Final Decomposition Temperature Research Articles

Effects of sodium hydroxide treatment on the properties of low‐density polyethylene composites filled with chicken feather fiber

The effects of alkali treatment with sodium hydroxide on the tensile properties, morphology, thermal degradation, and mass swell of low‐density polyethylene (LDPE)/(chicken feather fibers (CFF)) composites were studied. The LDPE/CFF composites were prepared by using a Z‐Blade mixer at 180oC and a rotor speed of 50 rpm. The LDPE/CFF‐Treated composites exhibited higher tensile strength, Young's modulus, and final decomposition temperature but had lower mass swell percentage and elongation at break than the LDPE/CFF composites. An SEM morphology study showed that the CFF treatment could significantly improve adhesion at the interface and lead to ingress of the fiber into the LDPE phase. Thermogravimetric analysis indicated that the LDPE/CFF‐Treated composites had higher thermal stability than the LDPE/CFF composites. J. VINYL ADDIT. TECHNOL., 20:36–41, 2014. © 2014 Society of Plastics Engineers

Rapid synthesis and thermal catalytic performance of N-doped ZnO/Ag nanocomposites

Abstract N-doped ZnO/Ag nanocomposites were rapidly synthesized by a deflagration method within tens of seconds, using urea as fuel and citric acid as vesicant. Characterization results showed that the samples were nanoparticles with an average size of about 15 nm. Most of Ag existed in the form of metallic Ag (0), and N was doped into the composite in the form of acceptor impurities. Compared with pure ZnO, the N-doped ZnO/Ag nanocomposites possessed a remarkably enhanced catalytic efficiency on the thermal decomposition of ammonium perchlorate. This is particularly true for the sample containing 4.0% Ag as it offered the best catalytic performance and reduced the final decomposition temperature of AP to 290 °C from 453 °C. The mechanism showed that the high decomposition rate of AP was due to N doping and Ag modification being able to transfer efficiently electrons from ClO4− to NH4+ in ammonium perchlorate.

Chicken feather fibers–recycled high-density polyethylene composites

The effects of ε-caprolactam on tensile properties, morphology, thermal degradation, and swelling behavior of recycled high-density polyethylene–chicken feather fiber composites (r-HDPE/CFF) were studied. The r-HDPE/CFF composites were prepared using Brabender Plasticorder at 160°C and a rotor speed of 50 r min−1 for 6 min. The r-HDPE/CFF/ε-caprolactam composites exhibit higher tensile strength, modulus of elasticity, and final decomposition temperature, but lower mass swell percentage and elongation at break than r-HDPE/CFF composites. Scanning electron microscopic morphology showed that the CFF was more widely dispersed in the r-HDPE matrix with the addition of ε-caprolactam as a coupling agent. It was also found that the addition of ε-caprolactam offers better thermal stability in r-HDPE/CFF/caprolactam composites than r-HDPE/CFF composites.

Properties of Chicken Feather Fiber-Filled Low-Density Polyethylene Composites: The Effect of Polyethylene Grafted Maleic Anhydride

The effects of polyethylene grafted maleic anhydride on tensile properties, morphology, thermal degradation, and swelling behavior of low density polyethylene/chicken feather fiber composites were studied. The LDPE/CFF composites were prepared using a Z-Blade mixer at 180°C and rotor speed of 50 rpm for 15 min. LDPE/CFF/PEgMAH composites exhibit higher tensile strength, Young's modulus, and final decomposition temperature, but lower mass swell percentage and elongation at break than LDPE/CFF composites. SEM morphology showed that the chicken feather fiber more widely dispersed in the LDPE matrix with the addition of polyethylene grafted maleic anhydride as a coupling agent. It was also found that the addition of PEgMAH offers better thermal stability in LDPE/CFF/PEgMAH composites than LDPE/CFF composites.

Novel hybrid copolymer by incorporating POSS into hard segments of thermoplastic elastomer SEBS via click coupling reaction

A novel organic–inorganic hybrid copolymer has been achieved by incorporating polyhedral oligomeric silsesquioxanes (POSS) into the hard polystyrene segments in thermoplastic elastomer of poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) via click coupling reaction of alkyne group in POSS with azido groups in SEBS by Cu(I)-catalyzed 1,3-dipolarcycloaddition. The alkyne-functionalized POSS could be synthesized via thiol-ene facile click reaction and subsequent amidation reaction with high conversion near to 100%. Azido-functionalized SEBS (SEBS–CH2N3) with different functionalities could be synthesized by chloromethylation of phenyl groups and subsequent azido reaction. The obvious POSS inorganic phase aggregates of around 30 nm in size formed and homogeneously dispersed in SEBS matrix. The SEBS-g-POSS copolymer presented a good hydrophobic property with contact angle of 94.8°. The final decomposition temperature was increased by c.a. 20 °C in comparison with that of SEBS. SEBS-g-POSS makes a contribution to improvements in tensile stress and modulus of PS/SEBS-g-POSS composites due to the hard core with Si–O–Si inorganic structure of POSS. Compared to parallel PS/SEBS composite without any inorganic phase, tensile strength and modulus of PS/SEBS-g-POSS (90/10) blend could be increased by 35% and by 10% respectively.

Mechanical and thermal properties of chemical treated kenaf fibres reinforced polyester composites

Kenaf fibre reinforced polyester biocomposites fabricated by hand lay-up technique by using propionic and succinic anhydride-modified kenaf fibres. Chemical structure, mechanical, thermal and morphological properties of kenaf fibres reinforced polyester biocomposites evaluated. The Fourier transform infrared study of modified kenaf fibres carried out to look at changes in functional groups after modification. It confirmed from Fourier transform infrared spectroscopy the variation in positions of functional groups. The mechanical (tensile, flexural and impact) property results revealed that biocomposites with modified kenaf fibres exhibited better properties as compared to untreated kenaf fibres-reinforced polyester biocomposites. Morphological studies show that treated kenaf biocomposites show better fibre/matrix interaction. Thermal analysis results of modified biocomposites exhibited higher initial and final decomposition temperatures. Modified biocomposites display less char residue as compared with unmodified kenaf fibres reinforced polyester composites.

PEI modified Leucaena leucocephala seed powder, a potential biosorbent for the decontamination of arsenic species from water bodies: bioremediation

Environmental contamination due to anthropogenic and natural sources is increasing day by day because of increase in population, industrialization and urbanization. Arsenic species released into the environment tend to persist indefinitely, circulating and eventually accumulating throughout the food chain, thus becoming a serious threat to the environment. The present study explores the effectiveness of Leucaena leucocephala seed powder (agricultural waste) in removing arsenic ions from aqueous solution. Batch studies were carried out to characterize As (III) and As (V) removal capability of L. leucocephala seed powder. Maximum biosorption capacity for As (III) and As (V) was found to be 81.88 and 92.61 %, respectively. Amino acid–arsenic interaction has been highlighted on the basis of shifting of FTIR bands of native LLSP. Morphological changes and reduction in pore area have been observed in modified LLSP. Modification on the native LLSP results into the increase in percentage sorption of As (III) and As (V) up to 85 and 99 %, respectively. Enhancement in the percentage sorption is due the increase in the stability of the biosorbent due to increase in the final decomposition temperature of the modified LLSP. The findings showed that L. leucocephala seed powder can easily be envisaged as a new, vibrant, low-cost biosorbent for arsenic clean-up operations.

Thermodynamic study of phosphogypsum decomposition by sulfur

Phosphogypsum (PG) is one of the most significant industrial solid wastes from the phosphorus chemical industry. In order to utilize PG more effectively, a new decomposition process of PG by sulfur as a reducer is proposed in this work. Thermodynamic study of the sulfur reduction process including two-step reactions was carried out by both thermodynamic simulation and experimental research. The simulation results indicate that sulfur changes its form in a complex way with rising temperature. The final decomposition temperature of PG by simulation is 993K in the first-step reaction, and this is in good agreement with that obtained by the experiments. For the second-step reaction, however, the final PG decomposition temperature from the experiments is 250K lower than the simulation results predict. The reaction heat of the sulfur reduction process is 27.95% less than that of the traditional coke reduction process at T=1473K based on enthalpy change calculations. This new process can reduce the emission of CO2 effectively and is more suitable for resource utilization of PG than the coke reduction process, so it may be a promising method for sulfuric acid production from PG.

Synthesis of Tung Oil-Based Bi-Dihydrogen-Maleimide

Started from Tung oil, a renewable biomass material of china, a new kind of bismaleimide, Tung oil-based bi-dihydrogen-maleimide (TOBBDHMI) was synthesized by the reaction of methyl-α-eleostearate-maleic anhydride adduct (MEMAA) and 4,4'-diphenylmethane disocyanate (MDI). The optimal conditions for synthesis were catalyst triethylamine dosage 1.0%, mole ratio of MEMAA to MDI 2.4:1, reaction temperature 75°C and reaction time 2 h, which gave yield 82.4% for TOBBDHMI (calculated from MDI). The melting point of the product was 186.6 °C~189.3 °C, initial decomposition temperature was 270 °C and final decomposition temperature was 510 °C, which showed the product has good heat resistance. The target product is potential to be used alone or with other bismaleimide monomers to improve polymeric materials’ heat resistance and/or mechanical properties.

Full factorial design‐of‐experiments for preparation of crosslinked dextran microspheres

AbstractThis work describes full factorial design‐of‐experiment methodology for exploration of effective parameters on physical properties of dextran microspheres prepared via an inverse emulsion (W/O) technique. Microspheres were prepared by chemical crosslinking of dextran dissolved in internal phase of the emulsion using epichlorohydrin. The input parameters were dextran concentration in the aqueous phase, crosslinking ratio, and concentrations of sodium hydroxide and span 80 as the reaction catalyst and surfactant, respectively. Chemical structure of the resulting microspheres was analyzed spectroscopically using Fourier‐transform infrared technique. Final decomposition temperature, mean particle size and its distribution and equilibrium swelling ratio were selected as output responses. Microspheres with smooth surface were obtained according to scanning electron micrographs. It was found that an increase in dextran concentration in the aqueous internal phase increases mean particle diameter of the resulting microspheres, significantly. Moreover, water uptake capacity for the microspheres was dependent on both the dextran concentration and crosslinking ratio. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A Study on Xinjiang Asphaltite as an Asphalt Modifier. Part I: Composition, Structure, and Thermal Behavior

Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA) were employed to investigate the composition, structure, and thermal behavior characteristics of Xinjiang asphaltite and Iran asphaltite. Infrared spectroscopy showed that both asphaltites were composed of predominantly highly condensed polycyclic aromatic rings with long alkyl groups and polar functional groups. NMR spectroscopy indicated that the hydrogens of the aromatic ring in both asphaltites were almost completely substituted. TGA curves showed that the initial decomposition temperature of Xinjiang asphaltite was around 190°C, whereas the final decomposition temperature is over 800°C. Xinjiang asphaltite exhibited the potential for asphalt modification due to its composition and structural characteristics, which are similar to asphaltene, though some of its components are more thermally stable than asphaltene.

Synthesis and Characterization of Homo- and Copolymers of N-4-Azodiphenyl Maleimide with Methyl Methacrylate and Styrene

The synthesis and free radical homopolymerization of N-4-azodiphenylmaleimide (ADPMI) and copolymerization of methyl methacrylate (MMA) and styrene (ST) with ADPMI using an AIBN initiator were performed in THF solvent at 70°C. A series of copolymers, ADPMI-MMA and ADPMI-ST, were prepared using different feed ratios of comonomers. The polymer samples have been characterized by solubility tests, intrinsic viscosity measurements, FT-IR, 1H-NMR spectral analysis, and thermo-gravimetric analysis. The values of monomer reactivity ratios r1 and r2 determined by Fineman-Ross and Kelen-Tudos methods are 0.16 and 0.63, and 0.26 and 0.25 in ADPMI/MMA and ADPMI/ST systems, respectively. Alfrey-Price Q-e values for ADPMI are Q = 2.27 and e = 1.92, and 0.41 and 1.949 for ADPMI/MMA and ADPMI/ST systems, respectively. It was found that the initial and final decomposition temperatures increased with the increase of ADPMI content in the copolymer samples.

Pyrolysis characteristics and kinetics of sewage sludge for different sizes and heating rates

The pyrolysis characteristics and kinetics of sewage sludge for different sizes (d 0.83 mm) and heating rates (5, 20, and 35 °C/min) were investigated in this article. The STA 409 was utilized for the sewage sludge thermogravimetric analysis. FTIR analysis was employed to study the functional groups and intermediates during the process of pyrolysis. Meanwhile, a new method was developed to calculate pyrolysis kinetic parameters (activated energy E, the frequency factor A, and reaction order n) with surface fitting tool in software MATLAB. The results show that all the TG curves are divided into three stages: evaporation temperature range (180–220 °C), main decomposition temperature range (220–650 °C), and final decomposition temperature range (650–780 °C). The sewage sludge of d < 0.25 mm obtains the largest total mass loss, especially at the heating rate of 5 °C/min. By FTIR analysis, the functional groups including NH, C–H, C=C, etc., are all found in the sewage sludge. There is a comparison between the FTIR spectra of sludge heated to 350 °C (temperature associated to maximum devolatilization rate in the second stage) and the FTIR spectra of sludge heated to 730 °C (temperature associated to maximum devolatilization rate in the third stage). In the second stage, the alcohols, ammonia, and carboxylic acid in the sludge have been mostly decomposed into gases, and only a little bit of compounds containing CH and OH of COOH exist. The pyrolysis kinetic parameters of second stage are as follows: the reaction orders are in the range of 1.6–1.8 and the activation energy is about 45 kJ/mol. The frequency factor increases with the increase of heating rate and sewage sludge size.

Thermal stability of the ‘cave’ mineral ardealite Ca2(HPO4)(SO4)·4H2O

Thermogravimetry combined with evolved gas mass spectrometry has been used to characterise the mineral ardealite and to ascertain the thermal stability of this ‘cave’ mineral. The mineral ardealite Ca2(HPO4)(SO4)·4H2O is formed through the reaction of calcite with bat guano. The mineral shows disorder, and the composition varies depending on the origin of the mineral. Thermal analysis shows that the mineral starts to decompose over the temperature range of 100–150 °C with some loss of water. The critical temperature for water loss is around 215 °C, and above this temperature, the mineral structure is altered. It is concluded that the mineral starts to decompose at 125 °C, with all waters of hydration being lost after 226 °C. Some loss of sulphate occurs over a broad temperature range centred upon 565 °C. The final decomposition temperature is 823 °C with loss of the sulphate and phosphate anions.

Consequence of doping mediated strain and the activation energy on the structural and optical properties of ZnO:Cr nanoparticles

We report on the sol–gel synthesis of Zn 1− x Cr x O ( x=0.0, 0.05, 0.10, 0.15 and 0.20) nanoparticles. These nanoparticles were characterized by using thermogravimetry/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and Photoluminescence (PL). Electronegativity of Cr ions (Cr 3+) reduces the final decomposition temperature by 40 °C and activation energy of the reaction when Cr is doped into ZnO. Doping of higher Cr concentration ( x≥0.10) into ZnO shows formation of secondary spinel (ZnCr 2O 4) phase along with the hexagonal (ZnO) and is revealed by XRD. Formation of secondary phase changes the activation energy of the reaction and thus the strain in ZnO lattice. In Raman spectra, additional Raman modes have been observed for Zn 1− x Cr x O nanoparticles, which can be assigned to the modes generated due to Cr doping. The Cr doping into ZnO is also supported by PL, in which vacancies are formed with Cr ion incorporation and emission band shifts towards higher wavelength.

A new method for evaluating the sewage sludge pyrolysis kinetics

A new method to simplify calculation the kinetics model is applied to sewage sludge pyrolysis based on the assumption that volatile run out as soon as it formed and during temperature arising process in this study. Difference method widely used to solve math problems is conducted to calculate kinetics parameters. Pyrolysis experiments are carried out at heating rates of 10, 15, 20, and 50 °C/min. All the TG curves are divided into three parts which are beginning decomposition temperature range, main decomposition temperature range, and final decomposition temperature range. The second one is employed to determine the parameters for more than 70% of the total mass loss occurs in this range. According to the developed method, the react order, reaction energy and pre-exponential factor are obtained, which are in the range of 3.9–4.1, 82.3–109.2 kJ/mol and 7.7 × 10 6–2.8 × 10 9/min, respectively, which are in the range of that reported previously. As a comparison experimental data with calculated data, the well fitting results indicate that this method is appropriate for simulating sludge pyrolysis kinetics.

Characterisation of thermally treated and untreated polyethylene–polypropylene blends using DSC, TGA and IR techniques

The thermal characteristics of thermally treated and untreated very low density polyethylene, isotactic polypropylene and their blends were investigated. Injection moulded blends containing five different weight percentages of VLDPE/iPP were prepared and thermally treated at 100°C for 2, 4, 7 and 14 days. Differential scanning calorimetry, thermogravimetry and infrared spectral analysis techniques were used to study the effect of thermal treatment and blending ratio on the thermal and chemical stability. The addition of PE had caused the Tm, heat of fusion and percentage crystallinity of PP main melting peak to decrease, indicating that both polymers are partially miscible. Tm has been found to increase with aging time, however, the heat of fusion is not significantly affected. The initial and final decomposition temperatures, maximum decomposition rate temperature, order of decomposition reaction, activation energy and activation enthalpy were calculated, in a dynamic nitrogen atmosphere, and discussed in terms of blending ratios and aging times. The IR spectra of all blends at different aging times do not show any degradation products.

Preparation and characterization of pH-responsive hydrogel magnetite nanocomposite

Hydrogel magnetite nanocomposite (HMNC) was fabricated by in situ development of magnetite nanoparticles in polyacrylamide (PAM) hydrogel. The formation of magnetite nanoparticles and their magnetic properties were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and super conducting quantum interference device. The average particle size was 3–5 nm as demonstrated by transmission electron microscopy. The thermal property of HMNC was determined by thermo-gravimetric analysis. It was found that HMNC had a lower thermal stability at the initial decomposition temperature and higher thermal stability at the final decomposition temperature. It was also found that HMNC showed pH sensitive behavior which is not present in plain hydrogel, and the HMNC prepared with a 100% iron salt solution showed a high protein adsorption characteristic at pH 7.0.

Preparation and properties of the heteropolyoxometalates of large organic cation with molybdotungstosilicic acids

Some new heteropolyoxometalates of large organic cations with molybdotungstosilicic acids (general formula: (CTMA)4SiMoxW12−xO40⋅mH2O⋅nDMF, x=0,2,4,6,8,10,12) were prepared by the reaction of cetyltrimethylammonium bromide (CTMAB,C16H33N(CH3)3Br) with H4SiMoxW12−xO40(x=0,2,4,6,8,10,12) in aqueous solution and recrystallization in DMF, and characterized by elemental analysis, IR spectra,TG-DTA and XRD techniques. The IR spectrum confirms the presence of Keggin structure and organic cations in these compounds, and it is indicated that the stretching vibration of the M-Od, M-Ob-M and Si-Oa becomes more red-shifted when molybdenum is gradually substituted for the tungsten atom. In particular, the thermal decomposition of the heteropolyoxometalates was studied in nitrogen atmosphere. The TG-DTA curves show that their thermal behaviors not only contain the release of water molecule, DMF molecule, CTMA and its fragments but also contains simultaneous collapse of Keggin anion. Their end products of the thermal decomposition are the mixture of WO3, MoO3 and SiO2. And from the final decomposition temperature of view, it is found that the thermal stability of these compounds gradually is decreased when the number of molybdenum atoms is increased.

Free Radical Copolymerization of Methyl Methacrylate and Styrene with N-(4-Carboxyphenyl)maleimide

The free radical copolymerization of methyl methacrylate (MMA) or styrene (St) with N-(4-carboxyphenyl)maleimide (CPMI) was carried with AIBN as an initiator in THF solvent at 80°C. A series of copolymers of MMA and St with CPMI were prepared using different feed ratios of comonomers. The values of monomer reactivity ratios (r1, r2) determined by Fineman-Ross and Kelen-Tudos methods are 0.26 and 2.51 in the CPMI/MMA system and 0.08 and 0.22 in the CPMI/St system. Alfrey–Price Q-e values for CPMI were calculated as Q = 1.05 and e = 0.41 in the CPMI/MMA system and Q = 1.21 and e = 0.91 in the CPMI/St system. The polymer samples have been characterized by solubility tests, intrinsic viscosity measurements, FT-IR and 1H-NMR spectral analysis, and thermo-gravimetric analysis. It was found that the initial and final decomposition temperatures increased with increasing the amount of CPMI in the copolymer. The integral procedural decomposition temperature and energy of activation of thermal degradation have also been reported.