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Polymers
Volume 14
Issue 10
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Polymers, Volume 14, Issue 10 (May-2 2022) – 200 articles

Cover Story (view full-size image): Microplastic contamination in the marine environment has become one of the biggest environmental problems that humans have to face. Their persistence in this ecosystem and their small size has increased the interest in the study of their possible health effects in living organisms and also in humans. In this study, the content of microplastics in the gastrointestinal tracts of European sea bass and gilt-head sea bream farmed in the Canary Islands has been evaluated to provide new information about the presence of microplastics in cultivated fish. View this paper
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17 pages, 4683 KiB  
Article
Experimental Study of Fatigue and Fracture Behavior of Carbon Fiber-Reinforced Polymer (CFRP) Straps
by Jing Gao, Penghai Xu, Lingyun Fan, Jinfeng Li, Giovanni Pietro Terrasi and Urs Meier
Polymers 2022, 14(10), 2129; https://doi.org/10.3390/polym14102129 - 23 May 2022
Cited by 3 | Viewed by 1930
Abstract
The hanger is one of the important components for through and half-through arch bridges. Conventional steel hangers are vulnerable to corrosion due to corrosive environments. Therefore, a new type of bridge hangers consisting of Carbon Fiber-Reinforced Polymer (CFRP) straps was developed recently. The [...] Read more.
The hanger is one of the important components for through and half-through arch bridges. Conventional steel hangers are vulnerable to corrosion due to corrosive environments. Therefore, a new type of bridge hangers consisting of Carbon Fiber-Reinforced Polymer (CFRP) straps was developed recently. The CFRP straps are self-anchored, which is formed by layers-winding, and they have great advantages in corrosive environments such as high resistance to corrosion. In this study, the fatigue and fracture behavior of CFRP straps has been experimentally investigated. Firstly, the tensile testing of four CFRP strap specimens was conducted to investigate the static fracture behavior of CFRP straps, and three stages were observed, including delamination, cracking, and brittle rupture. Then, a fatigue test of thirty-nine specimens (four groups) was carried out to study the fatigue behavior of CFRP straps, where two types of pins, titanium alloy pin and CFRP pin, and two loading frequencies, 10 Hz and 15 Hz, were used. The number of cycles to failure, displacement, fatigue failure strain, outside surface temperature at the vertex of specimen, and scanning electron microscope (SEM) photographs were recorded and analyzed to investigate the fatigue behavior of CFRP straps. The experiment results show that the temperature development at the vertex of the CFRP strap varies obviously if different pins are used due to the different friction coefficients. In addition, the fatigue life of CFRP straps decreases significantly with the increase in loading rate for the titanium pin, while it only reduces slightly with the increase in loading rate for the CFRP pin. Full article
(This article belongs to the Special Issue Polymers (or Adhesives) and Polymer Composites for Construction Application)
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21 pages, 4811 KiB  
Article
Compressive Strength Estimation of Geopolymer Composites through Novel Computational Approaches
by Muhammad Nasir Amin, Kaffayatullah Khan, Waqas Ahmad, Muhammad Faisal Javed, Hisham Jahangir Qureshi, Muhammad Umair Saleem, Muhammad Ghulam Qadir and Muhammad Iftikhar Faraz
Polymers 2022, 14(10), 2128; https://doi.org/10.3390/polym14102128 - 23 May 2022
Cited by 21 | Viewed by 2124
Abstract
The application of artificial intelligence approaches like machine learning (ML) to forecast material properties is an effective strategy to reduce multiple trials during experimentation. This study performed ML modeling on 481 mixes of geopolymer concrete with nine input variables, including curing time, curing [...] Read more.
The application of artificial intelligence approaches like machine learning (ML) to forecast material properties is an effective strategy to reduce multiple trials during experimentation. This study performed ML modeling on 481 mixes of geopolymer concrete with nine input variables, including curing time, curing temperature, specimen age, alkali/fly ash ratio, Na2SiO3/NaOH ratio, NaOH molarity, aggregate volume, superplasticizer, and water, with CS as the output variable. Four types of ML models were employed to anticipate the compressive strength of geopolymer concrete, and their performance was compared to find out the most accurate ML model. Two individual ML techniques, support vector machine and multi-layer perceptron neural network, and two ensembled ML methods, AdaBoost regressor and random forest, were employed to achieve the study’s aims. The performance of all models was confirmed using statistical analysis, k-fold evaluation, and correlation coefficient (R2). Moreover, the divergence of the estimated outcomes from those of the experimental results was noted to check the accuracy of the models. It was discovered that ensembled ML models estimated the compressive strength of the geopolymer concrete with higher precision than individual ML models, with random forest having the highest accuracy. Using these computational strategies will accelerate the application of construction materials by decreasing the experimental efforts. Full article
(This article belongs to the Special Issue Development in Geopolymers)
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16 pages, 4623 KiB  
Article
Tablet Formulations of Polymeric Electrospun Fibers for the Controlled Release of Drugs with pH-Dependent Solubility
by Valeria Friuli, Silvia Pisani, Bice Conti, Giovanna Bruni and Lauretta Maggi
Polymers 2022, 14(10), 2127; https://doi.org/10.3390/polym14102127 - 23 May 2022
Cited by 9 | Viewed by 1998
Abstract
A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The [...] Read more.
A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The best approach is to increase the dissolution rate of the drugs at the different pHs and only then modify its release behavior from the pharmaceutical form. This work aims to demonstrate the ability of properly designed polymeric nanofibers in enhancing the release rate of model drugs with different pH-dependent solubility in the different physiological pHs of the gastrointestinal tract. Polymeric nanofibers loaded with meloxicam and carvedilol were prepared using the electrospinning technique and were then included in properly designed tablet formulations to obtain fast or sustained release dosage forms. The nanofibers and the tablets were characterized for their morphological, physico-chemical and dissolution properties. The tablets are able to deliver the dose according to the expected release behavior, and zero-order, first-order, Higuchi, Korsmeyer–Peppas and Hixon–Crowell kinetics models were used to analyze the prevailing release mechanism of the tablets. This study shows that the electrospun fibers can be advantageously included in oral dosage forms to improve their release performances. Full article
(This article belongs to the Special Issue Fiber and Polymer Composites: Processing, Simulation, Properties and Applications)
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14 pages, 3274 KiB  
Review
Influence of the Polarity of the Plasticizer on the Mechanical Stability of the Filler Network by Simultaneous Mechanical and Dielectric Analysis
by Sahbi Aloui, Horst Deckmann, Jürgen Trimbach and Jorge Lacayo-Pineda
Polymers 2022, 14(10), 2126; https://doi.org/10.3390/polym14102126 - 23 May 2022
Cited by 1 | Viewed by 1506
Abstract
Four styrene butadiene rubber (SBR) compounds were prepared to investigate the influence of the plasticizer polarity on the mechanical stability of the filler network using simultaneous mechanical and dielectric analysis. One compound was prepared without plasticizer and serves as a reference. The other [...] Read more.
Four styrene butadiene rubber (SBR) compounds were prepared to investigate the influence of the plasticizer polarity on the mechanical stability of the filler network using simultaneous mechanical and dielectric analysis. One compound was prepared without plasticizer and serves as a reference. The other three compounds were expanded with different plasticizers that have different polarities. Compared with an SBR sample without plasticizer, the conductivity of mechanically unloaded oil-extended SBR samples decreases by an order of magnitude. The polarity of the plasticizer shows hardly any influence because the plasticizers only affect the distribution of the filler clusters. Under static load, the dielectric properties seem to be oil-dependent. However, this behavior also results from the new distribution of the filler clusters caused by the mechanical damage and supported by the polarity grade of the plasticizer used. The Cole–Cole equation affirms these observations. The Cole–Cole relaxation time τ and thus, the position of maximal dielectric loss increases as the polarity of the plasticizer used is also increased. This, in turn, decreases the broadness parameter α implying a broader response function. Full article
(This article belongs to the Special Issue Advanced Testing of Soft Polymer Materials)
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15 pages, 6148 KiB  
Article
Ammonio Methacrylate Copolymer (Type B)-Diltiazem Interactions in Solid Dispersions and Microsponge Drug-Delivery Systems
by Iliyan Kolev, Nadezhda Ivanova, Tanya Topouzova-Hristova, Tanya Dimova, Pavlina Koseva, Ivalina Vasileva, Sonya Ivanova, Anton Apostolov, Gergana Alexieva, Atanas Tzonev and Vesselin Strashilov
Polymers 2022, 14(10), 2125; https://doi.org/10.3390/polym14102125 - 23 May 2022
Viewed by 1858
Abstract
This paper presents a complex analytical study on the distribution, solubility, amorphization, and compatibility of diltiazem within the composition of Eudragit RS 100-based particles of microspongeous type. For this purpose, a methodology combining attenuated total reflectance Fourier transform infrared (ATR-FTIR) absorption spectroscopy, differential [...] Read more.
This paper presents a complex analytical study on the distribution, solubility, amorphization, and compatibility of diltiazem within the composition of Eudragit RS 100-based particles of microspongeous type. For this purpose, a methodology combining attenuated total reflectance Fourier transform infrared (ATR-FTIR) absorption spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDX), and in vitro dissolution study is proposed. The correct interpretation of the FTIR and drug-dissolution results was guaranteed by the implementation of two contrasting reference models: physical drug–polymer mixtures and casting-obtained, molecularly dispersed drug–polymer composites (solid dispersions). The spectral behavior of the drug–polymer composites in the carbonyl frequency (νCO) region was used as a quality marker for the degree of their interaction/mutual solubility. A spectral-pattern similarity between the microsponge particles and the solid dispersions indicated the molecular-type dispersion of the former. The comparative drug-desorption study and the qualitative observations over the DSC and SEM-EDX results confirmed the successful synthesis of a homogeneous coamorphous microsponge-type formulation with excellent drug-loading capacity and “controlled” dissolution profile. Among them, the drug-delivery particles with 25% diltiazem content (M-25) were recognized as the most promising, with the highest population of drug molecules in the polymer bulk and the most suitable desorption profile. Furthermore, an economical and effective analytical algorithm was developed for the comprehensive physicochemical characterization of complex delivery systems of this kind. Full article
(This article belongs to the Special Issue Polymers and Drug Delivery)
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24 pages, 3208 KiB  
Article
Constitutive Equations for Analyzing Stress Relaxation and Creep of Viscoelastic Materials Based on Standard Linear Solid Model Derived with Finite Loading Rate
by Che-Yu Lin, Yi-Cheng Chen, Chen-Hsin Lin and Ke-Vin Chang
Polymers 2022, 14(10), 2124; https://doi.org/10.3390/polym14102124 - 23 May 2022
Cited by 9 | Viewed by 5747
Abstract
The viscoelastic properties of materials such as polymers can be quantitatively evaluated by measuring and analyzing the viscoelastic behaviors such as stress relaxation and creep. The standard linear solid model is a classical and commonly used mathematical model for analyzing stress relaxation and [...] Read more.
The viscoelastic properties of materials such as polymers can be quantitatively evaluated by measuring and analyzing the viscoelastic behaviors such as stress relaxation and creep. The standard linear solid model is a classical and commonly used mathematical model for analyzing stress relaxation and creep behaviors. Traditionally, the constitutive equations for analyzing stress relaxation and creep behaviors based on the standard linear solid model are derived using the assumption that the loading is a step function, implying that the loading rate used in the loading process of stress relaxation and creep tests is infinite. Using such constitutive equations may cause significant errors in analyses since the loading rate must be finite (no matter how fast it is) in a real stress relaxation or creep experiment. The purpose of this paper is to introduce the constitutive equations for analyzing stress relaxation and creep behaviors based on the standard linear solid model derived with a finite loading rate. The finite element computational simulation results demonstrate that the constitutive equations derived with a finite loading rate can produce accurate results in the evaluation of all viscoelastic parameters regardless of the loading rate in most cases. It is recommended that the constitutive equations derived with a finite loading rate should replace the traditional ones derived with an infinite loading rate to analyze stress relaxation and creep behaviors for quantitatively evaluating the viscoelastic properties of materials. Full article
(This article belongs to the Special Issue Computational Modeling of Polymers)
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22 pages, 4028 KiB  
Review
Bone Mineralization in Electrospun-Based Bone Tissue Engineering
by Dong-Jin Lim
Polymers 2022, 14(10), 2123; https://doi.org/10.3390/polym14102123 - 23 May 2022
Cited by 7 | Viewed by 4745
Abstract
Increasing the demand for bone substitutes in the management of bone fractures, including osteoporotic fractures, makes bone tissue engineering (BTE) an ideal strategy for solving the constant shortage of bone grafts. Electrospun-based scaffolds have gained popularity in BTE because of their unique features, [...] Read more.
Increasing the demand for bone substitutes in the management of bone fractures, including osteoporotic fractures, makes bone tissue engineering (BTE) an ideal strategy for solving the constant shortage of bone grafts. Electrospun-based scaffolds have gained popularity in BTE because of their unique features, such as high porosity, a large surface-area-to-volume ratio, and their structural similarity to the native bone extracellular matrix (ECM). To imitate native bone mineralization through which bone minerals are deposited onto the bone matrix, a simple but robust post-treatment using a simulated body fluid (SBF) has been employed, thereby improving the osteogenic potential of these synthetic bone grafts. This study highlights recent electrospinning technologies that are helpful in creating more bone-like scaffolds, and addresses the progress of SBF development. Biomineralized electrospun bone scaffolds are also reviewed, based on the importance of bone mineralization in bone regeneration. This review summarizes the potential of SBF treatments for conferring the biphasic features of native bone ECM architectures onto electrospun-based bone scaffolds. Full article
(This article belongs to the Special Issue Nanomaterials Template for Organic or Composite Polymers in Biomedical Application II)
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14 pages, 2161 KiB  
Article
Effect of Preparation Conditions on Application Properties of Environment Friendly Polymer Soil Consolidation Agent
by Shaoli Wang, Shengju Song, Xuping Yang, Zhengqi Xiong, Chaoxing Luo, Yongxiu Xia, Donglu Wei, Shaobo Wang, Lili Liu, Hong Wang, Lifang Sun, Lichao Du and Shaofeng Li
Polymers 2022, 14(10), 2122; https://doi.org/10.3390/polym14102122 - 23 May 2022
Cited by 2 | Viewed by 1696
Abstract
In order to improve the survival rate of transplanted seedlings and improve the efficiency of seedling transplantation, we developed an environmental friendly polymer konjac glucomannan (KGM)/chitosan (CA)/polyvinyl alcohol (PVA) ternary blend soil consolidation agent to consolidate the soil ball at the root of [...] Read more.
In order to improve the survival rate of transplanted seedlings and improve the efficiency of seedling transplantation, we developed an environmental friendly polymer konjac glucomannan (KGM)/chitosan (CA)/polyvinyl alcohol (PVA) ternary blend soil consolidation agent to consolidate the soil ball at the root of transplanted seedlings. In the previous research, we found that although the prepared KGM/CA/PVA ternary blend soil consolidation agent can consolidate the soil ball at the root of the seedling, the medium solid content of the adhesive was high, which affects its spraying at the root of the seedling. At the same time, the preparation temperature of the KGM/CA/PVA ternary blend was also high. Therefore, to reduce the energy consumption and the cost of the KGM/CA/PVA ternary blend soil consolidation agent in the preparation process, this paper studied the influence of preparation conditions on the application performance of the environmental friendly polymer soil consolidation agent. We aimed to reduce the highest value CA content and preparation temperature of the KGM/CA/PVA ternary blend adhesive on the premise of ensuring the consolidation performance of the KGM/CA/PVA ternary blend adhesive on soil balls. It was prepared for the popularization and application of the environmental friendly polymer KGM/CA/PVA ternary blend soil consolidation agent in seedling transplanting. Through this study, it was found that the film-forming performance of the adhesive was better when the KGM content was 4.5%, the CA content was in the range of 2–3%, the PVA content was in the range of 3–4%, and the preparation temperature was higher than 50 °C. The polymer soil consolidation agent prepared under this condition has a good application prospect in seedling transplanting. Full article
(This article belongs to the Special Issue Eco Polymeric Materials and Natural Polymer)
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9 pages, 4595 KiB  
Article
Physical Properties of Slide-Ring Material Reinforced Ethylene Propylene Diene Rubber Composites
by Gyuri Kim, Pranabesh Sahu and Jeong Seok Oh
Polymers 2022, 14(10), 2121; https://doi.org/10.3390/polym14102121 - 23 May 2022
Cited by 5 | Viewed by 1950
Abstract
High-damping rubber composites were prepared by mixing ethylene propylene diene monomer rubber (EPDM) with slide-ring (SR) materials using a two-roll mill, followed by a compression molding technique. SR material has a novel supramolecular structure with unique softness and slidable crosslink junctions. The mechanical [...] Read more.
High-damping rubber composites were prepared by mixing ethylene propylene diene monomer rubber (EPDM) with slide-ring (SR) materials using a two-roll mill, followed by a compression molding technique. SR material has a novel supramolecular structure with unique softness and slidable crosslink junctions. The mechanical strength, thermal stability, compression set property, and damping performance of the composites were investigated. The use of the high damping SR phase dispersed in the EPDM matrix displayed improved physical properties and damping performance compared to those of virgin rubber. As SR content increases in the composites, the damping factor of SR/EPDM blends becomes higher at room temperature. In addition to this, the SR composites showed excellent improvements in the compression set properties. The composites showed a compression set improvement of 35–38% compared to virgin EPDM. These improvements are due to the “pulley effect” of slide-ring materials. Therefore, these materials present a robust platform for making novel elastomer composites for high-performance damping and sealing applications. Full article
(This article belongs to the Special Issue RubberCon 2021: Innovative Pioneers for Smart and Sustainable Rubber Technology)
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13 pages, 1000 KiB  
Article
Design and Economic Assessment of Alternative Evaporation Processes for Poly-Lactic Acid Production
by Jonghun Lim, Hyungtae Cho, Kwon-chan Son, Yup Yoo and Junghwan Kim
Polymers 2022, 14(10), 2120; https://doi.org/10.3390/polym14102120 - 23 May 2022
Cited by 2 | Viewed by 1943
Abstract
In this work, alternative evaporation processes for PLA production were designed with economic assessment. The suggested processes are the multiple-effect evaporation (MEE) process and thermal vapor recompression (TVR)-assisted evaporation process. First, the MEE process can efficiently reuse waste heat by additional column installation, [...] Read more.
In this work, alternative evaporation processes for PLA production were designed with economic assessment. The suggested processes are the multiple-effect evaporation (MEE) process and thermal vapor recompression (TVR)-assisted evaporation process. First, the MEE process can efficiently reuse waste heat by additional column installation, thereby reducing the steam energy consumption. The proposed MEE process involves five columns, and after the evaporation in each column, the waste heat of the emitted vapor is reused to heat steam in the reboiler of the next column. Second, the suggested TVR-assisted evaporation process utilizes an additional steam ejector and recovers waste heat from the emitted vapor by increasing the pressure using high-pressure driving steam at the steam ejector. Each alternative process was modeled to predict the steam energy consumption, and to determine the cost-optimal process; the total annualized cost (TAC) of each alternative process was calculated as evaluation criteria. In the simulation results, the alternative processes using MEE and TVR reduced the steam consumption by 71.36% and 89.97%, respectively, compared to the conventional process. As a result of economic assessment, the cost-optimal process is the alternative process using TVR and the TAC can be decreased by approximately 90%. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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22 pages, 1313 KiB  
Review
A Comprehensive Review of Biopolymer Fabrication in Additive Manufacturing Processing for 3D-Tissue-Engineering Scaffolds
by Nurulhuda Arifin, Izman Sudin, Nor Hasrul Akhmal Ngadiman and Mohamad Shaiful Ashrul Ishak
Polymers 2022, 14(10), 2119; https://doi.org/10.3390/polym14102119 - 23 May 2022
Cited by 15 | Viewed by 2811
Abstract
The selection of a scaffold-fabrication method becomes challenging due to the variety in manufacturing methods, biomaterials and technical requirements. The design and development of tissue engineering scaffolds depend upon the porosity, which provides interconnected pores, suitable mechanical strength, and the internal scaffold architecture. [...] Read more.
The selection of a scaffold-fabrication method becomes challenging due to the variety in manufacturing methods, biomaterials and technical requirements. The design and development of tissue engineering scaffolds depend upon the porosity, which provides interconnected pores, suitable mechanical strength, and the internal scaffold architecture. The technology of the additive manufacturing (AM) method via photo-polymerization 3D printing is reported to have the capability to fabricate high resolution and finely controlled dimensions of a scaffold. This technology is also easy to operate, low cost and enables fast printing, compared to traditional methods and other additive manufacturing techniques. This article aims to review the potential of the photo-polymerization 3D-printing technique in the fabrication of tissue engineering scaffolds. This review paper also highlights the comprehensive comparative study between photo-polymerization 3D printing with other scaffold fabrication techniques. Various parameter settings that influence mechanical properties, biocompatibility and porosity behavior are also discussed in detail. Full article
(This article belongs to the Special Issue Scaffolds and Surfaces with Biomedical Applications)
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24 pages, 22160 KiB  
Article
Spontaneous DNA Synapsis by Forming Noncanonical Intermolecular Structures
by Viacheslav Severov, Vladimir Tsvetkov, Nikolay Barinov, Vladislav Babenko, Dmitry Klinov and Galina Pozmogova
Polymers 2022, 14(10), 2118; https://doi.org/10.3390/polym14102118 - 23 May 2022
Cited by 2 | Viewed by 1720
Abstract
We report the spontaneous formation of DNA-DNA junctions in solution in the absence of proteins visualised using atomic force microscopy. The synapsis position fits with potential G-quadruplex (G4) sites. In contrast to the Holliday structure, these conjugates have an affinity for G4 antibodies. [...] Read more.
We report the spontaneous formation of DNA-DNA junctions in solution in the absence of proteins visualised using atomic force microscopy. The synapsis position fits with potential G-quadruplex (G4) sites. In contrast to the Holliday structure, these conjugates have an affinity for G4 antibodies. Molecular modelling was used to elucidate the possible G4/IM-synaptic complex structures. Our results indicate a new role of the intermolecular noncanonical structures in chromatin architecture and genomic rearrangement. Full article
(This article belongs to the Special Issue Nucleic Acids as Polymers)
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24 pages, 3966 KiB  
Review
A Critical Review of Additive Manufacturing Techniques and Associated Biomaterials Used in Bone Tissue Engineering
by Yanli Wu, Yongtao Lu, Ming Zhao, Sergei Bosiakov and Lei Li
Polymers 2022, 14(10), 2117; https://doi.org/10.3390/polym14102117 - 23 May 2022
Cited by 25 | Viewed by 3764
Abstract
With the ability to fabricate complex structures while meeting individual needs, additive manufacturing (AM) offers unprecedented opportunities for bone tissue engineering in the biomedical field. However, traditional metal implants have many adverse effects due to their poor integration with host tissues, and therefore [...] Read more.
With the ability to fabricate complex structures while meeting individual needs, additive manufacturing (AM) offers unprecedented opportunities for bone tissue engineering in the biomedical field. However, traditional metal implants have many adverse effects due to their poor integration with host tissues, and therefore new material implants with porous structures are gradually being developed that are suitable for clinical medical applications. From the perspectives of additive manufacturing technology and materials, this article discusses a suitable manufacturing process for ideal materials for biological bone tissue engineering. It begins with a review of the methods and applicable materials in existing additive manufacturing technologies and their applications in biomedicine, introducing the advantages and disadvantages of various AM technologies. The properties of materials including metals and polymers, commonly used AM technologies, recent developments, and their applications in bone tissue engineering are discussed in detail and summarized. In addition, the main challenges for different metallic and polymer materials, such as biodegradability, anisotropy, growth factors to promote the osteogenic capacity, and enhancement of mechanical properties are also introduced. Finally, the development prospects for AM technologies and biomaterials in bone tissue engineering are considered. Full article
(This article belongs to the Topic Material and Process Innovations for 3D Printing Applications)
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13 pages, 1439 KiB  
Article
Innovative Approach for Controlling Black Rot of Persimmon Fruits by Means of Nanobiotechnology from Nanochitosan and Rosmarinic Acid-Mediated Selenium Nanoparticles
by Mohamed F. Salem, Ahmed A. Tayel, Fahad Mohammed Alzuaibr and Ramadan A. Bakr
Polymers 2022, 14(10), 2116; https://doi.org/10.3390/polym14102116 - 23 May 2022
Cited by 8 | Viewed by 2884
Abstract
The protection of persimmon fruits (Diospyros kaki L.) from postharvest fungal infestation with Alternaria alternata (A. alternate; black rot) is a major agricultural and economic demand worldwide. Edible coatings (ECs) based on biopolymers and phytocompounds were proposed to maintain fruit [...] Read more.
The protection of persimmon fruits (Diospyros kaki L.) from postharvest fungal infestation with Alternaria alternata (A. alternate; black rot) is a major agricultural and economic demand worldwide. Edible coatings (ECs) based on biopolymers and phytocompounds were proposed to maintain fruit quality, especially with nanomaterials’ applications. Chitosan nanoparticles (NCt), rosmarinic acid bio-mediated selenium nanoparticles (RA/SeNPs) and their composites were produced, characterized and evaluated as ECs for managing persimmon black rot. The constructed NCt, RA/SeNPs and NCt/RA/SeNPs composite had diminished particles’ size diameters. The ECs solution of 1% NCt and NCt/RA/SeNPs composite led to a significant reduction of A. alternata radial growth in vitro, with 77.4 and 97.2%, respectively. The most powerful ECs formula contained 10 mg/mL from NCt/RA/SeNPs composite, which significantly reduced fungal growth than imazalil fungicide. The coating of persimmon with nanoparticles-based ECs resulted in a significant reduction of black rot disease severity and incidence in artificially infected fruits; the treatment with 1% of NCt/RA/SeNPs could completely (100%) hinder disease incidence and severity in coated fruits, whereas imazalil reduced them by 88.6 and 73.4%, respectively. The firmness of fruits is greatly augmented after ECs treatments, particularly with formulated coatings with 1% NCt/RA/SeNPs composite, which maintain fruits firmness by 85.7%. The produced ECs in the current study, based on NCt/RA/SeNPs composite, are greatly recommended as innovatively constructed human-friendly matrix to suppress the postharvest destructive fungi (A. alternata) and maintain the shelf-life and quality of persimmon fruits. Full article
(This article belongs to the Special Issue Chitosan-Based Nanocomposite Materials and Their Applications)
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13 pages, 449 KiB  
Review
Thermocatalytic Conversion of Plastics into Liquid Fuels over Clays
by Evgeniy S. Seliverstov, Lyubov V. Furda and Olga E. Lebedeva
Polymers 2022, 14(10), 2115; https://doi.org/10.3390/polym14102115 - 23 May 2022
Cited by 5 | Viewed by 2785
Abstract
Recycling polymer waste is a great challenge in the context of the growing use of plastics. Given the non-renewability of fossil fuels, the task of processing plastic waste into liquid fuels seems to be a promising one. Thermocatalytic conversion is one of the [...] Read more.
Recycling polymer waste is a great challenge in the context of the growing use of plastics. Given the non-renewability of fossil fuels, the task of processing plastic waste into liquid fuels seems to be a promising one. Thermocatalytic conversion is one of the methods that allows obtaining liquid products of the required hydrocarbon range. Clays and clay minerals can be distinguished among possible environmentally friendly, cheap, and common catalysts. The moderate acidity and the presence of both Lewis and Brønsted acid sites on the surface of clays favor heavier hydrocarbons in liquid products of reactions occurring in their pores. Liquids produced with the use of clays are often reported as being in the gasoline and diesel range. In this review, the comprehensive information on the thermocatalytic conversion of plastics over clays obtained during the last two decades was summarized. The main experimental parameters for catalytic conversion of plastics according to the articles’ analysis, were the reaction temperature, the acidity of modified catalysts, and the catalyst-to-plastic ratio. The best clay catalysts observed were the following: bentonite/spent fluid cracking catalyst for high-density polyethylene (HDPE); acid-restructured montmorillonite for medium-density polyethylene (MDPE); neat kaolin powder for low-density polyethylene (LDPE); Ni/acid-washed bentonite clay for polypropylene (PP); neat kaolin for polystyrene (PS); Fe-restructured natural clay for a mixture of polyethylene, PP, PS, polyvinyl chloride (PVC), and polyethylene terephthalate (PET). The main problem in using natural clays and clay minerals as catalysts is their heterogeneous composition, which can vary even within the same deposit. The serpentine group is of interest in studying its catalytic properties as fairly common clay minerals. Full article
(This article belongs to the Special Issue Recycling and Resource Recovery from Polymers II)
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16 pages, 3469 KiB  
Article
Immediate Release Formulation of Inhaled Beclomethasone Dipropionate-Hydroxypropyl-Beta-Cyclodextrin Composite Particles Produced Using Supercritical Assisted Atomization
by Hsien-Tsung Wu, Yao-Hsiang Chuang, Han-Cyuan Lin, Tzu-Chieh Hu, Yi-Jia Tu and Liang-Jung Chien
Polymers 2022, 14(10), 2114; https://doi.org/10.3390/polym14102114 - 23 May 2022
Cited by 7 | Viewed by 1791
Abstract
In this study, the enhanced solubilization performance of a poorly soluble drug, beclomethasone dipropionate (BDP), was investigated using hydroxypropyl-β-cyclodextrin (HP-β-CD) and ethanol. The enhanced solubility of the drug was determined using the phase solubility method and correlated as a function of both HP-β-CD [...] Read more.
In this study, the enhanced solubilization performance of a poorly soluble drug, beclomethasone dipropionate (BDP), was investigated using hydroxypropyl-β-cyclodextrin (HP-β-CD) and ethanol. The enhanced solubility of the drug was determined using the phase solubility method and correlated as a function of both HP-β-CD and ethanol concentrations. The effective progress of drug solubility originated from the formation of cyclodextrin and BDP inclusion complexes and increase in the lipophilicity of the medium, by aqueous ethanol, for hydrophobic BDP. BDP and HP-β-CD composite particles were produced using supercritical assisted atomization (SAA) with carbon dioxide as the spraying medium, 54.2% (w/w) aqueous ethanol as the solvent, and an optimal amount of the dispersion enhancer leucine. The effect of the mass ratio of HP-β-CD to BDP (Z) on the in vitro aerosolization and in vitro dissolution performance of BDP–HP-β-CD composite particles was evaluated. The aerosolization performance showed that the fine particles fraction (FPF) of the composite particles increased with increasing mass ratio. The water-soluble excipient (HP-β-CD) effectively enhance the dissolution rate of BDP from composite particles. This study suggests that BDP–HP-β-CD composite particles produced using SAA can be employed in immediate-release drug formulations for pulmonary delivery. Full article
(This article belongs to the Special Issue Polymers and Drug Delivery Systems II)
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15 pages, 3407 KiB  
Article
3D Printing Manufacturing of Polydimethyl-Siloxane/Zinc Oxide Micro-Optofluidic Device for Two-Phase Flows Control
by Giovanna Stella, Matteo Barcellona, Lorena Saitta, Claudio Tosto, Gianluca Cicala, Antonino Gulino, Maide Bucolo and Maria Elena Fragalà
Polymers 2022, 14(10), 2113; https://doi.org/10.3390/polym14102113 - 22 May 2022
Cited by 4 | Viewed by 1920
Abstract
Tailored ZnO surface functionalization was performed inside a polydimethyl-siloxane (PDMS) microchannel of a micro-optofluidic device (mofd) to modulate its surface hydrophobicity to develop a method for fine tuning the fluid dynamics inside a microchannel. The wetting behavior of the surface is [...] Read more.
Tailored ZnO surface functionalization was performed inside a polydimethyl-siloxane (PDMS) microchannel of a micro-optofluidic device (mofd) to modulate its surface hydrophobicity to develop a method for fine tuning the fluid dynamics inside a microchannel. The wetting behavior of the surface is of particular importance if two different phases are used for system operations. Therefore, the fluid dynamic behavior of two immiscible fluids, (i) air–water and (ii) air–glycerol/water in PDMS mofds and ZnO-PDMS mofds was investigated by using different experimental conditions. The results showed that air–glycerol/water fluid was always faster than air–water flow, despite the microchannel treatment: however, in the presence of ZnO microstructures, the velocity of the air–glycerol/water fluid decreased compared with that observed for the air–water fluid. This behavior was associated with the strong ability of glycerol to create an H-bond network with the exposed surface of the zinc oxide microparticles. The results presented in this paper allow an understanding of the role of ZnO functionalization, which allows control of the microfluidic two-phase flow using different liquids that undergo different chemical interactions with the surface chemical terminations of the microchannel. This chemical approach is proposed as a control strategy that is easily adaptable for any embedded micro-device. Full article
(This article belongs to the Topic Material and Process Innovations for 3D Printing Applications)
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12 pages, 3080 KiB  
Article
Analysis of Thermoelastic Interaction in a Polymeric Orthotropic Medium Using the Finite Element Method
by Ibrahim Abbas, Aatef Hobiny, Hashim Alshehri, Sorin Vlase and Marin Marin
Polymers 2022, 14(10), 2112; https://doi.org/10.3390/polym14102112 - 22 May 2022
Cited by 4 | Viewed by 1273
Abstract
In this work, the finite element technique is employed to evaluate the effects of thermal relaxation durations on temperature, displacements, and stresses in a two-dimensional, polymeric, orthotropic, elastic medium. The problem is considered in a homogeneous, polymeric, orthotropic medium in the context of [...] Read more.
In this work, the finite element technique is employed to evaluate the effects of thermal relaxation durations on temperature, displacements, and stresses in a two-dimensional, polymeric, orthotropic, elastic medium. The problem is considered in a homogeneous, polymeric, orthotropic medium in the context of the Green and Lindsay model with two thermal relaxation times. The bounding surface of the half-space was subjected to a heat flux with an exponentially decaying pulse. Finite element techniques were used to solve the governing formulations, with eight-node isoparametric rectangular elements with three degrees of freedom (DOF) per node. The developed method was calculated using numerical results applied to the polymeric, orthotropic medium. The findings were implemented and visually shown. Finally, the results were displayed to demonstrate the differences between classical dynamic coupling (CT), the Lord–Shulman (LS) and the Green and Lindsay (GL) models. Full article
(This article belongs to the Special Issue Computational Modeling of Polymers)
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19 pages, 2774 KiB  
Article
Influence of Lignin Content and Pressing Time on Plywood Properties Bonded with Cold-Setting Adhesive Based on Poly (Vinyl Alcohol), Lignin, and Hexamine
by Muhammad Adly Rahandi Lubis, Ahmad Labib, Sudarmanto, Fazhar Akbar, Arif Nuryawan, Petar Antov, Lubos Kristak, Antonios Nikolaos Papadopoulos and Antonio Pizzi
Polymers 2022, 14(10), 2111; https://doi.org/10.3390/polym14102111 - 22 May 2022
Cited by 24 | Viewed by 2900
Abstract
The sustainability, performance, and cost of production in the plywood industry depend on wood adhesives and the hot-pressing process. In this study, a cold-setting plywood adhesive was developed based on polyvinyl alcohol (PVOH), high-purity lignin, and hexamine. The influence of lignin content (10%, [...] Read more.
The sustainability, performance, and cost of production in the plywood industry depend on wood adhesives and the hot-pressing process. In this study, a cold-setting plywood adhesive was developed based on polyvinyl alcohol (PVOH), high-purity lignin, and hexamine. The influence of lignin content (10%, 15%, and 20%) and cold-pressing time (3, 6, 12, and 24 h) on cohesion, adhesion, and formaldehyde emission of plywood were investigated through physical, chemical, thermal, and mechanical analyses. The increased lignin addition level lowered the solids content, which resulted in reduced average viscosity of the adhesive. As a result, the cohesion strength of the adhesive formulation with 10% lignin addition was greater than those of 15% and 20% lignin content. Markedly, the adhesive formulation containing a 15% lignin addition level exhibited superior thermo-mechanical properties than the blends with 10% and 20% lignin content. This study showed that 10% and 15% lignin content in the adhesive resulted in better cohesion strength than that with 20% lignin content. However, statistical analysis revealed that the addition of 20% lignin in the adhesive and using a cold-pressing time of 24 h could produce plywood that was comparable to the control polyurethane resins, i.e., dry tensile shear strength (TSS) value of 0.95 MPa, modulus of rupture (MOR) ranging from 35.8 MPa, modulus of elasticity (MOE) values varying from 3980 MPa, and close-to-zero formaldehyde emission (FE) of 0.1 mg/L, which meets the strictest emission standards. This study demonstrated the feasibility of fabricating eco-friendly plywood bonded with PVOH–lignin–hexamine-based adhesive using cold pressing as an alternative to conventional plywood. Full article
(This article belongs to the Collection Wood Composites)
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12 pages, 7030 KiB  
Article
A U-Shaped Optical Fiber Temperature Sensor Coated with Electrospinning Polyvinyl Alcohol Nanofibers: Simulation and Experiment
by Yen-Lung Chou, Hsin-Yi Wen, Yu-Qiao Weng, Yi-Ching Liu, Chao-Wei Wu, Hsiang-Cheng Hsu and Chia-Chin Chiang
Polymers 2022, 14(10), 2110; https://doi.org/10.3390/polym14102110 - 22 May 2022
Cited by 14 | Viewed by 2138
Abstract
This study describes the fabrication of an electrospun, U-shaped optical fiber sensor for temperature measurements. The sensor is based on single mode fibers and was fabricated into a U-shaped optical fiber sensor through flame heating. This study applied electrospinning to coat PVA, a [...] Read more.
This study describes the fabrication of an electrospun, U-shaped optical fiber sensor for temperature measurements. The sensor is based on single mode fibers and was fabricated into a U-shaped optical fiber sensor through flame heating. This study applied electrospinning to coat PVA, a polymer, onto the sensor layer to reduce its sensitivity to humidity. The sensor is used to measure temperature variations ranging from 30 °C to 100 °C. The objectives of this study were to analyze the sensitivity variation of the sensor with different sensor layer thicknesses resulting from different electrospinning durations, as well as to simulate the wavelength signals generated at different electrospinning durations using COMSOL. The results revealed that the maximum wavelength sensitivity, transmission loss sensitivity, and linearity of the sensor were 25 dBm/°C, 70 pm/°C, and 0.956, respectively. Longer electrospinning durations resulted in thicker sensor layers and higher sensor sensitivity, that wavelength sensitivity of the sensor increased by 42%. Full article
(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)
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25 pages, 12699 KiB  
Article
Analysis of Sheep Wool-Based Composites for Building Insulation
by Tünde-Orsolya Dénes, Raluca Iştoan, Daniela Roxana Tǎmaş-Gavrea, Daniela Lucia Manea, Andreea Hegyi, Florin Popa and Ovidiu Vasile
Polymers 2022, 14(10), 2109; https://doi.org/10.3390/polym14102109 - 22 May 2022
Cited by 11 | Viewed by 5392
Abstract
The aim of this paper is to propose ecological thermal insulation materials that meet the goals of sustainability but also fulfill the imposed thermal performance requirements. This paper studies new composite materials based on sheep wool from the perspective of thermal conductivity. The [...] Read more.
The aim of this paper is to propose ecological thermal insulation materials that meet the goals of sustainability but also fulfill the imposed thermal performance requirements. This paper studies new composite materials based on sheep wool from the perspective of thermal conductivity. The composites were prepared using two types of binder: acrylic-polyurethane resin and natural rubber latex, which were applied to the wool fibres through different methods and percentages. Based on the obtained results of thermal conductivity, two types of samples were selected for further analysis, which aimed to determine the microstructure, chemical composition, water absorption, attack of microorganisms, water vapour permeability, hygrothermal adsorption characteristics and sound absorption of the samples. In order to analyse the variation of thermal conductivity, the following parameters were taken into account: thickness, density, type of binder and percentage of binder. Following the obtained results, it was observed that the value of the thermal conductivity of the samples varies between 0.0324 and 0.0436 W/mK. It was found that all the samples prepared and analysed in this study fulfil the national criteria for the thermal performance of thermal insulation material. After conducting the in-depth analysis of the two selected sample types, it was concluded that both materials have good sound absorption characteristics over the considered frequency range. In addition, as it was expected from the natural fibres, the samples had low resistance against the attack of microorganisms and water-related tests. Full article
(This article belongs to the Special Issue Development in Fiber-Reinforced Polymer Composites)
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19 pages, 3017 KiB  
Article
Electrospun Smart Oxygen Indicating Tag for Modified Atmosphere Packaging Applications: Fabrication, Characterization and Storage Stability
by Shivam Panwar, Narender Raju Panjagari, Ashish Kumar Singh, Gaurav Kr Deshwal, Richa Badola, Prashant Saurabh Minz, Gulden Goksen, Alexandru Rusu and Monica Trif
Polymers 2022, 14(10), 2108; https://doi.org/10.3390/polym14102108 - 21 May 2022
Cited by 5 | Viewed by 1861
Abstract
Pack integrity is essential for the success of modified atmosphere packaging of food products. Colorimetric oxygen leak indicators or tags are simple and smart tools that can depict the presence or absence of oxygen within a package. However, not many bio-based electrospun materials [...] Read more.
Pack integrity is essential for the success of modified atmosphere packaging of food products. Colorimetric oxygen leak indicators or tags are simple and smart tools that can depict the presence or absence of oxygen within a package. However, not many bio-based electrospun materials were explored for this purpose. Ultraviolet light-activated kappa-carrageenan-based smart oxygen indicating tag was developed using the electrospinning technique in this study and its stability during storage was determined. Kappa-carrageenan was used with redox dye, sacrificial electron donor, photocatalyst, and solvent for preparing oxygen indicating electrospun tag. Parameters of electrospinning namely flow rate of the polymer solution, the distance between spinneret and collector, and voltage applied were optimized using Taguchi L9 orthogonal design. Rheological and microstructural studies revealed that the electrospinning solution was pseudoplastic and the mat fibers were compact and non-woven with an average fiber size of 1–2 microns. Oxygen sensitivity at different oxygen concentrations revealed that the tag was sensitive enough to detect as low as 0.4% oxygen. The developed tag was stable for at least 60 days when stored in dark at 25 °C and 65% RH. The developed mat could be highly useful in modified atmosphere packaging applications to check seal integrity in oxygen devoid packages. Full article
(This article belongs to the Section Biomacromolecules, Biobased and Biodegradable Polymers)
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14 pages, 2599 KiB  
Article
Effects of Disinfection and Steam Sterilization on the Mechanical Properties of 3D SLA- and DLP-Printed Surgical Guides for Orthodontic Implant Placement
by Silvia Izabella Pop, Mircea Dudescu, Sorin Gheorghe Mihali, Mariana Păcurar and Dana Cristina Bratu
Polymers 2022, 14(10), 2107; https://doi.org/10.3390/polym14102107 - 21 May 2022
Cited by 9 | Viewed by 2197
Abstract
Three-dimensional printed surgical guides increase the precision of orthodontic mini-implant placement. The purpose of this research was to investigate the effects of disinfection and of two types of autoclave sterilization on the mechanical properties of 3D printed surgical guides obtained via the SLA [...] Read more.
Three-dimensional printed surgical guides increase the precision of orthodontic mini-implant placement. The purpose of this research was to investigate the effects of disinfection and of two types of autoclave sterilization on the mechanical properties of 3D printed surgical guides obtained via the SLA (stereolithography) and DLP (digital light processing) printing methods. A total of 96 standard specimens (48 SLA and 48 DLP) were printed to analyze the tensile and flexural properties of the materials. A total of 80 surgical guide (40 SLA and 40 DLP) specimens from each printing method were classified into four groups: CG (control group); G1, disinfected with 4% Gigasept (Gigasept Instru AF; Schülke & Mayer Gmbh, Norderstedt, Germany); G2, autoclave-sterilized (121 °C); and G3, autoclave-sterilized (134 °C). Significant differences in the maximum compressive load were determined between the groups comprising the DLP-(p < 0.001) and the SLA- (p < 0.001) printed surgical guides. Groups G2 (p = 0.001) and G3 (p = 0.029) showed significant parameter modifications compared with the CG. Disinfection with 4% Gigasept (Gigasept Instru AF; Schülke & Mayer Gmbh, Norderstedt, Germany) is suitable both for SLA- and DLP-printed surgical guides. Heat sterilization at both 121 °C and 134 °C modified the mechanical properties of the surgical guides. Full article
(This article belongs to the Special Issue High-Performance 3D Printing Polymers)
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19 pages, 7926 KiB  
Review
Modeling and Experimental Studies on Polymer Melting and Flow in Injection Molding
by Krzysztof Wilczyński, Krzysztof J. Wilczyński and Kamila Buziak
Polymers 2022, 14(10), 2106; https://doi.org/10.3390/polym14102106 - 21 May 2022
Cited by 12 | Viewed by 3979
Abstract
Injection molding, in addition to extrusion, is the most important technology in the polymer processing industry. When modeling injection molding, the global approach is necessary to take into account the solid polymer transport, polymer melting and the polymer melt flow. The model of [...] Read more.
Injection molding, in addition to extrusion, is the most important technology in the polymer processing industry. When modeling injection molding, the global approach is necessary to take into account the solid polymer transport, polymer melting and the polymer melt flow. The model of polymer melting is fundamental for the development of such a global injection molding model. In the paper, the state-of-the-art of modeling and experimentation of the flow and melting in injection molding machines has been presented and discussed. It has been concluded that the existing mathematical models have no strong experimental basis. Therefore, experimentation of the polymer flow and melting in the injection molding machine has been performed, and the effect of processing conditions: the screw speed, the plasticating stroke and the back pressure on the process course has been investigated. Starving in the beginning sections of the screw has been observed, which was not presented in the literature so far. The novel concepts of injection molding modeling have been discussed. Full article
(This article belongs to the Special Issue Advances in Screw Processing of Polymeric Materials - In Memory of Professor James Lindsay White)
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16 pages, 7429 KiB  
Article
Effect of Reinforcements and 3-D Printing Parameters on the Microstructure and Mechanical Properties of Acrylonitrile Butadiene Styrene (ABS) Polymer Composites
by Ved S. Vakharia, Mrityunjay Singh, Anton Salem, Michael C. Halbig and Jonathan A. Salem
Polymers 2022, 14(10), 2105; https://doi.org/10.3390/polym14102105 - 21 May 2022
Cited by 6 | Viewed by 1990
Abstract
Fused filament fabrication (FFF) systems utilize a wide variety of commercially available filaments, including Acrylonitrile Butadiene Styrene (ABS), as well as their variants. However, the effect of filament composition, reinforcements (chopped fibers and nanotubes), and 3-D printing variables on the microstructure and thermomechanical [...] Read more.
Fused filament fabrication (FFF) systems utilize a wide variety of commercially available filaments, including Acrylonitrile Butadiene Styrene (ABS), as well as their variants. However, the effect of filament composition, reinforcements (chopped fibers and nanotubes), and 3-D printing variables on the microstructure and thermomechanical behavior is not well understood, and systematic studies are needed. In this work, different types of ABS materials with and without carbon fiber and carbon nanotube reinforcements were printed with multiple print layer heights. The microstructure, elastic behavior, tensile behavior, and fracture toughness of 3-D printed materials were characterized. ABS material systems printed at a low print layer height of 0.1 mm outperformed those printed at a larger height of 0.2 mm. Carbon nanotube reinforcements result in significant improvement in the strength and elastic modulus of ABS materials. Printed coupons of ABS with carbon nanotubes achieve an ultimate strength of 34.18 MPa, while a premium grade ABS coupon achieved 28.75 MPa when printed with the same print layer heights. Samples of ABS with chopped carbon fiber show an ultimate strength of 27.25 MPa, due primarily to the significant porosity present in the filament. Elastic moduli and fracture toughness measured using dynamic and mechanical methods show similar trends as a function of layer height. The effects of different materials, reinforcements, and printing parameters on the microstructure and mechanical properties are discussed in detail. Full article
(This article belongs to the Special Issue Fabrication of Polymer Materials Using 3D/4D Printing for Different Applications)
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16 pages, 2056 KiB  
Article
Kinetic, Isotherm, and Equilibrium Investigation of Cr(VI) Ion Adsorption on Amine-Functionalized Porous Silica Beads
by Anzu Nishino, Ayane Taki, Hiromichi Asamoto, Hiroaki Minamisawa and Kazunori Yamada
Polymers 2022, 14(10), 2104; https://doi.org/10.3390/polym14102104 - 21 May 2022
Cited by 3 | Viewed by 1917
Abstract
The hexavalent chromium (Cr(VI)) ion adsorption properties were conferred to porous silica beads by introducing alkylamine chains through functionalization with an aminosilane coupling agent, [3-(2-aminoethylamino)propyl]triethoxysilane (AEAPTES), or with an epoxysilane coupling agent, (3-glycidyloxypropyl)triethoxysilane (GOPTES), and polyfunctional amine compounds or poly-ethylenimines (PEIs). The presence [...] Read more.
The hexavalent chromium (Cr(VI)) ion adsorption properties were conferred to porous silica beads by introducing alkylamine chains through functionalization with an aminosilane coupling agent, [3-(2-aminoethylamino)propyl]triethoxysilane (AEAPTES), or with an epoxysilane coupling agent, (3-glycidyloxypropyl)triethoxysilane (GOPTES), and polyfunctional amine compounds or poly-ethylenimines (PEIs). The presence of amino groups on the silica beads was confirmed by XPS and the amount of amino groups increased to 0.270 mmol/g by increasing the AEAPTES concentration and/or reaction time. The adsorption capacity of the silica beads functionalized with AEAPTES was the maximum at the initial pH value of 3.0 and the initial adsorption rate increased with an increase in the temperature. The adsorption capacity increased with an increase in the amount of amino groups at pH 3.0 and 30 °C. The adsorption behavior obeyed the pseudo-second order kinetic model and was well expressed by the Langmuir isotherm. These results support that Cr(VI) ion adsorption is accomplished through the electrostatic interaction between protonated amino groups and HCrO4− ions. In addition, the adsorption capacity further increased to 0.192–0.320 mmol/g by treating the GOPTES-treated silica beads with triethylenetetramine, pentaethylenehexamine, or PEI. These empirical, equilibria, and kinetic aspects obtained in this study support that the porous silica-based adsorbents prepared in this study can be applied to the removal of Cr(VI) ions. Full article
(This article belongs to the Special Issue Molecular Simulation and Modeling of Polymers)
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14 pages, 1499 KiB  
Article
Digestibility Kinetics of Polyhydroxyalkanoate and Poly(butylene succinate-co-adipate) after In Vitro Fermentation in Rumen Fluid
by Hailey Galyon, Samuel Vibostok, Jane Duncan, Gonzalo Ferreira, Abby Whittington, Kirk Havens, Jason McDevitt and Rebecca Cockrum
Polymers 2022, 14(10), 2103; https://doi.org/10.3390/polym14102103 - 21 May 2022
Cited by 3 | Viewed by 2017
Abstract
Using polyhydroxyalkanoate (PHA) materials for ruminal boluses could allow for longer sustained release of drugs and hormones that would reduce administration time and unneeded animal discomfort caused by continuous administration. The objective of this study was to determine ruminal degradability and kinetics of [...] Read more.
Using polyhydroxyalkanoate (PHA) materials for ruminal boluses could allow for longer sustained release of drugs and hormones that would reduce administration time and unneeded animal discomfort caused by continuous administration. The objective of this study was to determine ruminal degradability and kinetics of biodegradable polymers and blends. A proprietary PHA-based polymer, poly(butylene succinate-co-adipate) (PBSA), PBSA:PHA melt blends, and forage controls were incubated in rumen fluid for up to 240 h. Mass loss was measured after each incubation time, and digestion kinetic parameters were estimated. Thermogravimetric, differential scanning calorimetry, and intrinsic viscosity analyses were conducted on incubated samples. Generally, across treatments, mass loss was significant by 96 h with a minimum increase of 0.25% compared to 0 h but did not change thereafter. Degradation kinetics demonstrated that polymer treatments were still in the exponential degradation phase at 240 h with a maximum disappearance rate of 0.0031 %/h. Melting temperature increased, onset thermal degradation temperature decreased, and intrinsic viscosity decreased with incubation time, indicating structural changes to the polymers. Based on these preliminary findings, the first stage of degradation occurs within 24 h and PHA degrades slowly. However, further ruminal degradation studies of biodegradable polymers are warranted to elucidate maximum degradation and its characteristics. Full article
(This article belongs to the Special Issue Stabilization of Bio-Based Polymeric Materials)
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4 pages, 658 KiB  
Editorial
Graphene-Based Polymer Nanocomposites: Recent Advances
by Ana M. Díez-Pascual
Polymers 2022, 14(10), 2102; https://doi.org/10.3390/polym14102102 - 21 May 2022
Cited by 12 | Viewed by 2049
Abstract
Carbon-based nanomaterials are currently attracting a great deal of interest due to their unique chemical, optical, and electronic properties, which make them suitable for a broad range of uses, including supercapacitors, solar cells, fuel cells, lithium batteries, biomedicine, and so forth [...] Full article
(This article belongs to the Special Issue Graphene-Based Polymer Nanocomposites: Recent Advances)
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13 pages, 2972 KiB  
Article
Fabrication of Cross-Linked PMMA/SnO2 Nanocomposites for Highly Efficient Removal of Chromium (III) from Wastewater
by Nazeeha S. Alkayal
Polymers 2022, 14(10), 2101; https://doi.org/10.3390/polym14102101 - 21 May 2022
Cited by 5 | Viewed by 1700
Abstract
In recent times, developments in polymer application properties have required the design of different polymer structures more than ever. Cross-linked polymers (CPs) could be considered a good candidate material for potential applications when used in conjunction with nanoparticles. Cross-linked polymethyl methacrylate nanocomposites are [...] Read more.
In recent times, developments in polymer application properties have required the design of different polymer structures more than ever. Cross-linked polymers (CPs) could be considered a good candidate material for potential applications when used in conjunction with nanoparticles. Cross-linked polymethyl methacrylate nanocomposites are considered to be one of the most commonly polymeric adsorbents due to their varied and simple modification methods. A new class of C-PMMA/SnO2(a–d) nanocomposites have been fabricated as surface-selective adsorbents of Cr (III) with a good yield and different loading of SnO2 nanoparticles. The morphology, molecular structures, and thermal stability of the new cross-linked polymers were examined using a Scanning electron microscope (SEM), the Fourier Transform Infrared method (FTIR), X-ray diffraction (XRD), and Thermogravimetric Analysis (TGA). The adsorption study of C-PMMA/SnO2 was investigated, and an efficient level of adsorption for Cr (III) cations was detected. To evaluate the potential for the new polymers to be used as adsorbents against Cr (III) ions, the contact time, the initial concentration of Cr (III), and the effects of pH were studied. The introduction of SnO2 into the polymer network enhanced the efficiency of the adsorption of heavy metals. The C-PMMA/SnO2 is highly efficient at removing Cr (III) ions in wastewater samples at pH 6 for one hour. The adsorption study demonstrated that the adsorption capacity of C-PMMA/SnO2c for Cr (III) was 1.76 mg /g, and its adsorption isotherm agreed with the Langmuir adsorption model. Full article
(This article belongs to the Special Issue Functional Metal-Polymer Composites: Formation, Properties and Applications)
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13 pages, 3601 KiB  
Article
In Vitro Biocompatibility and Degradation Analysis of Mass-Produced Collagen Fibers
by Kiran M. Ali, Yihan Huang, Alaowei Y. Amanah, Nasif Mahmood, Taylor C. Suh and Jessica M. Gluck
Polymers 2022, 14(10), 2100; https://doi.org/10.3390/polym14102100 - 21 May 2022
Cited by 3 | Viewed by 2527
Abstract
Automation and mass-production are two of the many limitations in the tissue engineering industry. Textile fabrication methods such as electrospinning are used extensively in this field because of the resemblance of the extracellular matrix to the fiber structure. However, electrospinning has many limitations, [...] Read more.
Automation and mass-production are two of the many limitations in the tissue engineering industry. Textile fabrication methods such as electrospinning are used extensively in this field because of the resemblance of the extracellular matrix to the fiber structure. However, electrospinning has many limitations, including the ability to mass-produce, automate, and reproduce products. For this reason, this study evaluates the potential use of a traditional textile method such as spinning. Apart from mass production, these methods are also easy, efficient, and cost-effective. This study uses bovine-derived collagen fibers to create yarns using the traditional ring spinning method. The collagen yarns are proven to be biocompatible. Enzymatic biodegradability was also confirmed for its potential use in vivo. The results of this study prove the safety and efficacy of the material and the fabrication method. The material encourages higher cell proliferation and migration compared to tissue culture-treated plastic plates. The process is not only simple but is also streamlined and replicable, resulting in standardized products that can be reproduced. Full article
(This article belongs to the Special Issue Biomaterials for Tissue Engineering and Regeneration)
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