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This research aimed to show the possible impact of natural antioxidants on epoxidized natural rubber (ENR) and poly(lactic acid) (PLA) green composites. Thus, the ENR/PLA blends were prepared with the addition of three selected phytochemicals (catechin hydrate, eugenol and flavone). Obtained materials were submitted for solar aging. The analysis of the samples' features revealed that catechin hydrate is a natural substance that may delay the degradation of ENR/PLA blends under the abovementioned conditions. The blend loaded with catechin hydrate presented stable color parameters (dE < 3 a.u.), the highest aging coefficient (K = 0.38 a.u.) and the lowest carbonyl index based on FT-IR data (CI = 1.56) from among all specimens. What is more, this specimen prolonged the oxidation induction time in comparison with the reference samples. Gathered data prove the efficiency of catechin hydrate as an anti-aging additive. Additionally, it was found that a specimen loaded with flavone changed its color parameters significantly after solar aging (dE = 14.83 a.u.) so that it would be used as an aging indicator. Eventually, presented eco-friendly ENR-based compositions may be applied in polymer technology where materials presenting specific properties are desirable. [ABSTRACT FROM AUTHOR]

Polymers are indispensable component of modern sensor devices. Gauges play an important role in medicine, control of chemical reactions and identification of gases or may even be used as electric noses or tongues. These and many other types of sensors are described in the given article and some real-time applications examples are given among varied types of polymer-based sensors. However, studies on polymer sensors are still ongoing. New solutions are being sought and the mechanisms of the specific reactions occurring in polymer sensors are not fully understood. Their in-depth analysis still requires tremendous work. The attention of this article is drawn to the trends and challenges present in this field of study. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of dodecyl gallate (lauryl gallate), the main monomer flavanol found in green tea, was investigated on platinum electrodes using cyclic voltammetry (CV) and differential pulse (DPV) methods. The rate constant, electron transfer coefficient and diffusion coefficients were determined for dodecyl gallate electrochemical oxidation. The oxidation mechanism proceeds in sequential steps related to the hydroxyl groups in the aromatic ring of dodecyl gallate. The confirmed antioxidant activity of lauryl gallate justified its use in polymers, for instance, in an environment-friendly stabiliser aimed at improving the resistance to aging of elastomeric materials. Based on energy change during deformation, cross-linking density and oxygen induction time in the TG method, we confirmed the high antioxidant activity of lauryl gallate in polymers. Moreover, the research on biodegradation confirmed the environmentally friendly interest of the antioxidant by the fact that it increases the susceptibility of the elastomeric materials to disintegration by mildew mushrooms. [ABSTRACT FROM AUTHOR]

The 21st century is witnessing a return to green polymers made from renewable raw materials due to crude oil shortage and to ecological reasons. The main polymers meeting such conditions include aliphatic polyesters or biopolymers, the interest in which has been increasing over the last decade. The aim of our study was to obtain pro-ecological composites with increased resistance to aging using a biopolymer, epoxidized natural rubber (ENR) and polyester polycaprolactone (PCL). To improve the resistance of these composites to aging, we used natural anti-aging substances, mainly flavonoids and amino acids. After simulating climatic, UV, and thermo-oxidative conditions, we assessed the effect of the antioxidants used on the degradation capability of ENR/PCL composites. Based on the tensile strength test, cross-link density and calorimetric measurements, we observed a considerable increase in the aging resistance of ENR/PCL composites. At the same time, the ENR/PCL composites showed a high susceptibility to biodegradation by microorganisms, which allowed us to obtain polymeric products with controlled degradation capabilities. [ABSTRACT FROM AUTHOR]

Polymers made of renewable raw materials are attracting increasing interest because of diminishing oil deposits and the pro-ecological character of such polymers. The aim of our study was to create composites of polycaprolactone (PLC) and epoxidised natural rubber (ENR) using innovative natural additives. The cross-linking of composites was performed with the use of amino acids, flavonoids and fatty acids to eliminate sulphur and peroxides that are not environmentally friendly. Some of the cross-linkers used fulfilled the role of antioxidants. Based on WAXD, SEM and DSC examinations, we found good miscibility and compatibility of the polymers. All the innovative compounds used appeared to be good cross-linkers. The best ENR/PCL composite cross-linking effect was obtained with the use of quercetin, a flavonoid that also appeared to be a good anti-ageing substance. The mechanical properties of the composites were satisfactory. Their tensile strength ranged from 10 to 22MPa at elongation in the range of 292-436%. The ENR/PCL composites were more thermally stable than ENR vulcanisates due to their improved resistance to oxidation. Undoubtedly, these composites exhibit the features of innovative pro-ecological products. They meet current ecological requirements and can be widely used in medicine as well as in materials for common use, such as food packaging. [ABSTRACT FROM AUTHOR]

Abstract: In our studies, we propose the use of natural, pro-ecological substances, such as flavonoids to protect elastomers against ageing. One of these substances, namely morin hydrate, was incorporated into ethylene–octene rubbers (Engage); then the vulcanisates of Engage containing the antioxidant under investigation were subjected to ageing processes. The changes in deformation energy, colour and cross-linking density and OIT index of the vulcanisates of Engage were measured before and after each ageing process. The test results obtained show that morin hydrate has a very positive influence on the stability of the vulcanisates of Engage, protecting them against the negative effects of ageing. In addition to its anti-oxidative function, morin hydrate changes the colour of the final polymeric product, fulfilling the role of a natural pigment. Thus, morin hydrate is not only a natural antioxidant but also a pigment in the polymers, imparting to them the features of pro-ecological materials. [Copyright &y& Elsevier]

Abstract: A permanent increase of demand for polymers is closely connected with the issue of degradation. Nowadays aromatic amines or phenol derivatives are used to protect materials against ageing. In our studies, we want to propose the use of natural pro-ecological substances such as flavonoides to protect elastomers against ageing. Several flavonoides (hesperidin, hydroxymorin, hydroxyrutin, xanthone, flavon) were incorporated into ethylene-propylene rubbers (EPM, Dutral CO-054) and then the vulcanizates of EPM containing the anti-oxidants under investigation were subjected to UV, climatic and thermal ageing processes. The changes in deformation energy, color and cross-linking density of the EPM vulcanizates were then measured before and after each ageing process. Their carbonyl index was also determined. Based on the test results obtained, it has been found that the best protection is shown by hesperidin. [Copyright &y& Elsevier]

This study aimed to present the influence of bio-based and anthraquinone dyes and their combinations on the optical properties of ethylene-propylene (EPM) composites after thermo-oxidative and climatic aging. Therefore, the chosen polymer was filled with a natural, plant-origin flavonoid—quercetin, and with two commercial anthraquinone dyes (C.I. Solvent Yellow 163 and C.I. Solvent Red 207). The manufactured polymer composites were subjected to accelerated aging tests: weathering and thermo-oxidation, respectively. Examination of the materials' properties indicated that the combination of synthetic and natural dyes can result in better resistance to oxidizing agents and higher thermal stability of ethylene-propylene products. Moreover, color change of quercetin-containing samples due to exposure to simulated atmospheric conditions could be a promising solution for use as aging indicators in intelligent packaging materials that will inform about the ongoing degradation process. Another interesting finding is that these samples exhibited good fungistatic activity against Candida albicans yeast and Aspergillus niger mold. Overall, this novel solution based on hybrid polymer composites containing natural and commercial dyes is a more environmentally friendly alternative to traditional materials used in the plastic packaging industry with better and more desirable properties. [ABSTRACT FROM AUTHOR]

The following article debates on the properties of cellulose-filled ethylene-norbornene copolymer (EN) composites. Natural fibers employed in this study have been modified via two different approaches: solvent-involving (S) and newly developed non-solvent (NS). The second type of the treatment is fully eco-friendly and was carried out in the planetary mill without incorporation of any additional, waste-generating substances. Composite samples have been investigated with the use of spectroscopic methods (FT-IR), differential scanning calorimetry (DSC), static mechanical analysis, and surface-free energy measurements. It has been proved that the possible filler-polymer matrix interaction changes may occur due to the performed modifications. The highest reinforcement was evidenced for the composite sample filled with cellulose treated via a NS approach—TS = (34 ± 2) MPa, Eb = (380 ± 20)%. Additionally, a surface free energy polar part exhibited a significant increase for the same type of modification. Consequently, this could indicate easier wetting of the material which may contribute to the degradation process enhancement. Successfully developed cellulose-filled ethylene-norbornene copolymer composite compromises the rules of green chemistry and sustainable development by taking an advantage of renewable natural resources. This bio-inspired material may become an eco-friendly alternative for commonly used polymer blends. [ABSTRACT FROM AUTHOR]

When considering cellulose (UFC100) modification, most of the processes employ various solvents in the role of the reaction environment. The following article addresses a solvent-free method, thermal drying, which causes a moisture content decrease in cellulose fibers. Herein, the moisture content in UFC100 was analyzed with spectroscopic methods, thermogravimetric analysis, and differential scanning calorimetry. During water desorption, a moisture content drop from approximately 6% to 1% was evidenced. Moreover, drying may bring about a specific variation in cellulose's chemical structure. These changes affected the cellulose-filled polymer composite's properties, e.g., an increase in tensile strength from 17 MPa for the not-dried UFC100 to approximately 30 MPa (dried cellulose; 24 h, 100 °C) was observed. Furthermore, the obtained tensile test results were in good correspondence with Payne effect values, which changed from 0.82 MPa (not-dried UFC100) to 1.21 MPa (dried fibers). This raise proves the reinforcing nature of dried UFC100, as the Payne effect is dependent on the filler structure's development within a polymer matrix. This finding paves new opportunities for natural fiber applications in polymer composites by enabling a solvent-free and efficient cellulose modification approach that fulfils the sustainable development rules. [ABSTRACT FROM AUTHOR]