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16 pages, 4876 KiB

Open AccessArticle

Identification of Plastics in Mixtures and Blends through Pyrolysis-Gas Chromatography/Mass Spectrometry

by Chiara Gnoffo and Alberto Frache

Polymers 2024, 16(1), 71; https://doi.org/10.3390/polym16010071 - 26 Dec 2023

Cited by 2 | Viewed by 1152

In this paper, the possibility of detecting polymers in plastic mixtures and extruded blends has been investigated. Pyrolysis–gas chromatography/mass spectrometry (py-GC/MS) allows researchers to identify multicomponent mixtures and low amounts of polymers without high spatial resolution, background noise and constituents mix interfering, as [...] Read more.

In this paper, the possibility of detecting polymers in plastic mixtures and extruded blends has been investigated. Pyrolysis–gas chromatography/mass spectrometry (py-GC/MS) allows researchers to identify multicomponent mixtures and low amounts of polymers without high spatial resolution, background noise and constituents mix interfering, as with molecular spectrometry techniques normally used for this purpose, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy and differential scanning calorimetry (DSC). In total, 15 solid mixtures of low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyamide (PA) and polycarbonate (PC) in various combinations have been qualitatively analyzed after choosing their characteristic pyrolysis products and each polymer has been detected in every mix; thus, in extruded blends of high-density polyethylene (HDPE), PP and PS had varying weight percentages of the individual constituents ranging from 10 up to 90. Moreover, quantitative analysis of these polymers has been achieved in every blend with a trend that can be considered linear with coefficients of determination higher than 0.9, even though the limits of quantification are lower with respect to the ones reported in the literature, probably due to the extrusion process. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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17 pages, 7071 KiB

Open AccessArticle

Sub-10 nm Nanoparticle Detection Using Multi-Technique-Based Micro-Raman Spectroscopy

by Allan Bereczki, Jessica Dipold, Anderson Z. Freitas and Niklaus U. Wetter

Polymers 2023, 15(24), 4644; https://doi.org/10.3390/polym15244644 - 08 Dec 2023

Viewed by 885

Abstract

Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nano-sized pollutants and the possibility of interactions [...] Read more.

Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nano-sized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO₂ nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force Microscopy. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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13 pages, 3911 KiB

Open AccessArticle

Producing Blends of Polybutylene Adipate Terephthalate and Blood Meal That Are Safe to Render

by Casparus J. R. Verbeek, Priyal M. Yapa, Rachel Self and Mark Harrison

Polymers 2023, 15(18), 3750; https://doi.org/10.3390/polym15183750 - 13 Sep 2023

Viewed by 647

Abstract

Single-use plastic hygiene control products used during red meat processing can have severe negative impacts on the environment and cannot be processed with offal during rendering into meat and bone meal. However, plastics made from protein could potentially solve this problem as the [...] Read more.

Single-use plastic hygiene control products used during red meat processing can have severe negative impacts on the environment and cannot be processed with offal during rendering into meat and bone meal. However, plastics made from protein could potentially solve this problem as the material would be safe to render. The objective of this work was to prepare blends of blood meal and polybutylene adipate terephthalate (PBAT) in the absence of water using the interaction between PBAT and protein as the plasticisation mechanism. The ratio of protein to PBAT (1:1.3), as well as the choice of compatibiliser (PBAT-g-IA), was critical to form a homogenous, compatibilised blend with mechanical properties suitable for injection-moulded hygeine control products. This blend had a tensile strenght of 11.2 MPa, a chord modulus of 492 MPa, and 10% elongation at break. Using less PBAT in the blend, or using Surlyn™ as a compatibiliser, resulted in blends that were either too difficult to process or with inferior mechancial properies. Using simulated rendering, the new material was indistinguishable from tallow or meat and bone meal, suggesting that hygeine control products made from this new material will degrade sufficiently to be safe to render with offal after red meat processing. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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16 pages, 3109 KiB

Open AccessEditor’s ChoiceArticle

π-Electron-Extended Triazine-Based Covalent Organic Framework as Photocatalyst for Organic Pollution Degradation and H₂ Production from Water

by Jing Han Wang, Taher A. Gaber, Shiao-Wei Kuo and Ahmed F. M. EL-Mahdy

Polymers 2023, 15(7), 1685; https://doi.org/10.3390/polym15071685 - 28 Mar 2023

Cited by 7 | Viewed by 2196

Abstract

Herein, we report the efficient preparation of π-electron-extended triazine-based covalent organic framework (TFP-TPTPh COF) for photocatalysis and adsorption of the rhodamine B (RhB) dye molecule, as well as for photocatalytic hydrogen generation from water. The resultant TFP-TPTPh COF exhibited remarkable porosity, excellent crystallinity, [...] Read more.

Herein, we report the efficient preparation of π-electron-extended triazine-based covalent organic framework (TFP-TPTPh COF) for photocatalysis and adsorption of the rhodamine B (RhB) dye molecule, as well as for photocatalytic hydrogen generation from water. The resultant TFP-TPTPh COF exhibited remarkable porosity, excellent crystallinity, high surface area of 724 m² g⁻¹, and massive thermal stability with a char yield of 63.41%. The TFP-TPTPh COF demonstrated an excellent removal efficiency of RhB from water in 60 min when used as an adsorbent, and its maximum adsorption capacity (Q_m) of 480 mg g⁻¹ is among the highest Q_m values for porous polymers ever to be recorded. In addition, the TFP-TPTPh COF showed a remarkable photocatalytic degradation of RhB dye molecules with a reaction rate constant of 4.1 × 10⁻² min⁻¹ and an efficiency of 97.02% under ultraviolet–visible light irradiation. Furthermore, without additional co-catalysts, the TFP-TPTPh COF displayed an excellent photocatalytic capacity for reducing water to generate H₂ with a hydrogen evolution rate (HER) of 2712 μmol g⁻¹ h⁻¹. This highly active COF-based photocatalyst appears to be a useful material for dye removal from water, as well as solar energy processing and conversion. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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16 pages, 28013 KiB

Open AccessArticle

Medical-Grade Poly(Lactic Acid)/Hydroxyapatite Composite Films: Thermal and In Vitro Degradation Properties

by Leonard Bauer, Anamarija Rogina, Marica Ivanković and Hrvoje Ivanković

Polymers 2023, 15(6), 1512; https://doi.org/10.3390/polym15061512 - 18 Mar 2023

Cited by 6 | Viewed by 1789

Abstract

Production of biocompatible composite scaffolds shifts towards additive manufacturing where thermoplastic biodegradable polymers such as poly(lactic acid) (PLA) are used as matrices. Differences between industrial- and medical-grade polymers are often overlooked although they may affect properties and degradation behaviour as significantly as the [...] Read more.

Production of biocompatible composite scaffolds shifts towards additive manufacturing where thermoplastic biodegradable polymers such as poly(lactic acid) (PLA) are used as matrices. Differences between industrial- and medical-grade polymers are often overlooked although they may affect properties and degradation behaviour as significantly as the filler addition. In the present research, composite films based on medical-grade PLA and biogenic hydroxyapatite (HAp) with 0, 10, and 20 wt.% of HAp were prepared by solvent casting technique. The degradation of composites incubated in phosphate-buffered saline solution (PBS) at 37 °C after 10 weeks showed that the higher HAp content slowed down the hydrolytic PLA degradation and improved its thermal stability. Morphological nonuniformity after degradation was indicated by the different glass transition temperatures (T_g) throughout the film. The T_g of the inner part of the sample decreased significantly faster compared with the outer part. The decrease was observed prior to the weight loss of composite samples. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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24 pages, 8861 KiB

Open AccessArticle

Lignin-Loaded Carbon Nanoparticles as a Promising Control Agent against Fusarium verticillioides in Maize: Physiological and Biochemical Analyses

by Sherif Mohamed El-Ganainy, Mohamed A. Mosa, Ahmed Mahmoud Ismail and Ashraf E. Khalil

Polymers 2023, 15(5), 1193; https://doi.org/10.3390/polym15051193 - 27 Feb 2023

Cited by 4 | Viewed by 2022

Abstract

Lignin, a naturally occurring biopolymer, is produced primarily as a waste product by the pulp and paper industries and burned to produce electricity. Lignin-based nano- and microcarriers found in plants are promising biodegradable drug delivery platforms. Here, we highlight a few characteristics of [...] Read more.

Lignin, a naturally occurring biopolymer, is produced primarily as a waste product by the pulp and paper industries and burned to produce electricity. Lignin-based nano- and microcarriers found in plants are promising biodegradable drug delivery platforms. Here, we highlight a few characteristics of a potential antifungal nanocomposite consisting of carbon nanoparticles (C-NPs) with a defined size and shape containing lignin nanoparticles (L-NPs). Spectroscopic and microscopic studies verified that the lignin-loaded carbon nanoparticles (L-CNPs) were successfully prepared. Under in vitro and in vivo conditions, the antifungal activity of L-CNPs at various doses was effectively tested against a wild strain of F. verticillioides that causes maize stalk rot disease. In comparison to the commercial fungicide, Ridomil Gold SL (2%), L-CNPs introduced beneficial effects in the earliest stages of maize development (seed germination and radicle length). Additionally, L-CNP treatments promoted positive effects on maize seedlings, with a significant increment in the level of carotenoid, anthocyanin, and chlorophyll pigments for particular treatments. Finally, the soluble protein content displayed a favorable trend in response to particular dosages. Most importantly, treatments with L-CNPs at 100 and 500 mg/L significantly reduced stalk rot disease by 86% and 81%, respectively, compared to treatments with the chemical fungicide, which reduced the disease by 79%. These consequences are substantial considering the essential cellular function carried out by these special natural-based compounds. Finally, the intravenous L-CNPs treatments in both male and female mice that affected the clinical applications and toxicological assessments are explained. The results of this study suggest that L-CNPs are of high interest as biodegradable delivery vehicles and can be used to stimulate favorable biological responses in maize when administered in the recommended dosages, contributing to the idea of agro-nanotechnology by demonstrating their unique qualities as a cost-effective alternative compared to conventional commercial fungicides and environmentally benign nanopesticides for long-term plant protection. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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16 pages, 3962 KiB

Open AccessArticle

Characterization of Fungal Foams from Edible Mushrooms Using Different Agricultural Wastes as Substrates for Packaging Material

by Nur Mawaddah Majib, Sung Ting Sam, Noorulnajwa Diyana Yaacob, Nor Munirah Rohaizad and Wai Kian Tan

Polymers 2023, 15(4), 873; https://doi.org/10.3390/polym15040873 - 10 Feb 2023

Cited by 7 | Viewed by 3062

Abstract

Agricultural wastes and leaves, which are classified as lignocellulosic biomass, have been used as substrates in the production of fungal foams due to the significant growth of the mushroom industry in recent years. Foam derived from fungi can be utilized in a variety [...] Read more.

Agricultural wastes and leaves, which are classified as lignocellulosic biomass, have been used as substrates in the production of fungal foams due to the significant growth of the mushroom industry in recent years. Foam derived from fungi can be utilized in a variety of industrial applications, including the production of packaging materials. Here, white oyster mushrooms (Pleurotus florida) and yellow oyster mushrooms (Pleurotus citrinopileatus) were cultivated on rice husk, sawdust, sugarcane bagasse, and teak leaves. Fungal foams were produced after 30 days of incubation, which were then analyzed using scanning electron microscopy (SEM), thermal analysis (TGA), and chemical structure using Fourier-transform infrared spectroscopy. Mechanical testing examined the material’s hardness, resilience, and springiness, and water absorption tests were used to determine the durability of the fungal foams. Our findings demonstrated that fungal foams made from rice husk and teak leaves in both mycelium species showed better mechanical properties, thermal stability, and minimal water absorption compared to the other substrates, and can thus have great potential as efficient packaging materials. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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12 pages, 2586 KiB

Open AccessArticle

Copolymerization of Carbon Dioxide with 1,2-Butylene Oxide and Terpolymerization with Various Epoxides for Tailorable Properties

by Shuo Tang, Hongyi Suo, Rui Qu, Hao Tang, Miao Sun and Yusheng Qin

Polymers 2023, 15(3), 748; https://doi.org/10.3390/polym15030748 - 01 Feb 2023

Cited by 1 | Viewed by 1679

Abstract

The copolymerization of carbon dioxide (CO₂) with epoxides demonstrates promise as a new synthetic method for low-carbon polymer materials, such as aliphatic polycarbonate materials. In this study, a binary Schiff base cobalt system was successfully used to catalyze the copolymerization of [...] Read more.

The copolymerization of carbon dioxide (CO₂) with epoxides demonstrates promise as a new synthetic method for low-carbon polymer materials, such as aliphatic polycarbonate materials. In this study, a binary Schiff base cobalt system was successfully used to catalyze the copolymerization of 1,2-butylene oxide (BO) and CO₂ and its terpolymerization with other epoxides such as propylene oxide (PO) and cyclohexene oxide (CHO). ¹H nuclear magnetic resonance (¹H NMR), diffusion-ordered spectroscopy (DOSY), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) confirmed the successful synthesis of the alternating terpolymer. In addition, the effects of the polymerization reaction conditions and copolymerization monomer composition on the polymer structure and properties were examined systematically. By regulating the epoxide feed ratio, polycarbonates with an adjustable glass transition temperature (T_g) (11.2–67.8 °C) and hydrophilicity (water contact angle: 85.2–95.2°) were prepared. Thus, this ternary polymerization method provides an effective method of modulating the surface hydrophobicity of CO₂-based polymers and their biodegradation properties. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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23 pages, 5203 KiB

Open AccessArticle

Preparation and Performance of Biodegradable Poly(butylene adipate-co-terephthalate) Composites Reinforced with Novel AgSnO₂ Microparticles for Application in Food Packaging

by Raja Venkatesan, Krishnapandi Alagumalai and Seong-Cheol Kim

Polymers 2023, 15(3), 554; https://doi.org/10.3390/polym15030554 - 21 Jan 2023

Cited by 11 | Viewed by 2593

Abstract

Biodegradable composites with antimicrobial properties were prepared with microparticles of silver stannate (AgSnO₂) and poly(butylene adipate-co-terephthalate) (PBAT) and tested for applications in food packaging. The PBAT matrix was synthesized and confirmed by ¹H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, [...] Read more.

Biodegradable composites with antimicrobial properties were prepared with microparticles of silver stannate (AgSnO₂) and poly(butylene adipate-co-terephthalate) (PBAT) and tested for applications in food packaging. The PBAT matrix was synthesized and confirmed by ¹H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). Ultrasonic and coprecipitation methods were used to synthesize AgSnO₂. A two-step mixing method and a solvent cast technique were utilized to fabricate the PBAT composites (different weight % of AgSnO₂) for packaging foods. Attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, XRD, and scanning electron microscopy were used to investigate the formation, structure, and size of the composites. Thermogravimetric analysis and differential thermal calorimetry were used to examine the PBAT/AgSnO₂ composites. The best characteristics are exhibited in 5.0 wt. % AgSnO₂ loaded PBAT composite. The tensile strength, elongation at break, water vapor transmission rate, and oxygen transmission rate were 22.82 MPa, 237.00%, 125.20 g/m²/day, and 1104.62 cc/m²/day.atm, respectively. Incorporating AgSnO₂ enhanced the hydrophobicity of the PBAT materials as evaluated by the water contact angle. The 5.0 wt. % AgSnO₂/PBAT film shows a favorable zone of inhibition against the bacteria pathogens S. aureus and E. coli, according to an evaluation of its antimicrobial activity. The weight loss of 5% AgSnO₂/PBAT film was 78.4% after eight weeks in the natural soil environments. In addition, the results of food quality studies recommend that AgSnO₂/PBAT (5.0 wt. %) film had a longer food shelf life than the neat PBAT and commercial, increasing it from one to 14 days for carrot vegetables. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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16 pages, 1589 KiB

Open AccessArticle

Analysis of Fuel Alternative Products Obtained by the Pyrolysis of Diverse Types of Plastic Materials Isolated from a Dumpsite Origin in Pakistan

by Nuzhat Javed, Sana Muhammad, Shazia Iram, Muhammad Wajahat Ramay, Shaan Bibi Jaffri, Mariem Damak, György Fekete, Zsolt Varga, András Székács and László Aleksza

Polymers 2023, 15(1), 24; https://doi.org/10.3390/polym15010024 - 21 Dec 2022

Cited by 1 | Viewed by 3665

Abstract

The current energy crisis and waste management problems have compelled people to find alternatives to conventional non-renewable fuels and utilize waste to recover energy. Pyrolysis of plastics, which make up a considerable portion of municipal and industrial waste, has emerged as a feasible [...] Read more.

The current energy crisis and waste management problems have compelled people to find alternatives to conventional non-renewable fuels and utilize waste to recover energy. Pyrolysis of plastics, which make up a considerable portion of municipal and industrial waste, has emerged as a feasible resolution to both satisfy our energy needs and mitigate the issue of plastic waste. This study was therefore conducted to find a solution for plastic waste management problems, as well as to find an alternative to mitigate the current energy crisis. Pyrolysis of five of the most commonly used plastics, polyethylene terephthalate (PET), high- and low-density polyethylene (HDPE, LDPE), polypropylene (PP), and polystyrene (PS), was executed in a pyrolytic reactor designed utilizing a cylindrical shaped stainless steel container with pressure and temperature gauges and a condenser to cool down the hydrocarbons produced. The liquid products collected were highly flammable and their chemical properties revealed them as fuel alternatives. Among them, the highest yield of fuel conversion (82%) was observed for HDPE followed by PP, PS, LDPE, PS, and PET (61.8%, 58.0%, 50.0%, and 11.0%, respectively). The calorific values of the products, 46.2, 46.2, 45.9, 42.8 and 42.4 MJ/kg for LPDE, PP, HPDE, PS, and PET, respectively, were comparable to those of diesel and gasoline. Spectroscopic and chromatographic analysis proved the presence of alkanes and alkenes with carbon number ranges of C₉–C₁₅, C₉–C₂₄, C₁₀–C₂₁, C₁₀–C₂₈, and C₉–C₁₇ for PP, PET, HDPE, LDPE, and PS, respectively. If implemented, the study will prove to be beneficial and contribute to mitigating the major energy and environmental issues of developing countries, as well as enhance entrepreneurship opportunities by replicating the process at small-scale and industrial levels. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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Review

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29 pages, 5226 KiB

Open AccessReview

Matrix-Assisted Laser Desorption and Electrospray Ionization Tandem Mass Spectrometry of Microbial and Synthetic Biodegradable Polymers

by Paola Rizzarelli and Marco Rapisarda

Polymers 2023, 15(10), 2356; https://doi.org/10.3390/polym15102356 - 18 May 2023

Cited by 3 | Viewed by 1632

Abstract

The in-depth structural and compositional investigation of biodegradable polymeric materials, neat or partly degraded, is crucial for their successful applications. Obviously, an exhaustive structural analysis of all synthetic macromolecules is essential in polymer chemistry to confirm the accomplishment of a preparation procedure, identify [...] Read more.

The in-depth structural and compositional investigation of biodegradable polymeric materials, neat or partly degraded, is crucial for their successful applications. Obviously, an exhaustive structural analysis of all synthetic macromolecules is essential in polymer chemistry to confirm the accomplishment of a preparation procedure, identify degradation products originating from side reactions, and monitor chemical–physical properties. Advanced mass spectrometry (MS) techniques have been increasingly applied in biodegradable polymer studies with a relevant role in their further development, valuation, and extension of application fields. However, single-stage MS is not always sufficient to identify unambiguously the polymer structure. Thus, tandem mass spectrometry (MS/MS) has more recently been employed for detailed structure characterization and in degradation and drug release monitoring of polymeric samples, among which are biodegradable polymers. This review aims to run through the investigations carried out by the soft ionization technique matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS) MS/MS in biodegradable polymers and present the resulting information. Full article

(This article belongs to the Special Issue Polymers: Environmental Aspects)

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