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Polymers
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Polymer/Biopolymer Stabilization and Degradation
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Polymer/Biopolymer Stabilization and Degradation

A topical collection in Polymers (ISSN 2073-4360). This collection belongs to the section "Polymer Processing and Engineering".

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Editors

Dr. Dan Rosu

E-Mail Website
Collection Editor
Centre of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry, 41A Gr. Ghica-Voda Alley, 700487 Iasi, Romania
Interests: synthesis and characterization of phenolic, epoxy and vinyl-ester resins; extractions and characterization of natural products; theoretical aspects regarding polymers adhesive and cohesive capacity; correlation of molecular structure characteristics with adhesive properties of macromolecular compounds; aspects regarding synthetic adhesives properties and characterization, methods of control and their testing; complex capitalization of the vegetable biomass, respectively of polymer waste products through pyrolysis; synthesis and characterization of interpenetrating polymer networks; studies of thermal degradation and polymers compatibility (study of decomposition processes, establishing the mechanisms and kinetics of thermal degradation); studies of polymers photochemical behavior. Recent researches regarding polymers aging under light, especially UV radiation from the solar spectrum, as well as polymers photostabilization
Dr. Cristian-Dragos Varganici

E-Mail Website
Collection Editor
Centre of Advanced Research in Bionanoconjugates and Biopolymers, "Petru Poni" Institute of Macromolecular Chemistry, Gr.Ghica Voda Alley 41A, 700487 Iasi, Romania
Interests: thermal degradation and polymer compatibility (decomposition processes and mechanisms and kinetics of thermal degradation); structure–property relationships in polymers; polymer photochemical behavior; aging of polymers under environmental factors, especially UV radiation from the solar spectrum; polymer photostabilization

Topical Collection Information

Dear Colleagues,

Due to their structures, the polymeric materials used in various application areas are characterized by limited stability during exposure to an environment. Therefore, their specific properties decline during long-term exploitation. Conditions such as processing, storage, and service conditions also add structural imperfections that contribute to the lowering of the material’s lifetime. Accurate results from weathering tests must be obtained by the manufacturers, since the lifetime and extent of an application depend on molecular modifications. Polymer degradation occurs through bond cleavage, radical diffusion, oxidation, and crosslinking. The main factors that contribute synergistically to polymer degradation are heat, light (especially in the UV region), humidity, microorganisms, pollutants, and mechanical charge. Environmental factors must be correlated with the material’s structure. Laboratory-accelerated and field tests take place similarly but not identically in polymers. The main difference between the two procedures resides in the concentrations of radicals and their migration in the material bulk. The diffusion of free radicals is influenced by such factors as bond strength, morphology, molecular weight distribution, crosslinking degree, crystallinity, inorganic filler(s), stabilizers, mechanical charge, processing conditions, and sample history. The planning of laboratory and field testing of polymers may be designed in combination with the various factors taken into account. This Topic Collection is concerned with the thermal, photochemical, and microbiological behavior of polymer-based materials. We hope to share new concepts related to the behavior of polymeric materials under environmental factors, both under laboratory and outdoor exposure conditions. In this way, we seek to bring new insights into the different degradation mechanisms of polymers. Both original research papers and review articles are welcome.

Dr. Dan Rosu
Dr. Cristian–Dragos Varganici
Collection Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • polymers
  • multicomponent polymer-based materials
  • thermal behavior
  • thermal stability
  • evolved gases analysis
  • thermal degradation kinetics
  • thermal degradation mechanisms
  • thermal transitions in polymers
  • thermal analysis devices
  • photochemical behavior of polymers
  • photocrosslinking
  • photostabilization
  • photocatalysis
  • UV irradiation devices
  • photodegradation mechanisms
  • life-time prediction from thermal and photochemical data
  • biodegradation of polymers

Related Special Issues

Published Papers (6 papers)

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2023

Jump to: 2022, 2021, 2020

30 pages, 41662 KiB  
Review
A Comprehensive Review on the Thermal Stability Assessment of Polymers and Composites for Aeronautics and Space Applications
by Giuseppina Barra, Liberata Guadagno, Marialuigia Raimondo, Maria Gabriella Santonicola, Elisa Toto and Stefano Vecchio Ciprioti
Polymers 2023, 15(18), 3786; https://doi.org/10.3390/polym15183786 - 16 Sep 2023
Cited by 5 | Viewed by 2052
Abstract
This review article provides an exhaustive survey on experimental investigations regarding the thermal stability assessment of polymers and polymer-based composites intended for applications in the aeronautical and space fields. This review aims to: (1) come up with a systematic and critical overview of [...] Read more.
This review article provides an exhaustive survey on experimental investigations regarding the thermal stability assessment of polymers and polymer-based composites intended for applications in the aeronautical and space fields. This review aims to: (1) come up with a systematic and critical overview of the state-of-the-art knowledge and research on the thermal stability of various polymers and composites, such as polyimides, epoxy composites, and carbon-filled composites; (2) identify the key factors, mechanisms, methods, and challenges that affect the thermal stability of polymers and composites, such as the temperature, radiation, oxygen, and degradation; (3) highlight the current and potential applications, benefits, limitations, and opportunities of polymers and composites with high thermal stability, such as thermal control, structural reinforcement, protection, and energy conversion; (4) give a glimpse of future research directions by providing indications for improving the thermal stability of polymers and composites, such as novel materials, hybrid composites, smart materials, and advanced processing methods. In this context, thermal analysis plays a crucial role in the development of polyimide-based materials for the radiation shielding of space solar cells or spacecraft components. The main strategies that have been explored to improve the processability, optical transparency, and radiation resistance of polyimide-based materials without compromising their thermal stability are highlighted. The combination of different types of polyimides, such as linear and hyperbranched, as well as the incorporation of bulky pendant groups, are reported as routes for improving the mechanical behavior and optical transparency while retaining the thermal stability and radiation shielding properties. Furthermore, the thermal stability of polymer/carbon nanocomposites is discussed with particular reference to the role of the filler in radiation monitoring systems and electromagnetic interference shielding in the space environment. Finally, the thermal stability of epoxy-based composites and how it is influenced by the type and content of epoxy resin, curing agent, degree of cross-linking, and the addition of fillers or modifiers are critically reviewed. Some studies have reported that incorporating mesoporous silica micro-filler or microencapsulated phase change materials (MPCM) into epoxy resin can enhance its thermal stability and mechanical properties. The mesoporous silica composite exhibited the highest glass transition temperature and activation energy for thermal degradation among all the epoxy-silica nano/micro-composites. Indeed, an average activation energy value of 148.86 kJ/mol was recorded for the thermal degradation of unfilled epoxy resin. The maximum activation energy range was instead recorded for composites loaded with mesoporous microsilica. The EMC-5p50 sample showed the highest mean value of 217.6 kJ/mol. This remarkable enhancement was ascribed to the polymer invading the silica pores and forging formidable interfacial bonds. Full article
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26 pages, 1941 KiB  
Review
Wall Materials for Encapsulating Bioactive Compounds via Spray-Drying: A Review
by Elsa Díaz-Montes
Polymers 2023, 15(12), 2659; https://doi.org/10.3390/polym15122659 - 12 Jun 2023
Cited by 5 | Viewed by 4230
Abstract
Spray-drying is a continuous encapsulation method that effectively preserves, stabilizes, and retards the degradation of bioactive compounds by encapsulating them within a wall material. The resulting capsules exhibit diverse characteristics influenced by factors such as operating conditions (e.g., air temperature and feed rate) [...] Read more.
Spray-drying is a continuous encapsulation method that effectively preserves, stabilizes, and retards the degradation of bioactive compounds by encapsulating them within a wall material. The resulting capsules exhibit diverse characteristics influenced by factors such as operating conditions (e.g., air temperature and feed rate) and the interactions between the bioactive compounds and the wall material. This review aims to compile recent research (within the past 5 years) on spray-drying for bioactive compound encapsulation, emphasizing the significance of wall materials in spray-drying and their impact on encapsulation yield, efficiency, and capsule morphology. Full article
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2022

Jump to: 2023, 2021, 2020

17 pages, 3778 KiB  
Article
Effect of the Coupling Agent (3-Aminopropyl) Triethoxysilane on the Structure and Fire Behavior of Solvent-Free One-Pot Synthesized Silica-Epoxy Nanocomposites
by Francesco Branda, Dambarudhar Parida, Robin Pauer, Massimo Durante, Sabyasachi Gaan, Giulio Malucelli and Aurelio Bifulco
Polymers 2022, 14(18), 3853; https://doi.org/10.3390/polym14183853 - 15 Sep 2022
Cited by 4 | Viewed by 1734
Abstract
Uniformly distributed silica/epoxy nanocomposites (2 and 6 wt.% silica content) were obtained through a “solvent-free one-pot” process. The inorganic phases were obtained through “in situ” sol-gel chemistry from two precursors, tetraethyl orthosilicate (TEOS) and (3-aminopropyl)-triethoxysilane (APTES). APTES acts as a coupling agent. Surprisingly [...] Read more.
Uniformly distributed silica/epoxy nanocomposites (2 and 6 wt.% silica content) were obtained through a “solvent-free one-pot” process. The inorganic phases were obtained through “in situ” sol-gel chemistry from two precursors, tetraethyl orthosilicate (TEOS) and (3-aminopropyl)-triethoxysilane (APTES). APTES acts as a coupling agent. Surprisingly when changing TEOS/APTES molar ratio (from 2.32 to 1.25), two opposite trends of glass transformation temperature (Tg) were observed for silica loading, i.e., at lower content, a decreased Tg (for 2 wt.% silica) and at higher content an increased Tg (for 6 wt.% silica) was observed. High-Resolution Transmission Electron Microscopy (HRTEM) showed the formation of multi-sheet silica-based nanoparticles with decreasing size at a lower TEOS/APTES molar ratio. Based on a recently proposed mechanism, the experimental results can be explained by the formation of a co-continuous hybrid network due to reorganization of the epoxy matrix around two different “in situ” sol-gel derived silicatic phases, i.e., micelles formed mainly by APTES and multi-sheet silica nanoparticles. Moreover, the concentration of APTES affected the size distribution of the multi-sheet silica-based nanoparticles, leading to the formation of structures that became smaller at a higher content. Flammability and forced-combustion tests proved that the nanocomposites exhibited excellent fire retardancy. Full article
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21 pages, 8877 KiB  
Article
Effect of Hardener Type on the Photochemical and Antifungal Performance of Epoxy and Oligophosphonate S–IPNs
by Cristian-Dragos Varganici, Liliana Rosu, Dan Rosu, Corneliu Hamciuc, Irina Rosca and Ana-Lavinia Vasiliu
Polymers 2022, 14(18), 3784; https://doi.org/10.3390/polym14183784 - 09 Sep 2022
Cited by 4 | Viewed by 1346
Abstract
Due to their highly reactive character and multiple crosslinking capacity, epoxy resins are one of the worldwide market-dominating classes of thermosetting polymers and are present in a wide range of technical applications, including structural adhesives, coatings and polymer matrices for composite materials. Despite [...] Read more.
Due to their highly reactive character and multiple crosslinking capacity, epoxy resins are one of the worldwide market-dominating classes of thermosetting polymers and are present in a wide range of technical applications, including structural adhesives, coatings and polymer matrices for composite materials. Despite their excellent features, epoxy resins are known to be highly flammable and possess low thermal stability and a brittle character and crack easily under impact forces. An efficient approach towards eliminating such drawbacks resides in obtaining epoxy-based semi-interpenetrating polymer networks, which possess excellent control over the morphology. The article describes the comparative effect of three hardeners (aromatic, cycloaliphatic and aliphatic) in the presence of an oligophosphonate (–R–O–PO(C6H5)–O–) (2 wt.% phosphorus) on the photochemical, fire and antifungal performance of bisphenol A diglycidyl ether semi-interpenetrating polymer networks. The networks are designed as future potential outdoor protective coatings for different substrates. The fire resistance capacity of the networks was undertaken with microscale combustion calorimetry before and after photochemical aging. Structural changes during photoirradiation were monitored via color modification studies, Fourier-transform infrared spectroscopy, differential scanning calorimetry, morphological assessment through scanning electron microscopy and mass loss measurements in order to propose the action mode of the hardeners and the oligophosphonate on the material properties. Microbiological testing was also undertaken with the aid of three specific wood decaying fungi as a first substrate. Full article
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2021

Jump to: 2023, 2022, 2020

22 pages, 4959 KiB  
Article
Photochemical Stability of a Cotton Fabric Surface Dyed with a Reactive Triphenodioxazine Dye
by Liliana Rosu, Cristian-Catalin Gavat, Dan Rosu, Cristian-Dragos Varganici and Fanica Mustata
Polymers 2021, 13(22), 3986; https://doi.org/10.3390/polym13223986 - 18 Nov 2021
Cited by 5 | Viewed by 1963
Abstract
The paper describes the photochemical stability of a commercial triphenodioxazine dye (Reactive Blue_204) linked onto a cotton fabric. Preliminary studies have shown that as a result of irradiation, the dye and its photodegradation products can pass directly onto the skin under conditions that [...] Read more.
The paper describes the photochemical stability of a commercial triphenodioxazine dye (Reactive Blue_204) linked onto a cotton fabric. Preliminary studies have shown that as a result of irradiation, the dye and its photodegradation products can pass directly onto the skin under conditions that mimic human perspiration and cause side-effects. The cotton dyed fabric was photo irradiated at different time intervals. Standard methods were employed to evaluate the color strength at various levels of pH, temperature, dyeing contact time, and salt concentration. The influence of UV radiation at different doses (λ > 300 nm) on the structural and color modifications of the dyed cotton fabrics was studied. Structural modifications before and after irradiation were compared by applying FTIR, UV–Vis, and near infrared chemical imaging (NIR–CI) techniques. Color modifications were investigated with the CIELAB system. Color differences significantly increased with the irradiation dose. High irradiation doses caused changes in the dye structure. Full article
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2020

Jump to: 2023, 2022, 2021

12 pages, 4054 KiB  
Article
Study on the Synthesis and Thermal Stability of Silicone Resin Containing Trifluorovinyl Ether Groups
by Rui Huang, Jinshui Yao, Qiuhong Mu, Dan Peng, Hui Zhao and Zhizhou Yang
Polymers 2020, 12(10), 2284; https://doi.org/10.3390/polym12102284 - 05 Oct 2020
Cited by 16 | Viewed by 3527
Abstract
Silicone resin is a high-temperature resistant material with excellent performance. The improvement of its thermal stability has always been the pursuit of researchers. In this paper, a sequence of silicone resins containing trifluorovinyl ether groups were prepared by the co-hydrolysis-polycondensation of methyl alkoxysilane [...] Read more.
Silicone resin is a high-temperature resistant material with excellent performance. The improvement of its thermal stability has always been the pursuit of researchers. In this paper, a sequence of silicone resins containing trifluorovinyl ether groups were prepared by the co-hydrolysis-polycondensation of methyl alkoxysilane monomers and {4-[trifluorovinyl(oxygen)]phenyl}methyldiethoxysilane. The structures of the silicone resins were characterized by FT-IR and 1H NMR. The curing process of them was studied by DSC and FT-IR spectra, and results showed that the curing of the resins included the condensation of the Si-OH groups and the [2 + 2] cyclodimerization reaction of the TFVE groups, which converted to perfluorocyclobutane structure after curing. The thermal stability and thermal degradation behavior of them was studied by TGA and FT-IR spectra. Compared with the pure methyl silicone resin, silicone resins containing TFVE groups showed better thermal stability under both N2 and air atmosphere. Their hydrophobic properties were characterized by contact angle test. Results showed that PFCB structure also improved the hydrophobicity of the silicone resin. Full article
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