Polymers

Editorial

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2 pages, 165 KiB

Open AccessEditorial

Natural Degradation: Polymer Degradation under Different Conditions

by Alexandre A. Vetcher and Alexey L. Iordanskii

Polymers 2022, 14(17), 3595; https://doi.org/10.3390/polym14173595 - 31 Aug 2022

Cited by 2 | Viewed by 1344

Abstract

Natural degradation (ND) is currently one of the main directions of polymer research [...] Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

Research

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25 pages, 5305 KiB

Open AccessArticle

Effects of Titanium–Silica Oxide on Degradation Behavior and Antimicrobial Activity of Poly (Lactic Acid) Composites

by Arpaporn Teamsinsungvon, Chaiwat Ruksakulpiwat and Yupaporn Ruksakulpiwat

Polymers 2022, 14(16), 3310; https://doi.org/10.3390/polym14163310 - 14 Aug 2022

Cited by 6 | Viewed by 1872

Abstract

A mixed oxide of titania–silica oxides (Ti_xSi_y oxides) was successfully prepared via the sol–gel technique from our previous work. The use of Ti_xSi_y oxides to improve the mechanical properties, photocatalytic efficiency, antibacterial property, permeability tests, and biodegradability [...] Read more.

A mixed oxide of titania–silica oxides (Ti_xSi_y oxides) was successfully prepared via the sol–gel technique from our previous work. The use of Ti_xSi_y oxides to improve the mechanical properties, photocatalytic efficiency, antibacterial property, permeability tests, and biodegradability of polylactic acid (PLA) was demonstrated in this study. The influence of different types and contents of Ti_xSi_y oxides on crystallization behavior, mechanical properties, thermal properties, and morphological properties was presented. In addition, the effect of using Ti_xSi_y oxides as a filler in PLA composites on these properties was compared with the use of titanium dioxide (TiO₂), silicon dioxide (SiO₂), and TiO₂SiO₂. Among the prepared biocomposite films, the PLA/Ti_xSi_y films showed an improvement in the tensile strength and Young’s modulus (up to 5% and 31%, respectively) in comparison to neat PLA films. Photocatalytic efficiency to degrade methylene blue (MB), hydrolytic degradation, and in vitro degradation of PLA are significantly improved with the addition of Ti_xSi_y oxides. Furthermore, PLA with the addition of Ti_xSi_y oxides exhibited an excellent antibacterial effect on Gram-negative bacteria (Escherichia coli or E. coli) and Gram-positive bacteria (Staphylococcus aureus or S. aureus), indicating the improved antimicrobial effectiveness of PLA composites. Importantly, up to 5% Ti_xSi_y loading could promote more PLA degradation via the water absorption ability of mixed oxides. According to the research results, the PLA composite films produced with Ti_xSi_y oxide were transparent, capable of screening UV radiation, and exhibited superior antibacterial efficacy, making them an excellent food packaging material. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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17 pages, 2178 KiB

Open AccessArticle

Determination of the Influence of Multiple Closed Recycling Loops on the Property Profile of Different Polyolefins

by Johanna Langwieser, Andrea Schweighuber, Alexander Felgel-Farnholz, Christian Marschik, Wolfgang Buchberger and Joerg Fischer

Polymers 2022, 14(12), 2429; https://doi.org/10.3390/polym14122429 - 15 Jun 2022

Cited by 8 | Viewed by 2247

Abstract

In a circular economy, polymeric materials are used in multiple loops to manufacture products. Therefore, closed-loops are also envisaged for the mechanical recycling of plastics, in which plastic is used for products that are in turn collected and reprocessed again and again to [...] Read more.

In a circular economy, polymeric materials are used in multiple loops to manufacture products. Therefore, closed-loops are also envisaged for the mechanical recycling of plastics, in which plastic is used for products that are in turn collected and reprocessed again and again to make further products. However, this reprocessing involves degradation processes within the plastics, which become apparent through changes in the property profile of the material. In the present paper, the influence of multiple recycling loops on the material properties of four different polyolefins was analyzed. Two different closed-loop cycles with industrially sized processing machines were defined, and each polyolefin was processed and reprocessed within the predefined cycles. For the investigation of the effect of the respective loops, samples were taken after each loop. The samples were characterized by high-pressure liquid chromatography coupled to a quadru-pole time-of-flight MS, high-temperature gel permeation chromatography, melt flow rate measurements, infrared spectroscopy, differential thermal analysis, and tensile tests. With increasing number of processing loops, the tested polyolefins showed continuous material degradation, which resulted in significant changes in the property profiles. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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16 pages, 4785 KiB

Open AccessArticle

Evaluation and Characterization of Ultrathin Poly(3-hydroxybutyrate) Fibers Loaded with Tetraphenylporphyrin and Its Complexes with Fe(III) and Sn(IV)

by Svetlana G. Karpova, Natalia A. Chumakova, Anton V. Lobanov, Anatoly A. Olkhov, Alexandre A. Vetcher and Alexey L. Iordanskii

Polymers 2022, 14(3), 610; https://doi.org/10.3390/polym14030610 - 4 Feb 2022

Cited by 4 | Viewed by 1832

Abstract

The effect of small additions (1–5 wt.%) of tetraphenylporphyrin (TPP) and its complexes with Fe (III) and Sn (IV) on the structure and properties of ultrathin fibers based on poly(3-hydroxybutyrate) (PHB) has been studied. A comprehensive study of biopolymer compositions included X-ray diffraction [...] Read more.

The effect of small additions (1–5 wt.%) of tetraphenylporphyrin (TPP) and its complexes with Fe (III) and Sn (IV) on the structure and properties of ultrathin fibers based on poly(3-hydroxybutyrate) (PHB) has been studied. A comprehensive study of biopolymer compositions included X-ray diffraction (XRD), differential scanning calorimetry (DSC), spin probe electron paramagnetic resonance method (EPR), and scanning electron microscopy (SEM). It was demonstrated that the addition of these dopants to the PHB fibers modifies their morphology, crystallinity and segmental dynamics in the amorphous regions. The annealing at 140 °C affects crystallinity and molecular mobility in the amorphous regions of the fibers, however the observed changes exhibit multidirectional behavior, depending on the type of porphyrin and its concentration in the fiber. Fibers exposure to an aqueous medium at 70 °C causes a nonlinear change in the enthalpy of melting and challenging nature of a change of the molecular dynamics. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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15 pages, 5304 KiB

Open AccessArticle

Progressing Ultragreen, Energy-Efficient Biobased Depolymerization of Poly(ethylene terephthalate) via Microwave-Assisted Green Deep Eutectic Solvent and Enzymatic Treatment

by Olivia A. Attallah, Muhammad Azeem, Efstratios Nikolaivits, Evangelos Topakas and Margaret Brennan Fournet

Polymers 2022, 14(1), 109; https://doi.org/10.3390/polym14010109 - 29 Dec 2021

Cited by 10 | Viewed by 3755

Abstract

Effective interfacing of energy-efficient and biobased technologies presents an all-green route to achieving continuous circular production, utilization, and reproduction of plastics. Here, we show combined ultragreen chemical and biocatalytic depolymerization of polyethylene terephthalate (PET) using deep eutectic solvent (DES)-based low-energy microwave (MW) treatment [...] Read more.

Effective interfacing of energy-efficient and biobased technologies presents an all-green route to achieving continuous circular production, utilization, and reproduction of plastics. Here, we show combined ultragreen chemical and biocatalytic depolymerization of polyethylene terephthalate (PET) using deep eutectic solvent (DES)-based low-energy microwave (MW) treatment followed by enzymatic hydrolysis. DESs are emerging as attractive sustainable catalysts due to their low toxicity, biodegradability, and unique biological compatibility. A green DES with triplet composition of choline chloride, glycerol, and urea was selected for PET depolymerization under MW irradiation without the use of additional depolymerization agents. Treatment conditions were studied using Box-Behnken design (BBD) with respect to MW irradiation time, MW power, and volume of DES. Under the optimized conditions of 20 mL DES volume, 260 W MW power, and 3 min MW time, a significant increase in the carbonyl index and PET percentage weight loss was observed. The combined MW-assisted DES depolymerization and enzymatic hydrolysis of the treated PET residue using LCC variant ICCG resulted in a total monomer conversion of ≈16% (w/w) in the form of terephthalic acid, mono-(2-hydroxyethyl) terephthalate, and bis-(2-hydroxyethyl) terephthalate. Such high monomer conversion in comparison to enzymatically hydrolyzed virgin PET (1.56% (w/w)) could be attributed to the recognized depolymerization effect of the selected DES MW treatment process. Hence, MW-assisted DES technology proved itself as an efficient process for boosting the biodepolymerization of PET in an ultrafast and eco-friendly manner. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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17 pages, 5974 KiB

Open AccessArticle

Mechanical Properties and Thermal Conductivity of Thermal Insulation Board Containing Recycled Thermosetting Polyurethane and Thermoplastic

by Ping He, Haoda Ruan, Congyang Wang and Hao Lu

Polymers 2021, 13(24), 4411; https://doi.org/10.3390/polym13244411 - 16 Dec 2021

Cited by 11 | Viewed by 4243

Abstract

This study used a mechanochemical method to analyze the recycling mechanism of polyurethane foam and optimize the recycling process. The use of mechanochemical methods to regenerate the polyurethane foam powder breaks the C–O bond of the polyurethane foam and greatly enhances the activity [...] Read more.

This study used a mechanochemical method to analyze the recycling mechanism of polyurethane foam and optimize the recycling process. The use of mechanochemical methods to regenerate the polyurethane foam powder breaks the C–O bond of the polyurethane foam and greatly enhances the activity of the powder. Based on orthogonal test design, the mesh, proportion, temperature, and time were selected to produce nine recycled boards by heat pressing. Then, the influence of four factors on the thermal conductivity and tensile strength of the recycled board was analyzed. The results show that 120 mesh polyurethane foam powder has strong activity, and the tensile strength can reach 9.913 Mpa when it is formed at 205 °C and 40 min with 50% PP powder. With the help of the low thermal conductivity of the polyurethane foam, the thermal conductivity of the recycled board can reach 0.037 W/m·K at the parameter of 40 mesh, 80%, 185 °C, 30 min. This research provides an effective method for the recycling of polyurethane foam. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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17 pages, 2402 KiB

Open AccessArticle

Pyrolytic Behavior of Polyvinyl Chloride: Kinetics, Mechanisms, Thermodynamics, and Artificial Neural Network Application

by Mohammed Al-Yaari and Ibrahim Dubdub

Polymers 2021, 13(24), 4359; https://doi.org/10.3390/polym13244359 - 13 Dec 2021

Cited by 16 | Viewed by 3299

Abstract

Pyrolysis of waste polyvinyl chloride (PVC) is considered a promising and highly efficient treatment method. This work aims to investigate the kinetics, and thermodynamics of the process of PVC pyrolysis. Thermogravimetry of PVC pyrolysis at three heating rates (5, 10, and 20 K/min) [...] Read more.

Pyrolysis of waste polyvinyl chloride (PVC) is considered a promising and highly efficient treatment method. This work aims to investigate the kinetics, and thermodynamics of the process of PVC pyrolysis. Thermogravimetry of PVC pyrolysis at three heating rates (5, 10, and 20 K/min) showed two reaction stages covering the temperature ranges of 490–675 K, and 675–825 K, respectively. Three integral isoconversional models, namely Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), and Starink, were used to obtain the activation energy (E_a), and pre-exponential factor (A) of the PVC pyrolysis. On the other hand, the Coats-Redfern non-isoconversional model was used to determine the most appropriate solid-state reaction mechanism/s for both stages. Values of E_a, and A, obtained by the isoconversional models, were very close and the average values were, for stage I: E_a = 75 kJ/mol, A = 1.81 × 10⁶ min⁻¹; for stage II: E_a = 140 kJ/mol, A = 4.84 × 10⁹ min⁻¹. In addition, while the recommended mechanism of the first stage reaction was P2, F3 was the most suitable mechanism for the reaction of stage II. The appropriateness of the mechanisms was confirmed by the compensation effect. Thermodynamic study of the process of PVC pyrolysis confirmed that both reactions are endothermic and nonspontaneous with promising production of bioenergy. Furthermore, a highly efficient artificial neural network (ANN) model has been developed to predict the weight left % during the PVC pyrolysis as a function of the temperature and heating rate. The 2-10-10-1 topology with TANSIG-LOGSIG transfer function and feed-forward back-propagation characteristics was used. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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14 pages, 5641 KiB

Open AccessArticle

Effect of Engineered Biomaterials and Magnetite on Wastewater Treatment: Biogas and Kinetic Evaluation

by Gloria Amo-Duodu, Emmanuel Kweinor Tetteh, Sudesh Rathilal, Edward Kwaku Armah, Jeremiah Adedeji, Martha Noro Chollom and Maggie Chetty

Polymers 2021, 13(24), 4323; https://doi.org/10.3390/polym13244323 - 10 Dec 2021

Cited by 16 | Viewed by 2848

Abstract

In this study, the principle of sustaining circular economy is presented as a way of recovering valuable resources from wastewater and utilizing its energy potential via anaerobic digestion (AD) of municipality wastewater. Biostimulation of the AD process was investigated to improve its treatability [...] Read more.

In this study, the principle of sustaining circular economy is presented as a way of recovering valuable resources from wastewater and utilizing its energy potential via anaerobic digestion (AD) of municipality wastewater. Biostimulation of the AD process was investigated to improve its treatability efficiency, biogas production, and kinetic stability. Addressing this together with agricultural waste such as eggshells (CE), banana peel (PB), and calcined banana peels (BI) were employed and compared to magnetite (Fe₃O₄) as biostimulation additives via 1 L biochemical methane potential tests. With a working volume of 0.8 L (charge with inoculum to substrate ratio of 3:5 v/v) and 1.5 g of the additives, each bioreactor was operated at a mesophilic temperature of 40 °C for 30 days while being compared to a control bioreactor. Scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis was used to reveal the absorbent’s morphology at high magnification of 10 kx and surface pore size of 20.8 µm. The results showed over 70% biodegradation efficiency in removing the organic contaminants (chemical oxygen demand, color, and turbidity) as well as enhancing the biogas production. Among the setups, the bioreactor with Fe₃O₄ additives was found to be the most efficient, with an average daily biogas production of 40 mL/day and a cumulative yield of 1117 mL/day. The kinetic dynamics were evaluated with the cumulative biogas produced by each bioreactor via the first order modified Gompertz and Chen and Hashimoto kinetic models. The modified Gompertz model was found to be the most reliable, with good predictability. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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9 pages, 1300 KiB

Open AccessCommunication

Alteration of Relative Rates of Biodegradation and Regeneration of Cervical Spine Cartilage through the Restoration of Arterial Blood Flow Access to Rhomboid Fossa: A Hypothesis

by Kirill V. Zhukov, Alexandre A. Vetcher, Bagrat A. Gasparuan and Alexander Y. Shishonin

Polymers 2021, 13(23), 4248; https://doi.org/10.3390/polym13234248 - 3 Dec 2021

Cited by 13 | Viewed by 2136

Abstract

We found the logical way to prove the existence of the mechanism that maintains the rates of biodegradation and regeneration of cervical spine cartilage. We demonstrate, that after we restore access to arterial blood flow through cervical vertebral arteries to rhomboid fossa it [...] Read more.

We found the logical way to prove the existence of the mechanism that maintains the rates of biodegradation and regeneration of cervical spine cartilage. We demonstrate, that after we restore access to arterial blood flow through cervical vertebral arteries to rhomboid fossa it causes the prevalence of regeneration over biodegradation. This is in the frames of consideration of the human body as a dissipative structure. Then the recovery of the body should be considered as a reduction of the relative rates of decay below the regeneration ones. Then the recovery of cervical spine cartilage through redirecting of inner dissipative flow depends on the information about oxygen availability that is provided from oxygen detectors in the rhomboid fossa to the cerebellum. Our proposed approach explains already collected data, which satisfies all the scientific requirements. This allows us to draw conclusions that permit reconsidering the way of dealing with multiple chronic diseases. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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15 pages, 5018 KiB

Open AccessArticle

Thermo-Oxidative Destruction and Biodegradation of Nanomaterials from Composites of Poly(3-hydroxybutyrate) and Chitosan

by Anatoly A. Olkhov, Elena E. Mastalygina, Vasily A. Ovchinnikov, Tatiana V. Monakhova, Alexandre A. Vetcher and Alexey L. Iordanskii

Polymers 2021, 13(20), 3528; https://doi.org/10.3390/polym13203528 - 14 Oct 2021

Cited by 4 | Viewed by 2385

Abstract

A complex of structure-sensitive methods of morphology analysis was applied to study film materials obtained from blends of poly(3-hydroxybutyrate) (PHB) and chitosan (CHT) by pouring from a solution, and nonwoven fibrous materials obtained by the method of electrospinning (ES). It was found that [...] Read more.

A complex of structure-sensitive methods of morphology analysis was applied to study film materials obtained from blends of poly(3-hydroxybutyrate) (PHB) and chitosan (CHT) by pouring from a solution, and nonwoven fibrous materials obtained by the method of electrospinning (ES). It was found that with the addition of CHT to PHB, a heterophase system with a nonequilibrium stressed structure at the interface was formed. This system, if undergone accelerated oxidation and hydrolysis, contributed to the intensification of the growth of microorganisms. On the other hand, the antimicrobial properties of CHT led to inhibition of the biodegradation process. Nonwoven nanofiber materials, since having a large specific surface area of contact with an aggressive agent, demonstrated an increased ability to be thermo-oxidative and for biological degradation in comparison with film materials. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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13 pages, 5117 KiB

Open AccessArticle

Characteristics of Biodegradable Gelatin Methacrylate Hydrogel Designed to Improve Osteoinduction and Effect of Additional Binding of Tannic Acid on Hydrogel

by Ji-Bong Choi, Yu-Kyoung Kim, Seon-Mi Byeon, Jung-Eun Park, Tae-Sung Bae, Yong-Seok Jang and Min-Ho Lee

Polymers 2021, 13(15), 2535; https://doi.org/10.3390/polym13152535 - 31 Jul 2021

Cited by 3 | Viewed by 3471

Abstract

In this study, a hydrogel using single and double crosslinking was prepared using GelMA, a natural polymer, and the effect was evaluated when the double crosslinked hydrogel and tannic acid were treated. The resulting hydrogel was subjected to physicochemical property evaluation, biocompatibility evaluation, [...] Read more.

In this study, a hydrogel using single and double crosslinking was prepared using GelMA, a natural polymer, and the effect was evaluated when the double crosslinked hydrogel and tannic acid were treated. The resulting hydrogel was subjected to physicochemical property evaluation, biocompatibility evaluation, and animal testing. The free radicals generated through APS/TEMED have a scaffold form with a porous structure in the hydrogel, and have a more stable structure through photo crosslinking. The double crosslinked hydrogel had improved mechanical strength and better results in cell compatibility tests than the single crosslinked group. Moreover, in the hydrogel transplanted into the femur of a rat, the double crosslinked group showed an osteoinductive response due to the attachment of bone minerals after 4 and 8 weeks, but the single crosslinked group did not show an osteoinductive response due to rapid degradation. Treatment with a high concentration of tannic acid showed significantly improved mechanical strength through H-bonding. However, cell adhesion and proliferation were limited compared to the untreated group due to the limitation of water absorption capacity, and no osteoinduction reaction was observed. As a result, it was confirmed that the treatment of high-concentration tannic acid significantly improved mechanical strength, but it was not a suitable method for improving bone induction due to the limitation of water absorption. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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Review

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32 pages, 2320 KiB

Open AccessReview

Parameters Influencing Moisture Diffusion in Epoxy-Based Materials during Hygrothermal Ageing—A Review by Statistical Analysis

by Camille Gillet, Ferhat Tamssaouet, Bouchra Hassoune-Rhabbour, Tatiana Tchalla and Valérie Nassiet

Polymers 2022, 14(14), 2832; https://doi.org/10.3390/polym14142832 - 12 Jul 2022

Cited by 15 | Viewed by 2377

Abstract

The hygrothermal ageing of epoxy resins and epoxy matrix composite materials has been studied many times in the literature. Models have been developed to represent the diffusion behaviour of the materials. For reversible diffusions, Fick, Dual–Fick and Carter

a n d

Kibler models [...] Read more.

The hygrothermal ageing of epoxy resins and epoxy matrix composite materials has been studied many times in the literature. Models have been developed to represent the diffusion behaviour of the materials. For reversible diffusions, Fick, Dual–Fick and Carter

a n d

Kibler models are widely used. Many parameters, correlated or not, have been identified. The objectives of this review by statistical analysis are to confirm or infirm these correlations, to highlight other correlations if they exist, and to establish which are the most important to study. This study focuses on the parameters of the Fick, Dual–Fick and Carter

a n d

Kibler models. For this purpose, statistical analyses are performed on data extracted and calculated from individuals described in the literature. Box plot and PCA analyses were chosen. Differences are then noticeable according to the different qualitative parameters chosen in the study. Moreover, correlations, already observed in the literature for quantitative variables, are confirmed. On the other hand, differences appear which may suggest that the models used are inappropriate for certain materials. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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0 pages, 4594 KiB

Open AccessReview

Biopolymeric Nanoparticles–Multifunctional Materials of the Future

by Andrey A. Vodyashkin, Parfait Kezimana, Alexandre A. Vetcher and Yaroslav M. Stanishevskiy

Polymers 2022, 14(11), 2287; https://doi.org/10.3390/polym14112287 - 4 Jun 2022

Cited by 34 | Viewed by 4328

Abstract

Nanotechnology plays an important role in biological research, especially in the development of delivery systems with lower toxicity and greater efficiency. These include not only metallic nanoparticles, but also biopolymeric nanoparticles. Biopolymeric nanoparticles (BPNs) are mainly developed for their provision of several advantages, [...] Read more.

Nanotechnology plays an important role in biological research, especially in the development of delivery systems with lower toxicity and greater efficiency. These include not only metallic nanoparticles, but also biopolymeric nanoparticles. Biopolymeric nanoparticles (BPNs) are mainly developed for their provision of several advantages, such as biocompatibility, biodegradability, and minimal toxicity, in addition to the general advantages of nanoparticles. Therefore, given that biopolymers are biodegradable, natural, and environmentally friendly, they have attracted great attention due to their multiple applications in biomedicine, such as drug delivery, antibacterial activity, etc. This review on biopolymeric nanoparticles highlights their various synthesis methods, such as the ionic gelation method, nanoprecipitation method, and microemulsion method. In addition, the review also covers the applications of biodegradable polymeric nanoparticles in different areas—especially in the pharmaceutical, biomedical, and agricultural domains. In conclusion, the present review highlights recent advances in the synthesis and applications of biopolymeric nanoparticles and presents both fundamental and applied aspects that can be used for further development in the field of biopolymeric nanoparticles. Full article

(This article belongs to the Special Issue Natural Degradation: Polymer Degradation under Different Conditions)

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