retardants, biocides, nucleating agents, antistatic compounds, fillers, dyes, pigments (nano, micro, and macro) to name but only a few each serving a particular function and not necessarily all at the same time in the one package. This article presents a general perspective on the type, mode of action, properties, uses, and problems (and circumvention) based on some of the more important key additives. The properties and behavior of many additives in this regard relates very much to the initial incorporation and formulation and in turn is often a major controlling factor in end use performance from a physical, esthetic, structural, mechanical, and chemical point of view. Indeed, with many polymers like PVC, for example, one enters a highly complex world of interactions which can in many cases destroy or even enhance the activity of functional processing additives. Some of these will be highlighted and hopefully the aim being here to enthuse the polymer and additive manufacturers and technologists in the processing laboratories to become more aware of potential issues and problems. [ABSTRACT FROM AUTHOR]

Accurate evaluation of the reliability of photovoltaic (PV) packaging materials is critically important for the long‐term safe operation of modules. However, the complexity of the laminated systems due to their multilayered and multicomponent structures and diverse aging mechanisms makes a thorough system evaluation very challenging, especially when the degradation is non‐uniform through the thickness. In such a case, neither surface nor bulk measurements can present a clear picture of the degradation profile. In this study, fluorescence imaging was developed to visualize the degradation depth‐profiles of an aged laminated PV system. A glass/ethylene vinyl acetate (EVA) encapsulant/poly(ethylene terephthalate) (PET)‐PET‐EVA (PPE) backsheet laminate was weathered with the glass‐side facing an ultraviolet (UV) light source for 3840 h. Cross‐sectional fluorescence images revealed a non‐uniform distribution of degradation species across the thickness of the EVA encapsulant, providing greater insight into the mechanisms of degradation, which are unavailable by traditional bulk‐based methods. In addition, strong fluorescence emissions were observed from the two thin adhesive layers of the aged backsheet, indicating severe degradation of the adhesives and a potential for interlayer delamination. This method is further confirmed with other microscale characterization techniques. The changes in optical (yellowness index), chemical (oxidation, UV absorber concentration), mechanical (Derjaguin‐Muller‐Toporov modulus), and thermal (melting enthalpy) properties of the EVA encapsulant were found to be related to fluorescence profiles, following the attenuation of UV light. This study highlights that fluorescence imaging is a spatially‐resolved and sensitive method for rapid failure assessment and in‐depth mechanism study for complex PV‐laminated system. [ABSTRACT FROM AUTHOR]

Polyurethanes represent one of the most frequently used polymeric matrixes in composites. Although there have been many studies focused on the weather resistance of polyurethanes, this important property is unheeded during the reinforcing phase. In this article, the effects of ultraviolet (UV) radiation on the changes in optical properties of commercially available glass fibre reinforcements containing various polymeric binders used as compatibilising agents for the polymeric matrix in the final composite products were studied. The standardised experiments were performed using accelerated ageing equipment, q‐lab ultraviolet tester, in dry mode. Chemical modification of the binder in the form of polyesters or silanes by UV irradiation was studied using Fourier Transform–infrared spectroscopy. Changes in the optical properties caused by the degradation processes of polymeric components due to UV irradiation were evaluated based on colour changes in the examined samples using the yellowness index; statistical evaluation of the data obtained was conducted with an Anderson–Darling test of normality and an ANOVA test. It was demonstrated that both the amount of the binder and the glass fibre reinforcement's construction play a more important role than the chemical structure of the binder. [ABSTRACT FROM AUTHOR]

Enzymatic pretreatment of seeds is a novel approach that enhances the health benefits of the extracted oil. The study investigated the influence of the enzymatic pretreatment of seeds on the quality of oil from different pomegranate cultivars. The quality of the ultrasound-assisted (and ethanol-extracted) oil was studied, with respect to the refractive index (RI), yellowness index (YI), conjugated dienes (K232), peroxide value (PV) ρ-anisidine value (AV), total oxidation value (TOTOX), total carotenoid content (TCC), total phenolic compounds (TPC), fatty acid composition, phytosterol composition, ferric reducing antioxidant power (FRAP), and 2.2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging capacity. The seeds of three different pomegranate cultivars (‘Wonderful’, ‘Herskawitz’, and ‘Acco’) were digested with an equal mixture of Pectinex Ultra SPL, Flavourzyme 100 L, and cellulase crude enzymes, at a concentration, pH, temperature, and time of 1.7%, 4.5, 40 °C, and 5 h, respectively. Enzymatic pretreatment of PS increased oil yield, PV, TPC, TCC, and DPPH radical scavenging capacity, but decreased the YI. The levels of K232, AV and TOTOX, fatty acids, phytosterols, RI, and FRAP, were not significantly affected by enzymatic pretreatment of PS. Principal component analysis (PCA) established that oil extracted from the ‘Acco’ seed after enzymatic pretreatment had higher yield, TPC, TCC, and DPPH radical scavenging capacity. Therefore, enzyme-pretreated ‘Acco’ pomegranate fruit seed is a source of quality seed oil with excellent antioxidant properties.

Highlights • Color changes in aged PV modules are measured with low cost fiber optic spectrometers. • Yellowness Index can be used to quantify the drift from withe into yellow. • Yellowness Index and power loss in an UV degraded PV module are correlated. Abstract The main objective of this paper is to investigate the possibility of evaluating the color changes in real photovoltaic modules from reflectance measurements. To accomplish this main objective, the work has been organized into three main axis: (1). Exploring the possibility of using simplified instrumentation and techniques for the measurement of color parameters in solar cells. (2). Identifying a simple parameter as an indicator of solar module color appearance and (3). Exploring the possibility of correlating that parameter with solar module degradation. It is explored the use of reflectance and related magnitude Yellowness Index (YI) as an indicator of photovoltaic (PV) solar module surface color change and degradation. While spectrometric quantities as transmittance have been used as a measurement of separated encapsulant and backsheet characteristics, in the present paper reflectance of the surface of real PV solar mono and polycrystalline modules are analyzed. With the objective of verifying the applicability of such measurements in real PV installations, the correctness of using simplified measurement geometries and portable spectrometers is tested. It is found that 45°/45° and hemispheric reflectance supply similar results. Consequently portable fiber optic spectrometers and simple fiber optic probes with their holders can be used. We found that 45°/45° and hemispheric reflectance with their associated Yellowness Index can be used indistinctly in the cases analyzed as a good indicator of superficial color changes. We have also concluded that Yellowness Index is a good indicator of changes in appearance in PV modules. It is observed an increase of Yellowness Index with ultraviolet dose supplied to a solar module and a reduction in its maximum power. [ABSTRACT FROM AUTHOR]

Polyimide (PI) composite films with thicknesses of approximately 100 µm were prepared via a sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMS) with poly(amic acid) (PAA) composite solutions using a thermal imidization process. PAA was synthesized by a conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid (DABA), which has a carboxylic acid side group, and 2,2′-bis(trifluoromethyl)benzidine (TFMB), with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) in N,N-dimethylacetamide (DMAc). The PAA–silica composite solutions were prepared by mixing PAA with carboxylic acid side groups and various amounts of APTMS in a sol–gel process in DMAc using hydrochloric acid as a catalyst. The obtained PI–silica composite films showed relatively good thermal stability, and the thermal stability increased with increasing APTMS content. The optical properties and in-plane coefficient of thermal expansion (CTE) values of the PI–silica composite films were investigated. The CTE of the PI–silica composite films changed from 52.0 to 42.1 ppm/°C as the initial content of APTMS varied. The haze values and yellowness indices of the composite films increased as a function of the APTMS content.

The current study aims to investigate the influence of UV aging on the properties of green polyurethane (MBPU) and polyurethane/nanosilica composite (MBPU/NS) coatings synthesized from transesterified castor oil and palm oil isocyanate for an exposure period of 1250 h. Changes in the mechanical properties, structural features, morphological and coating properties have been monitored at every 250 h by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and colorimetry etc. MBPU/NS with 2.5 wt% of NS has been considered to be the optimum composition for a comparative UV aging analysis against neat MBPU. FTIR and XPS analysis revealed changes in chemical structure of MBPU and MBPU/NS-2.5 composite with reduction in -NHCO, C-C, C=O group concentrations. SEM and AFM micrographs indicated increase in roughness parameter with appearance of blisters and cracks on the exposed surface. Mechanical test results showed that UV aging decreases the tensile strength and elongation at break due to chain scission. The yellowness index (ΔYI) follows a systematic increasing trend with increment in irradiation time which indicates photodegradation of polyurethane. However, MBPU/NS-2.5 exhibited lower photo-oxidative degradation which can be due to its high UV absorption ability. Graphical Abstract: [ABSTRACT FROM AUTHOR]

An attempt has been made to compare the effect of electrochemical bleaching with conventional bleaching of cotton. Electric current is used in the preparation of a bleaching agent to replace bleaching powder. The NaOCl generated from electrolytic cell (2.5-3.5V potential difference) is sufficient to produce powerful bleaching agent with available chlorine varying from 1.2 g/L to 1.3g/L. Time required for bleaching reduces to 10-20 min, as compared to 90 min in conventional bleaching. Whiteness index, brightness index and yellowness index have been measured by a spectrophotometer. There is a remarkable increase in whiteness index and brightness index and decrease in yellowness index in the electrochemically bleached samples as compared to that in conventionally bleached cotton. Dye uptake values show an increasing trend with electrochemical bleaching. The present study aims for achieving the desired efficiency to remove conventional drawbacks of sodium hypochlorite bleaching. [ABSTRACT FROM AUTHOR]

In this study, the effect or absence thereof of discoloured ethylene vinyl acetate (EVA) on the electrical characteristics of photovoltaic (PV) modules was investigated. The field samples for discoloured EVA were PV modules that had been in operation for 25 years since 1986 in a modulated climate in South Korea. The I-V characteristics of 25-year-old, discoloured single crystalline silicon (sc-Si) PV modules were measured, and the results showed that the maximum power (Pmp) had degraded by approximately 25.5 %. The sc-Si single-cell PV module had a discoloured EVA, which was separated from it to determine the correlation between the discoloration of EVA and power degradation. The yellowness index (YI) of the EVA was in the range of 36–44. The relationship between the YI and transmission of 25-year-old discoloured EVA was also determined through measurements. The short-circuit current (Isc) and Pmp of the PV modules were measured, which were found to be degraded by 22.2 % and 21.3 %, respectively, owing to the discoloured EVA. The output characteristics of the solar cell in the discoloured region of the EVA were analysed. The results showed that the Isc degradation rate varied linearly with the EVA discoloration area. The discoloration of the EVA was the main effect (83.5 %) among the failure modes of the 25-year-old sc-Si PV module. It accounted for 0.85 % of the 1.02 % annual degradation of the PV module. Isc and Pmp exhibited linear degradation corresponding to areas of 25 %, 50 %, 75 %, and 100 % discoloration in single-cell PV modules. • Analysis of 25-year-old single crystalline silicon modules to determine degradation rate • Separate of discoloured EVA from the 25-year-old sc-Si PV module • Degradation of Short-circuit current parameter by discoloured EVA exhibit quantitatively [ABSTRACT FROM AUTHOR]

• Presents an expert perspective on the phenomenon of yellowing in the manufacture and processing degradation of polymer materials. • Structural and stability relationships are described for thermal stabilisers confirming the role of quinone-imine and methide formation. • Origin of yellowing processes described for a range of aromatic and aromatic amine polymers. • Conventional and unconventional methods of inhibition of the yellowing processes are provided. In the formulation or processing and post-use of polymer materials, one of the most important facets giving significant concern to the polymer industry is that of discolouration or more specifically the "Yellowing" phenomenon. Although the literature is abundant covering various aspects of this problem it can be what one may describe as a serious "bug" in the progress of many polymer applications and indeed can limit their acceptance in many products. These may be in clear films and bottles, white goods or recycling and post-use where heat and light can discolour polymer materials. The science underpinning the yellowing can be due to the additives, more importantly, the phenolic/amine antioxidants and/or inherent in the polymers themselves especially polyaromatics such as polyesters or polycarbonates, epoxy-amines, and polystyrene to name but a few. In many industrial applications solving or overcoming this issue is not always easy and can be problematic. The chemistry of these processes will be discussed and highlighted and effective modes of stabilisation and/or inhibition presented with often unconventional detailed examples and their structural developments for optimisation of additive performance. Thus, examples of chemical treatment processes to minimise polymer yellowing will also be presented where polyglycols and various chemical reducing agents provide some useful ideas. Hopefully, a clearer understanding of the types of chemistries involved in yellowing and their minimisation will provide a useful way forward for the polymer and additive manufacturers and technologists in unravelling and solving their potential issues and problems at many of the stages of polymer manufacture and processing. [ABSTRACT FROM AUTHOR]

By applying the method known as Atmospheric Freeze-Drying (AFD) which uses low temperature and calcium chloride or silica gel as hygroscopic agents, two varieties of potatoe (Gabriela and Chaucha) were dehydrated. Three different pre-treatments were performed on the potatoes for the analyses. From the obtained data, following values were estimated: (i) the coefficients of surface mass transfer (from 61.77 to 148.55 kg·m-2·s-1), (ii) the heat transfer (from 5.75 to11.22 W·m-2·°C-1), (iii) the un-dimensionless number (from 1.03 to3.98), (iv) the drying time (from 200.00 to 303.26 h) and (v) the rehydration index (1.7 - 2.7). Furthermore, the mass transfer mechanism that controls the AFD was assessed. This process was assessed, and changes in the colour of the products at three different stages of the process using the Yellowness Index, and the microbiological properties of the atmospheric freeze-dried potatoes, were analysed. It was concluded that, the drying of potato slices by AFD can eliminate microbial growth and chemical reactions, and the pre-treatments step is necessary to prevent browning.

Four monomeric reactive hindered piperidinol derivatives, such as 4-methacryloyl-1,2,2,6,6-pentamethyl-piperidinyl (MPMP), 4-acryloyl-1,2,2,6,6-pentamethyl-piperidinyl (APMP), 4-methacryloyl-2,2,6,6-tetramethyl-piperidinyl (MTMP), and 4-acryloyl-2,2,6,6-tetramethyl-piperidinyl (ATMP), were applied as reactive hindered amine light stabilizers (r-HALS) in UV-curable coatings. The effect of r-HALS on the UV-curing kinetics of the UV-curable coatings of different monomers or oligomers has been previously investigated. Polymer coatings were prepared by means of UV-curing technology; experiments were conducted manually on photoaging indoors, monitoring the Yellowness Index (YI) in the photooxidation process, and adding r-HALS. The experiments were done to review its photoprotection effect on UV-cured coatings. Subsequently, they were compared with typical commercial HALS through parallel experiments to investigate the photooxidation aging mechanism of polymer coatings, and the effective concentration was determined from the changing circumstances of YI, thus comparing their differences in photostabilizing effect in situ of the polymer coatings. [ABSTRACT FROM AUTHOR]

Natural ageing of plastics is caused by all weathering factors in the course of time, the most significant ones being UV-radiation, temperature and humidity. Polystyrene is a widely used thermoplastics material that ages rapidly when exposed to ultraviolet radiation, particularly in direct, outdoor exposure. The main criteria for estimating ageing of high-impact polystyrene are changes in colour and mechanical properties. Polystyrene ageing is different under indoor and outdoor exposure conditions. By the addition of antioxidants and light stabilizers, polystyrene stability is increased, i.e. thermal and photooxidative degradation are slowed down or stopped. In this paper, natural ageing of unstabilised and stabilised PS-HI 485 and flame retardant polystyrene PSVM 40902 AF-N, to which two different masterbatches of light stabilizers were added, is investigated. Unstabilised PS-HI 485 yellowed significantly under indoor and outdoor conditions. UV-stabilized PS-HI 485 did not yellow under indoor conditions in the period of 13 months, but it yellowed slightly and changed its mechanical properties under outdoor conditions in the same period of exposure. Flame retardant polystyrene PSVM 40902 AF-N is prepared by adding 26.6% halogen additive free of decabromo-diphenyl-ether in polystyrene based masterbatch. Non-stabilized PSVM 40902 AF-N yellowed under indoor and outdoor test conditions. Under indoor conditions, UV-stabilized PSVM 40902 AF-N yellowed very lightly but under outdoor conditions in direct exposure to weathering factors, it yellowed significantly and changed its mechanical properties. [ABSTRACT FROM AUTHOR]

Thermo-mechanical, optical and physical properties of polypropylene (PP)/lignocellulosic fibre-filled/maleated PP composites were studied as a function of extrusion screw speeds. All materials were extruded at four screw speeds and injection moulded as dogbone specimens. The density, yellowness index (YI) and Fourier-transform infrared spectra were determined for the processed specimens. Tensile properties and coefficient of linear thermal expansion (CLTE) were also determined. The densities of the composites remained constant within the same composition. YI and absorbances of carbonyl, vinylidene and hydroxyl groups, which are indicators of thermo-oxidation, decreased with a shorter extruder residence time. The CLTE and tensile properties showed peak properties at intermediate screw speeds. The analysis suggested optimising the residence time assisting in achieving a balance of properties. [ABSTRACT FROM AUTHOR]

Low photo- and water-resistance is often cited as the problem of MDI-based WBPU. This study addressed this problem. Water-borne poly(urethane-urea)s (WBPUs) were synthesized using a pre-polymer mixing process from 4,4'-methylenebis(phenyl isocyanate)(MDI)/4,4-dicyclohexylmethyl diisocyanate (H12MDI) (15/85 mole %)/dimethylol propionic acid (DMPA)/ethylene diamine (EDA)/triethylamine (TEA) with different poly(propylene glycol) (PPG, Mn = 2000)/hydroxyl terminated poly(dimethylsiloxane) (PDMS, Mn = ∼550) molar ratios. This study highlights the effect of PDMS content on the inherent viscosity, hydrogen-bonding, storage modulus, tan δ peak intensity, tensile modulus/strength, elongation (%) at break, water swelling (%), contact angle, and the yellowness index of WBPUs containing MDI. The mechanical properties (strength/modulus), water-resistance and photo-resistance of WBPUs containing MDI increased significantly in proportion to the PDMS content. These results indicate the potential for using multi-performance WBPU with PDPS for WBPU coatings. [ABSTRACT FROM AUTHOR]

The effect of ozone treatment on the properties of raw and degummed mulberry and tassar silk fabrics has recently been studied, and the investigation of results has been published. The variables, namely, wet pickup, pH and treatment time used in the treatment have shown a significant effect on properties such as the yellowness index, breaking strength, breaking elongation, amino group content, weight and flexural rigidity of the silk fabrics. In addition to this study, a comparative analysis has been made to find the difference in properties of ozone-treated raw and degummed mulberry and tassar silk fabrics, for conditions that showed a significant effect on the properties, and these are presented in this paper. The results show that ozone treatment has a pronounced effect on the properties of mulberry raw and tassar raw silk fabrics compared with mulberry degummed and tassar degummed silk fabrics. [ABSTRACT FROM AUTHOR]

B. moil silk plain habutai fabric is studied as the research object. Using different forms of ultraviolet irradiation, we can study the properties of silk aging process diversification. We draw the conclusion : it applies the concept of yellowness index to characterize the surface of B. mori silk fabric yellowing situation. With the irradiation time increasing, yellowness index shows a slow growth trend. What's more, artificial sweat soaking irradiation treatment on the yellowing index is greater than direct irradiation. The mechanical properties of the fabric decline in vary degrees. Infrared absorption peaks of silk don't significantly change, but according to the crystallinity derived formula proposed by Magoshi and Bhat, we can find the crystallinity of silk is increasing. [ABSTRACT FROM AUTHOR]

The color stabilization of antimicrobial blends was studied by using poly(hexamethylene guanidine) phosphate (PHMG) as a highly efficient biocidal and nontoxic agent. The Taguchi method was used to determine the optimum conditions for the blending of PHMG in polypropylene (PP) matrix. To improve the yellowing phenomena, two kinds of stabilizer were used together: tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)](IN1010) from phenol and tris(2,4-di-t-butylphenylphosphite) (IF168) from phosphorus. According to blend composition and mixing condition, six factors were chosen, with five levels being set for each factor. The orthogonal array was selected as the most suitable for fabricating the experimental design, L25, with 6 columns and 25 variations. The-smaller-the-better was used as an optimization criterion. The optimum conditions for these parameters were 10 phr for PHMG, 2 phr for IN1010, 1 phr for IF168, 10 min for mixing time, 210 °C for mixing temperature, and 30 rpm for rotation speed. Under these conditions, the yellowness index of the blend was 1.52. The processibility of the blends was investigated by Advanced Rheometric Expansion System (ARES). The blend with 0.5 w% PHMG content, diluted with PP, exhibited an antimicrobial characteristic in the shake flask method. [ABSTRACT FROM AUTHOR]

A most common problem encountered in radiosterilization of solid drugs is discoloration or yellowing. By pharmacopoeia method, discoloration can be assessed by measuring absorbance of solutions of irradiated solid samples at 450 nm. We propose to evaluate discoloration of solid samples directly by recording their diffuse reflectance spectra. Further, the reflectance spectrum is used to compute various color parameters: CIE XYZ tristimulus value, CIE Lab, $$\Delta E_{{\text{ab}}}^ * $$ (color difference), yellowness index (YI), dominant wavelength, and excitation purity by CIE method. The investigation of difference reflectance spectra and color parameters revealed that for fluoroquinolones, e-beam was more damaging than gamma radiation, whereas for cephalosporins, trend was reversed. The quantum of discoloration with gamma radiation and e-beam is found to be nearly equal when assessed by pharmacopeia method, and it is therefore inadequate to assess small color differences. The color parameters $$\Delta E_{{\text{ab}}}^ * $$ and ΔYI are found to be reliable indicators of discoloration. The tolerance limits proposed in terms of $$/Delta E_{{\text{ab}}}^ * $$ and ΔYI are ±2 and ±10 U, respectively. The dominant wavelength for all compounds has shifted to higher values indicating change in hue but defining color tolerance limit with this parameter requires adjunct excitation purity value. [ABSTRACT FROM AUTHOR]

Cyclic olefin copolymers, mCOC, produced using a metallocene catalyst, have been developed since 1990. Besides their high cost and difficulty of processing, oxidation and degradation are one of the critical problems in commercializing high-Tg mCOC products. In this work, a series of mCOCs whose Tg values were 132 °C, 194 °C and 260 °C were synthesized successfully. Additionally, high-performance phosphorine antioxidants, 1,4-di[6-oxo-dibenz[c,e][1,2] oxaphosphorine] benzene (HPB) and 2,5-di-tert-butyl-1,4-di[6-oxo-dibenz[c,e][1,2] oxaphosphorine]benzene(HTPB) were synthesized. The oxidation induction time (OIT), the carbonyl index (CI) and the yellowness index (YI) were determined by DSC, FTIR and spectrophotometry, respectively. The results indicate that blending phosphorine antioxidants with hindered phenolic antioxidant, increases the OIT from 31.8 to 44.1 mins and causes the synergy to exceed 180 %. The CI variation showed that the embrittlement time could be increased from 100 hrs to over 450 hrs by thermal aging at 140 °C. Finally, the YI dropped from 29.3 to 9.2. Briefly, HTPB and HPB, successfully synthesized herein, exhibit a synergy with hindered phenolic agents in antioxidant performance for mCOC polymer. [ABSTRACT FROM AUTHOR]

Using a new advanced solution technology, NOVA Chemicals Corporation has developed an improved family of polyethylene resins, some of which are ideally suited for specific applications, for example, medium density for hygiene films and linear low density for stretch films. This new technology has been used to produce polyethylene resins with tailored molecular structure and processability. This new technology is based on an improved solution polymerization process using a new Ziegler­Natta catalyst. The rheological properties, particularly draw resonance, together with the physical and mechanical properties of cast films made from these new resins are presented in this paper. In addition, there is a discussion on the results of an investigation on the effects that different types and levels of stabilizers have on resin processing behavior and film stability. [ABSTRACT FROM AUTHOR]

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In this study we have evaluated both synthetic amorphous silica and naturally occurring crystalline silica as antiblocking agents in presence of a slip additive to assess their effectiveness on the performance of an octene based linear low density polyethylene (LLDPE) copolymer. A series of formulations were prepared with three different antiblocking agents along with a slip additive. The slip agent “erucamide” was added to the formulations at five different concentrations, resulting in a total of 35 formulations. The film properties including%haze, yellowness index, coefficient of friction, and blocking force were measured. An experimental design approach was employed to determine the effect of slip and antiblock additives on the blocking force using selected formulations. The main contributing factor in reducing blocking was attributed to the antiblocking agents, with SuperflossTM (a high crystalline silica) being most effective. However, it resulted in lower clarity films. The synthetic silica type antiblocking agents maintained a balance between clarity and blocking force, thus showing promise in high clarity film applications. [ABSTRACT FROM PUBLISHER]

Enzymatic pretreatment of seeds is a novel approach that enhances the health benefits of the extracted oil. The study investigated the influence of the enzymatic pretreatment of seeds on the quality of oil from different pomegranate cultivars. The quality of the ultrasound-assisted (and ethanol-extracted) oil was studied, with respect to the refractive index (RI), yellowness index (YI), conjugated dienes (K232), peroxide value (PV) ρ-anisidine value (AV), total oxidation value (TOTOX), total carotenoid content (TCC), total phenolic compounds (TPC), fatty acid composition, phytosterol composition, ferric reducing antioxidant power (FRAP), and 2.2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging capacity. The seeds of three different pomegranate cultivars ('Wonderful', 'Herskawitz', and 'Acco') were digested with an equal mixture of Pectinex Ultra SPL, Flavourzyme 100 L, and cellulase crude enzymes, at a concentration, pH, temperature, and time of 1.7%, 4.5, 40 °C, and 5 h, respectively. Enzymatic pretreatment of PS increased oil yield, PV, TPC, TCC, and DPPH radical scavenging capacity, but decreased the YI. The levels of K232, AV and TOTOX, fatty acids, phytosterols, RI, and FRAP, were not significantly affected by enzymatic pretreatment of PS. Principal component analysis (PCA) established that oil extracted from the 'Acco' seed after enzymatic pretreatment had higher yield, TPC, TCC, and DPPH radical scavenging capacity. Therefore, enzyme-pretreated 'Acco' pomegranate fruit seed is a source of quality seed oil with excellent antioxidant properties. [ABSTRACT FROM AUTHOR]

The variations in the viscosity and gloss (yellowness and whiteness index) in isotactic polypropylene, heterophasic E-P copolymers and polyethylene were measured during photo-oxidation. The samples underwent extensive reduction in intrinsic viscosity [[UNKNOWN]] upon U.V. irradiation. The kinetics of oxidative degradation have also been studied using polychromatic light at 60°C in air. These parameters appear to be a sensitive criteria to characterize the photo-oxidative transformation of polymers. The course of degradation is random and the yellowing process brought by the short wavelength U.V. light is accompanied by a photobleaching reaction which is caused by the light of longer wavelengths. [ABSTRACT FROM PUBLISHER]

The effect of previous alkali (sodium carbonate) treatments at different concentrations on the properties of wool bleached with solutions of hydrogen peroxide at different concentrations was evaluated. Optical, chemical and mechanical properties of bleached and unbleached unscoured wool and of pretreated and bleached wool were determined. Treatment with the sodium carbonate solutions leads to a decrease of both degree of whiteness and the Yellowness Index of the original wool; bleaching of pretreated wool yields a lower degree of whiteness than bleaching of wool pretreated with sodium carbonate. On the other hand, the Yellowness Index of bleached wools is not altered by the alkali pretreatment. The alkali solubility of pretreated, bleached wool is lower than that of untreated wool bleached at the same peroxide concentration. At a given concentration of hydrogen peroxide, the content of cysteic acid of pretreated, bleached wool is independent of the severity of the previous alkali treatment and lower than that of I wool not treated with alkali. The wet tensile strength is much more sensitive to the alkali and hydrogen peroxide treatments than the dry strength. [ABSTRACT FROM AUTHOR]

The impregnation of wool with thioglycollic acid (TGA) and its subsequent exposure to a source of blue light results in considerable and rapid photochemical bleaching. TGA will reduce wool, which causes deterioration, but a zinc complex of TGA has been found to cause accelerated photochemical bleaching without serious damage to the fibre. These properties may be of use in industry as a rapid bleaching method, or in domestic laundering to retard the yellowing of wool goods drying in sunlight. [ABSTRACT FROM AUTHOR]

An account is given of the use of tristimulus colorimetry to specify the colours of Australian wools. Greasy wools, scoured wools, scouring liquor, and fabrics were measured, and the results are expressed by means of polar co-ordinates. The radial measure in the Hunter (α, β) colour space, that is, saturation, indicates the degree of discoloration. It is shown that, with the widely used yellowness-index formula, 100 (X-Z)/Y, the results obtained have a linear relationship with saturation. This index may therefore be used as a single-co-ordinate measure of the yellowness of Australian wools and of fabrics that have been bleached or yellowed. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented about a research paper entitled "A Pressed-disk Technique for Preparing Wool Samples for Yellowness Measurement," by D. B. Green, A. S. Little and W. Parkin.

Polyimide (PI) composite films with thicknesses of approximately 100 µm were prepared via a sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMS) with poly(amic acid) (PAA) composite solutions using a thermal imidization process. PAA was synthesized by a conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid (DABA), which has a carboxylic acid side group, and 2,2′-bis(trifluoromethyl)benzidine (TFMB), with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) in N,N-dimethylacetamide (DMAc). The PAA–silica composite solutions were prepared by mixing PAA with carboxylic acid side groups and various amounts of APTMS in a sol–gel process in DMAc using hydrochloric acid as a catalyst. The obtained PI–silica composite films showed relatively good thermal stability, and the thermal stability increased with increasing APTMS content. The optical properties and in-plane coefficient of thermal expansion (CTE) values of the PI–silica composite films were investigated. The CTE of the PI–silica composite films changed from 52.0 to 42.1 ppm/°C as the initial content of APTMS varied. The haze values and yellowness indices of the composite films increased as a function of the APTMS content. [ABSTRACT FROM AUTHOR]

Corona treatment in air and air/chlorine atmospheres, does alter the wool fiber so it appears visually significantly more yellow than the untreated wool. The yellowness of wool after corona treatment, particularly that done in the presence of chlorine, may be reduced to the yellowness associated with non-corona treated, unbleached wool by scouring or solvent treatment. The amount of material extractable from wool is not greatly increased by corona treatment, suggesting that corona treatment is restricted to the surface layer of keratin fibers. [ABSTRACT FROM PUBLISHER]