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Polymers
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Thermal Analysis of Polymer Materials
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Thermal Analysis of Polymer Materials

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Analysis and Characterization".

Deadline for manuscript submissions: closed (31 March 2020) | Viewed by 66812

Special Issue Editors

Prof. Dr. T. M. Indra Mahlia

grade E-Mail Website
Guest Editor
School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
Interests: sustainable energy; energy and fuels; renewable energy; techno-economic analysis and life-cycle cost analysis
Special Issues, Collections and Topics in MDPI journals
Dr. Md Mofijur Rahman

E-Mail Website
Guest Editor
Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
Interests: renewable energy; alternative fuel; IC engine
Special Issues, Collections and Topics in MDPI journals
Dr. Muhammad Roil Bilad

E-Mail Website
Guest Editor
Department of Chemical Engineering, Universiti Teknologi Petronas, Seri Iskandar 32610, Malaysia
Interests: membrane bioreactor; water and wastewater treatment; resource recovery from waste; membrane technology; waste to energy; electrolysis; forward osmosis; membrane distillation; process modeling and simulation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Thermal analysis is an important characterization tool in the field of materials sciences because specific physico-chemical properties of synthetic polymers, bio-based polymers, nanomaterials, materials and biomaterials can be determined through thermal analysis. The thermal analysis of materials encompasses a variety of methods including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), dynamic mechanic analysis (DMA), dielectric thermal analysis (DTEA), isothermal titration calorimetry (ITC) and heat transfer analysis to detect changes in material properties as a function of temperature. In addition, thermal analysis can be used to monitor the structural changes and crystallinity of different polymer materials during the heating, cooling and isothermal measurements. Knowledge of the thermal behaviour of polymers can be used to tailor and design certain properties of end-product material during polymer processing.

This Special Issue will provide readers with up-to-date research on recent progress in the thermal analysis field and polymer processing into more applied materials such as polymeric membranes on polymer-based materials from different perspectives, including but not limited to materials sciences, thermal behaviour, kinetics and thermodynamics. Contributions on synthetic polymers, bio-based polymers, nanomaterials, polymer-based materials and biomaterials, polymer characterization, processing, and application are of interest.

Prof. Dr. T M Indra Mahlia
Dr. Md Mofijur Rahman
Dr. Muhammad Roil Bilad
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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

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

Keywords

  • Thermal analysis
  • Thermogravimetry
  • Thermal conductivity
  • Scanning calorimetry
  • Thermo-optical analysis
  • Polymer characterization
  • Polymer applications

Published Papers (15 papers)

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Research

15 pages, 3442 KiB  
Article
Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study
by Yu-Hao Chen, Palraj Ranganathan, Chin-Wen Chen, Yi-Huan Lee and Syang-Peng Rwei
Polymers 2020, 12(5), 1067; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12051067 - 06 May 2020
Cited by 12 | Viewed by 3313
Abstract
The crystallization behavior of novel polyamide 6 (PA6) copolyamides with different amounts of bis (2-aminoethyl) adipamide/adipic acid (BAEA/AA) segment was investigated. The wide-angle X-ray diffraction (WAXD) results showed that as the amount of BAEA/AA segment increased to 10 mole%, the crystalline forms of [...] Read more.
The crystallization behavior of novel polyamide 6 (PA6) copolyamides with different amounts of bis (2-aminoethyl) adipamide/adipic acid (BAEA/AA) segment was investigated. The wide-angle X-ray diffraction (WAXD) results showed that as the amount of BAEA/AA segment increased to 10 mole%, the crystalline forms of all PA6 copolyamide were transferred from the stable α-form to the unstable γ-form because of the complex polymer structure. According to studies of crystallization kinetics, the Avrami exponent (n) values for all copolyamide samples ranged from 1.43 to 3.67 under isothermal conditions, implying that the crystallization is involved in the two- to three-dimensional growth at a high temperature of isothermal condition. The copolyamides provided a slower crystallization rate and higher crystallization activation energy (ΔEa) than neat PA6. Polyamide containing 10 mole% of BEAE/AA content exhibited a unique crystallization behavior in the coexistence of the α and γ forms. These results deepen our understanding of the relationship between BAEA/AA content, crystal structure, and its crystallization behavior in low-melting PA6, and they make these types of copolyamides useful for their practical application. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 2249 KiB  
Article
Pyrolysis of Low Density Polyethylene: Kinetic Study Using TGA Data and ANN Prediction
by Ibrahim Dubdub and Mohammed Al-Yaari
Polymers 2020, 12(4), 891; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040891 - 12 Apr 2020
Cited by 66 | Viewed by 6732
Abstract
Pyrolysis of waste low-density polyethylene (LDPE) is considered to be a highly efficient, promising treatment method. This work aims to investigate the kinetics of LDPE pyrolysis using three model-free methods (Friedman, Flynn-Wall-Qzawa (FWO), and Kissinger-Akahira-Sunose (KAS)), two model-fitting methods (Arrhenius and Coats-Redfern), as [...] Read more.
Pyrolysis of waste low-density polyethylene (LDPE) is considered to be a highly efficient, promising treatment method. This work aims to investigate the kinetics of LDPE pyrolysis using three model-free methods (Friedman, Flynn-Wall-Qzawa (FWO), and Kissinger-Akahira-Sunose (KAS)), two model-fitting methods (Arrhenius and Coats-Redfern), as well as to develop, for the first time, a highly efficient artificial neural network (ANN) model to predict the kinetic parameters of LDPE pyrolysis. Thermogravimetric (TG) and derivative thermogravimetric (DTG) thermograms at 5, 10, 20 and 40 K min−1 showed only a single pyrolysis zone, implying a single reaction. The values of the kinetic parameters (E and A) of LDPE pyrolysis have been calculated at different conversions by three model-free methods and the average values of the obtained activation energies are in good agreement and ranging between 193 and 195 kJ mol−1. In addition, these kinetic parameters at different heating rates have been calculated using Arrhenius and Coats-Redfern methods. Moreover, a feed-forward ANN with backpropagation model, with 10 neurons in two hidden layers and logsig-logsig transfer functions, has been employed to predict the thermogravimetric analysis (TGA) kinetic data. Results showed good agreement between the ANN-predicted and experimental data (R > 0.9999). Then, the selected network topology was tested for extra new input data with a highly efficient performance. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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18 pages, 902 KiB  
Article
Melting Kinetics of Nascent Poly(tetrafluoroethylene) Powder
by Fotis Christakopoulos, Enrico Troisi and Theo A. Tervoort
Polymers 2020, 12(4), 791; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040791 - 02 Apr 2020
Cited by 6 | Viewed by 2647
Abstract
The melting behavior of nascent poly(tetrafluoroethylene) (PTFE) was investigated by way of differential scanning calorimetry (DSC). It is well known that the melting temperature of nascent PTFE is about 344 ∘ C, but reduces to 327 ∘ C for once molten material. In [...] Read more.
The melting behavior of nascent poly(tetrafluoroethylene) (PTFE) was investigated by way of differential scanning calorimetry (DSC). It is well known that the melting temperature of nascent PTFE is about 344 ∘ C, but reduces to 327 ∘ C for once molten material. In this study, the melting temperature of nascent PTFE crystals was found to strongly depend on heating rate, decreasing considerably for slow heating rates. In addition, during isothermal experiments in the temperature range of 327 ∘ C < T < 344 ∘ C, delayed melting of PTFE was observed, with complete melting only occurring after up to several hours. The melting kinetics of nascent PTFE were analyzed by means of the isoconversional methodology, and an apparent activation energy of melting, dependent on the conversion, was determined. The compensation effect was utilized in order to derive the pre-exponential factor of the kinetic model. The numerical reconstruction of the kinetic model was compared with literature models and an Avrami-Erofeev model was identified as best fit of the experimental data. The predictions of the kinetic model were in good agreement with the observed time-dependent melting of nascent PTFE during isothermal and constant heating-rate experiments. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 2772 KiB  
Article
Catalytic Fast Pyrolysis of Poly (Ethylene Terephthalate) (PET) with Zeolite and Nickel Chloride
by Hang Jia, Haoxi Ben, Ying Luo and Rui Wang
Polymers 2020, 12(3), 705; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12030705 - 23 Mar 2020
Cited by 54 | Viewed by 5303
Abstract
The pyrolysis of poly (ethylene terephthalate) (PET) in the presence of ZSM-5 zeolite and NiCl2 as a catalyst was studied at different temperatures under N2 atmosphere. Quantitative 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) were applied [...] Read more.
The pyrolysis of poly (ethylene terephthalate) (PET) in the presence of ZSM-5 zeolite and NiCl2 as a catalyst was studied at different temperatures under N2 atmosphere. Quantitative 13C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) were applied to characterize the waxy and solid residue. The carboxyl and aliphatic hydroxyl groups in the waxy residue have been greatly depleted after the use of zeolite during pyrolysis on the basis of the results of 13C NMR and FT-IR analysis. The proportion of aromatic hydroxyl groups increased by 21.82% when the mass ratio of zeolite to PET was set to 2.0/1.0. The results indicate that ZSM-5 is able to facilitate the decomposition of carboxyl, aliphatic groups, and ether bonds in the primary products produced from the pyrolysis of PET. In addition, the deoxygenation effects on the waxy products have been significantly enhanced with the addition of zeolite based on the results of NMR. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 2090 KiB  
Article
Kinetics and Thermodynamics of Thermal Degradation of Different Starches and Estimation the OH Group and H2O Content on the Surface by TG/DTG-DTA
by Marita Pigłowska, Beata Kurc, Łukasz Rymaniak, Piotr Lijewski and Paweł Fuć
Polymers 2020, 12(2), 357; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12020357 - 06 Feb 2020
Cited by 55 | Viewed by 5323
Abstract
The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats–Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The [...] Read more.
The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats–Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The study also shows a proposed method for reactive hydroxyl groups content on the starch surface determination, and values were in range of 960.21–1078.76 mg OH per 1 g of starch. Thermal processing revealed the thermophysical properties of biomass for the kinetics of decomposition estimation. Activation energies reached the values in range of approximately 66.5–167 kJ·mol−1. This research also enables the determination of the temperature conditions required for becoming the desired form of material. Therefore, it is necessary to achieve the requested compact porous structure in an activation process, because in the native state, the polymer exhibits limited applications as a result of thermal decomposition, low shear stress, retrogradation, and syneresis, hence the low solubility in organic solvents. Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 1927 KiB  
Article
Thermal Decomposition Mechanism and Kinetics Study of Plastic Waste Chlorinated Polyvinyl Chloride
by Ru Zhou, Biqing Huang, Yanming Ding, Wenjuan Li and Jingjing Mu
Polymers 2019, 11(12), 2080; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11122080 - 12 Dec 2019
Cited by 24 | Viewed by 4284
Abstract
Chlorinated polyvinyl chloride (CPVC), as a new type of engineering plastic waste, has been used widely due to its good heat resistance, mechanical properties and corrosion resistance, while it has become an important part of solid waste. The pyrolysis behaviors of CPVC waste [...] Read more.
Chlorinated polyvinyl chloride (CPVC), as a new type of engineering plastic waste, has been used widely due to its good heat resistance, mechanical properties and corrosion resistance, while it has become an important part of solid waste. The pyrolysis behaviors of CPVC waste were analyzed based on thermogravimetric experiments to explore its reaction mechanism. Compared with polyvinyl chloride (PVC) pyrolysis, CPVC pyrolysis mechanism was divided into two stages and speculated to be dominated by the dehydrochlorination and cyclization/aromatization processes. A common model-free method, Flynn-Wall-Ozawa method, was applied to estimate the activation energy values at different conversion rates. Meanwhile, a typical model-fitting method, Coats-Redfern method, was used to predict the possible reaction model by the comparison of activation energy obtained from model-free method, thereby the first order reaction-order model and fourth order reaction-order model were established corresponding to these two stages. Eventually, based on the initial kinetic parameter values computed by model-free method and reaction model established by model-fitting method, kinetic parameters were optimized by Shuffled Complex Evolution algorithm and further applied to predict the CPVC pyrolysis behaviors during the whole temperature range. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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17 pages, 6103 KiB  
Article
Durability and Electrical Conductivity of Carbon Fiber Cloth/Ethylene Propylene Diene Monomer Rubber Composite for Active Deicing and Snow Melting
by Shuanye Han, Haibin Wei, Leilei Han and Qinglin Li
Polymers 2019, 11(12), 2051; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11122051 - 10 Dec 2019
Cited by 12 | Viewed by 3649
Abstract
To reduce the impact of road ice and snow disaster, it is necessary to adopt low energy consumption and efficient active deicing and snow melting methods. In this article, three functional components are combined into a conductive ethylene propylene diene monomer (EPDM) rubber [...] Read more.
To reduce the impact of road ice and snow disaster, it is necessary to adopt low energy consumption and efficient active deicing and snow melting methods. In this article, three functional components are combined into a conductive ethylene propylene diene monomer (EPDM) rubber composite material with good interface bonding. Among them, the mechanical and electrical properties of the composite material are enhanced by using carbon fiber cloth as a heating layer. EPDM rubber plays a mainly protective role. Further, aluminum silicate fiber cloth is used as a thermal insulation layer. The mechanical properties of EPDM rubber composites reinforced by carbon fiber cloth and the thermal behaviors of the composite material in high and low temperature environments were studied. The heat generation and heat transfer effect of the composite were analyzed by electrothermal tests. The results show that the conductive EPDM rubber composite material has good temperature durability, outstanding mechanical stability, and excellent heat production capacity. The feasibility of the material for road active deicing and snow melting is verified. It is a kind of electric heating deicing material with broad application prospects. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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16 pages, 3186 KiB  
Article
The Yield Prediction of Synthetic Fuel Production from Pyrolysis of Plastic Waste by Levenberg–Marquardt Approach in Feedforward Neural Networks Model
by Faisal Abnisa, Shafferina Dayana Anuar Sharuddin, Mohd Fauzi bin Zanil, Wan Mohd Ashri Wan Daud and Teuku Meurah Indra Mahlia
Polymers 2019, 11(11), 1853; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11111853 - 10 Nov 2019
Cited by 19 | Viewed by 5187
Abstract
The conversion of plastic waste into fuel by pyrolysis has been recognized as a potential strategy for commercialization. The amount of plastic waste is basically different for each country which normally refers to non-recycled plastics data; consequently, the production target will also be [...] Read more.
The conversion of plastic waste into fuel by pyrolysis has been recognized as a potential strategy for commercialization. The amount of plastic waste is basically different for each country which normally refers to non-recycled plastics data; consequently, the production target will also be different. This study attempted to build a model to predict fuel production from different non-recycled plastics data. The predictive model was developed via Levenberg-Marquardt approach in feed-forward neural networks model. The optimal number of hidden neurons was selected based on the lowest total of the mean square error. The proposed model was evaluated using the statistical analysis and graphical presentation for its accuracy and reliability. The results showed that the model was capable to predict product yields from pyrolysis of non-recycled plastics with high accuracy and the output values were strongly correlated with the values in literature. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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22 pages, 11018 KiB  
Article
Effect of Alkyl Chain Length in POSS Nanocage on Non-Isothermal Crystallization Behavior of PCL/Amino-POSS Nanocomposites
by M. Dolores Fernández, Dailyn J. Guzmán, Johnny R. Ramos and M. Jesús Fernández
Polymers 2019, 11(10), 1719; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11101719 - 19 Oct 2019
Cited by 9 | Viewed by 2818
Abstract
The study of the non-isothermal crystallization behavior of polymers is of great importance due to the effect of degree of crystallinity and crystallization process on the polymer properties. The effect of aminopropylisobutyl polyhedral oligomeric silsesquioxane (APIBPOSS) and aminopropylisooctyl polyhedral oligomeric silsesquioxane (APIOPOSS) on [...] Read more.
The study of the non-isothermal crystallization behavior of polymers is of great importance due to the effect of degree of crystallinity and crystallization process on the polymer properties. The effect of aminopropylisobutyl polyhedral oligomeric silsesquioxane (APIBPOSS) and aminopropylisooctyl polyhedral oligomeric silsesquioxane (APIOPOSS) on poly(ε-caprolactone) (PCL) crystallization is studied by differential scanning calorimetry (DSC) under non-isothermal conditions and polarized optical microscopy (POM). The crystallization kinetics is analyzed using the Avrami and Mo models, and effective activation energies are evaluated by the Friedman isoconversional method. The results show that the compatibility between polyhedral oligomeric silsesquioxanes (POSS) and PCL and POSS loading affect the crystallization process. A higher crystallization temperature, a narrower size distribution of crystallite, and a faster crystallization rate are obtained in the presence of all the studied contents of APIBPOSS and at lower contents of APIOPOSS. At APIOPOSS contents higher than 2 wt %, the crystallization temperature is lowered, the size distribution of crystallite is broadened, and the crystallization process is retarded. The presence of POSS leads to an increase in the number of nucleation sites, and a reduction in the size of the crystallite and the overall degree of crystallinity, as a result of the confinement of PCL chains caused by POSS nanoparticles. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 3340 KiB  
Article
Mechanical and Thermal Properties of Montmorillonite-Reinforced Polypropylene/Rice Husk Hybrid Nanocomposites
by Khaliq Majeed, Ashfaq Ahmed, Muhammad Saifullah Abu Bakar, Teuku Meurah Indra Mahlia, Naheed Saba, Azman Hassan, Mohammad Jawaid, Murid Hussain, Javed Iqbal and Zulfiqar Ali
Polymers 2019, 11(10), 1557; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11101557 - 25 Sep 2019
Cited by 32 | Viewed by 3732
Abstract
In recent years, there has been considerable interest in the use of natural fibers as potential reinforcing fillers in polymer composites despite their hydrophilicity, which limits their widespread commercial application. The present study explored the fabrication of nanocomposites by melt mixing, using an [...] Read more.
In recent years, there has been considerable interest in the use of natural fibers as potential reinforcing fillers in polymer composites despite their hydrophilicity, which limits their widespread commercial application. The present study explored the fabrication of nanocomposites by melt mixing, using an internal mixer followed by a compression molding technique, and incorporating rice husk (RH) as a renewable natural filler, montmorillonite (MMT) nanoclay as water-resistant reinforcing nanoparticles, and polypropylene-grafted maleic anhydride (PP-g-MAH) as a compatibilizing agent. To correlate the effect of MMT delamination and MMT/RH dispersion in the composites, the mechanical and thermal properties of the composites were studied. XRD analysis revealed delamination of MMT platelets due to an increase in their interlayer spacing, and SEM micrographs indicated improved dispersion of the filler(s) from the use of compatibilizers. The mechanical properties were improved by the incorporation of MMT into the PP/RH system and the reinforcing effect was remarkable as a result of the use of compatibilizing agent. Prolonged water exposure of the prepared samples decreased their tensile and flexural properties. Interestingly, the maximum decrease was observed for PP/RH composites and the minimum was for MMT-reinforced and PP-g-MAH-compatibilized PP/RH composites. DSC results revealed an increase in crystallinity with the addition of filler(s), while the melting and crystallization temperatures remained unaltered. TGA revealed that MMT addition and its delamination in the composite systems improved the thermal stability of the developed nanocomposites. Overall, we conclude that MMT nanoclay is an effective water-resistant reinforcing nanoparticle that enhances the durability, mechanical properties, and thermal stability of composites. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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13 pages, 3163 KiB  
Article
Preparation and Characterization of PVA/PDDA/Nano-Zirconia Composite Anion Exchange Membranes for Fuel Cells
by Asep Muhamad Samsudin and Viktor Hacker
Polymers 2019, 11(9), 1399; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11091399 - 26 Aug 2019
Cited by 26 | Viewed by 6371
Abstract
Anion exchange membranes (AEMs) contribute significantly to enhance the performance and efficiency of alkaline polymer electrolyte fuel cells (APEFCs). A sequence of composite anion exchange membranes (AEMs) consisting of poly(vinyl alcohol) (PVA), poly(diallyldimethylammonium chloride) (PDDA), and nano-zirconia (NZ) has been prepared by a [...] Read more.
Anion exchange membranes (AEMs) contribute significantly to enhance the performance and efficiency of alkaline polymer electrolyte fuel cells (APEFCs). A sequence of composite anion exchange membranes (AEMs) consisting of poly(vinyl alcohol) (PVA), poly(diallyldimethylammonium chloride) (PDDA), and nano-zirconia (NZ) has been prepared by a solution casting technique. The effect of zirconia mass ratio on attribute and performance of composite AEMs was investigated. The chemical structures, morphology, thermal, and mechanical properties of AEMs were characterized by FTIR, SEM, thermogravimetric analysis, and universal testing machine, respectively. The performance of composite AEMs was verified using water uptake, swelling degree, ion-exchange capacity, and OH− conductivity measurement. The nano-zirconia was homogeneously dispersed in the PVA/PDDA AEMs matrix. The mechanical properties of the composite AEMs were considerably enhanced with the addition of NZ. Through the introduction of 1.5 wt.% NZ, PVA/PDDA/NZ composite AEMs acquired the highest hydroxide conductivity of 31.57 mS·cm−1 at ambient condition. This study demonstrates that the PVA/PDDA/NZ AEMs are a potential candidate for APEFCs application. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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14 pages, 43043 KiB  
Article
Coordination Dynamics and Thermal Stability with Aminal Metallogels and Liquids
by Peter J. Boul, Diana K. Rasner, Peter D. Jarowski and Carl J. Thaemlitz
Polymers 2019, 11(8), 1237; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11081237 - 26 Jul 2019
Viewed by 3182
Abstract
In this article, we review a dynamic covalent gel system developed as a high temperature well construction fluid. The key gel/fluid phase changes and related materials properties are addressable via the constitutional and coordination dynamics of the equilibrium and non-equilibrium molecular species comprising [...] Read more.
In this article, we review a dynamic covalent gel system developed as a high temperature well construction fluid. The key gel/fluid phase changes and related materials properties are addressable via the constitutional and coordination dynamics of the equilibrium and non-equilibrium molecular species comprising the material. The interplay between these species and external stimuli leads to material adaptability. Specifically, the introduction of metal ions into a non-equilibrium hemiaminal gel reverts this phase into a non-equilibrium liquid. When heated, this liquid transforms itself catalytically into the thermodynamically favoured closed-ring polyhexahydrotriazine (PHT) gel product. The temperature stability of different PHT gel formulations is evaluated as a function of the inclusion of various salts. It is possible to revert this thermodynamic PHT gel back into a liquid. This pH dependent transformation depends on the R groups linking the hexahydrotriazines (HTs) to one another. While polyethylene glycol (PEG) based PHT gels revert to liquids with water and mild protonation conditions, in comparison, polypropylene glycol (PPG) based gels require stronger acid conditions with heat, or a different more nucleophilically driven ring-opening mechanism by, for example, phosphines. The covalent dynamic chemistry in this chemical system gives way to many possible applications in addition to the high temperature solution-gelation (sol-gels) for which it has been primarily designed. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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18 pages, 4794 KiB  
Article
Enhanced Thermal and Dynamic Mechanical Properties of Synthetic/Natural Hybrid Composites with Graphene Nanoplateletes
by Naveen Jesuarockiam, Mohammad Jawaid, Edi Syams Zainudin, Mohamed Thariq Hameed Sultan and Ridwan Yahaya
Polymers 2019, 11(7), 1085; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11071085 - 26 Jun 2019
Cited by 108 | Viewed by 5186
Abstract
The aim of the present research work is to enhance the thermal and dynamic mechanical properties of Kevlar/Cocos nucifera sheath (CS)/epoxy composites with graphene nano platelets (GNP). Laminates were fabricated through the hand lay-up method followed by hot pressing. GNP at different [...] Read more.
The aim of the present research work is to enhance the thermal and dynamic mechanical properties of Kevlar/Cocos nucifera sheath (CS)/epoxy composites with graphene nano platelets (GNP). Laminates were fabricated through the hand lay-up method followed by hot pressing. GNP at different wt.% (0.25, 0.5, and 0.75) were incorporated with epoxy resin through ultra-sonication. Kevlar/CS composites with different weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were fabricated while maintaining a fiber/matrix weight ratio at 45/55. Thermal degradation and viscoelastic properties were evaluated using thermogravimetric analysys (TGA), differential scanning calorimetric (DSC) analysis, and a dynamic mechanical analyser (DMA). The obtained results revealed that Kevlar/CS (25/75) hybrid composites at 0.75 wt.% of GNP exhibited similar thermal stability compared to Kevlar/epoxy (100/0) composites at 0 wt.% of GNP. It has been corroborated with DSC observation that GNP act as a thermal barrier. However, DMA results showed that the Kevlar/CS (50/50) hybrid composites at 0.75 wt.% of GNP exhibited almost equal viscoelastic properties compared to Kevlar/epoxy (100/0) composites at 0 wt.% GNP due to effective crosslinking, which improves the stress transfer rate. Hence, this research proved that Kevlar can be efficiently (50%) replaced with CS at an optimal GNP loading for structural applications. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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12 pages, 5169 KiB  
Article
Nonisothermal Crystallization of Surface-Treated Alumina and Aluminum Nitride-Filled Polylactic Acid Hybrid Composites
by Zelalem Lule and Jooheon Kim
Polymers 2019, 11(6), 1077; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11061077 - 21 Jun 2019
Cited by 9 | Viewed by 3876
Abstract
This work investigates the nonisothermal crystallization and melting behavior of polylactic acid (PLA), filled with treated and untreated alumina and nano-aluminum nitride hybrid composites. Analysis by attenuated total reflectance Fourier transform infrared spectroscopy revealed that the treated fillers and the PLA matrix developed [...] Read more.
This work investigates the nonisothermal crystallization and melting behavior of polylactic acid (PLA), filled with treated and untreated alumina and nano-aluminum nitride hybrid composites. Analysis by attenuated total reflectance Fourier transform infrared spectroscopy revealed that the treated fillers and the PLA matrix developed a good interaction. The crystallization and melting behaviors of the PLA hybrid composites were investigated using differential scanning calorimetry showed that the degree of crystallinity increased with the addition of hybrid fillers. Unlike the untreated PLA composites, the complete crystallization of the treated PLA hybrid composites hindered cold crystallization during the second heating cycle. The crystallization kinetics studied using the Avrami model indicated that the crystallization rate of PLA was affected by the inclusion of filler particles. X-ray diffraction analysis confirmed crystal formation with the incorporation of filler particles. The inclusion of nano-aluminum nitride (AlN) and the increase in the crystallinity led to an improvement of the storage modulus. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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Article
Development of A Novel Corrugated Polyvinylidene difluoride Membrane via Improved Imprinting Technique for Membrane Distillation
by Normi Izati Mat Nawi, Muhammad Roil Bilad, Nurazrina Zolkhiflee, Nik Abdul Hadi Nordin, Woei Jye Lau, Thanitporn Narkkun, Kajornsak Faungnawakij, Nasrul Arahman and Teuku Meurah Indra Mahlia
Polymers 2019, 11(5), 865; https://0-doi-org.brum.beds.ac.uk/10.3390/polym11050865 - 13 May 2019
Cited by 33 | Viewed by 3779
Abstract
Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance [...] Read more.
Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm−2h−1 and a salt rejection of >99%, higher than the referenced flat membrane (flux of 18.0 Lm−2h−1 and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm−2h−1. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance. Full article
(This article belongs to the Special Issue Thermal Analysis of Polymer Materials)
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