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Polymers
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Thermal Properties and Applications of Polymers
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Thermal Properties and Applications of Polymers

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

Deadline for manuscript submissions: closed (28 February 2019) | Viewed by 59907

Special Issue Editor

Prof. Dr. Xiao Hu

E-Mail Website1 Website2
Guest Editor
Department of Physics and Astronomy, College of Science and Mathematics, Rowan University, Glassboro, NJ 08028, USA
Interests: polymer; biomaterials; biomacromolecules; regenerative medicine; drug delivery; nanotechnology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Thermal analysis is a critical analytical and characterization tool in the field of materials sciences and analytical chemistry. Specific physical and chemical properties of synthetic polymers, nanomaterials, composite materials and biomaterials with different phases and morphology can be determined through thermal analysis. Traditional thermal analysis techniques include 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 (such as thermal diffusivity and thermal conductivity analysis). Some techniques such as DSC were further developed into modulated-temperature DSC (MTDSC), pressure perturbation calorimetry (PPC), micro/nano DSC, as well as fast-scan DSC (F-DSC). These various thermal methods characterize the mechanical properties, mass, temperatures, heats and/or specific heat capacity changes at the thermodynamic and kinetic transitions of different materials, such as low molecular-mass substances, amorphous and semicrystalline synthetic polymers and also biopolymers.  Moreover, thermal analysis can also help quantitatively monitor the structural changes of materials during the heating, cooling and isothermal measurements. In this Special Issue, we will highlight recent accomplishments of thermal analysis on polymer based materials, and illustrate new methods developed in the field. We hope these reviews and research studies can provide a broad view of how material thermodynamic theories and methods have been used in the last decade.

Dr. Xiao Hu
Guest Editor

Keywords

  • Thermal analysis
  • Thermal diffusivity and thermal conductivity
  • Glass transition, crystallization, melting

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Published Papers (11 papers)

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20 pages, 4718 KiB  
Article
Chemically Reduced Graphene Oxide-Reinforced Poly(Lactic Acid)/Poly(Ethylene Glycol) Nanocomposites: Preparation, Characterization, and Applications in Electromagnetic Interference Shielding
by Ahmad Fahad Ahmad, Sidek Ab Aziz, Zulkifly Abbas, Suzan Jabbar Obaiys, Khamirul Amin Matori, Mohd Hafiz Mohd Zaid, Haider K. Raad and Umar Sa’ad Aliyu
Polymers 2019, 11(4), 661; https://doi.org/10.3390/polym11040661 - 11 Apr 2019
Cited by 25 | Viewed by 5555
Abstract
In this study, a nanocomposite of reduced graphene oxide (RGO) nanofiller-reinforcement poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG) matrix was prepared via the melt blending method. The flexibility of PLA was improved by blending the polymer with a PEG plasticizer as a second polymer. To [...] Read more.
In this study, a nanocomposite of reduced graphene oxide (RGO) nanofiller-reinforcement poly(lactic acid) (PLA)/poly(ethylene glycol) (PEG) matrix was prepared via the melt blending method. The flexibility of PLA was improved by blending the polymer with a PEG plasticizer as a second polymer. To enhance the electromagnetic interference shielding properties of the nanocomposite, different RGO wt % were combined with the PLA/PEG blend. Using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction, the structural, microstructure, and morphological properties of the polymer and the RGO/PLA/PEG nanocomposites were examined. These studies showed that the RGO addition did not considerably affect the crystallinity of the resulting nanomaterials. Thermal analysis (TGA) reveals that the addition of RGO highly improved the thermal stability of PLA/PEG nanocomposites. The dielectric properties and electromagnetic interference shielding effectiveness of the synthesized nanocomposites were calculated and showed a higher SE total value than the target value (20 dB). On the other hand, the results showed an increased power loss by increasing the frequency and conversely decreased with an increased percentage of filler. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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17 pages, 5879 KiB  
Article
Isothermal Crystallization Kinetics Study of Fully Aliphatic PA6 Copolyamides: Effect of Novel Long-Chain Polyamide Salt as a Comonomer
by Syang-Peng Rwei, Palraj Ranganathan and Yi-Huan Lee
Polymers 2019, 11(3), 472; https://doi.org/10.3390/polym11030472 - 12 Mar 2019
Cited by 28 | Viewed by 6263
Abstract
N1, N6-bis (4-aminobutyl) adipamide (BABA) diamine and sebacic acid (SA), also called BABA/SA polyamide salt, were used in a typical melt polymerization processes of polyamide 6 (PA6) to form a series of PA6-BABA/SA copolyamides. The effects of BABA/SA on [...] Read more.
N1, N6-bis (4-aminobutyl) adipamide (BABA) diamine and sebacic acid (SA), also called BABA/SA polyamide salt, were used in a typical melt polymerization processes of polyamide 6 (PA6) to form a series of PA6-BABA/SA copolyamides. The effects of BABA/SA on the isothermal crystallization kinetics of PA6-BABA/SA were studied for the first time. An isothermal crystallization analysis demonstrates that the PA6-BABA/SA matrix provided a higher crystallization rate and shorter half-crystallization time than virgin PA6 did. The degree of crystallization of the PA6-BABA/SA30 matrix was also the lowest among all of the samples considered herein. This result is attributed to the high nucleation efficacy of a small amount of BABA/SA in the crystallization of PA6. Values of the Avrami exponent (n) from 1.84 to 3.91 were observed for all of the polyamide samples, suggesting that the crystallization was involved via a two- to three-dimensional growth mechanism. These findings deepen our understanding of the structure–property relationship of PA6-BABA/SA copolyamides, favoring their practical application. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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16 pages, 5560 KiB  
Article
Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites
by Zengheng Hao, Lu Li, Bo Yang, Xingyue Sheng, Xia Liao, Leilei He and Pan Liu
Polymers 2019, 11(3), 433; https://doi.org/10.3390/polym11030433 - 06 Mar 2019
Cited by 7 | Viewed by 3126
Abstract
In this study, the hyperbranched polyester grafted graphene oxide (GO-H202) was synthesized, and the isotactic polypropylene/graphene oxide (iPP/GO) composites were prepared. Results of X-ray photoelectron spectra (XPS), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) revealed the successful synthesis of GO-H202, while [...] Read more.
In this study, the hyperbranched polyester grafted graphene oxide (GO-H202) was synthesized, and the isotactic polypropylene/graphene oxide (iPP/GO) composites were prepared. Results of X-ray photoelectron spectra (XPS), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) revealed the successful synthesis of GO-H202, while thermogravimetric analysis (TGA) indicated that the weight ratio of grafting was about 35 wt %. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were carried out to investigate the role of GO and GO-H202 on the crystallization kinetics of the composites. Results suggested that the addition of GO enhanced the nucleation rate and crystallizability of the composites, while GO-H202 exhibited a higher crystallization acceleration effect compared to neat GO; results of isothermal crystallization kinetics and self-nucleation isothermal crystallization kinetics showed that both the overall crystallization rate and crystal growth rate increase after the addition of GO and GO-H202, and the crystallization acceleration of GO-H202 became evidently stronger compared to GO. Moreover, the variation trends of Avrami exponent n with the isothermal crystallization temperature TcISO changed significantly after the addition of GO or GO-H202, which might imply that the addition of GO and GO-H202 lead to different crystallization dimensionalities during the isothermal crystallization of the composites. The related mechanism was also discussed. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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13 pages, 3634 KiB  
Article
Synthesis and Physical Properties of Non-Crystalline Nylon 6 Containing Dimer Acid
by Ching-Nan Huang, Chang-Mou Wu, Hao-Wen Lo, Chiu-Chun Lai, Wei-Feng Teng, Lung-Chang Liu and Chien-Ming Chen
Polymers 2019, 11(2), 386; https://doi.org/10.3390/polym11020386 - 25 Feb 2019
Cited by 12 | Viewed by 5737
Abstract
In this study, a long carbon chain dimer acid is introduced into a nylon 6 structure and is copolymerized with different structural amines to produce amorphous nylon 6 by 4,4′-methylenebis(2-methylcyclohexylamine) (MMCA) in different copolymerization ratios. The effect of different structures and copolymerization ratios [...] Read more.
In this study, a long carbon chain dimer acid is introduced into a nylon 6 structure and is copolymerized with different structural amines to produce amorphous nylon 6 by 4,4′-methylenebis(2-methylcyclohexylamine) (MMCA) in different copolymerization ratios. The effect of different structures and copolymerization ratios on the properties of nylon 6 is determined, along with the thermal properties, crystallinity, water absorption, dynamic mechanical properties, and optical properties. It is found that the melting point and the thermal cracking temperature Td10 of nylon 6 are respectively between 176 °C and 213 °C and 378 °C to 405 °C. The effect of introducing a bicyclohexane group containing a methyl side chain is greater than that of a meta-benzene ring, so COMM (synthesized by Caprolactam (C), dimer oleic acid (OA), and 4,4′-Methylenebis(2-methylcyclohexylamine) (MMCA)) has the lowest melting point, enthalpy, and crystallinity. As the copolymerization ratio increases, its thermal properties decrease. 10% is the lowest crystallinity. The amine structure containing a bicycloalkyl group has lower water absorption and a 10% copolymerization ratio gives the lowest water absorption. It contains the bicycloalkyl group, COM (synthesized by Caprolactam (C), dimer oleic acid (OA) and 4,4′-Methylenebis(cyclohexylamine) (MCA)), which has the highest loss modulus. The lowest loss modulus is noted for a copolymerization ratio of 7% and the value of tan δ increases as the copolymerization ratio increases. The introduction of nylon 6 with the bicycloalkyl groups, COMM and COM, significantly increases transparency. As the copolymerization ratio increases, the transparency increases and the haze decreases. The best optical properties are achieved for 10% copolymerization. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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11 pages, 2165 KiB  
Article
Thermal Properties of TiO2NP/CNT/LDPE Hybrid Nanocomposite Films
by Moustafa M. Zagho, Mariam Al Ali AlMaadeed and Khaliq Majeed
Polymers 2018, 10(11), 1270; https://doi.org/10.3390/polym10111270 - 15 Nov 2018
Cited by 18 | Viewed by 3836
Abstract
This work aims to investigate the effect of hybrid filler concentration on the thermal stability of low-density polyethylene (LDPE) matrices. LDPE-based composite films were synthesized by melt mixing, followed by compression molding, to study the influence of titanium oxide nanoparticles (TONPs) and/or multi-walled [...] Read more.
This work aims to investigate the effect of hybrid filler concentration on the thermal stability of low-density polyethylene (LDPE) matrices. LDPE-based composite films were synthesized by melt mixing, followed by compression molding, to study the influence of titanium oxide nanoparticles (TONPs) and/or multi-walled carbon nanotubes (CNTs) on the thermal properties of LDPE matrices. Fourier transform infrared (FTIR) spectroscopy confirmed the slight increase in the band intensities after TONP addition and a remarkable surge after the incorporation of CNTs. The value of crystallization temperature (Tc) was not modified after incorporating TONPs, while an enhancement was observed after adding the hybrid fillers. The melting temperature (Tm) was not changed after introducing the CNTs and CNT/TONP hybrid fillers. The percentage crystallinity (Xc %) was increased by 4% and 6%, after incorporating 1 wt % and 3 wt % CNTs, respectively. The TONP incorporation did not modify the Xc %. Moreover, thermal gravimetric analysis (TGA) thermograms confirmed the increased thermal stability after introducing CNTs and hybrid fillers compared to TONP incorporation. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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11 pages, 2957 KiB  
Article
Morphology and Thermal Properties of Calcium Alginate/Reduced Graphene Oxide Composites
by Wanting Zhao, Yan Qi, Yue Wang, Yun Xue, Peng Xu, Zichao Li and Qun Li
Polymers 2018, 10(9), 990; https://doi.org/10.3390/polym10090990 - 05 Sep 2018
Cited by 47 | Viewed by 6349
Abstract
Calcium alginate (CaAlg) is a kind of biodegradable and eco-friendly functional material, and CaAlg/reduced graphene oxide (rGO) composites are expected to be applied as new textile, heat-generating, and flame-retardant materials. In this paper, the CaAlg/rGO composites were prepared by a sol-gel method and [...] Read more.
Calcium alginate (CaAlg) is a kind of biodegradable and eco-friendly functional material, and CaAlg/reduced graphene oxide (rGO) composites are expected to be applied as new textile, heat-generating, and flame-retardant materials. In this paper, the CaAlg/rGO composites were prepared by a sol-gel method and their morphological and thermal properties were studied. The results showed that the introduction of rGO can efficiently improve the thermal stability of CaAlg. Further study showed that rGO increased the carbon formation rate by 4.1%, indicating that the thermal stability was improved by the promotion of carbon formation. Moreover, the weight loss rate of the composites was faster at 180–200 °C than that of CaAlg, after which the rate was less comparatively, suggesting the better thermal stability of the composite. This maybe because the high heat transfer efficiency of rGO allowed the material to reach the temperature of the thermal decomposition of the glycan molecule chain within a short time, and then promoted carbon formation. The thermal cracking mechanism of the composites is proposed based on the experimental data. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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12 pages, 3931 KiB  
Article
Preparation of Novel Epoxy Resins Bearing Phthalazinone Moiety and Their Application as High-Temperature Adhesives
by Liwei Wang, Jinyan Wang, Yu Qi, Fengfeng Zhang, Zhihuan Weng and Xigao Jian
Polymers 2018, 10(7), 708; https://doi.org/10.3390/polym10070708 - 26 Jun 2018
Cited by 10 | Viewed by 5072
Abstract
Most polymer-based adhesives exhibit some degree of degradation at temperatures above 200 °C, and so there is a need for the development of adhesives that can be used at high temperatures. A series of poly(phthalazinone ether nitrile sulfone ketone)s terminated with epoxy (E-PPENSK) [...] Read more.
Most polymer-based adhesives exhibit some degree of degradation at temperatures above 200 °C, and so there is a need for the development of adhesives that can be used at high temperatures. A series of poly(phthalazinone ether nitrile sulfone ketone)s terminated with epoxy (E-PPENSK) and amine (A-PPENSK) groups have been prepared, which have been used as precursors can be applied for high-temperature resistant epoxy adhesives. The structured of these E-PPENSK (epoxy resin) and A-PPENSK (curing agent) components have been characterized by 1H nuclear magnetic resonance (NMR) and Fourier transform–infrared spectroscopy (FT–IR) studies, with the effects of molecular weights and molar ratios on the gel content of their polymers being determined. Cured epoxy resins derived from E-PPENSK and A-PPENSK showed good thermal stability, with an optimal resin retaining 95% of its weight at 484 °C, which gave a char yield of 62%. This adhesive was found to exhibit good mechanical strength, with a single-lap adhesive joint (A-3000/E-6000) exhibiting a shear strength of 48.7 MPa. Heating this adhesive at 450 °C for 1 h afforded a polymer that still exhibited good shear strength of 17.8 MPa, indicating that these adhesives are potentially good candidates for high-temperature applications. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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13 pages, 3476 KiB  
Article
Molecular Design and Property Prediction of Sterically Confined Polyimides for Thermally Stable and Transparent Materials
by Ki-Ho Nam, Hoi Kil Choi, Hyeonuk Yeo, Nam-Ho You, Bon-Cheol Ku and Jaesang Yu
Polymers 2018, 10(6), 630; https://doi.org/10.3390/polym10060630 - 07 Jun 2018
Cited by 15 | Viewed by 4446
Abstract
To meet the demand for next-generation flexible optoelectronic devices, it is crucial to accurately establish the chemical structure-property relationships of new optical polymer films from a theoretical point of view, prior to production. In the current study, computer-aided simulations of newly designed poly(ester [...] Read more.
To meet the demand for next-generation flexible optoelectronic devices, it is crucial to accurately establish the chemical structure-property relationships of new optical polymer films from a theoretical point of view, prior to production. In the current study, computer-aided simulations of newly designed poly(ester imide)s (PEsIs) with various side groups (–H, –CH3, and –CF3) and substituted positions were employed to study substituent-derived steric effects on their optical and thermal properties. From calculations of the dihedral angle distribution of the model compounds, it was found that the torsion angle of the C–N imide bonds was effectively constrained by the judicious introduction of di-, tetra-, and hexa-substituted aromatic diamines with –CF3 groups. A high degree of fluorination of the PEsI repeating units resulted in weaker intra- and intermolecular conjugations. Their behavior was consistent with the molecular orbital energies obtained using density functional theory (DFT). In addition, various potential energy components of the PEsIs were investigated, and their role in glass-transition behavior was studied. The van der Waals energy (EvdW) played a crucial role in the segmental chain motion, which had an abrupt change near glass-transition temperature (Tg). The more effective steric effect caused by –CF3 substituents at the 3-position of the 4-aminophenyl group significantly improved the chain rigidity, and showed high thermal stability (Tg > 731 K) when compared with the –CH3 substituent at the same position, by highly distorting (89.7°) the conformation of the main chain. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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15 pages, 30887 KiB  
Article
Synthesis of Zirconium-Containing Polyhedral Oligometallasilsesquioxane as an Efficient Thermal Stabilizer for Silicone Rubber
by Jiedong Qiu, Xuejun Lai, Hongqiang Li, Xingrong Zeng and Zhuopeng Zhang
Polymers 2018, 10(5), 520; https://doi.org/10.3390/polym10050520 - 11 May 2018
Cited by 16 | Viewed by 4579
Abstract
Free radicals play a negative role during the thermal degradation of silicone rubber (SR). Quenching free radicals is proposed to be an efficient way to improve the thermal-oxidative stability of SR. In this work, a novel zirconium-containing polyhedral oligometallasilsesquioxane (Zr-POSS) with free-radical quenching [...] Read more.
Free radicals play a negative role during the thermal degradation of silicone rubber (SR). Quenching free radicals is proposed to be an efficient way to improve the thermal-oxidative stability of SR. In this work, a novel zirconium-containing polyhedral oligometallasilsesquioxane (Zr-POSS) with free-radical quenching capability was synthesized and characterized. The incorporation of Zr-POSS effectively improved the thermal-oxidative stability of SR. The T5 (temperature at 5% weight loss) of SR/Zr-POSS significantly increased by 31.7 °C when compared to the unmodified SR. Notably, after aging 12 h at 280 °C, SR/Zr-POSS was still retaining about 65%, 60%, 75%, and 100% of the tensile strength, tear strength, elongation at break, and hardness before aging, respectively, while the mechanical properties of the unmodified SR were significantly decreased. The possible mechanism of Zr-POSS for improving the thermal-oxidative stability of SR was intensively studied and it was revealed that the POSS structure could act as a limiting point to suppress the random scission reaction of backbone. Furthermore, Zr could quench the free radicals by its empty orbital and transformation of valence states. Therefore, it effectively suppressed the thermal-oxidative degradation and crosslinking reaction of the side chains. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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13 pages, 2502 KiB  
Article
Thermal Study of Polyols for the Technological Application as Plasticizers in Food Industry
by Alberto Toxqui-Terán, César Leyva-Porras, Miguel Ángel Ruíz-Cabrera, Pedro Cruz-Alcantar and María Zenaida Saavedra-Leos
Polymers 2018, 10(5), 467; https://doi.org/10.3390/polym10050467 - 25 Apr 2018
Cited by 14 | Viewed by 5275
Abstract
In this work is presented the complete thermal analysis of polyols by direct methods such as simultaneous thermogravimetric and differential thermal analyzer (TGA-DTA), differential scanning calorimetry (DSC), modulated DSC (MDSC), and supercooling MDSC. The different thermal events in the temperature range of 113–553 [...] Read more.
In this work is presented the complete thermal analysis of polyols by direct methods such as simultaneous thermogravimetric and differential thermal analyzer (TGA-DTA), differential scanning calorimetry (DSC), modulated DSC (MDSC), and supercooling MDSC. The different thermal events in the temperature range of 113–553 K were identified for glycerol (GL), ethylene glycol (EG), and propylene glycol (PG). Boiling temperature (TB) decreased as GL > EG > PG, but increased with the heating rate. GL showed a complex thermal event at 191–199 K, identified as the glass transition temperature (Tg) and devitrification temperature (Tdv), and a liquid–liquid transition (TL-L) at 215–221 K was identified as the supercooling temperature. EG showed several thermal events such as Tg and Tdv at 154 K, crystallization temperature (Tc) at 175 K, and melting temperature (Tm) at 255 K. PG also showed a complex thermal event (Tg and Tdv) at 167 K, a second devitrification at 193 K, and TL-L at 245 K. For PG, crystallization was not observed, indicating that, during the cooling, the liquid remained as an amorphous solid. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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11 pages, 4724 KiB  
Article
Thermal Conductivity of Aluminosilicate- and Aluminum Oxide-Filled Thermosets for Injection Molding: Effect of Filler Content, Filler Size and Filler Geometry
by Yang Zhao, Zhanyu Zhai and Dietmar Drummer
Polymers 2018, 10(4), 457; https://doi.org/10.3390/polym10040457 - 20 Apr 2018
Cited by 20 | Viewed by 8697
Abstract
In this study, epoxy molding compounds (EMCs) with aluminosilicate (AlS) and aluminum oxide (AlO) were fabricated as fillers by a twin-screw-extruder (TSE) and shaped to plate samples using injection molding. AlS and AlO, electrical insulating mineral materials, were used as fillers to improve [...] Read more.
In this study, epoxy molding compounds (EMCs) with aluminosilicate (AlS) and aluminum oxide (AlO) were fabricated as fillers by a twin-screw-extruder (TSE) and shaped to plate samples using injection molding. AlS and AlO, electrical insulating mineral materials, were used as fillers to improve the thermal conductivity (λc) of composites. Composites with different filler particle sizes, filler contents and filler geometry were fabricated and the influence of these variables on the λc was studied. The λc of composites was measured with the hot-disk method. The distribution of fillers in composites was observed using scanning electron microscopy (SEM). Using the Lewis-Nielsen equation, experimental values of λc were compared with those predicted. The predicted results fit the experimental values well. The result showed that λc increases significantly when the filler content of composites is approximately over 50 vol %. Full article
(This article belongs to the Special Issue Thermal Properties and Applications of Polymers)
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