Poly(trimethylene terephthalate)/magnesium hydroxide composites with on‐demand thickening at high temperatures

Magnesium hydroxide, when melt extruded with poly(trimethylene terephthalate) (PTT) at low concentrations (1–3 wt.%), can be melt processed during extrusion and injection molding. When the polymer is heated in the melt to 295°C, the viscosity of the composite behaves similarly to control samples and the viscosity decreases as a function of temperature. When the temperature of the composite is raised above 295°C (above the normal processing conditions for PTT), a significant change in the melt rheology of the composite is observed relative to unfilled compositions. This change in melt rheology coincides with the decomposition temperature of magnesium hydroxide and formation of magnesium oxide, a common thickening agent employed in unsaturated polyester resins. Lower processing temperature polyesters, including PTT, enable processing of the polymer in the presence of magnesium hydroxide under normal conditions. The viscosity modifier ‘turns on’ when the composite sees elevated temperature where magnesium oxide is known to form. The magnesium oxide is hypothesized to interact with PTT carboxyl end groups, providing the observed increase in viscosity. The rheological response observed in the composites is dependent on the concentration of magnesium hydroxide. During burning, the viscosity modifier results in a non‐dripping formulation of PTT. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,characterization, and thermal degradation of novel poly(2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate)

A novel methacrylate monomer containing benzofuran side group, 2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate (BOEMA), was synthesized from esterification reaction of 2‐bromo‐1‐(5‐bromo benzofuran‐2‐yl) ethanone with sodium methacrylate at 85°C in the presence of 1,4‐dioxane solvent. After characterization with Fourier transform infrared spectrophotometer, nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), its homopolymerization was carried out by free radical polymerization at 60°C in the presence of benzoyl peroxide initiator and 1,4‐dioxane solvent. The glass transition temperature (T_g) of the synthesized novel polymer, poly(2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate) [poly(BOEMA)], was determined to be 137°C with differential scanning calorimetry technique. Thermal degradation kinetics of poly(BOEMA) was investigated by thermogravimetric analysis method at different heating rates with 5°C/min intervals between measurements. From dynamic measurements, the analysis of each process mechanism of Coats–Redfern and Van Krevelen methods showed that the most probable model for the decomposition process of poly(BOEMA) homopolymer agrees with the random nucleation, F₁ mechanism. The apparent decomposition activation energies of poly(BOEMA) by Kissinger's and Flynn–Wall–Ozawa methods in the studied conversion range were 188.47 and 180.13 kJ/mol, respectively. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Thermal characteristics and pyrolysis of methyl‐di(phenylethynyl)silane resin

Thermal stability of a recently synthesized polymeric methyl‐di(phenylethynyl)silane (MDPES) resin was studied using a number of thermal and spectrometric analytical techniques. The polymer exhibits extremely high thermal stability. Thermogravimetric analysis (TGA) shows that the temperature of 5% weight loss (T_d5) was 615°C and total weight loss at 800°C was 8.9%, in nitrogen atmosphere, while in air, T_d5 was found to be 562°C, and total weight loss at 800°C was found to be 55.8% of the initial weight. Differential thermal degradation (DTG) studies show that the thermal degradation of MDPES resin was single‐stage in air and two‐stage in nitrogen. The thermal degradation kinetics was studied using dynamic TGA, and the apparent activation energies were estimated to be 120.5 and 114.8 kJ/mol in air, respectively, by Kissinger and Coats–Redfern method. The white flaky pyrolysis residue was identified to be silicon dioxide by FTIR and EDS, indicating that the thermal stability of polymer may be enhanced by the formation of a thin silicon dioxide film on the material surface. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 605–610, 2007     

水氯镁石制备金属镁的过程集成与能量分析

以无水氯化镁和氧化镁作为中间产物,电解和热还原为两个关键方法,集成各种相关过程,构建了从水氯镁石到金属镁的综合过程网络,其中涉及24个物种、20个化学过程和25个工艺路线;建立了最低能耗分析模型用于简单和复合过程的能量分析;利用物质的标准生成焓和多温等压摩尔热容,计算得出全部反应过程及工艺过程的能量消耗和热量移除。结果表明基于还原法的最优路径是水氯镁石用石灰法转为氢氧化镁,进而煅烧成氧化镁,再铝热还原成金属镁,该过程能耗360.15 kJ/mol,放出热量–315.46 kJ/mol;基于电解法的最优路径是石灰乳法生成氢氧化镁,再煅烧成氧化镁,通过在熔融电解质中电解生成金属镁,该过程能耗738.54 kJ/mol,放出热量–135.42 kJ/mol。无水氯化镁制备耗能高,不在最优路径中。     

氢氧化镁纳米棒的制备及热分解动力学研究

以氯化镁和轻质氧化镁为原料,采用液相法制备出碱式氯化镁纳米棒;再以碱式氯化镁纳米棒为前驱物,经沉淀转化法合成出直径约100～150nm,长约3～5μm的氢氧化镁纳米棒。采用Romero方法,对非等温热重法得到的氢氧化镁纳米棒热分解动力学数据处理分析后,得出氢氧化镁纳米棒的热分解反应遵循随机成核和随后生长（F1）机理,表观活化能E=187kJ／mol,指前因子A=3．84×10^11。     

典型垃圾材料的热分解动力学

对垃圾材料的热分解动力学研究目的在于研究垃圾材料的热解特性,文中对典型垃圾材料聚氯乙烯(PVC)和纸进行热分解动力学研究.用综合热分析仪分别测试PVC及纸在升温速率为10,15,20,30 K/min时的TG-DSC曲线,获取PVC和纸在最大质量损失速率时的温度Tmax及其他动力学参数.然后用Kissinger法和Fl...     

Permeation of methyl chloride and benzene through FEP Teflon

Permeabilities and diffusivities of methyl chloride and benzene vapors at low activities in FEP Teflon membranes were measured in a continuous-flow permeation cell, at temperatures ranging from 47°C to 150°C. In all cases investigated, the permeabilities and diffusivities were independent of the penetrant partial pressure, and the permeation process was well described by a Henry's law sorption–Fickian diffusion model. The activation energies for permeation and diffusion and the sorption enthalpy were respectively 34.8 kJ/mol, 50.1 kJ/mol, and ?15.3 kJ/mol for methyl chloride and 49.5 kJ/mol, 69.1 kJ/mol, and ?19.6 kJ/mol for benzene. The diffusional activation energies for these two substances and other low molecular weight hydrocarbons correlate reasonably well with the Lennard–Jones collision diameters of the penetrant molecules. The solubilities correlate approximately with the penetrant boiling points, but the highly polar nature of methyl chloride and the aromaticity of benzene lead to deviations between the solubilities of these substances and those of nonpolar aliphatics with the same tendency to condense from the vapor phase.     

Synthesis and characterization of nanocellulose reinforced full‐interpenetrating polymer network based on poly(vinyl alcohol) and polyacrylamide (both crosslinked) composite films

An interpenetrating polymer network (IPN) is a novel blend of two polymers at least one of which is synthesized or crosslinked in the immediate presence of the other so that there is the least possibility of any gross phase separation. Full‐IPNs, prepared from poly(vinyl alcohol) and polyacrylamide, have shown superior performances over the conventional individual polymers. The ranges of applications have grown rapidly for such class of materials. Cellulose nanoparticles extracted from sugarcane bagasse in‐house are used to reinforce this PVA/PAAm (80:20) full‐IPN in different proportions during the synthesis of IPN. The characteristics of this new series of IPN composite materials have been evaluated by Fourier transform infrared spectroscopic analysis, mechanical, thermal (thermogravimetric analysis and differential scanning calorimetry), and scanning electron microscopy techniques. A loading of 5 wt% of nanocellulose lead to the highest tensile strength amongst the different IPN composite films. Although the non‐reinforced full‐IPN and the various reinforced composites with nanocelluloses are almost identical in their thermal stability, they prove to be much superior compared to the neat polymers. POLYM. COMPOS., 38:1720–1731, 2017. © 2015 Society of Plastics Engineers     

Effect of zeolite filler on the thermal degradation kinetics of polypropylene

In this study, the thermal degradation behavior of polypropylene (PP) and PP–zeolite composites was investigated. Clinoptilolite, a natural zeolitic tuff, was used as the filler material in composites. The effects of both pure clinoptilolite and silver‐ion‐exchanged clinoptilolite on the thermal degradation kinetics of the PP composites was studied with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Polymer degradation was evaluated with DSC at heating rates of 5, 10, and 20°C/min from room temperature to 500°C. The silver concentration (4.36, 27.85, and 183.8 mg of Ag/g of zeolite) was the selected parameter under consideration. From the DSC curves, we observed that the heat of degradation values of the composites containing 2–6% silver‐exchanged zeolite (321–390 kJ/kg) were larger than that of the pure PP (258 kJ/kg). From the DSC results, we confirmed that the PP–zeolite composites can be used at higher temperatures than the pure PP polymer because of its higher thermal stability. The thermal decomposition activation energies of the composites were calculated with both the Kissinger and Ozawa models. The values predicted from these two equations were in close agreement. From the TGA curves, we found that zeolite addition into the PP matrix slowed the decomposition reaction; however, silver‐exchanged zeolite addition into the matrix accelerated the reaction. The higher the silver concentration was, the lower were the thermal decomposition activation energies we obtained. As a result, PP was much more susceptible to thermal decomposition in the presence of silver‐exchanged zeolite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 143–148, 2006     

Conducting nanocomposites of polyacrylamide with acetylene black and polyaniline

A conducting nanocomposite of polyacrylamide (PAA) with acetylene black was prepared via Na₂AsO₃‐K₂CrO₄ redox initiated polymerization of acrylamide in water containing a suspension of acetylene black. FTIR analyses confirmed the presence of PAA in the nanocomposites. The composite possessed lower thermal stability than AB and exhibited three stages of decomposition upto 430°C. DSC thermogram revealed three endotherms due to minor thermal degradation (at ∼100°C), melting and decomposition (at ∼230°C) and major decomposition (at ∼430°C). TEM analyses indicated the formation of globular composite particles with sizes in 30–70 nm range. In contrast to the very low conductivity of the base polymer the composite showed a dramatic increase in conductivity (0.19–6.0 S/cm) depending upon AB loading. Log (conductivity) –1/T plot showed a change in slope at ∼127°C indicating the manifestation of an intrinsic conductivity region and an impurity conductivity region. The activation energy for conduction as estimated from the slope of region I was 0.008 eV/mol. The C–V plot was linear showing a metallic behavior. For comparison in conductivity PAA‐polyaniline composite was also prepared which however displayed much lower conductivity values. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis,characterization, and ligating behavior of poly[N,N‐p‐phenylene bisacryl (methacryl)amide]

Monomers of diacylated amine were synthesized by the reaction of acryloyl chloride or methacryloyl chloride with p‐phenylenediamine. Heating DMF solution of these monomers at 75°C in the presence of AIBN as an initiator gave the corresponding polymer. The solid metallopolymer complexes with different metal salts were isolated either by the in situ addition of the monomer, metal salt, and initiator at 75°C or by the reaction of the isolated polymer with the metal salt at 150°C. The monomers, polymers, and their metallopolymer compounds were characterized using elemental analysis, IR, NMR (¹H and ¹³C), and MS spectral measurements in addition to thermal analysis. The IR data showed that the coordinating atoms of the polymer are dependent on the reaction temperature. The ion selectivity of the isolated polymers toward different metal ions either for a single metal ion or in a mixture as aqueous solutions are studied by the batch techniques. Energy dispersive spectroscopy (EDS) measurements showed that both polymers are more selective to Hg²⁺ and Pb²⁺. The morphology of the polymers and their metallopolymer complexes at different temperature was also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2412–2422, 2006     

氧化镁蒸氨反应的动力学和机理研究

以轻烧粉和氯化铵反应为出发点,研究了氧化镁蒸氨反应过程的动力学和反应机理。结果表明：当反应30 min时,70~90 ℃条件下溶液中镁离子浓度约为0.14 mol/L,100 ℃时浓度为0.5 mol/L。XRD结果表明,蒸氨过程中未反应生成Mg2+的氧化镁以氢氧化镁存在于滤渣中。随着煅烧温度的升高,氧化镁水化反应活化能逐渐增加。当煅烧温度为600 ℃时,反应活化能为64.789 9 kJ/mol;当煅烧温度为800 ℃时,反应活化能为81.350 6 kJ/mol。氢氧化镁和氧化镁按不同物质的量比混合进行蒸氨反应时,蒸氨速率随体系中氢氧化镁含量的增加而升高。氧化镁蒸氨体系可分为2个阶段：第一阶段,氧化镁在铵盐体系中进行水化反应生成氢氧化镁,同时部分氧化镁和氢氧化镁进行蒸氨反应生成镁离子;第二阶段,整个体系完全变成氢氧化镁蒸氨体系。     

Effect of bilayered stearate ion‐modified Mg?Al layered double hydroxide on the thermal and mechanical properties of silicone rubber nanocomposites

The homogeneous dispersion of nanofillers in polymer matrices to form polymer nanocomposites remains a challenge in the development of high‐performance polymer materials for various applications. In the work reported, a stearate ion‐modified Mg? Al layered double hydroxide (St‐LDH) as nanofiller was incorporated in a silicone rubber (SR) matrix by solution intercalation and subsequently characterized. X‐ray diffraction and transmission electron microscopy studies confirm the formation of a predominantly exfoliated dispersion of St‐LDH layers of 75–100 nm in width and about 1–2 nm in thickness in the SR. Thermogravimetric analysis shows that the thermal degradation temperature of the exfoliated SR/St‐LDH (1 wt%) nanocomposites is about 80 °C higher than that of pure SR. Differential scanning calorimetric studies indicate that the melting and crystallization temperatures are higher by 4 and 10 °C for 5 and 8 wt% St‐LDH‐loaded SR nanocomposites compared to neat SR. A significant improvement of 97% in tensile strength and 714% in storage modulus and a reduction of 82% in oxygen permeability have been achieved at 3 wt% St‐LDH loading in SR. Copyright © 2011 Society of Chemical Industry     

Continuous distribution kinetics for the thermal degradation of LDPE in solution

Polymer degradation in solution has several advantages over melt pyrolysis. The degradation of low‐density polyethylene (LDPE) occurs at much lower temperatures in solution (280–360°C) than in conventional melt pyrolysis (400–450°C). The thermal degradation kinetics of LDPE in solution was investigated in this work. LDPE was dissolved in liquid paraffin and degraded for 3 h at various temperatures (280–360°C). Samples were taken at specific times and analyzed with high‐pressure liquid chromatography/gel permeation chromatography for the molecular weight distribution (MWD). The time evolution of the MWD was modeled with continuous distribution kinetics. Data indicated that LDPE followed random‐chain‐scission degradation. The rapid initial drop in molecular weight, observed up to 45 min, was attributed to the presence of weak links in the polymer. The rate coefficients for the breakage of weak and strong links were determined, and the corresponding average activation energies were calculated to be 88 and 24 kJ/mol, respectively. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 681–690, 2002; DOI 10.1002/app.2344     

ESR study on the effect of temperature on the diffusion of oxygen into PMMA and PVAC polymers

The free radicals produced by γ irradiation in the polymer network are formed with ionizing radiation. The decay rates of radicals in the temperature range were used to estimate the diffusion coefficient of oxygen into polymeric spheres by an electron spin resonance (ESR) technique. The ESR results showed that the activation energy of the diffusion of oxygen into poly(methyl methacrylate) (PMMA) in the temperature range 10–40°C is 29.6 kJ/mol. There are two activation energies of the diffusion of oxygen into poly(vinyl acetate) (PVAc) in the temperature range 25–50°C. The activation energies below and above 35°C, which is the glass transition temperature of PVAc, were found to be 16.8 and 82.5 kJ/mol, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1203–1207, 1999     

Synthesis,spectral, and thermal characterization of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain derived from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone

A series of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain were synthesized from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone (BHPMBCH) and aliphatic and aromatic diacid chlorides. The diol precursor, BHPMBCH, was synthesized from 2,6‐bis(4‐hydroxy‐3‐methoxybenzylidene)cyclohexanone and 3‐bromo‐1‐propanol. The solubility of the polymers was tested in various solvents. The intrinsic viscosity of the synthesized polymers, determined by an Oswald viscometer, was found to be 0.06–0.80 g/dL. The molecular structures of the monomer and polymers were confirmed by Fourier transform infrared, ultraviolet–visible, ¹H‐NMR, and ¹³C‐NMR spectral analyses. The thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. The thermogravimetric analysis data revealed that the polymers were stable up to 220°C and started degrading thereafter. The thermal stability initially increased with increasing spacer length and then decreased due to negative effects of the spacer. The self‐extinguishing properties of the synthesized polymers were studied by the determination of the limiting oxygen index values with Van Krevelen's equation. In addition, the photocrosslinking properties of the polymer chain were studied with UV spectroscopy, and we observed that the rate of photocrosslinking increased significantly with increasing methylene carbon chain length of the acid spacer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of polystyrene modified with fluorine atoms: Monomer reactivity ratios and thermal behavior

Homo‐ and copolymers of 4‐fluorostyrene (FSt) and styrene (St) were synthesized with different feed ratios using free radical bulk polymerization with azobisisobutyronitrile (AIBN) as initiator. It yielded series of (co)polymers with various amounts of included FSt, P(St‐co‐FSt) (5–50 mol%) and PFSt. The effect of the initiator concentration on the molecular weights of the homopolymers, that is, PSt and PFSt was investigated. Copolymer compositions were determined by nuclear magnetic resonance spectroscopy. The relative reactivity ratios of both comonomers were determined by applying the conventional linearization methods of Jaacks (J), Finemann–Ross (F–R), inverted Finemann–Ross (IF–R), and Kelen‐Tüdos (K–T). The reactivity ratios values of St and FSt obtained from J plot are 1.06 and 0.84, F–R plot are 1.18 and 1.06, IF–R 1.01 and 0.86, and K–T plot 1.04 and 0.88, respectively. Thermal properties of prepared (co)polymers, that is, glass transition temperature (T_g) and thermal stability, were determined from differential scanning calorimetry and thermogravimetrical measurements. The lack of significant influence of FSt comonomer content on T_g of (co)polymers was observed. Additionally, the thermal degradation kinetics of obtained PSt and PFSt was studied by thermogravimetric analysis. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa model [E(O) and A(O), respectively] and Kissinger model [E(K) and A(K), respectively]. The activation energy and the frequency factor of PFSt (253 kJ/mol) were higher than PSt (236 kJ/mol). The resulting activation energies estimated using the two methods were quite close. POLYM. ENG. SCI., 54:1170–1181, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of water‐soluble polymers and their utilization in chromium sorption

In this article, we study the sorption of chromium from aqueous solutions using water‐soluble polymers (WSPs): poly[2‐(acryloyloxy) ethyl] trimethylammonium chloride, P(ClAETA); poly[2‐(methacryloyloxy) ethyl] trimethylammonium methyl sulfate, P(SAETA); and poly(sodium 4‐styrenesulfonate), P(NaSS). These WSPs were obtained by radical polymerization and purified by fractionation through ultrafiltration membranes with different molar mass cut‐offs (30 and 100 kDa). The characterization was carried out by thermogravimetric analysis (TGA), FTIR, and ¹H‐NMR spectroscopies and scanning electron microscopy/energy dispersive X‐ray spectroscopy. The chromium retention properties of the polymers were determined in terms of pH, optimal polymer concentration, and the effect of interfering ions. The results show yields above 80% for all of the synthesized WSPs. Characterization by spectroscopy confirmed the chemical structure of the polymers. TGA shows thermal decomposition temperatures of 264 and 324 °C for P(ClAETA) and P(SAETA), respectively. In the case of P(NaSS), the first thermal decomposition begins at approximately 450 °C. Maximum retention of Cr(VI) (100%) by the polymers P(ClAETA) and P(SAETA) was achieved at pH 9, and the maximum retention of Cr(III) (100%) was achieved by P(NaSS) at pH 3. The optimal polymer:Cr molar ratio obtained was 20:1. The retention of chromium(VI) was decreased by the presence of interfering ions, and the hydrodynamic flux was almost constant during ultrafiltration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45355.     

Cure kinetics of an epoxidized hemp oil based bioresin system

A novel epoxidized hemp oil (EHO) based bioresin was synthesized by epoxidation in situ with peroxyacetic acid. In this research the cure kinetics of an EHO based bioresin system cured with triethylenetetramine (TETA) was studied by differential scanning calorimetry using both isothermal and nonisothermal data. The results show that the curing behavior can be modeled with a modified Kamal autocatalytic model that accounts for a shift to a diffusion‐controlled reaction postvitrification. The total order of the reaction was found to decrease with an increase in temperature from ～ 5.2 at 110°C to ～ 2.4 at 120°C. Dynamic activation energies were determined from the Kissinger (51.8 kJ/mol) and Ozawa‐Flynn‐Wall (56.3 kJ/mol) methods. Activation energies determined from the autocatalytic method were 139.5 kJ/mol and ?80.5 kJ/mol. The observed negative activation energy is thought to be due to an unidentified competitive reaction that gives rise to the appearance of k₂ decreasing with increasing temperature. The agreement of fit of the model predictions with experimental values was satisfactory for all temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of novel crosslinkable second‐order nonlinear optical polymers based on 2,3,4,5,6‐pentafluorostyrene

Two crosslinkable second‐order nonlinear optical polymers were prepared by copolymerization of 2,3,4,5,6‐pentafluorostyrene, styrene (St), glycidyl methacrylate (GMA) and 1‐(4‐nitrophenyl)‐2‐(4‐{[2‐(methacryloyloxy) ethyl] ethylamino}‐phenyl) diazene (DR1M) via the sealed‐tube reaction technique. These polymers were characterized using ¹H, ¹³C and ¹⁹F NMR spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crosslinkable polymers have high molecular weights, good organosolubility, excellent film‐forming properties and high glass transition (106–110 °C) and thermal decomposition temperatures (290–350 °C) after being crosslinked. Furthermore, the polymer films possess not only high values (12–16 pm V^?1) of electro‐optical coefficient (r₃₃) at 1.3 µm wavelength but also low optical loss (1.7 dB cm^?1) at 1.55 µm wavelength, which is of interest for applications in electro‐optical devices. Copyright © 2004 Society of Chemical Industry