Thermal stability of polypropylene–montmorillonite clay nanocomposites: Limitation of the thermogravimetric analysis
TL;DR: In this article, the influence of the presence of montmorillonite clay in the degradation of composites, showing the limitations of TGA and emphasizing the importance of complementary analyzes such as differential scanning calorimetry (DSC) and oxidation induction time (OIT).
About: This article is published in Polymer Degradation and Stability.The article was published on 2015-01-01. It has received 57 citations till now. The article focuses on the topics: Thermogravimetric analysis & Organoclay.
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TL;DR: In this article, a review highlights an ongoing shift of barrier coatings from traditional synthetic polymers to sustainable breakthrough materials for paper-based packaging and films, highlighting the implications of selecting different materials and processing options.
Abstract: Background The technology of food packaging is responding to significant market dynamics such as the rapid growth in e-commerce and preservation of fresh food, a sector that accounts for over 40% of plastic waste. Further, mandates for sustainability and recent changes in national governmental policies and regulations that include banning single-use plastic products as observed in sweeping reforms in Europe, Asia, and several US States are forcing industries and consumers to find alternative solutions. Scope and approach This review highlights an ongoing shift of barrier coatings from traditional synthetic polymers to sustainable breakthrough materials for paper-based packaging and films. Advantages, challenges and adapting feasibility of these materials are described, highlighting the implications of selecting different materials and processing options. A brief description on progress in methods of coating technologies is also included. Finally, the end fate of the barrier materials is classified depending on the packaging type, coating materials used and sorting facility availability. Key findings and conclusions Different types of coatings, such as water-based biopolymers, due to their greater environmental compatibility, are making inroads into more traditional petroleum-based wax and plastic laminate paperboard products for fresh food bakery, frozen food, and take-out containers applications. In addition, nano-biocomposites have been studied at an accelerating pace for developing active and smart packaging. Based on the momentum of recent developments, a strong pace of continuing developments in the field can be expected.
60 citations
24 Apr 2020
TL;DR: To reveal the structure and release properties of bentonite-alginate nanocomposites, bentonite of different amounts was incorporated into alginate by the sol–gel route and dominated by Fickian diffusion depending on the permeability of the matrix.
Abstract: To reveal the structure and release properties of bentonite-alginate nanocomposites, bentonite of different amounts was incorporated into alginate by the sol–gel route. The structure of the composi...
44 citations
TL;DR: In this article, the physical properties of clay aerogel composites, including thermal conductivity, fire resistance, thermal stability and water absorption, and how they are influenced by the microstructure, processing parameters and composition have been discussed.
Abstract: A prior study conducted by the authors had investigated the mechanical enhancement of clay aerogel composites; this paper is an extension to the previous study and focuses on the physical properties of clay aerogel composites. Different physical properties of clay aerogel composites, including thermal conductivity, fire resistance, thermal stability and water absorption, and how they are influenced by the microstructure, processing parameters and composition have been discussed. The results show that the addition of Poly (vinyl alcohol) of different molecular weights as well as controlling the processing parameters to create an open cell structure could effectively lower the thermal conductivity. The fire performance could be enhanced with the addition of fire retardant additives without altering the aerogel structure, and with the correct polymer and modification, the clay aerogels could act as excellent liquid absorbents. Clay aerogel is a relatively new class of aerogels, the accumulated database presented here should serve as most useful information in order to realize the full potentials of clay aerogels in many different applications.
33 citations
TL;DR: In this paper, a review illustrates the applications of Thermal Analysis (TA) techniques in nanomaterials research in the past decade (2010-2020) and brings valuable insight into the evidence of the ability of TA techniques to investigate the physical and chemical properties of the nano-materials.
29 citations
TL;DR: In this research work, graphene nanoplatelets (GNP) were selected as alternative reinforcing nanofillers to enhance the properties of polypropylene (PP) using different compatibilizers calledpolypropylene grafted maleic anhydride (PP-g-MA) and ethylene-octene elastomer graftedmaleic anHydride (POE-g -MA).
Abstract: In this research work, graphene nanoplatelets (GNP) were selected as alternative reinforcing nanofillers to enhance the properties of polypropylene (PP) using different compatibilizers called polypropylene grafted maleic anhydride (PP-g-MA) and ethylene-octene elastomer grafted maleic anhydride (POE-g-MA). A twin screw extruder was used to compound PP, GNP, and either the PP-g-MA or POE-g-MA compatibilizer. The effect of GNP loading on mechanical and thermal properties of neat PP was investigated. Furthermore, the influence and performance of different compatibilizers on the final properties, such as mechanical and thermal, were discussed and reported. Tensile, flexural, impact, melting temperature, crystallization temperature, and thermal stability were evaluated by using a universal testing system, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). For mechanical properties, it was found that increasing GNP content from 1 wt.% to 5 wt.% increased tensile strength of the neat PP up to 4 MPa. The influence of compatibilizers on the mechanical properties had been discussed and reported. For instance, the addition of PP-g-MA compatibilizer improved tensile strength of neat PP with GNP loading. However, the addition of compatibilizer POE-g-MA slightly decreased the tensile strength of neat PP. A similar trend of behavior was observed for flexural strength. For thermal properties, it was found that both GNP loading and compatibilizers have no significant influence on both crystallization and melting temperature of neat PP. For thermal stability, however, it was found that increasing the GNP loading had a significant influence on improving the thermal behavior of neat PP. Furthermore, the addition of compatibilizers into the PP/GNP nanocomposite had slightly improved the thermal stability of neat PP.
28 citations
Cites background from "Thermal stability of polypropylene–..."
...where ∆Hm is the measured melting enthalpy, f is the weight fraction of the PP phase, and ∆H ◦ m is the enthalpy of 100% crystalline PP, which is 209 J/g [19]....
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...% Crystallinity (Xc) = 100× ∆Hm f× ∆H◦m , (1) where ∆Hm is the measured melting enthalpy, f is the weight fraction of the PP phase, and ∆H ◦ m is the enthalpy of 100% crystalline PP, which is 209 J/g [19]....
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References
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TL;DR: A review of the academic and industrial aspects of the preparation, characterization, materials properties, crystallization behavior, melt rheology, and processing of polymer/layered silicate nanocomposites is given in this article.
6,343 citations
"Thermal stability of polypropylene–..." refers background in this paper
...Secondly, the higher the organoclay content, the slower the gases diffusion (volatiles output and oxygen input) through the polymeric mass due to the barrier effect [6,20]....
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...On the other hand, DSC is based on endo and exothermic events in an inert environment with a closed sample holder [20]....
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...In the case of polymeric materials, the mass loss occurs from the low molar mass volatile fragments formation after several autocatalytic degradation cycles [20,21]....
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TL;DR: The thermal stability of organically modified layered silicate (OLS) plays a key role in the synthesis and processing of polymer-layered silicate nanocomposites as discussed by the authors.
Abstract: The thermal stability of organically modified layered silicate (OLS) plays a key role in the synthesis and processing of polymer-layered silicate (PLS) nanocomposites. The nonoxidative thermal degradation of montmorillonite and alkyl quaternary ammonium-modified montmorillonite were examined using conventional and high-resolution TGA combined with Fourier transform infrared spectroscopy and mass spectrometry (TG−FTIR−MS) and pyrolysis/GC−MS. The onset temperature of decomposition of these OLSs was approximately 155 °C via TGA and 180 °C via TGA−MS, where TGA−MS enables the differentiation of water desorbtion from true organic decomposition. Analysis of products (GC−MS) indicates that the initial degradation of the surfactant in the OLS follows a Hoffmann elimination reaction and that the architecture (trimethyl or dimethyl), chain length, surfactant mixture, exchanged ratio, or preconditioning (washing) does not alter the initial onset temperatures. Catalytic sites on the aluminosilicate layer reduce ther...
961 citations
TL;DR: In this article, a detailed examination of factors influencing thermal stability, including the role of chemical constitution of organic modifier, composition and structure of nanocomposites, and mechanisms of improvement of thermal stability in polymer/montmorillonite composites, is presented.
553 citations
"Thermal stability of polypropylene–..." refers background in this paper
...The degradation of quaternary ammonium salt used as organic modifier can influence the degradation of polymeric matrix degradation [33]....
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TL;DR: In this article, the non-oxidative thermal degradation chemistry of alkyl and aryl quaternary phosphonium-modified montmorillonites (P-MMT) was examined using TGA combined with pyrolysis/GC-MS.
Abstract: Organically modified layered silicates (OLS) with high thermal stability are critical for synthesis and processing of polymer layered silicate nanocomposites (PLSN). In the current study, the non-oxidative thermal degradation chemistry of alkyl and aryl quaternary phosphonium-modified montmorillonites (P-MMT) was examined using TGA combined with pyrolysis/GC-MS. The morphology evolution at elevated temperature was investigated using in-situ high-temperature X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The onset decomposition temperature via TGA of these P-MMTs ranged from 190 to 230 °C. The initial degradation of the alkyl P-MMTs follows potentially two reaction pathways - ‚-elimination [E‚] and nucleophilic displacement at phosphorus [SN(P)] reflecting the multiple environments of the surfactant in the silicate. Aryl P-MMT decomposition proceeds via either a reductive elimination through a five-coordinate intermediate or radical generation through homologous cleavage of the P-phenyl bond. Overall, the interlayer environment of the montmorillonite has a more severe effect on stability of the phosphonium surfactant than previously reported for ammonium-modified montmorillonite (N-MMT). Nonetheless, the overall thermal stability of P-MMT is higher than that of N-MMT. These observations indicate that, in addition to their conventional purpose as stabilizers, phosphonium salts offer unique opportunities for melting processing polymer layered silicate nanocomposites.
351 citations
TL;DR: In this paper, the effect of chemical variation (alkyl chain length, number of alkyls, and unsaturation) of organic modifiers on the thermal stability of the organically exchanged montmorillonite are discussed.
320 citations