Synthesis,characterization, and thermal degradation kinetics of the copolymer poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate)

A copolymer of 4‐methoxybenzyl methacrylate and isobornyl methacrylate was synthesized by atom transfer radical polymerization. The structure of poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate) was confirmed by means of Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR techniques. The molecular weight distribution values of the copolymer were determined with gel permeation chromatography. The number‐average molecular weight and polydispersity index values of poly(4‐methoxybenzyl methacrylate‐co‐isobornyl methacrylate) were found to be 12,500 and 1.5, respectively. The kinetics of the thermal degradation of the copolymer was investigated with thermogravimetric analysis at different heating rates. The activation energy values obtained with the Kissinger, Flynn–Wall–Ozawa, and Tang methods were determined to be 166.38, 167.54, and 167.47 kJ/mol, respectively. Different integral and differential methods were used, and the results were compared with these values. Doyle approximation was also used for comparing the experimental results to master plots. An analysis of the experimental results suggested that the reaction mechanism was an R₁ deceleration type in the conversion range studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermogravimetric analysis of blends of low‐density polyethylene and poly(dimethyl siloxane) rubber: The effects of compatibilizers

The thermal stability of vulcanizates of low‐density polyethylene (LDPE), poly(dimethyl siloxane) (PDMS) rubber, and their blends was studied by nonisothermal thermogravimetry. Four ethylene copolymers [ethylene methyl acrylate (EMA), ethylene vinyl acetate, ethylene acrylic acid, and a zinc‐salt‐based ionomer (Lotek 4200)] were used as compatibilizers for the blend systems. The thermograms and derivatograms of the blends showed that thermal degradation took place in two stages, whereas those for the base polymers showed single‐stage degradation. Kinetic studies of the blends and pure components showed that the degradation followed first‐order reaction kinetics. The activation energy at 10% degradation was determined with the Freeman–Carroll method and was at a maximum (42.34 kcal/mol) for the 25:75 LDPE/PDMS rubber blend. The half‐life at 200°C was evaluated by the Flynn–Wall method and was at a maximum (812.5 days) for the same blend. Out of four compatibilizers, EMA showed the maximum activation energy (34.25 kcal/mol) for degradation and a maximum half‐life (695.3 days), indicating that EMA was the best compatibilizer for the blend system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 635–642, 2003     

Copolymerization kinetics of poly(acrylonitrile‐ran‐2‐ethenyl‐pyridine) and its degradation apparent activation energy

2‐Ethenyl‐pyridine (EPD) was first used to successfully copolymerize with acrylonitrile (AN) in a H₂O/dimethyl formamide (DMF) mixture by using azobisisobutyronitrile as the initiator. Kinetics of copolymerization and degradation of poly(AN‐ran‐EPD) were discussed. The kinetic equation of copolymerization and the apparent activation energy of degradation of poly(AN‐ran‐EPD) were obtained. In H₂O‐rich reaction medium, copolymerization followed the suspension polymerization more, but in DMF‐rich reaction medium, copolymerization followed the solution polymerization more. Increase in DMF concentration in the solvent mixture lead to a rapid increase in the degradation apparent activation energy. The apparent activation energy decreased quickly with an increase in EPD concentration, and such a change became less prominent as the molar ratio of EPD/AN went beyond 3/100. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Apparent activation energy of degradation of poly[acrylonitrile‐co‐(N‐vinylpyrrolidone)]

Differential scanning calorimetry results of the degradation of poly[acrylonitrile‐co‐(N‐vinylpyrrolidone)] in air are presented. The apparent activation energy of degradation was calculated using Kissinger's method. The effect of copolymerization conditions on the apparent activation energy was studied. Increasing the dimethylformamide concentration in the solvent mixture led to a rapid increase in the degradation apparent activation energy. The apparent activation energy decreased rapidly with increase in the comononer N‐vinylpyrrolidone concentration, and this change becomes less prominent as the weight ratio of N‐vinylpyrrolidone/acrylonitrile rises above 5/95. The apparent activation energy also increases with increasing copolymerization temperature. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of conducting poly(aniline‐co‐diaminodiphenylsulfone) copolymers

Polyaniline, poly(aniline‐co‐4,4′‐diaminodiphenylsulfone), and poly(4,4′‐diaminodiphenylsulfone) were synthesized by ammonium peroxydisulfate oxidation and characterized by a number of techniques, including infrared spectroscopy, ultraviolet–visible absorption spectroscopy, ¹H‐NMR, thermogravimetric analysis, and differential scanning calorimetry. These copolymers had enhanced solubility in common organic solvents in comparison with polyaniline. The conductivities of the HCl‐doped polymers ranged from 1 S cm^?1 for polyaniline to 10^?8 S cm^?1 for poly(4,4′‐diaminodiphenylsulfone). The copolymer compositions showed that block copolymers of 4,4′‐diaminodiphenylsulfone (r₁ > 1) and aniline (r₂ < 1) formed and that the reactivity of 4,4′‐diaminodiphenylsulfone was greater than that of aniline. The results were explained by the effect of the ? SO₂? group present in the polymer structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2337–2347, 2003     

Synthesis,characterization, and thermal degradation kinetics of poly(decamethylene 2‐oxoglutarate)

Poly(decamethylene 2‐oxoglutarate) [poly (DMOG)] was synthesized by a melt polycondensation reaction. The structure of poly(DMOG) was confirmed by means of Fourier transform infrared, ¹H‐NMR, and ¹³C NMR spectroscopies. The molecular weight distribution values of poly(DMOG) were determined with size exclusion chromatography. The number‐average molecular weight, weight‐average molecular weight, and polydispersity index values of poly(DMOG) were found to be 13,200, 19,000, and 1.439, respectively. Also, characterization was made by thermogravimetry (TG)–dynamic thermal analysis. The kinetics of the thermal degradation of poly (DMOG) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(DMOG) occurred in one stage. The apparent activation energies of thermal decomposition for poly(DMOG), as determined by the Tang method, the Flynn–Wall–Ozawa method, the Kissinger–Akahira–Sunose method, and the Coats–Redfern method were 122.5, 126.8, 121.4, and 122.9 kJ/mol, respectively. The mechanism function and pre‐exponential factor were also determined by the master plots method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal degradation kinetics of poly(N‐adamantyl‐exo‐nadimide) synthesized by addition polymerization

The thermal decomposition behavior and degradation kinetics of poly(N‐adamantyl‐exo‐nadimide) were investigated with thermogravimetric analysis under dynamic conditions at five different heating rates: 10, 15, 20, 25, and 30°C/min. The derivative thermogravimetry curves of poly(N‐adamantyl‐exo‐nadimide) showed that its thermal degradation process had one weight‐loss step. The apparent activation energy of poly(N‐adamantyl‐exo‐nadimide) was estimated to be about 214.4 kJ/mol with the Ozawa–Flynn–Wall method. The most likely decomposition process was an F1 deceleration type in terms of the Coats–Redfern and Phadnis–Deshpande results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3003–3009, 2007     

Thermal degradation kinetics of poly(O,O‐diethyl‐O‐allylthiophosphate‐co‐acrylonitrile) in nitrogen

The nonisothermal degradation kinetics of the copolymer poly(O,O‐diethyl‐O‐allylthiophosphate‐co‐acrylonitrile), which was synthesized with O,O‐diethyl‐O‐allylthiophosphate and acrylonitrile, were studied by thermogravimetry/derivative thermogravimetry techniques. The kinetic parameters, including the activation energy and the pre‐exponential factor of the copolymer degradation process, were calculated by the Kissinger and Flynn–Wall–Ozawa methods. The thermal degradation mechanism of the copolymer was also studied with the Satava–Sestak method. The results show that the activation energies were 138.17 kJ/mol with the Kissinger method and 141.63 kJ/mol with the Flynn–Wall–Ozawa method. The degradation of the copolymer followed a kinetic model of a phase boundary reaction and the kinetic equation could be expressed as G(α) = 1 ? (1 ? α)⁴ [where G(α) is the integral function of conversion and α is the extent of conversion of the reactant decomposed at time t]. The reaction order was 4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly(acrylamide‐co‐maleic acid) hydrogels for removal of Cr(VI) from aqueous solutions,Part 1: Synthesis and swelling characterization

The swelling behavior of poly (acrylamide‐co‐maleic acid) hydrogels has been investigated in distilled water at 30°C. The gels were characterized with respect to structural parameters, Fourier transform infrared, and thermogravimetric analysis. The gels showed fair pH‐dependent swelling and exhibited double “s”‐shaped curve between equilibrium water uptake and pH of the swelling media. The two pK_a values, as determined from the curve, were found to be 2.46 and 6.58. The activation energy of the water uptake process for plain and acid containing gels was found to be 7.93 and 3.26 kJ mol^?1 respectively. Similarly, the enthalpy of mixing between dry polymer and solvent showed positive values, thus indicting endothermic nature of the process, and the values increased from 10.06 to 16.29 kJ mol^?1 with increase in acid content from 2.1 × 10^?1 to 4.7 × 10^?1 mM respectively. There was an optimum initiator concentration 24.0 × 10^?2 mM and reaction temperature 60°C at which gels synthesized showed maximum absorbency. The dilution of the reaction mixture resulted in the formation of hydrogels with enhanced absorbency. Finally, the gels with varying content of monomer acid in the feed mixture showed different swelling behavior when studied in the medium of pH 1.0 and 7.0. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2759–2769, 2006     

Synthesis and characterization of a copolymer: Poly(aniline‐co‐fluoroaniline)

In the present article, we report the chemical synthesis and characterization of poly(aniline‐co‐fluoroaniline) [poly(An‐FAn)]. The copolymerization of aniline and 2‐fluoroaniline was carried out by chemical method in acidic medium. The characterization of poly(aniline‐co‐fluoroaniline) was done using FTIR, UV‐visible spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrography (SEM), and a four‐points‐probe conductivity method. X‐ray diffraction (XRD) and SEM characterization reveal crystalline nature of doped copolymer compared to undoped copolymer. The observed decrease in the conductivity of the copolymer relative to polyaniline is attributed to the incorporation of the fluoro moieties into the polyaniline chain. The chemically synthesized copolymer shows good solubility in common organic solvents, and is, therefore, technological useful. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1460–1466, 2001     

Studies on molecular transport of n‐alkanes through poly(tetrafluoroethylene‐co‐propylene) elastomeric membrane

Molecular transport of a series of n‐alkanes through commercial TFE elastomer (FA 150L) has been studied in the temperature range 30–50 °C using sorption‐gravimetric method. The Fickian diffusion equation was used to calculate the diffusion coefficients, which were dependent on the size of the alkanes and temperature. The diffusion coefficients at 30°C varied from 4.53 × 10^?8 cm²/s (n‐heptane) to 0.18 × 10^?8 cm²/s (n‐hexadecane). The liquid concentration profiles have also been computed using analytical solution of Fick's equation with the appropriate initial and boundary conditions and these were presented as a function of penetration depth of molecular migration and time of immersion. These results have been discussed in terms of molecular size of alkanes as well as temperature. In all the liquid penetrants, the transport phenomenon was found to follow the anomalous behavior. From the temperature dependence of diffusion and permeation coefficients, the Arrhenius activation parameters have been estimated. These parameters do not exhibit any systematic variation with the size of the penetrants. The resulting low diffusion coefficients, contribute to the superior barrier performance of the membrane, is due, in part, to the high glass transition temperature of Aflas? TFE elastomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2228–2235, 2006     

Degradation kinetics of poly(HDDA‐co‐MMA)

1,6‐hexanediol diacrylate (HDDA) and methyl methacrylate (MMA) were copolymerized in different weight ratios using UV light induced photo‐polymerization to give poly(HDDA‐co‐MMA). Differential scanning calorimetry shows that copolymer was formed. The thermogravimetric and differential scanning calorimetric studies with different heating rates were carried out on these copolymers to understand the nature of degradation and to determine its kinetics. Different kinetic models were adopted to evaluate various parameters like the activation energy, the order, and the frequency factor. These analyses are important to study the binder removal from 3D‐shaped ceramic objects made by techniques like Solid free form fabrication. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal degradation of poly(dimethylsilylene) and poly(tetramethyldisilylene‐co‐styrene)

Thermal degradation of poly(dimethylsilylene) homopolymer (PDMS) and poly(tetramethyldisilylene‐co‐styrene) copolymer (PTMDSS) was investigated by pyrolysis‐gas chromatography and thermogravimetry (TG). PDMS decomposes by depolymerization, producing linear and cyclic oligomeric products, whereas PTMDSS decomposes by random degradation along the chain resulting in each monomeric product and various other combination products. The homopolymer was found to be much less stable than the copolymer. The decomposition mechanisms leading to the formation of various products are shown. The kinetic parameters of thermal degradation were evaluated by different integral methods using TG data. The activation energies of decomposition (E) for the homopolymer and the copolymer are found to be 122 and 181 kJ/mol, respectively, and the corresponding values of order of reaction are 1 and 1.5. The observed difference in the thermal stability and the values of the kinetic parameters for decomposition of these polymers are explained in relation with the mechanism of decomposition. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Thermal decomposition kinetics of poly(nButMA‐b‐St) diblock copolymer synthesized by ATRP

The reaction mechanism of decomposition process and the kinetic parameters of the poly(n‐butyl methacrylate‐b‐styrene), poly(nButMA‐b‐St), diblock copolymer synthesized by atom transfer radical polymerization (ATRP) were investigated by thermogravimetric analysis (TGA) at different heating rates. TGA curves showed that the thermal decomposition occurred in one stage. The apparent activation energies of thermal decomposition for copolymer, as determined by the Kissinger's, Flynn–Wall–Ozawa and Tang methods, which does not require knowledge of the reaction mechanism (RM), were 112.52, 116.54, and 113.41 kJ/mol, respectively. The experimental results were compared with master plots, in the range of the Doyle approximation. Analysis of experimental results suggests that in the conversion range studied, 3–18%, the actual RM is an A₂ sigmoidal type. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On the thermal degradation of poly(styrene sulfone)s. V. Thermogravimetric kinetic simulation of polyacrylamide pyrolysis

The kinetics involved in the thermal degradation of polyacrylamide under nitrogen atmosphere were studied by using consecutive reactions of a kinetic model to dynamic thermogravimetric data. The model proposed correlates the thermograms obtained at thermogravimetric and differential thermogravimetric data with the same set of kinetic parameters. The first stage of polyacrylamide decomposition, where the deamonation of the polyacrylamide and the dehydration of acrylamide units and the formation of a proportion of unvolatile imides and nitrile and aliphatic organic compounds can be fitted satisfactorily when in a model based on a single reaction. The second stage, corresponding to the breakdown of the imides formed and the polymer backbone, also can be correctly represented by a model based on a single reaction. In this article, a discussion about the applicability of the model is presented and the results obtained are compared to those obtained by Flynns's and Friedman's analytical methods, respectively. The maximum decomposition temperature, shape index for dynamic condition and lifetime, and degree of decomposition for isothermal condition of thermal behavior of polyacrylamide are predicted via mathematical simulation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1540–1548, 2002     

Kinetic study of the thermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate and 2‐hydroxyethyl methacrylate copolymers

The kinetics of nonisothermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate (PDMMA), 2‐hydroxyethyl methacrylate (HEMA), and vinyl‐pyrrolidone (VPy) copolymers were investigated by thermogravimetry (TG) and differential thermal analysis (DTA). The data indicated that the major weight loss occurs in the range of 270 to 450°C. The decomposition characteristics showed essentially two regimes and varied depending on the temperature and the copolymer composition. The apparent kinetic parameters of the decompositions were estimated from both TG and DTA data by using the alternative calculation methods. The results suggest that the weight loss rates may be represented, depending on the type of sample, by a reaction model of overall order 1.0 to 1.6, with an activation energy of approximately 65–95 kJ mol^?1. The DTA data estimated considerably higher values for the overall activation energies, around 198–240 kJ mol^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1500–1508, 2005     

Investigation of thermal degradation and flammability of polyamide‐6 and polyamide‐6 nanocomposites

In this paper, polyamide‐6 and polyamide‐6 nanocomposites were prepared by direct melt intercalation technique. The thermal degradation behavior of both polyamide‐6 and polyamide‐6 clay nanocomposites has been studied. The apparent activation energy of the nanocomposites is almost the same with that of pure polymer under nitrogen, but the apparent activation energy of the nanocomposites is greatly enhanced in air atmosphere. This increasing trend coincides with the thermal analysis and the cone calorimeter results, which may suggest that the polymer/clay nanocomposites have a higher thermal stability and lower flammability. The kinetic analysis also indicates that the pyrolytic degradation and the thermal oxidative degradation of PA6 and PA6/OMT nanocomposites are two kinds of different reaction models. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2297–2303, 2007     

Characterization of polyacrylonitrile,poly(acrylonitrile‐co‐vinyl acetate), and poly(acrylonitrile‐co‐itaconic acid) based activated carbon nanofibers

In this study, three different acrylonitrile (AN)‐based polymers, including polyacrylonitrile (PAN), poly(acrylonitrile‐co‐vinyl acetate) [P(AN‐co‐VAc)], and poly(acrylonitrile‐co‐itaconic acid) [P(AN‐co‐IA)], were used as precursors to synthesize activated carbon nanofibers (ACNFs). An electrospinning method was used to produce nanofibers. Oxidative stabilization, carbonization, and finally, activation through a specific heating regimen were applied to the electrospun fibers to produce ACNFs. Stabilization, carbonization, and activation were carried out at 230, 600, and 750 °C, respectively. Scanning electron microscopy, thermogravimetric analysis (TGA), and porosimetry were used to characterize the fibers in each step. According to the fiber diameter variation measurements, the pore extension procedure overcame the shrinkage of the fibers with copolymer precursors. However, the shrinkage process dominated the scene for the PAN homopolymer, and this led to an increase in the fiber diameter. The 328 m²/g Brunauer–Emmett–Teller surface area for ACNFs with PAN precursor were augmented to 614 and 564 m²/g for P(AN‐co‐VAc) and P(AN‐co‐IA), respectively. The TGA results show that the P(AN‐co‐IA)‐based ACNFs exhibited a higher thermal durability in comparison to the fibers of PAN and P(AN‐co‐VAc). The application of these copolymers instead of AN homopolymer enhanced the thermal stability and increased the surface area of the ACNFs even in low‐temperature carbonization and activation processes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44381.     

Design,synthesis, and characterization of a potential flame retardant poly(lactic acid‐co‐pyrimidine‐2,4,5,6‐tetramine) via direct melt polycondensation

Directly starting from d ,l ‐lactic acid (LA) and pyrimidine‐2,4,5,6‐tetramine (PTA), the copolymer P(LA‐co‐PTA) as a novel potential solid compatible polymeric flame retardant is synthesized as designed via melt polycondensation. When the molar feed ratio LA/PTA is 60/1, the optimal synthetic conditions are discussed. After the prepolymerization at 140°C for 8 h, using 0.5 wt % stannous oxide as the catalyst, the melt copolymerization at 160°C for 4 h gives the copolymer with the biggest intrinsic viscosity 0.88 dL g^?1. The structures and properties of P(LA‐co‐PTA)s at different molar feed ratios are characterized by FT‐IR, ¹H‐NMR, ¹³C‐NMR, GPC, XRD, DSC, and TGA. The decomposition temperatures of P(LA‐co‐PTA)s are higher than these of homopolymer poly(d,l ‐lactic acid) (PDLLA). All copolymers have higher char yield than PDLLA, and the more PTA in the feed content, the higher char yield. What's more, there are some residues at 700–800°C, indicating that P(LA‐co‐PTA)s have good charring ability. When the monomer PTA is introduced into polylactic acid by chemical bonding as purine (PU) unit formed during the condensation, both the PTA's relatively higher nitrogen content and the PU's similar structure with flame retardant benzimidazole are beneficial to improve the thermal stability and charring ability, especially the latter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40275.     

Functionalization of poly(tetrafluoroethylene‐co‐ethylene) film by radiation‐induced graft copolymerization

To introduce functional moieties to Tefzel film, a copolymer of tetrafluoroethylene and ethylene, graft copolymerization of vinyl monomers such as acrylonitrile (AN) and methacrylonitrile (MAN) was attempted by a preirradiation method in aqueous medium. Optimum conditions for obtaining the maximum percentage of grafting have been evaluated for both monomers. Maximum grafting of AN (52.2%) and MAN (77.7%) is obtained at a total dose of 3.14 and 2.69 × 10⁴ Gy, respectively, using [AN] = 3.018 mol/L and [MAN] = 1.177 mol/L in 10 mL of water. The effect of aliphatic alcohols of varying chain length, such as methanol, ethanol, isopropanol, n‐butanol, and cyclohexanol, on percentage add‐on of AN and MAN has also been studied. It has been found that all the alcohols decreased the percentage of grafting. Characterization of Tefzel and grafted Tefzel films has been carried out by IR spectroscopy and thermogravimetric analysis. Grafted Tefzel film has been found to have improved thermal resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1171–1178, 2000