Research

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13 pages, 2730 KiB

Open AccessArticle

Green Synthetic Approaches of 2-Hydrazonothiazol-4(5H)-ones Using Sustainable Barium Oxide-Chitosan Nanocomposite Catalyst

by Khaled D. Khalil, Sayed M. Riyadh, Ali H. Bashal, Tariq Z. Abolibda and Sobhi M. Gomha

Polymers 2023, 15(18), 3817; https://doi.org/10.3390/polym15183817 - 19 Sep 2023

Viewed by 1017

Abstract

The diverse applications of metal oxide-biopolymer matrix as a nanocomposite heterogenous catalyst have caused many researches to scrutinize the potential of this framework. In this study, a novel hybrid barium oxide-chitosan nanocomposite was synthesized through a facile and cost-effective co-precipitation method by doping [...] Read more.

The diverse applications of metal oxide-biopolymer matrix as a nanocomposite heterogenous catalyst have caused many researches to scrutinize the potential of this framework. In this study, a novel hybrid barium oxide-chitosan nanocomposite was synthesized through a facile and cost-effective co-precipitation method by doping barium oxide nanoparticles within the chitosan matrix at a weight percentage of 20 wt.% BaO-chitosan. A thin film of the novel hybrid material was produced by casting the nanocomposite solution in a petri dish. Several instrumental methods, including Fourier-transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), were used to analyze and characterize the structure of the BaO-CS nanocomposite. The chemical interaction with barium oxide molecules resulted in a noticeable displacement of the most significant chitosan-specific peaks in the FTIR spectra. When the surface morphology of SEM graphs was analyzed, a dramatic morphological change in the chitosan surface was also discovered; this morphological change can be attributed to the surface adsorption of BaO molecules. Additionally, the patterns of the XRD demonstrated that the crystallinity of the material, chitosan, appears to be enhanced upon interaction with barium oxide molecules with the active sites, OH and NH₂ groups, along the chitosan backbone. The prepared BaO-CS nanocomposite can be used successfully as an effective heterogenous recyclable catalyst for the reaction of N,N′-(alkane-diyl)bis(2-chloroacetamide) with 2-(arylidinehydrazine)-1-carbothioamide as a novel synthetic approach to prepare 2-hydrazonothiazol-4(5H)-ones. This new method provides a number of benefits, including quick and permissive reaction conditions, better reaction yields, and sustainable catalysts for multiple uses. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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13 pages, 6949 KiB

Open AccessArticle

Four-Dimensionally Printed Continuous Carbon Fiber-Reinforced Shape Memory Polymer Composites with Diverse Deformation Based on an Inhomogeneous Temperature Field

by Hongyan Wang, Zhongsen Zhang, Kunkun Fu and Yan Li

Polymers 2023, 15(18), 3740; https://doi.org/10.3390/polym15183740 - 12 Sep 2023

Cited by 1 | Viewed by 1349

Abstract

Four-dimensionally printed continuous carbon fiber-reinforced shape memory polymer composite (CFSMPC) is a smart material with the ability to bear loads and undergo deformation. The deformation of CFSMPC can be driven by the electrothermal effect of carbon fibers. In this study, the effect of [...] Read more.

Four-dimensionally printed continuous carbon fiber-reinforced shape memory polymer composite (CFSMPC) is a smart material with the ability to bear loads and undergo deformation. The deformation of CFSMPC can be driven by the electrothermal effect of carbon fibers. In this study, the effect of temperature on the shape memory recovery performance of polylactic acid (PLA) was first studied experimentally. Continuous carbon fibers were incorporated into PLA to design CFSMPCs with thickness gradients and hand-shaped structures, respectively. The distribution strategy of the carbon fibers was determined based on simulations of the electrically driven shape recovery process of the aforementioned structures. Both the simulations and experiments demonstrated that the electrification of the CFSMPC structures resulted in an inhomogeneous temperature field, leading to distinct deformation recovery processes. Eventually, a precise unfolding was achieved for the thickness gradient structure and the five fingers in the hand-shaped structure by utilizing a safe voltage of 6 V. This demonstrates that the 4D-printed CFSMPC with diverse deformations based on an inhomogeneous temperature field has potential applications in actuators, reconfigurable devices, and other fields. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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17 pages, 19245 KiB

Open AccessArticle

Construction of Fluorescent Conjugated Polytriazole Containing Double-Decker Silsesquioxane: Click Polymerization and Thermal Stability

by Chia-Husan Chiang, Mohamed Gamal Mohamed, Wei-Cheng Chen, Manivannan Madhu, Wei-Lung Tseng and Shiao-Wei Kuo

Polymers 2023, 15(2), 331; https://doi.org/10.3390/polym15020331 - 09 Jan 2023

Cited by 4 | Viewed by 1641

Abstract

This study synthesized two azide-functionalized monomers through p-dichloro xylene and double-decker silsesquioxane (DDSQ) units with NaN₃ to form DB-N₃ and DDSQ-N₃ monomers, respectively. In addition, five different propargyl-functionalized monomers were also prepared from hydroquinone, bisphenol A, bis(4-hydroxyphenyl)methanone, 2,4-dihydroxybenzaldehyde (then [...] Read more.

This study synthesized two azide-functionalized monomers through p-dichloro xylene and double-decker silsesquioxane (DDSQ) units with NaN₃ to form DB-N₃ and DDSQ-N₃ monomers, respectively. In addition, five different propargyl-functionalized monomers were also prepared from hydroquinone, bisphenol A, bis(4-hydroxyphenyl)methanone, 2,4-dihydroxybenzaldehyde (then reacted with hydrazine hydrate solution) and 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethene with propargyl bromide to form P-B, P-BPA, P-CO, P-NP, and P-TPE monomers, respectively. As a result, various DDSQ-based main chain copolymers could be synthesized using Cu(I)-catalyzed click polymerization through DDSQ-N₃ with different propargyl-functionalized monomers, of which the chemical structure and molecular weight could be confirmed by using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) analyses. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy analyses also could characterize the thermal stability, morphology, and optical behaviors of these DDSQ-based copolymers. All results indicate that the incorporation of an inorganic DDSQ cage could improve the thermal stability such as thermal decomposition temperature and char yield, because of the DDSQ dispersion homogeneously in the copolymer matrix, and this would then affect the optical properties of NP and TPE units in this work. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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18 pages, 5871 KiB

Open AccessArticle

The Effect of the Extrusion Method on Processing and Selected Properties of Poly(3-hydroxybutyric-co-3-hydroxyvaleric Acid)-Based Biocomposites with Flax and Hemp Fibers

by Grzegorz Janowski, Wiesław Frącz, Łukasz Bąk and Tomasz Trzepieciński

Polymers 2022, 14(24), 5370; https://doi.org/10.3390/polym14245370 - 08 Dec 2022

Cited by 5 | Viewed by 1565

Abstract

The paper presents a comparative analysis of two extrusion methods of biocomposites with a poly(3-hydroxybutyrate-co-3-hydroxyvalerate acid) (PHBV) matrix filled with flax and hemp fibers in terms of biopolymer production, its processing in the further injection process, and an evaluation of the mechanical and [...] Read more.

The paper presents a comparative analysis of two extrusion methods of biocomposites with a poly(3-hydroxybutyrate-co-3-hydroxyvalerate acid) (PHBV) matrix filled with flax and hemp fibers in terms of biopolymer production, its processing in the further injection process, and an evaluation of the mechanical and functional properties of the products. Biocomposites containing 15% by weight of the filler were produced using single- and twin-screw extruders. The biocomposites were then processed by injection molding and then, among other things, the pressures in the mold cavity during processing were analyzed. The produced samples were tested by means of the following tests: uniaxial tensile strength, hardness, and impact tensile strength. The biocomposite’s microstructure was also analyzed using scanning electron microscopy (SEM), as were the shrinkage and water absorption of the manufactured products. In addition, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were performed. It was found that the extrusion method changed significantly the geometry of the filler fibers and the processing capabilities of the manufactured materials. Significant differences in the mechanical and functional properties of the obtained biocomposite products were also found. On their basis, the advantages and disadvantages of both extrusion methods were discussed. Most of the obtained properties of injection products indicate the choice of single-screw extrusion. The products were characterized by slightly better mechanical properties and lower processing shrinkage. In turn, composites obtained by the screw method were characterized by lower water absorption and lower viscosity of the composite during injection molding. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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17 pages, 4396 KiB

Open AccessArticle

Prediction of Critical Buckling Load on Open Cross-Section Columns of Flax/PLA Green Composites

by Liu Jiao-Wang, Sergio Puerta-Hueso, David Pedroche and Carlos Santiuste

Polymers 2022, 14(23), 5095; https://doi.org/10.3390/polym14235095 - 23 Nov 2022

Cited by 1 | Viewed by 1170

Abstract

The present work aims to analyze the buckling behavior of nonlinear elastic columns with different open cross-sections and slenderness ratios to verify the limits of the modified Ludwick law to predict the critical buckling load. The results of the analytical formulation based on [...] Read more.

The present work aims to analyze the buckling behavior of nonlinear elastic columns with different open cross-sections and slenderness ratios to verify the limits of the modified Ludwick law to predict the critical buckling load. The results of the analytical formulation based on the modified Ludwick law are compared with a FEM numerical model using the Marlow hyperelastic behavior and experimental results conducted on flax/PLA specimens with three different open cross-sections. The comparative results show that the numerical predictions agree with the experimental results in all the cases. The FEM model can exactly reproduce the buckling behavior of the C-section columns. However, the prediction errors for the C90 and C180 columns are higher than for the C60 columns. Moreover, the theoretical estimations indicate that the C90 cross-section column is the limit of application of the modified Ludwick law to predict the critical buckling load of nonlinear elastic columns with open cross-sections, and the C180 column is out of the prediction limits. Generally, the numerical and theoretical models underestimated the scattering effects of the predictions because more experimental variables were not considered by the models. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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14 pages, 2186 KiB

Open AccessArticle

Stress Relaxation Behavior of Poly(Methyl Methacrylate)/Graphene Composites: Ultraviolet Irradiation

by Yu-Cheng Ju, Donyau Chiang, Ming-Yen Tsai, Hao Ouyang and Sanboh Lee

Polymers 2022, 14(19), 4192; https://doi.org/10.3390/polym14194192 - 06 Oct 2022

Cited by 2 | Viewed by 1746

Abstract

The graphene/poly (methyl methacrylate) (PMMA) composites are a promising candidate for electronic, optoelectrical, and environmental applications. Understanding the mechanical degradation of PMMA-based materials is of practical importance in improving the reliability and lifespan of the associated structures and systems. In this study, we [...] Read more.

The graphene/poly (methyl methacrylate) (PMMA) composites are a promising candidate for electronic, optoelectrical, and environmental applications. Understanding the mechanical degradation of PMMA-based materials is of practical importance in improving the reliability and lifespan of the associated structures and systems. In this study, we investigate the effects of functionalized graphene (FG) and UV irradiation on the stress–relaxation of PMMA. Uniaxial tensile and stress –relaxation tests are performed to evaluate the mechanical properties of the composites. The mechanical strength and elongation at the break increase with the graphene concentration but decrease with the increase of the irradiation dose. Raman spectroscopy and intrinsic viscosity measurement are applied to examine the root cause of the degradation in the composites. UV irradiation leads to polymer chain scission and loss of molecular weight. The Kelvin representation of the standard linear solid model (SLSM) is used to describe the stress–relaxation curves of the composites. The value of the elastic modulus in the Kelvin element decreases with the increase in temperature. The viscosity follows the Arrhenius equation. The activation energy of viscosity increases with the increasing FGs concentration because the FGs hinder the chain motion of PMMA. However, UV irradiation makes chain scission of PMMA/FGs composite so that the polymer chain moves more easily and the activation energy of stress relaxation lowers. The steady-state stress follows the van ’t Hoff equation that stress relaxation is an exothermal deformation process. Although Maxwell’s representation of SLSM is mathematically identical to the Kelvin representation of SLSM, the former cannot interpret the stress–relaxation behavior of PMMA/FGs composite, which is against the concept of Young’s modulus as a decreasing temperature function. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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14 pages, 48922 KiB

Open AccessArticle

Scalable Manufacturing Process and Multifunctional Performance of Cotton Fibre-Reinforced Poly(Lactic Acid) (PLA) Bio-Composites Coated by Graphene Oxide

by Yilin He, Shuying Wu, Anthony Chun Yin Yuen, Feng Huang, Cyrille Boyer, Chun H. Wang and Jin Zhang

Polymers 2022, 14(19), 3946; https://doi.org/10.3390/polym14193946 - 21 Sep 2022

Cited by 3 | Viewed by 1667

Abstract

Natural fibre biopolymer composites with both fibres and matrix being derived from biomaterials are increasingly used in demanding applications, such as sensing, packaging, building, and transport, and require good electrical, thermal, and flame retardant properties. Herein, an investigation of the effectiveness of functionalising [...] Read more.

Natural fibre biopolymer composites with both fibres and matrix being derived from biomaterials are increasingly used in demanding applications, such as sensing, packaging, building, and transport, and require good electrical, thermal, and flame retardant properties. Herein, an investigation of the effectiveness of functionalising nonwoven cotton/poly(lactic acid) (PLA) fibre mats with graphene oxide nanosheets has been reported by using a facile dip-coating method followed by thermal reduction for enhancing the electric, thermal, and abrasion-resistance properties. The manufacturing processes for preparing biocomposites and introducing functionality are readily scalable. Experimental results reveal that with the addition of less than 0.5 wt% graphene nanoplatelets, the biocomposites showed significant improvements in abrasion resistance, electrical conductivity, thermal conductivity, and diffusivity. Furthermore, the composite shows excellent piezo-resistivity to act as strain sensors with a gauge factor of 2.59 at strains up to 1%. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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18 pages, 4056 KiB

Open AccessArticle

Influence of Starch on the Structure–Properties Relationship in Polyethylene Glycol/Polycaprolactone Diol Polyurethanes

by Jhoan F. Cespedes, Said Arévalo-Alquichire, Luis E. Diaz and Manuel F. Valero

Polymers 2022, 14(15), 3184; https://doi.org/10.3390/polym14153184 - 04 Aug 2022

Cited by 1 | Viewed by 1870

Abstract

Improvements in the antithrombogenicity activity of biomaterials for cardiovascular applications are necessary to meet the demand for vascular grafts in the world. Zwitterionic compounds tend to be used due to their anti-fouling properties, which reduce platelet adhesions and protein absorptions. Therefore, in this [...] Read more.

Improvements in the antithrombogenicity activity of biomaterials for cardiovascular applications are necessary to meet the demand for vascular grafts in the world. Zwitterionic compounds tend to be used due to their anti-fouling properties, which reduce platelet adhesions and protein absorptions. Therefore, in this research, potato starch (AL-N) and zwitterionic starch (AL-Z) (obtained by Williamson etherification) were included as fillers in polyurethane (PU) matrices from polycaprolactone diol (PCL), polyethylene glycol (PEG), pentaerythritol (PE) and isophorone diisocyanate (IPDI) in order to study their effect in terms of their physicochemical, mechanical and thermal properties. We conducted our evaluation using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), contact angle analysis, swelling behavior, thermogravimetric analysis (TGA), tensile/strain analysis, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), dynamic mechanic analysis (DMA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The results showed that AL-N and AL-Z modified these properties, where AL-N improved tensile strength, and AL-Z increased the hydrophilicity of polyurethanes matrices; additionally, AL-N had interactions with the soft segments, and AL-Z had interactions with the hard segments. Finally, both fillers reduced the degree of crystallinity and did not affect the thermal stability of polyurethanes. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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Review

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14 pages, 4659 KiB

Open AccessReview

Progress of Polymer Application in Coated Proppant and Ultra-Low Density Proppant

by Tao Chen, Jie Gao, Yuan Zhao, Tian Liang, Guowen Hu and Xiaobing Han

Polymers 2022, 14(24), 5534; https://doi.org/10.3390/polym14245534 - 17 Dec 2022

Cited by 3 | Viewed by 1647

Abstract

Design, synthesis and application of low-density proppant (LDP) are of great significance for efficient and clean exploitation of low permeability oil and gas. On the basis of a brief introduction of hydraulic fracturing and the application of traditional proppants, this review systematically summarized [...] Read more.

Design, synthesis and application of low-density proppant (LDP) are of great significance for efficient and clean exploitation of low permeability oil and gas. On the basis of a brief introduction of hydraulic fracturing and the application of traditional proppants, this review systematically summarized the polymer application progress in LDP, including coated sand, coated ceramics, coated nutshells, especially for polymer composites based ultra-low density proppant (ULDP). Finally, the existing problems and future development direction are also prospected. Full article

(This article belongs to the Special Issue Advances in Polymer Composites II)

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