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  • Author or Editor: Yuan Hu x
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Abstract

Phosphorus-modified siloxanes monomer DOPO-IPDI-AMEO (DIA) was synthesized and characterized by 1H nuclear magnetic resonance (H NMR), 31P NMR, and Fourier transform infrared spectra (FTIR). It hydrolyzed and grew an organic–inorganic hybrid coating on the surface of cotton fabrics via sol–gel process. The conversion of gel reaction was characterized by solid-state 29Si NMR. The effect of the modified organic–inorganic hybrid materials on thermal properties of cotton fabrics was investigated by thermogravimetric (TG) analysis, real time Fourier transform infrared (RT-FTIR), and microscale combustion calorimetry (MCC) experiments. In addition, thermogravimetry-Fourier transform infrared spectra (TG-FTIR) were used to investigate the released degradation products. The characterization information represented that DIA has been prepared successfully. Also the conversion of gel reaction was fairly high. The TG data showed that char residues increased with the addition of the DIA coating. While the peak heat release rate (PHRR) decreased with the presence of the coating in MCC test. Moreover, the flammable degradation products dropped obviously, which can be observed from the data of TG-FTIR.

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Abstract

Ferric pyrophosphate (FePP) was used as additive to study its synergistic effect of thermal degradation on cotton fabrics. The microscale combustion calorimetry (MCC), thermogravimetric analysis (TG), Raman spectroscopy and Real Time Fourier transform infrared spectroscopy (RT-FTIR) were utilized to evaluate the synergistic effects of FePP on cotton/DIA. The MCC results revealed that cotton/DIA/FePP generated less combustion heat during heating than that of cotton/DIA. TG results showed that presence of FePP improved the thermal stability of materials. The Raman spectroscopy test showed that FePP can ameliorate the structural organization level of the carbon and the graphitization degree of the char. RT-FTIR data revealed the mechanism of the influence of FePP, which can catalyze the break of the flame retardant as well as promote the char forming.

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Abstract

A char-forming agent (CFA) and silica-gel-microencapsulated ammonium polyphosphate (MCAPP) were selected to form novel intumescent flame retardant system (IFRs), and then the influence of this novel IFRs on the thermal and flame retardant properties of low-density polyethylene (LDPE) were studied. The results of cone calorimetry show that the flame retardant properties of LDPE with 30 wt% novel IFR (CFA/MCAPP = 1:3) improve remarkably. The heat release rate peak, total heat release (THR) decreases, respectively, from 1479.6 to 273.5 kW m−2 and from 108.0 to 80.5 MJ m−2. The LDPE composite with CFA/MCAPP = 1:3 has the excellent water resistance, and it can still obtain a UL-94 V-0 rating after treated with water at 70 °C for 168 h.

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Abstract

The combustion properties and pyrolysis behavior of cigarette paper under the pyrolysis conditions of cigarette smouldering were investigated by micro-scale combustion calorimetry (MCC), thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG-FTIR), respectively. MCC results demonstrated that the combustion and pyrolysis behavior are influenced by heating rate obviously. TG-FTIR results illustrated that the composition of the gaseous products were mainly composed of CO2, H2O carbonyl compounds, CO, and methanol. Flash pyrolysis experiment in combination with high performance liquid chromatography (FPy-HPLC) was used to study the pyrolytic formation of eight carbonyl compounds (i.e., formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone, and butyraldehyde) during the pyrolysis of cigarette paper under the pyrolysis conditions of cigarette puffing. Moreover, the solid char formed after the flash pyrolysis experiments were studied by X-ray photoelectron spectroscopy (XPS). It had been found that the pyrolysis temperature influenced the formation of carbonyl compounds and the composition of char greatly.

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Abstract

In the article, the thermal oxidative degradation kinetics of pure polypropylene/aluminum trihydroxide (PP/ATH) and PP/ATH/organo Fe-montmorillonite (Fe-OMT) nanocomposites were investigated using Kissinger, Friedman and Flynn–Wall–Ozawa methods. The results showed that thermal oxidative degradation of PP/ATH/Fe-OMT nanocomposites to PP/ATH were complex reaction: the whole process of thermal oxidative degradation were composed with the decomposition of ATH, the cracking and charring of the backbone chains of PP, and the oxidative degradation of char, which the curses of energy mutative with the process of thermal oxidative degradation. The control steps were different in each degradation stage. The activation energy was high in the original degradation stage. It was due to the molecular structure and may closely relate with onset temperature. In the intermediate process, the activation energy was low. In the last stage of the degradation, the activation energy was graveled because the carbon may be oxidized. In the whole process of thermal oxidative degradation, the activation energy of PP/ATH/Fe-OMT nanocomposite was higher than that of PP/ATH.

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Abstract  

Two methods for estimating the critical temperature (T b) of thermal explosion for the highly nitrated nitrocellulose (HNNC) are derived from the Semenov's thermal explosion theory and two non-isothermal kinetic equations, d/dt=Af()e–E/RT and d/dt=Af()[1+E/(RT)(1–T o/T)]e–E/RT, using reasonable hypotheses. We can easily obtain the values of the thermal decomposition activation energy (E), the onset temperature (T e) and the initial temperature (T o) at which DSC curve deviates from the baseline of the non-isothermal DSC curve of HNNC, and then calculate the critical temperature (T b) of thermal explosion by the two derived formulae. The results obtained with the two methods for HNNC are in agreement to each other.

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Abstract  

A Cu–Zn–Al catalyst was prepared by the co-precipitation method and was applied for the hydrogenation of dimethyl adipate. Selectivity to 1,6-hexanediol exceeding 99% was obtained at 99% conversion of dimethyl adipate. The catalyst was highly efficient and stable. The influences of the calcination temperature of the catalyst were studied.

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Abstract

The morphology, thermal degradation, and flame retardancy of epoxy (EP) composites containing microcrystalline cellulose whisker (MCW) and microencapsulated ammonium polyphosphate (MFAPP) were investigated using optical microscopy, limiting oxygen index (LOI), UL-94, thermogravimetry (TG), microscale combustion calorimeter, and TG-FTIR. EP/MFAPP/MCW composites can pass V-0 in UL-94 test at 6 wt% loading, and its peak heat release rate decreases when compared with EP and EP/MFAPP. The reason is that the presence of MCW strengthens the charring capacity of EP composites in a fire. The results of TG and TG-FTIR show that at low temperature, MFAPP stimulates the dehydration of MCW and EP, and produces gas which is helpful for the formation of an intumescent char. Moreover, the residue at high temperature does not release any flammable gas and is a good insulation layer on the surface of the sample, which protects the underlying material in a fire.

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Abstract  

The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation

\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{{\text{d}}y}}{{dt}} = - 10^{16.4} \exp \left( { - \frac{{210380}}{{RT}}} \right)y - 10^{16.7} \exp \left( { - \frac{{171205}}{{RT}}} \right)y(1 - y)$$ \end{document}
and that for the latter 50% mass-loss of HNNC described by the reaction equations
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{dy}}{{dy}} = - 10^{16.3} \exp \left( { - \frac{{169483}}{{RT}}} \right)y\quad (n = 1)$$ \end{document}
and
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{dy}}{{dt}} = - 10^{16.8} \exp \left( { - \frac{{165597}}{{RT}}} \right)y^{2.61} \quad (n \ne 1)$$ \end{document}

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Abstract

A quantitative method including peak-fitting for determination of the content of short chain branching (SCB) in ethylene/α-olefin copolymers based on differential scanning calorimetry is described. After stepwise isothermal crystallization, the fractions with similar SCB and lamellar thickness are sorted into groups. The content of each group is determined using the peak-fitting area. The statistical terms, the arithmetic mean SCB content , the weighted mean SCB content and the branching broadness index are calculated. Through comparing with the SCB contents measured by 13CNMR analysis, the results show that this method can quantitatively characterize the content of SCB in ethylene/α-olefin copolymers with a high degree of accuracy.

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