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13 pages, 4056 KiB

Open AccessArticle

Biorenewable Oxypropylated Pentane-1,2,5-triol as a Source for Incorporation in Rigid Polyurethane Foams

by Georgy Grancharov, Mariya-Desislava Atanasova, Radostina Kalinova, Pencho Tuleshkov, Petar D. Petrov, Maya K. Marinova, Martin A. Ravutsov and Svilen P. Simeonov

Polymers 2023, 15(20), 4148; https://doi.org/10.3390/polym15204148 - 19 Oct 2023

Viewed by 782

Abstract

In this study, as a product from the efficient Achmatowicz rearrangement and mild subsequent hydrogenation–reduction reactions of biorenewable C5 alcohols derived from lignocellulose, pentane-1,2,5-triol was successfully used after oxypropylation in the preparation of rigid polyurethane foams—one of the most important classes of polymeric [...] Read more.

In this study, as a product from the efficient Achmatowicz rearrangement and mild subsequent hydrogenation–reduction reactions of biorenewable C5 alcohols derived from lignocellulose, pentane-1,2,5-triol was successfully used after oxypropylation in the preparation of rigid polyurethane foams—one of the most important classes of polymeric materials. Despite the broad range of applications, the production of polyurethanes is still highly dependent on petrochemical materials considering the need of renewable raw materials and new process technologies for the production of polyol or isocyanate components as a key point for the sustainable development of polyurethane foams. The synthesized oxypropylated pentane-1,2,5-triol was analyzed using proton NMR spectroscopy, hydroxyl number, and viscosity, whereas the newly obtained foams incorporated with up to 30% biorenewable polyol were characterized using compressive stress, thermogravimetry, dynamic mechanical analysis, and scanning electron microscopy. The modified rigid polyurethanes showed better compressive strength (>400.0 kPa), a comparable thermal degradation range at 325–450 °C, and similar morphological properties to those of commercial polyurethane formulations. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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19 pages, 1715 KiB

Open AccessArticle

Unfolding of Lignin Structure Using Size-Exclusion Fractionation

by Audrey LaVallie, Anastasia A. Andrianova, Joshua Schumaker, Sarah Reagen, Shelly Lu, Irina P. Smoliakova, Evguenii I. Kozliak and Alena Kubátová

Polymers 2023, 15(19), 3956; https://doi.org/10.3390/polym15193956 - 30 Sep 2023

Cited by 1 | Viewed by 885

Abstract

The heterogeneous and recalcitrant structure of lignin hinders its practical application. Here, we describe how new approaches to lignin characterization can reveal structural details that could ultimately lead to its more efficient utilization. A suite of methods, which enabled mass balance closure, the [...] Read more.

The heterogeneous and recalcitrant structure of lignin hinders its practical application. Here, we describe how new approaches to lignin characterization can reveal structural details that could ultimately lead to its more efficient utilization. A suite of methods, which enabled mass balance closure, the evaluation of structural features, and an accurate molecular weight (MW) determination, were employed and revealed unexpected structural features of the five alkali lignin fractions obtained with preparative size-exclusion chromatography (SEC). A thermal carbon analysis (TCA) provided quantitative temperature profiles based on sequential carbon evolution, including the final oxidation of char. The TCA results, supported with thermal desorption/pyrolysis gas chromatography–mass spectrometry (TD-Py-GC-MS) and ³¹P NMR spectroscopy, revealed the unfolding of the lignin structure as a result of the SEC fractionation, due to the disruption of the interactions between the high- and low-MW components. The “unraveled” lignin revealed poorly accessible hydroxyl groups and showed an altered thermal behavior. The fractionated lignin produced significantly less char upon pyrolysis, 2 vs. 47%. It also featured a higher occurrence of low-MW thermal evolution products, particularly guaiacol carbonyls, and more than double the number of OH groups accessible for phosphitylation. These observations indicate pronounced alterations in the lignin intermolecular association following size-exclusion fractionation, which may be used for more efficient lignin processing in biorefineries. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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19 pages, 9776 KiB

Open AccessArticle

Study of the Degradation of a TPS/PCL/Fique Biocomposite Material in Soil, Compost, and Water

by Fabián Steven Mosquera Rodríguez, Alejandro Quintero Vélez, Estivinson Córdoba Urrutia, Howard Ramírez-Malule and Jose Herminsul Mina Hernandez

Polymers 2023, 15(19), 3952; https://doi.org/10.3390/polym15193952 - 30 Sep 2023

Cited by 1 | Viewed by 1043

Abstract

The degradability of the biocomposite produced from a binary mixture of thermoplastic banana starch (TPS) and polycaprolactone (PCL) reinforced with fique fibers (Fs) was evaluated in three different environments (soil, compost, water). An experimental design with two factors (soil and compost) and three [...] Read more.

The degradability of the biocomposite produced from a binary mixture of thermoplastic banana starch (TPS) and polycaprolactone (PCL) reinforced with fique fibers (Fs) was evaluated in three different environments (soil, compost, water). An experimental design with two factors (soil and compost) and three levels (5, 10, and 20 cm) was used, with additional tests for a third aqueous environment (water from the lake of the Universidad del Valle) at a depth of 20 cm. The biocomposite was prepared from the implementation of a twin-screw extrusion process of the binary mixture TPS/PCL and fique fibers (54, 36, and 10% composition, respectively), followed by hot compression molding, and after that, generating ASTM D638 type V specimens using a stainless-steel die. The specimens were dried and buried according to the experimental design, for a total experimental time of 90 days, and removing samples every 30 days. After 90 days, all samples showed signs of degradation, where the best results were obtained in the compost at a depth of 20 cm (34 ± 4% mass loss and a decrease in tensile strength of 77.3%, which indicates that the material lost mechanical properties). TPS was the fastest disappearing component and promoted the degradation of the composite material as it disappeared. Finally, the aqueous media presented the lowest degradation results, losing only 20% of its initial mass after 90 days of the experiment, being the least effective environment in which the biocomposite can end up. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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11 pages, 3263 KiB

Open AccessArticle

Biodegradation Potential of Polyethylene Terephthalate by the Two Insect Gut Symbionts Xanthomonas sp. HY-74 and Bacillus sp. HY-75

by Jong-Hoon Kim, So-Hye Lee, Byeong-Min Lee, Kwang-Hee Son and Ho-Yong Park

Polymers 2023, 15(17), 3546; https://doi.org/10.3390/polym15173546 - 25 Aug 2023

Cited by 1 | Viewed by 1402

Abstract

Polyethylene terephthalate (PET) is a plastic material that is widely used in beverage bottles, food packaging, and other consumer products, which is highly resistant to biodegradation. In this study, we investigated the effects of two insect gut symbionts, Xanthomonas sp. HY-74 and Bacillus [...] Read more.

Polyethylene terephthalate (PET) is a plastic material that is widely used in beverage bottles, food packaging, and other consumer products, which is highly resistant to biodegradation. In this study, we investigated the effects of two insect gut symbionts, Xanthomonas sp. HY-74 and Bacillus sp. HY-75, during PET biodegradation. Both strains degraded PET-containing agar plates, and the sole nutrition source assay showed that HY-74 had different degradation rates depending on the presence of specific carbon and nitrogen sources, whereas HY-75 exhibited comparable degradation across all tested conditions. The two strains biodegraded the PET film with 1.57 ± 0.21% and 1.42 ± 0.46% weight loss after 6 weeks, respectively. Changes in the morphology and structure of the PET films, such as erosion, scratching, and surface roughening, were determined using scanning electron microscopy (SEM). Further, the two strains biodegraded PET powder, broke it into its degradation products, and changed the surface functional groups. This is the first study to investigate the biodegradation of PET by Hymenoptera gut-derived microbes and offers promising insights into the potential applications of insect gut symbionts in PET waste management. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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12 pages, 2231 KiB

Open AccessArticle

Degradation of Polylactic Acid Polymer and Biocomposites Exposed to Controlled Climatic Ageing: Mechanical and Thermal Properties and Structure

by Adam Vašíček, Petr Lenfeld and Luboš Běhálek

Polymers 2023, 15(14), 2977; https://doi.org/10.3390/polym15142977 - 08 Jul 2023

Cited by 4 | Viewed by 1014

Abstract

This paper deals with the study of the degradation of polylactic acid (PLA) material structures and biocomposite systems with a PLA matrix containing ground natural particulate waste fillers, buckwheat husks and egg shells. Waste fillers were used without difficult cleaning operations to describe [...] Read more.

This paper deals with the study of the degradation of polylactic acid (PLA) material structures and biocomposite systems with a PLA matrix containing ground natural particulate waste fillers, buckwheat husks and egg shells. Waste fillers were used without difficult cleaning operations to describe the effect of the raw waste material on PLA. Biocomposites with raw waste materials are increasingly coming to the forefront in car interiors and packaging products. The prepared material systems were exposed to controlled climatic ageing simulating long-term solar radiation and cyclic outdoor conditions. The degradation of the biocomposite systems was evaluated via thermal (differential scanning calorimetry) and mechanical properties (tensile and flexural tests, Charpy impact toughness). In addition to evaluating the degradation of the material structures using standardized tests, the influence and effect of controlled climatic ageing was visually assessed using SEM images (electron microscopy) of the surfaces and fracture surfaces of the test specimens. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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15 pages, 1785 KiB

Open AccessArticle

Effect of Drug Encapsulation and Hydrothermal Exposure on the Structure and Molecular Dynamics of the Binary System Poly(3-hydroxybutyrate)-chitosan

by S. G. Karpova, A. A. Olkhov, I. A. Varyan, A. A. Popov and A. L. Iordanskii

Polymers 2023, 15(10), 2260; https://doi.org/10.3390/polym15102260 - 10 May 2023

Viewed by 1275

Abstract

In this work, film materials based on binary compositions of poly-(3-hydroxybutyrate) (PHB) and chitosan with different ratios of polymer components in the range from 0/100 to 100/0 wt. % were studied. Using a combination of thermal (DSC) and relaxation (EPR) measurements, the influence [...] Read more.

In this work, film materials based on binary compositions of poly-(3-hydroxybutyrate) (PHB) and chitosan with different ratios of polymer components in the range from 0/100 to 100/0 wt. % were studied. Using a combination of thermal (DSC) and relaxation (EPR) measurements, the influence of the encapsulation temperature of the drug substance (DS) of dipyridamole (DPD) and moderately hot water (at 70 °C) on the characteristics of the PHB crystal structure and the diffusion rotational mobility of the stable TEMPO radical in the amorphous regions of the PHB/chitosan compositions is shown. The low-temperature extended maximum on the DSC endotherms made it possible to obtain additional information about the state of the chitosan hydrogen bond network. This allowed us to determine the enthalpies of thermal destruction of these bonds. In addition, it is shown that when PHB and chitosan are mixed, significant changes are observed in the degree of crystallinity of PHB, degree of destruction of hydrogen bonds in chitosan, segmental mobility, sorption capacity of the radical, and the activation energy of rotational diffusion in the amorphous regions of the PHB/chitosan composition. The characteristic point of polymer compositions was found to correspond to the ratio of the components of the mixture 50/50%, for which the inversion transition of PHB from dispersed material to dispersion medium is assumed. Encapsulation of DPD in the composition leads to higher crystallinity and to a decrease in the enthalpy of hydrogen bond breaking, and it also slows down segmental mobility. Exposure to an aqueous medium at 70 °C is also accompanied by sharp changes in the concentration of hydrogen bonds in chitosan, the degree of PHB crystallinity, and molecular dynamics. The conducted research made it possible for the first time to conduct a comprehensive analysis of the mechanism of action of a number of aggressive external factors (such as temperature, water, and the introduced additive in the form of a drug) on the structural and dynamic characteristics of the PHB/chitosan film material at the molecular level. These film materials have the potential to serve as a therapeutic system for controlled drug delivery. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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14 pages, 4012 KiB

Open AccessArticle

Assessing the Biodegradability of PHB-Based Materials with Different Surface Areas: A Comparative Study on Soil Exposure of Films and Electrospun Materials

by Kristina G. Gasparyan, Polina M. Tyubaeva, Ivetta A. Varyan, Alexandre A. Vetcher and Anatoly A. Popov

Polymers 2023, 15(9), 2042; https://doi.org/10.3390/polym15092042 - 25 Apr 2023

Cited by 3 | Viewed by 1486

Abstract

Due to the current environmental situation, biopolymers are replacing the usual synthetic polymers, and special attention is being paid to poly-3-hydroxybutyrate (PHB), which is a biodegradable polymer of natural origin. In this paper, the rate of biodegradation of films and fibers based on [...] Read more.

Due to the current environmental situation, biopolymers are replacing the usual synthetic polymers, and special attention is being paid to poly-3-hydroxybutyrate (PHB), which is a biodegradable polymer of natural origin. In this paper, the rate of biodegradation of films and fibers based on PHB was compared. The influence of exposure to soil on the structure and properties of materials was evaluated using methods of mechanical analysis, the DSC method and FTIR spectroscopy. The results showed rapid decomposition of the fibrous material and also showed how the surface of the material affects the rate of biodegradation and the mechanical properties of the material. It was found that maximum strength decreased by 91% in the fibrous material and by 49% in the film. Additionally, the DSC method showed that the crystallinity of the fiber after exposure to the soil decreased. It was established that the rate of degradation is influenced by different factors, including the surface area of the material and its susceptibility to soil microorganisms. The results obtained are of great importance for planning the structure of features in the manufacture of biopolymer consumer products in areas such as medicine, packaging, filters, protective layers and coatings, etc. Therefore, an understanding of the biodegradation mechanisms of PHB could lead to the development of effective medical devices, packaging materials and different objects with a short working lifespan. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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15 pages, 3619 KiB

Open AccessArticle

Structural Rearrangements of Polylactide/Natural Rubber Composites during Hydro- and Biotic Degradation

by Yulia V. Tertyshnaya, Maria V. Podzorova, Anastasia V. Khramkova, Vasily A. Ovchinnikov and Aleksey V. Krivandin

Polymers 2023, 15(8), 1930; https://doi.org/10.3390/polym15081930 - 19 Apr 2023

Cited by 2 | Viewed by 1230

Abstract

In the work, the impact of the biological medium and water on structural rearrangements in pure polylactide and polylactide/natural rubber film composites was studied. Polylactide/natural rubber films with a rubber content of 5, 10, and 15 wt.% were obtained by the solution method. [...] Read more.

In the work, the impact of the biological medium and water on structural rearrangements in pure polylactide and polylactide/natural rubber film composites was studied. Polylactide/natural rubber films with a rubber content of 5, 10, and 15 wt.% were obtained by the solution method. Biotic degradation was carried out according to the Sturm method at a temperature of 22 ± 2 °C. Hydrolytic degradation was studied at the same temperature in distilled water. The structural characteristics were controlled by thermophysical, optical, spectral, and diffraction methods. Optical microscopy revealed the surface erosion of all samples after exposure to microbiota and water. Differential scanning calorimetry showed a decrease in the degree of crystallinity of polylactide by 2–4% after the Sturm test, and a tendency to an increase in the degree of crystallinity after the action of water was noted. Changes in the chemical structure were shown in the spectra recorded by infrared spectroscopy. Due to degradation, significant changes in the intensities of the bands in the regions of 3500–2900 and 1700–1500 cm⁻¹ were shown. The X-ray diffraction method established differences in diffraction patterns in very defective and less damaged regions of polylactide composites. It was determined that pure polylactide hydrolyzed more readily under the action of distilled water than polylactide/natural rubber composites. Film composites were more rapidly subjected to biotic degradation. The degree of biodegradation of polylactide/natural rubber composites increased with the rise in the content of natural rubber in the compositions. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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15 pages, 4518 KiB

Open AccessArticle

Application of Unsupervised Learning for the Evaluation of Burial Behavior of Geomaterials in Peatlands: Case of Lignin Moieties Yielded by Alkaline Oxidative Cleavage

by Khaled Younes, Sara Moghnie, Lina Khader, Emil Obeid, Omar Mouhtady, Laurent Grasset and Nimer Murshid

Polymers 2023, 15(5), 1200; https://doi.org/10.3390/polym15051200 - 27 Feb 2023

Cited by 1 | Viewed by 1439

Abstract

Tropical Peatlands accumulate organic matter (OM) and a significant source of carbon dioxide (CO₂) and methane (CH₄) under anoxic conditions. However, it is still ambiguous where in the peat profile these OM and gases are produced. The composition of [...] Read more.

Tropical Peatlands accumulate organic matter (OM) and a significant source of carbon dioxide (CO₂) and methane (CH₄) under anoxic conditions. However, it is still ambiguous where in the peat profile these OM and gases are produced. The composition of organic macromolecules that are present in peatland ecosystems are mainly lignin and polysaccharides. As greater concentrations of lignin are found to be strongly related to the high CO₂ and CH₄ concentrations under anoxic conditions in the surface peat, the need to study the degradation of lignin under anoxic and oxic conditions has emerged. In this study, we found that the “Wet Chemical Degradation” approach is the most preferable and qualified to evaluate the lignin degradation in soils accurately. Then, we applied PCA for the molecular fingerprint consisting of 11 major phenolic sub-units produced by alkaline oxidation using cupric oxide (II) along with alkaline hydrolysis of the lignin sample presented in the investigated peat column called “Sagnes”. The development of various characteristic indicators for lignin degradation state on the basis of the relative distribution of lignin phenols was measured by chromatography after CuO-NaOH oxidation. In order to achieve this aim, the so-called Principal Component Analysis (PCA) has been applied for the molecular fingerprint composed of the phenolic sub-units, yielded by CuO-NaOH oxidation. This approach aims to seek the efficiency of the already available proxies and potentially create new ones for the investigation of lignin burial along a peatland. Lignin phenol vegetation index (LPVI) is used for comparison. LPVI showed a higher correlation with PC1 rather than PC2. This confirms the potential of the application of LPVI to decipher vegetation change, even in a dynamic system as the peatland. The population is composed of the depth peat samples, and the variables are the proxies and relative contributions of the 11 yielded phenolic sub-units. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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15 pages, 3328 KiB

Open AccessArticle

Changes in the Electrophysical Parameters of Nanomodified Elastomers Caused by Electric Current’s Passage

by Alexandr V. Shchegolkov, Aleksei V. Shchegolkov, Natalia V. Zemtsova, Yaroslav M. Stanishevskiy and Alexandre A. Vetcher

Polymers 2023, 15(1), 249; https://doi.org/10.3390/polym15010249 - 03 Jan 2023

Cited by 2 | Viewed by 1957

Abstract

The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements’ manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, [...] Read more.

The development of reliable and effective functional materials that can be used in various technological fields and environmental conditions is one of the goals of modern nanotechnology. Heating elements’ manufacturing requires understanding the laws of heat transfer under conditions of different supply voltages, as this expands the possibilities of such materials’ application. Elastomers based on silicon-organic compounds and polyurethane modified with multi-walled carbon nanotubes (MWCNTs) were studied at various concentrations of Ni/MgO or Co-Mo/MgO and voltages (220, 250, and 300 V). It was found that an increase in voltage from 220 to 300 V leads to an initial increase in specific power on one-third followed by a subsequent decrease in a specific power when switched on again to 220 V (for −40 °C) of up to ~44%. In turn, for a polyurethane matrix, an increase in voltage to 300 V leads to an initial peak power value of ~15% and a decrease in power when switched on again by 220 V (for −40 °C) to ~36% (Ni/MgO -MWCNT). The conducted studies have shown that the use of a polyurethane matrix reduces power degradation (associated with voltage surges above 220 V) by 2.59% for Ni/MgO–based MWCNT and by 10.42% for Co-Mo/MgO. This is due to the better heat resistance of polyurethane and the structural features of the polymer and the MWCNT. The current studies allow us to take the next step in the development of functional materials for electric heating and demonstrate the safety of using heaters at a higher voltage of up to 300 V, which does not lead to their ignition, but only causes changes in electrophysical parameters. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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17 pages, 3725 KiB

Open AccessArticle

Effect of Magnetized Coagulants on Wastewater Treatment: Rice Starch and Chitosan Ratios Evaluation

by Nomthandazo Precious Sibiya, Gloria Amo-Duodu, Emmanuel Kweinor Tetteh and Sudesh Rathilal

Polymers 2022, 14(20), 4342; https://doi.org/10.3390/polym14204342 - 15 Oct 2022

Cited by 6 | Viewed by 2155

Abstract

Coagulation with synthetic chemicals has been used to treat a wide range of industrial effluents. Herein, the unique characteristics of industrial effluents being detrimental to the environment warrants urgent resource-efficient and eco-friendly solutions. Therefore, the study investigated the use of two magnetized coagulants [...] Read more.

Coagulation with synthetic chemicals has been used to treat a wide range of industrial effluents. Herein, the unique characteristics of industrial effluents being detrimental to the environment warrants urgent resource-efficient and eco-friendly solutions. Therefore, the study investigated the use of two magnetized coagulants (chitosan magnetite (CF) and rice starch magnetite (RF)), prepared via co-precipitation in three different ratios (1:2, 1:1 and 2:1) of natural coagulants (chitosan or rice starch) and magnetite nanoparticles (F) as alternative coagulants to alum for the treatment of wastewater. A Brunauer–Emmett–Teller (BET) analyzer, an X-ray diffraction (XRD) analyzer, and energy-dispersive X-ray (EDX) spectroscopy were used to characterize the surface area, crystal structure, and elemental composition of the coagulants. The influences of settling time (10–60 min) on the reduction of turbidity, color, phosphate, and absorbance were studied. This was carried out with a jar test coupled with six beakers operated under coagulation conditions of rapid stirring (150 rpm) and gentle stirring (30 rpm). Wastewater with an initial concentration of 45.6 NTU turbidity, 315 Pt. Co color, 1.18 mg/L phosphate, 352 mg/L chemical oxygen demand (COD), and 73.4% absorbance was used. The RF with a ratio of 1:1 was found to be the best magnetized coagulant with over 80% contaminant removal and 90% absorbance. The treatability performance of RF (1:1) has clearly demonstrated that it is feasible for wastewater treatment. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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15 pages, 17587 KiB

Open AccessArticle

Cellulose Fibre Degradation in Cellulose/Steel Hybrid Geotextiles under Outdoor Weathering Conditions

by Avinash Pradip Manian, Barbara Paul, Helene Lanter, Thomas Bechtold and Tung Pham

Polymers 2022, 14(19), 4179; https://doi.org/10.3390/polym14194179 - 05 Oct 2022

Cited by 2 | Viewed by 1708

Abstract

Risks from rockfall and land sliding can be controlled by high-tensile steel nets and meshes which stabilise critical areas. In many cases, a recultivation of the land is also desired. However, high-tensile steel meshes alone are not always sufficient, depending on the location [...] Read more.

Risks from rockfall and land sliding can be controlled by high-tensile steel nets and meshes which stabilise critical areas. In many cases, a recultivation of the land is also desired. However, high-tensile steel meshes alone are not always sufficient, depending on the location and the inclination of the stabilised slope, to achieve rapid greening. Cellulose fibres exhibit high water binding capacity which supports plant growth. In this work, a hybrid structure consisting of a nonwoven cellulose fibre web and a steel mesh was produced and tested under outdoor conditions over a period of 61 weeks. The cellulose fibres are intended to support plant growth and soil fixation, and thus the biodegradation of the structure is highly relevant, as these fibres will become part of the soil and must be biodegradable. The biodegradation of the cellulose fibres over the period of outdoor testing was monitored by microscopy and analytical methods. The enzymatic degradation of the cellulose fibres led to a reduction in the average degree of polymerisation and also a reduction in the moisture content, as polymer chain hydrolysis occurs more rapidly in the amorphous regions of the fibres. FTIR analysis and determination of carboxylic group content did not indicate substantial changes in the remaining parts of the cellulose fibre. Plant growth covered geotextiles almost completely during the period of testing, which demonstrated their good compatibility with the greening process. Over the total period of 61 weeks, the residual parts of the biodegradable cellulose web merged with the soil beneath and growing plants. This indicates the potential of such hybrid concepts to contribute a positive effect in greening barren and stony land, in addition to the stabilising function of the steel net. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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16 pages, 2261 KiB

Open AccessArticle

Mechanism of Multi-Stage Degradation in Hot Bitumen of Micronized Powder Elastomeric Modifiers from Worn-Out Tire’s Rubber

by Vadim Nikol’skii, Tatiana Dudareva, Irina Krasotkina, Irina Gordeeva, Viktoriya Gorbatova, Alexandre A. Vetcher and Alexander Botin

Polymers 2022, 14(19), 4112; https://doi.org/10.3390/polym14194112 - 30 Sep 2022

Cited by 5 | Viewed by 1388

Abstract

For the first time, by atomic force microscopy (AFM) methods, micro- and nanofragments of micronized powder elastomeric modifier (PEM) formed at the short-term (3 min at 160 °C) interaction of PEM with hot bitumen have been demonstrated. It is the technology of high-temperature [...] Read more.

For the first time, by atomic force microscopy (AFM) methods, micro- and nanofragments of micronized powder elastomeric modifier (PEM) formed at the short-term (3 min at 160 °C) interaction of PEM with hot bitumen have been demonstrated. It is the technology of high-temperature shear-induced grinding of a worn-out tire’s crumb rubber or its co-grinding with styrene–butadiene–styrene (SBS) block copolymer which provides the creation of the PEM structure inclined to rapid degradation in hot bitumen. The formation just after the preparation process of a new structure of a modified binder, more resistant to external effects, is supported by the data of rheological tests. Performance tests for a modified binder using Superpave standard adopted by the road industry for bituminous binders showed an extended temperature range, resistance to rutting, and low-temperature and fatigue cracking. The better resistance to low-temperature and fatigue cracking is certainly related to energy absorption and crack growth stopping in the presence of micron and submicron resilient PEM fragments in accordance with the mechanism of increasing impact toughness in plastics. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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16 pages, 4662 KiB

Open AccessArticle

Acceleration of Polybutylene Succinate Biodegradation by Terribacillus sp. JY49 Isolated from a Marine Environment

by Su Hyun Kim, Jang Yeon Cho, Do Hyun Cho, Hee Ju Jung, Byung Chan Kim, Shashi Kant Bhatia, See-Hyoung Park, Kyungmoon Park and Yung-Hun Yang

Polymers 2022, 14(19), 3978; https://doi.org/10.3390/polym14193978 - 23 Sep 2022

Cited by 14 | Viewed by 2744

Abstract

Polybutylene succinate (PBS) is a bioplastic substitute for synthetic plastics that are made from petroleum-based products such as polyethylene and polypropylene. However, the biodegradation rate of PBS is still low and similar to that of polylactic acid (PLA). Moreover, our knowledge about degrader [...] Read more.

Polybutylene succinate (PBS) is a bioplastic substitute for synthetic plastics that are made from petroleum-based products such as polyethylene and polypropylene. However, the biodegradation rate of PBS is still low and similar to that of polylactic acid (PLA). Moreover, our knowledge about degrader species is limited to a few fungi and mixed consortia. Here, to identify a bacterial degrader to accelerate PBS degradation, we screened and isolated Terribacillus sp. JY49, which showed significant degradability. In order to optimize solid and liquid culture conditions, the effect of factors such as temperature, additional carbon sources, and salt concentrations on degradation was confirmed. We observed a degradation yield of 22.3% after 7 days when adding 1% of glucose. Additionally, NaCl was added to liquid media, and degradation yield was decreased but PBS films were broken into pieces. Comparing the degree of PBS degradation during 10 days, the degradation yield was 31.4% after 10 days at 30 °C. Alteration of physical properties of films was analyzed by using scanning electron microscopy (SEM), gel permeation chromatography (GPC), and Fourier transform infrared (FT-IR). In addition, Terribacillus sp. JY49 showed clear zones on poly(butylene adipate-co-terephthalate) (PBAT), polycaprolactone (PCL), and copolymers such as P(3HB-co-3HV) and P(3HV-co-4HB), exhibiting a broad spectrum of degradation activities on bioplastics. However, there was no significant difference in absorbance when esterase activity was examined for different types of bioplastics. Overall, Terribacillus sp. JY49 is a potential bacterial strain that can degrade PBS and other bioplastics, and this is the first report of Terribacillus sp. as a bioplastic degrader. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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Review

Jump to: Research

13 pages, 2048 KiB

Open AccessReview

Recent Advantages on Waste Management in Hydrogen Industry

by Alexander V. Shchegolkov, Aleksei V. Shchegolkov, Natalia V. Zemtsova, Yaroslav M. Stanishevskiy and Alexandre A. Vetcher

Polymers 2022, 14(22), 4992; https://doi.org/10.3390/polym14224992 - 18 Nov 2022

Cited by 4 | Viewed by 1625

Abstract

The turn to hydrogen as an energy source is a fundamentally important task facing the global energetics, aviation and automotive industries. This step would reduce the negative man-made impact on the environment on the one hand, and provide previously inaccessible power modes and [...] Read more.

The turn to hydrogen as an energy source is a fundamentally important task facing the global energetics, aviation and automotive industries. This step would reduce the negative man-made impact on the environment on the one hand, and provide previously inaccessible power modes and increased resources for technical systems, predetermining the development of an absolutely new life cycle for important areas of technology, on the other. The most important aspect in this case is the development of next-generation technologies for hydrogen industry waste management that will definitely reduce the negative impact of technology on the environment. We consider the approaches and methods related to new technologies in the area of hydrogen storage (HS), which requires the use of specialized equipment equipped with efficient and controlled temperature control systems, as well as the involvement of innovative materials that allow HS in solid form. Technologies for controlling hydrogen production and storage systems are of great importance, and can be implemented using neural networks, making it possible to significantly improve all technological stages according to the criteria of energy efficiency reliability, safety, and eco-friendliness. The recent advantages in these directions are also reviewed. Full article

(This article belongs to the Special Issue Natural Degradation: Management of Polymer Degradation)

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