Thermal degradation investigation of poly(ethylene terephthalate)/fibrous silicate nanocomposites (original) (raw)
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Thermochimica Acta, 2010
The properties of reactive polymer blends are strongly influenced by the interchange/exchange reactions. The effect of nanofillers on these reactions, in particular transreactions, has not yet fully understood. This work is devoted to investigate transesterification and its consequent effect on degradation behavior of phenoxy/poly(trimethylene terephthalate) (PTT) nanocomposites using thermal analysis techniques. 1 H NMR results showed that the maximum extent of transreactions occurred in the blends loaded with just 1 wt.% nanoclay. A mechanism based on nanoconfinement was proposed to show how nanoclay particles affect transreactions of the blend constituents. Thermal degradation kinetic studies, using KAS isoconversion method, revealed that addition of only 1 wt.% clay improves thermal stability of the pristine blend whereas higher amount of clay accelerates degradation process. An attempt was made to establish correlations among these changes in thermal degradation behavior, the extent of transreactions and dynamic mechanical properties.
Characterization and thermal degradation of polypropylene–montmorillonite nanocomposites
Polymer Degradation and Stability, 2006
Polypropylene (PP)emontmorillonite nanocomposites have been prepared using isotactic PP homopolymers with different rheological properties, and a maleic anhydride grafted PP. Morphology and structure of the composites were investigated by using X-ray techniques (WAXD, SAXS) and transmission electron microscopy (TEM). The absence of pristine clusters of the clay and the presence of intercalated and exfoliated structures were shown for all the investigated samples. The nanocomposite prepared by using maleic anhydride grafted PP showed a widespread exfoliation. The thermal behaviour and degradation have been studied by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The incorporation of the montmorillonite improves the thermal stability in air atmosphere of all the investigated PPs, thanks to a physical barrier effect of the silicate layers.
Journal of Polymer Research, 2011
Blends of Poly(ethylene terephthalate), (PET), and poly(ethylene naphthalene 2,6-dicarboxylate), (PEN), were prepared in a twin-screw extruder. Samples were investigated by differential scanning calorimetry (DSC) and proton nuclear magnetic resonance (1 H NMR) measurements to evaluate the extent of transesterification reaction. X-ray diffraction (XRD) test was performed to examine the effect of transesterification reactions on crystalline structure of the blends. Thermogravimetry analysis (TGA) was used to study thermal decomposition of the blends which could be explained by the level of transesterification reaction for various blend compositions. The kinetic of the decomposition reaction was analyzed by Freeman-Carroll and Chang models. It was found that these two methods were acceptable models for describing the thermal decomposition of the blends however, the Chang model showed better correlation with the experimental data as compared to the other model. Results revealed that progress of transesterification reaction in blends depends on temperature and mixing time, which have dominant role in thermal behavior and decomposition kinetic of the blends. Effect of nanoclay on transesterification reactions and degradation behavior was also investigated. It was found that the nanoclay inhibited the transesterification reactions and reduced the thermal stability of the blends. PET degraded much faster than PEN in O 2 environment while, an opposite trend was observed in N 2 atmosphere.
Polymers for Advanced Technologies, 2019
ence and absence of an ethylene-butylacrylate-glycidyl methacrylate terpolymer as compatibilizer were prepared by melt-mixing process. A matrix-droplet-type morphology confirmed by transmission electron microscope (TEM) and scanning electron microscopy (SEM) studies is formed in presence and absence of the compatibilizer in which the clay platelets were mainly localized in the polylactic acid (PLA) dispersed phase. Degradation studies by means of thermogravimetry analysis (TGA) and analysis of degradation activation energy (E a), T max (maximum degradation temperature), and ΔT (difference between initial and final degradation temperatures) parameters for each polymer component of the system revealed that incorporation of less stable PLA phase to polypropylene (PP) decreases E a and T max parameters, and hence, reduces the thermal stability of PP phase, while incorporation of clay nanoplatelets to the neat blend further reduces its thermal stability attributed to their lack of localization in PP phase. Compatibilization of the filled system results in migration of clay nanoplatelets toward PP and improves E a and T max of PP phase. On the other hand, the E a and T max of PLA phase of the blend were increased with incorporation of clay and its localization within that phase, while compatibilization of the filled system slightly reduces thermal stability of PLA phase due to migration of clay toward PP. A correlation was found between E a and intensity of the thermogravimetry analysis Fourier-transform infrared spectroscopy (TGA-FTIR) peaks of the evolved products. Using the Criado method, a detailed analysis on degradation mechanism of each component was performed, and the changes in the degradation mechanism of the developed systems were determined.
Journal of Applied Polymer Science, 2009
Layered-silicate-based polymer–clay nanocomposite materials were prepared depending on the surface modification of montmorillonite (MMT). Nanocomposites consisting of poly(butylene terephthalate) (PBT) as a matrix and dispersed inorganic clay modified with cetyl pyridinium chloride (CPC), benzyl dimethyl N-hexadecyl ammonium chloride, and hexadecyl trimethyl ammonium bromide by direct melt intercalation were studied. The organoclay loading was varied from 1 to 5 wt %. The organoclays were characterized with X-ray diffraction (XRD) to compute the crystallographic spacing and with thermogravimetric analysis to study the thermal stability. Detailed investigations of the mechanical and thermal properties as well as a dispersion study by XRD of the PBT/clay nanocomposites were conducted. X-ray scattering showed that the layers of organoclay were intercalated with intercalating agents. According to the results of a differential scanning calorimetry analysis, clay acted as a nucleating agent, affecting the crystallization. The PBT nanocomposites containing clay treated with CPC showed good mechanical properties because of intercalation into the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Journal of Applied Polymer Science, 2019
Poly(ethylene terephthalate)/poly(lactic acid) (PET/PLA) blends with composition of 90/10 and 75/25 (wt %/wt %) along with two types of graphenic materials, namely graphene oxide (GO) and exfoliated graphite (xGnP), were prepared through one-step melt mixing process. The Thermal, thermo-oxidative, and hydrolytic degradation characteristics of the developed degradable PET-based nanocomposites were investigated. Thermal degradation studies by thermogravimetry analysis and melt rheological analysis in N 2 atmosphere, revealed that unlike xGnP, the addition of GO to the blends reduced their thermal stability leading to reduction of viscosity and elasticity of the blends. The behavior was attributed to the role of GO in enhancing the chain scission reactions. In the air atmosphere, the barrier properties of the graphenic materials prevailed. Compared to xGnP, the relatively well-dispersed GO showed better barrier against oxygen and increased the thermo-oxidative stability of the blends. Investigation of the hydrocatalytic degradation of developed systems, at different pH of 2 and 4, over a period of 40 days at 37 C, showed that the amount of weight loss of the GO-containing nanocomposite systems was higher than that of xGnP. The overall results of thermal, thermo-oxidative, and hydrocatalytic degradation studies confirmed the prominent role of GO in the development of degradable PET-based products.
Polymer Degradation and Stability, 2015
The development of nanocomposite materials with polymeric matrices, especially those using layered silicates, provides an alternative to composites with conventional fillers. One of the controversial aspects in the scientific literature about polypropylene-montmorillonite nanocomposites (PP/OMMT) regards its thermal stability compared to the PP matrix. The aim of this work is to evaluate the influence of the presence of montmorillonite clay in the degradation of composites, showing the limitations of thermogravimetric analysis (TGA) and emphasizing the importance of complementary analyzes such as differential scanning calorimetry (DSC) and oxidation induction time (OIT). The TGA results showed that the higher the organoclay content, the higher the temperature at which the release of volatiles takes place. However, the OIT results indicated a lower temperature for the onset of exothermic reactions for these materials and consequently the stability of the material is reduced. The use of DSC method simulating conditions of TGA, called oxidation induction temperature or dynamic OIT, was used to evaluate the stability of the composites explaining the divergence between the TGA and OIT results. The thermal analysis results were correlated to organoclay morphology, as evaluated by WAXS. It was concluded that the clay contributed to the beginning of exothermic oxidation reactions and to the kinetics decrease of volatile release and its formation.
Journal of Analytical and Applied Pyrolysis, 2012
In the present study poly(propylene sebacate) (PPSeb) nanocomposites containing 2 wt% of fumed silica nanoparticles (SiO 2 ) or multiwalled carbon nanotubes (MWCNTs), or montmorillonite (MMT) were prepared by in situ polymerization. The thermal degradation of nanocomposites was studied using thermogravimetric analysis (TGA). It was found that the addition of MWCNTs and MMT enhances the thermal stability of the polymer, while SiO 2 nanoparticles do not affect it. From the variation of the activation energy (E) with increasing degree of conversion it was found that the decomposition of nanocomposites proceeded with a complex reaction mechanism with the participation of at least two different steps. To evaluate the thermal decomposition mechanisms and mainly the effect of nanoparticles on the thermal decomposition of PPSeb, TGA/FTIR and a combination of TG-gas chromatography-mass spectrometry (TG/GC-MS) were used. From mass ions detection of the formed decomposition compounds it was found that the decomposition of PPSeb and its nanocomposites, takes place mainly through ˇ-hydrogen bond scission and, secondarily, through ˛-hydrogen bond scission. The main decomposition products were aldehydes, alcohols, allyl, diallyl, and carboxylic acids.
Thermal degradation kinetics of PET/SWCNTs nanocomposites prepared by the in situ polymerization
Journal of Thermal Analysis and Calorimetry, 2014
The decomposition and thermal behavior of poly(ethylene terephthalate) (PET)/carbon nanotubes (CNTs) nanocomposites were studied using thermogravimetric (TG) analysis in air atmosphere. A series of PET/ single-walled CNTs (SWCNTs) materials of varying nanoparticles concentration were prepared using the in situ polymerization technique. Transmission electron microscopy and scanning electron microscopy micrographs verified that the dispersion of the SWCNTs in the PET matrix was homogeneous, while some relatively small aggregates co-existed at higher filler concentration. Two-stage decomposition was observed in the experiments. During first stage, strong chemical bonds are broken, i.e., aliphatic bonds and benzyl ring containing molecules decompose into small molecules in the gaseous phase. During second stage, when temperature is higher, the remaining nanotubes along with the residues of the first stage are burned. Kissinger and Coats-Redfern (5, 10, 20, 50 K min -1 ) methods were applied to TG data to obtain kinetic parameters (activation energy, Arrhenius constant at 600 K and A factor) and Criado method to kinetics model analysis. In this kinetic model, energy activation is increasing with the increase of nanotubes concentration.