Derivative Thermogravimetry Research Articles

Thermal degradation kinetics of industrial batch crosslinked polyethylene

AbstractPolyethylene (PE) is one of the most used polymers which can be applied since to flexible packaging to general goods industries, representing 32% of the total market share. Crosslinking PE (XPE) is of considerable practical importance since it increases the upper application temperature limit and improves mechanical performance. The objective of this work was to investigate the thermal degradation kinetics in inert (nitrogen) and oxidative (oxygen) environments of XPEs industrial formulations, with the crosslinking agent content between 0% and 1.5%. PE and XPE specimens were characterized by thermogravimetry (TG) and the computed data modeled using ASTM E698. Increasing the heating rates shifted the degradation rate (dα/dt) and weight loss to higher temperatures, whereas XPEs showed greater thermal stability related to PE. Deconvolution of derivative thermogravimetry (DTG) peaks displayed to be an important tool during kinetics analysis providing understanding and reliable data which affords excellent fits between theoretical and experimental data. In plots acquired using ASTM E698 the degradation activation energy (Ea) increased along with the degradation; morphological and structural changes are suggested in the higher Ea range. Among investigated compounds, 0.5XPE presented the best performance, that is, the greatest thermal stability in both atmospheres.

Thermal Decomposition Characteristics and Kinetic Analysis of Chicken Manure in Various Atmospheres

Thermal decomposition technology is one of the main ways to treat biomass wastes. By utilizing chicken manure as raw material, thermogravimetric and derivative thermogravimetry (TG and DTG) are carried out on chicken manure at various heating rates (5, 10, 15, and 20 °C/min) under nitrogen and air atmosphere to explore the thermal decomposition characteristics and kinetics. The obtained results indicate that there are great discrepancies between them in these two atmospheres. Chicken manure is pyrolyzed under nitrogen; however, it is first thermally decomposed and then developed for combustion under air. The temperature range of the main peak of thermal decomposition in the air atmosphere is significantly lower than that in the nitrogen atmosphere by about 30 °C. Furthermore, the fluctuation of the DTG curve pertinent to the air atmosphere is commonly greater than that obtained in the nitrogen atmosphere, and the main combustion section usually presents an obvious W-shape peak. The thermal decomposition kinetics of the chicken manure is also determined as random nucleation model F1 by employing the Malek method, and the mechanism function is derived by f(α)=1−α. Under nitrogen atmosphere, the activation energy is between 24.18~31.55 kJ·mol−1. Under air atmospheric conditions, the minimum activation energy of the second temperature section is 8.85 kJ·mol−1, and the activation energy of the first section is less than that of the third section. In the presence of both nitrogen and air, the best result for the thermal decomposition of the sample is attained under the action of 10 °C/min heating rate. The corresponding activation energies are 31.55 kJ·mol−1 and 95.91 kJ·mol−1, respectively.

Kinetic and thermodynamic analyses of co-pyrolysis of pine wood and polyethylene plastic based on Fraser-Suzuki deconvolution procedure

Co-pyrolysis of biomass and plastics is a promising way to produce high-quality liquid fuel, and the knowledge on its kinetic and thermodynamic behaviors is crucial for designing an efficient reactor system. In this study, kinetic triplets and major thermodynamic parameters of both non-catalytic and catalytic co-pyrolysis of pine wood and high-density polyethylene (HDPE) were evaluated. Due to the complexity of co-pyrolysis process, Fraser-Suzuki function was adopted to deconvolute the derivative thermogravimetric (DTG) curves into four pseudo-components; namely pseudo- cellulose, hemicellulose, lignin and HDPE. For non-catalytic co-pyrolysis, average apparent activation energy of pseudo-hemicellulose, cellulose, lignin and HDPE were 137.12, 166.81, 227.2, 246.56 kJ/mol, respectively. The presence of HZSM-5 decreased both activation energy and pre-exponential factor and affected reaction mechanisms of each component. The activation energy of HDPE decreased by about 35% after addition of catalyst. The thermodynamic analyses revealed that external energy was required for all components to form activated complex, and this process was favored by addition of catalyst HZSM-5. Results obtained in this work are expected to provide more precise fundamental information for further scale-up of co-pyrolysis process.

Systematical Study on the Influencing Factors of Synchronous Thermal Analyses of Samples-Taking the Chalcanthite as an Example.

Thermal analysis is widely used for the measurement of the relationship between temperature and physical properties of the materials. Many studies have reported different thermal analysis methods, including thermogravimetry (TG), derivative thermogravimetry (DTG), differential heat analysis (DTA), and differential scanning calorimetry (DSC), but few comprehensively studied the factors influencing TG-DTA by the combined thermogravimetry–differential thermal methods. In this study, taking chalcanthite as the research object, the thermogravimetric–differential thermal analyses were systematically conducted by using synchronous thermal analyzer technology. The results demonstrate that 1) DTA curves of low- and medium-weight chalcanthite show five dehydration endothermic peaks, while TG curves do not display obvious weight-loss steps; DTA and TG curves of high-weight chalcanthite samples, on the other hand, illustrate three endothermic peaks, indicating three-step loss of crystalline water; 2) higher weight of samples may cause longer time of internal heat transfer and larger temperature gradient, consequently resulting in the expansion of DTA peak shape and the decline of resolution as well as the increase of the peak temperature; 3) the weight-loss deviation between the measured and theoretical data is relatively higher in the low-weight samples than that in the medium- and high-weight samples; 4) the heating rate can increase the DTA curve peak and thermal inertia and the temperature at the thermodynamic equilibrium, causing the temperature lagging behind and the overall peak moving toward high temperature; 5) sample grinding may destroy the structure of the crystal, thereby breaking the relatively weak chemical bond, and thus affects the structure of thermogravimetric–differential thermal analyses. These suggest that the sample weight, heating rate, and sample grinding probably have significant effects on the thermogravimetric–differential thermal analyses. Therefore, proper experimental conditions are needed to obtain the accurate results during the thermogravimetric–differential thermal analyses. This study can provide a basis and reference for future synchronous thermal analyses.

Suppression of Sulfate-Induced Expansion with Lime-Silica Fume Blends.

Sulfate-induced expansion resulting from the formation of ettringite in sulfate-bearing soil stabilised with calcium-based stabilisers is a problematic issue with technical and economic implications. Thus, this research examines the viability of the co-addition of lime (L) and silica fume (S) at varying binder dosages (4, 6, and 10 wt%), with a view of establishing the optimum blend of L–S for suppressing the ettringite-induced expansion of artificially high sulfate-dosed soil (kaolinite-K and gypsum-G). To do so, a series of laboratory specimens, designed using different gypsum and lime concentrations, were investigated using unconfined compression strength (UCS), linear expansion, and derivative thermo-gravimetric analysis (DTG) as the main criteria for the examination. The research outcomes indicated that the increasing substitution of L with S induces a gradual reduction on the UCS and linear expansion at binder levels of 4 and 6 wt%, while its usage in a high binder level (10 wt%), can yield an expansion reduction, with no compromise on the UCS performance. Therefore, silica fume has the potential for restricting ettringite formation and suppressing the expansion, of which 3L7S is the optimum blending ratio for suppressing the expansion.

A new approach to the synthesis of CuFe2O4@CeO2 direct Z‐scheme with a core‐shell structure for enhanced photo‐degradation of methyl violet under ultraviolet and visible‐light irradiation

AbstractA direct Z‐scheme photocatalyst CuFe2O4@CeO2 core‐shell was applied in the photocatalytic degradation of the methyl violet dye 2B (MV). In first, CuFe2O4 and CeO2 were synthesized via sol–gel method, and then CuFe2O4@CeO2 nanocomposite was prepared using microwave process. The nanoparticles were characterized by thermogravimetric analysis (TG and derivative thermogravimetry [DTG]), atomic absorption spectroscopy (AAS), Brunauer–Emmett–Teller (BET) analysis, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy dispersive‐X‐ray (EDX) and ultraviolet (UV)–visible diffuse reflectance/absorption spectroscopy. The photocatalytic activity of CuFe2O4@CeO2 nanocomposite was evaluated by the photo‐degradation of the MV under UV and visible‐light irradiation. MV does not rapidly degrade itself in UV or visible‐light but the process is accelerated upon the addition of semiconductors with a wide band‐gap. The CuFe2O4@CeO2 nanocomposite shows an important MV decomposition rate under visible‐light irradiation (95.35% within 1.5 h) as compared to UV‐light (86.10% within 2.5 h). The excellent activity of CuFe2O4@CeO2 under UV and visible‐light was mainly attributed to direct Z‐scheme which are originated from a core‐shell structure which prompted the generation of ˙OH radical species responsible for the photo‐degradation of the substance. However, this could also be due to the large specific surface area and/or efficient UV–vis harvesting.

Grafting Schiff base Cu(II) complex on magnetic graphene oxide as an efficient recyclable catalyst for the synthesis of 4H-pyrano[2,3-b]pyridine-3-carboxylate derivatives

Schiff base Cu(II) complex (Sc–Cu) stabilized on the surface of graphene oxide modified magnetic nanoparticles (GO/Fe3O4) using 3-chloropropyltrimethoxysilane ((MeO)3Si-PrCl) as a linker, (GO/Fe3O4@SPSc-Cu), was prepared, characterized and used as a magnetically separable and reusable heterogeneous catalyst in the multi-component reaction of aldehyde, 3-cyano-6-hydroxy-4-methyl-pyridine-2(1H)-one, and ethyl acetoacetate to afford a series of novel 4H-pyrano[2,3-b]pyridine-3-carboxylate derivatives under solvent-free conditions. The structure of the catalyst (GO/Fe3O4@SPSc-Cu) was characterized by Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping, transmission electron microscopy (TEM), high resolution TEM (HRTEM), fast Fourier transform (FFT), scanning TEM (STEM), X-ray diffraction (XRD), thermogravimetry/derivative thermogravimetry (TG/DTG), and vibrating sample magnetometer (VSM) analyses. Various spectral analyses such as 1H and 13C NMR, FT-IR and ESI-MS were used to determine the structure of the products. The catalyst demonstrated good to excellent catalytic efficiency for reactions under green conditions using a wide range of substrates. The advantages of this process include a simple reaction set-up, high yield, short reaction time, environmentally friendliness, recyclable catalyst and easy separation of the products. In addition, the catalyst was recovered through magnetic decantation and reused for five consecutive cycles.

New alginic acid derivatives ester for methylene blue dye adsorption: kinetic, isotherm, thermodynamic, and mechanism study.

In this paper, the application of ester materials prepared by grafting different carbon chain lengths of diols in alginic acid (AA) by a simple, fast and efficient method for the adsorption of methylene blue (MB) is studied. The AA ester derivatives are characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Zeta potential before and after MB adsorption. This study shows a significant improvement in the adsorption capacity of MB by AA after its esterification with a Qmax value up to 454.545mg/g for the best adsorbent "Poly(AA-g-EG)". The experimental data are studied according to two isothermal models (Langmuir and Freundlich) and two kinetic models (pseudo-second order and intra-particle diffusion). The adsorption of MB is also evaluated thermodynamically. An adsorption mechanism of MB is established.

The experimental investigation and data–driven modeling for thermal decomposition kinetics of Green River Shale

Given that kerogen is a source of vast amount of hydrocarbons and organically–bound inorganic elements, it’s important to understand the thermal decomposition kinetics of kerogen. Green River Shale contains a significant amount of immature kerogen (Type I), which can be an ideal source for the sample of experimental study. In this study, Thermogravimetric Analysis and Derivative Thermogravimetry (TGA/DTG) was used to quantify the weight loss during the pyrolysis process of the Green River Shale from Utah and subsequently establish the kinetic model of thermal decomposition of kerogen based on the Friedman method followed by the data–driven modeling approach. A two–step reaction mechanism and components of production during the pyrolysis were determined by implementing Thermogravimetry Analysis–Differential Scanning Calorimetry–Gas Chromatography (TGA–DSC–GC). The chemical bonds were analyzed with Fourier–Transform Infrared spectroscopy (FTIR) before and after the pyrolysis. From the experiments, we observed the two–stage reactions in the hydrocarbon evolution window when the heating rate was lower than 30 °C/min, while only one stage was observed with the higher heating rates. C14 hydrocarbon was generated continuously during the hydrocarbon evolution, which indicated that the Green River Shale contained a plentiful amount of it. The kinetic parameters were obtained for the decomposition of organic and inorganic mixture and the organic matter (kerogen) only. The Artificial Neural Network (ANN) method was implemented to train the kinetic parameters obtained from the TGA/DTG experiment. The prediction of extrapolated cases showed a good performance when the heating rate was smaller than 5 °C/min. The generated proxy model can be coupled with various physical models to simulate the thermal decomposition of kerogen with high accuracy.

Green synthesis of nanosilver using Fomes fomentarius mushroom extract over aramid fabrics with improved coloration effects

Silver nanoparticles (AgNPs) were greenly synthesized over aramid fabrics from wild mushroom ( Fomes fomentarius) to develop colorful products. The localized surface plasmon resonance characteristics of AgNPs provided versatile coloration effects on fabrics, with improved color strength ( K/ S) and other colorimetric values ( L*, a*, and b*). The stability of the colored materials was also investigated in terms of color fastness to wash and rubbing (both wet and dry states). The characteristics of deposited AgNPs over aramid materials were characterized by X-ray fluorescence spectroscopy testing of solid fabric samples. Morphological properties of the aramid substrates were investigated using SEM (scanning electron microscopy) testing to check the surfaces both for nanosilver-treated and untreated materials. Moreover, the developed nanoparticles were also confirmed further using SEM-deployed energy-dispersive X-ray spectroscopy and elemental mapping analysis. The chemical bonding between the aramid fiber and deposited AgNPs was tested using Fourier infrared spectroscopy analysis. The thermal stability of the aramid fabrics was examined in order to investigate their behavior when exposed to heat in terms of thermogravimetric analysis and derivative thermogravimetry analysis. The K/ S values and darkness values were increasing with the increased loading of the nanosilver precursor. Moreover, statistical analysis was also conducted in terms of the coefficient of variation ( R2) to understand the significance of the connection between the nanosilver loading and coloration characteristics, and found a significant relationship. Overall, a novel, sustainable, and facile biosynthesis route of AgNPs is reported in this current research.

Physico-Chemical and Thermomechanical Analysis and ‎Characterization of ‎a Thermoplastic Composite Material Reinforced by Washingtonia Filifera Novel Vegetable Fibers

In this paper, ‎morphological, physico-chemical and thermal properties investigations‎ are carried out for a ‎novel ‎composite material reinforced by Washingtonia Filifera (WF) palm fibers using a 20 weight (wt) % loading rate. The experimental analysis by Scanning Electron Microscopy (SEM) shows the longitudinal roughness of the surface, which plays a very important role in the adhesion between the WF fibers and the High Density ‎PolyethylenE (HDPE) resin. FTIR tests of the composite (WF 20%/ HDPE) represent out of plane vibrations involving ring and CH2 symmetric bending in cellulose chain.‎ Thermogravimetric analysis (TGA) and Derivative thermogravimetric ‎(DTG) thermal analysis show a thermal stability at 210°C, 2.5% residual mass ‎and 745 °C maximum ‎temperature. X-Ray Diffraction (XRD) analysis shows that the ‎crystallinity index is 59.2%, with a size of ‎‎23 nm. Using tensile tests, a Young modulus of 858.6 MPa, ‎17% elongation and a maximum stress of 15 MPa ‎are found. The obtained characteristics of WF reinforced composite are better than those of Bamboo reinforced composites which has been proven to have characteristics superior to those of standard particleboard and medium density fiberboard used mainly in the construction industry.

Synthesis of biopolymer chitosan-based hydrogels with and without a crosslinker for the removal of industrial dye procion blue HERD: a comparative study

ABSTRACT The current study reports the preparation and application of bio-based polymer composite hydrogel with and without a crosslinker for the removal of industrial dye procion blue HERD (PB). Biopolymer chitosan, acrylic acid as a monomer and potassium persulphate (K2S2O8) as an initiator synthesise composite hydrogel. The crosslinked composite hydrogel is synthesised by the microwave irradiation technique using thiourea (CH4N2S) as a crosslinker. Chitosan-based hydrogel synthesised without crosslinker (CH) and with crosslinker thiourea (CH-T) is analysed using techniques, such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTG) and derivative thermogravimetric analysis (DTA). The adsorption capacity of CH and CH-T for the removal of PB from an aqueous solution is investigated. The removal efficiency of hydrogel is 90% in a solution of pH 7 for a constant dose of PB (5 mg L−1). The experimental data attained for the adsorption of industrial dye (PB) onto CH and CH-T showed a perfect fit for Freundlich and Langmuir isotherms. The perfect fit of experimental data for PB decolorisation is observed for pseudo-second-order kinetic equation with k values 10.17 × 10−3 mg−1 min−1 and 6.719 × 10−3 mg−1 min−1 with CH and CH-T, respectively.

Thermogravimetric Kinetic Analysis of Non-Recyclable Waste CO2 Gasification with Catalysts Using Coats–Redfern Method

In the present study, the effect of dolomite and olivine as catalysts on the carbon dioxide (CO2) gasification of a candidate renewable solid recovered fuel, known as Subcoal™ was determined. Thermogravimetric analysis (TGA) was used to produce the TGA curves and derivative thermogravimetry (DTG) for the gasification reaction at different loadings of the catalyst (5, 10, 15 wt.%). The XRD results showed that the crystallinity proportion in Subcoal™ powder and ash was 42% and 38%, respectively. The Arrhenius constants of the gasification reaction were estimated using the model-fitting Coats–Redfern (CR) method. The results showed that the mass loss reaction time and thermal degradation decreased with the increase in catalyst content. The degradation reaction for complete conversion mainly consists of three sequences: dehydration, devolatilisation, and char/ash formation. The complete amount of thermal degradation of the Subcoal™ sample obtained with dolomite was lower than with olivine. In terms of kinetic analysis, 19 mechanism models of heterogeneous solid-state reaction were compared by the CR method to identify the most applicable model to the case in consideration. Among all models, G14 provided excellent linearity for dolomite and G15 for olivine at 15 wt.% of catalyst. Both catalysts reduced the activation energy (Ea) as the concentration increased. However, dolomite displayed higher CO2 gasification efficiency of catalysis and reduction in Ea. At 15 wt.% loading, the Ea was 41.1 and 77.5 kJ/mol for dolomite and olivine, respectively. Calcination of the mineral catalyst is substantial in improving the activity through enlarging the active surface area and number of pores. In light of the study findings, dolomite is a suitable mineral catalyst for the industrial-scale of non-recyclable waste such as Subcoal™ gasification.

Thermochemical Characterization of Cycas Circinalis Seed Shell to Evaluate their Potential as Biofuel Source

Increased environmental pollution anxieties and quest for high energy demand from renewable energy sources forced to use lignocellulosic biomass to produce Bio-fuels. Cycas circinalis seed shell is a plant-derived bio-waste readily available in the southern coastal part of India. This research aims to explore the thermochemical characteristic of Cycas circinalis seed shells. Substantial volume reduction of feedstock and low processing time makes the thermal conversion route more attractive than any other method of waste to energy conversion. Biomass degradation behavior is studied by Thermogravimetric and derivative thermogravimetric analysis (TGA and DTG); this depicts biomass degradation in three primary stages, each corresponding to the decomposition of hemicellulose, cellulose, and lignin components. Functional groups were determined by Fourier transform infrared (FTIR) spectroscopy. The obtained calorific value of biomass was found to be 16.17 MJ/Kg. Proximity analysis results showed the percentage of moisture content, volatile matter, ash content, and fixed carbon as7.95%,77.35%,2.05%,12.65%respectively. The ultimate analysis determines the composition of significant elements present in Cycas ciricinails. Carbon, Hydrogen, and Oxygen are found to be 45.54%, 6.5 %, and 47.16 %, respectively. Sulfur and nitrogen component values were observed to be lower, which is also a promising result in view of environmental concerns.

Effect of Bound Water Content on Secondary Compression of Three Marine Silty Clays

Secondary compression studies can provide insights for evaluating the engineering potential and environmental impact of soil. The objective of this research was to investigate the effect of bound water content on the secondary compression of marine silty clay. To this end, a novel method was established based on thermogravimetric analysis (TGA) to determine the contents and limits of strongly bound water and weakly bound water for three typical marine silty clays including Tianjin mucky silty clay (TJ), Qingdao mucky silty clay (QD), and Weihai silty clay (WH). A total of 17 groups of uniaxial confined compression tests were performed for reconstituted samples at different absolute water contents under the condition of multistage loading to investigate their secondary compression characteristics. The results show that the initial dehydration temperature of strongly bound water (Ts) corresponds to the peak of the derivative thermogravimetry (DTG) curve. The values of Ts for TJ, QD and WH are 112.35 °C, 109.67 °C and 118.46 °C, respectively. The initial dehydration temperatures of weakly bound water (Tw) for TJ, QD and WH are 55.26 °C, 52.56 °C and 56.56 °C, respectively. The secondary compression coefficient Cα changes little before the strongly bound water limit and increases dramatically as weakly bound water content increases at the same vertical stress. A piecewise linear model and a quadratic polynomial model are established for calculating the average secondary compression coefficient from bound water content. Weakly bound water is the determining factor controlling secondary compression. Increasing the bound water content weakens the connection force and friction force among the particles and the viscosity of weakly bound water. The results will guide decisions on long-term settlement assessment and facilitate understanding of the secondary compression mechanism of marine silty clays affected by bound water.

Palladium supported on ethylenediaminetetraacetic acid functionalized cellulose: synthesis, characterization, and its application in carbon–carbon cross-coupling reactions

Through the esterification of cellulose (Cell) with ethylenediaminetetraacetic dianhydride, ethylenediaminetetraacetic acid-functionalized cellulose (Cell-EDTA) was conveniently obtained. Furtherly a novel and efficient Cell-EDTA-supported palladium catalyst (Pd@Cell-EDTA) was easily prepared via coordination of Cell-EDTA with PdCl2. The as-prepared Pd@Cell-EDTA was fully characterized by inductively coupled plasma atomic emission spectrometry, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, energy-dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and derivative thermogravimetric analysis techniques. Then Pd@Cell-EDTA was successfully exerted as catalysts in Suzuki reactions and Sonogashira reactions. Due to the interactions of carboxylic groups, nitrogen atoms, and hydroxyl groups on cellulose, the Pd complex showed excellent activity towards these carbon–carbon cross-coupling reactions. The catalyst recycling experiments for Suzuki model reaction showed that the catalyst can be reused at least five times without significant losing its catalytic performance. The present cellulose-based Pd@Cell-EDTA catalyst offers the salient features of wide application, excellent catalytic activity, good reusability, tolerance of broad scope of substrate, and environmental benign. Graphical Abstract

Thermal decomposition mechanism and pyrolysis products of waste bischofite calcined at high temperature

The thermal behavior of bischofite waste and MgCl2•6H2O was investigated by thermogravimetric analysis–derivative thermogravimetry (TGA-DTG) and X-ray diffraction (XRD). TGA-DTG results showed that the pyrolysis behavior and weight loss of bischofite were different from those of MgCl2•6H2O due to large number of impurities. The effects of temperature, atmosphere, and heating rate on the pyrolysis mechanism and products of bischofite were studied in detail by using XRD. The pyrolysis temperature remarkably affected the pyrolysis products. The mixture of MgO and Mg(OH)Cl coexisted at high temperatures of 550 and 600 °C. However, the presence of MgCl2 was confirmed by calcination at 650 and 700 °C for 0.5 h except MgO. Through calcination at 700 °C for up to 2.0 h, the pyrolysis products of bischofite and MgCl2•6H2O were predominantly MgO, and the atmosphere had no effect on the content of MgO. Low heating rate was favorable for pyrolyzing bischofite into MgO, and the content of MgO reached 94.1% at the heating rate of 5.0 °C/min. After further purification by washing, the content of MgO in the final product increased to 99.0%. This study provided an effective route for the comprehensive utilization of bischofite resources in salt lakes.

Cost-Effective Fabrication of Modified Palygorskite-Reinforced Rigid Polyurethane Foam Nanocomposites.

Integration of nanoclay minerals into rigid polyurethane foams (RPUFs) is a cost-effective solution to enhance foam’s performance via environmental protection technology. In this work, palygorskite/RPUFs nanocomposites (Pal/RPUFNs) with excellent mechanical properties and thermal stability were prepared via a one-step method, using 4,4’-diphenylmethane diisocyanate and polyether polyol as the starting materials, coupled with Pal modified by silane coupling agent KH570. The effects of the modified Pal on the mechanics, morphology, and thermal properties of the nanocomposites were studied systematically. When the content of the modified Pal was 8 wt% of polyether polyol, the elastic modulus and compressive strength of the Pal/RPUFNs were increased by ca. 131% and 97%, respectively. The scanning electron microscopy images indicated that the addition of the modified Pal significantly decreased the cell diameter of the Pal/RPUFNs. The results of thermogravimetric and derivative thermogravimetry analyses revealed that the addition of the modified Pal increased the thermal weight loss central temperature of the Pal/RPUFNs, showing better thermal stability in comparison with the pure RPUFs. A self-made evaluation device was used to estimate the thermal insulation ability of the Pal/RPUFNs. It was found that the small cell size and uniform cellular structure were keys to improving the thermal insulation performance of the RPUFs. The prepared Pal/RPUFNs are expected to have great potential in the field of building insulation.

Thermal Analysis of the Essential Oil of Aniba rosaeodora Ducke by TGA and DSC

Thermal analysis comprises a group of techniques to measure a physical property of a sample subjected to controlled temperature programming, including thermogravimetry (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). The species Aniba duckei Kostermans, synonymous with Aniba rosaeodora Ducke, occurs in the Amazon and is also known as rosewood. Essential oils are complex oily aromatic liquids obtained by extraction from highly volatile aromatic plant materials as secondary metabolites. This research aimed to chemically and thermally characterize the essential oil of Aniba duckei. Gas chromatography was used for the quantification, by the external standard method, of the main component. The thermal study of the oil and the linalool standard was carried out using DSC and TG-DTG. The essential oil yield was 1.93% and the analysis by GC-MS confirmed the majority presence of linalool, with a concentration of 89.34% in the oil. The technical analysis revealed some similarity between the curves of pure linalool and essential oil, which is attributed to the high content of linalool in the oil. The differences between the boiling points and enthalpies of the linalool and oil pattern are justified by the presence of minor components, their concentrations in the oil and because they are substances of different polarities, molecular masses and intermolecular forces. The techniques proved to be efficient to characterize the oil. The results of the thermal analysis of the essential oil of the Aniba rosaeodora plant species are unprecedented, enabling the determination of linalool in by DSC.

Experimental analysis on water penetration resistance and micro properties of concrete: Effect of supplementary cementitious materials, seawater, sea-sand and water-binder ratio

To evaluate the water penetration resistance of seawater and sea-sand concrete (SSC), this study conducts water penetration test and capillary water absorption test. And scanning electron microscope (SEM), mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), Thermogravimetric analysis and derivative thermogravimetry (TGA-DGA) were used to reveal the micro morphology, pore size distribution, porosity and hydration products of SSC. The effects of water-binder (w/b) ratio, supplementary cementitious materials (SCMs) (fly ash (FA) and limestone and calcined clay (LC2)), and curing age on the resistance to water penetration and micro performance of SSC were studied. The results show that with the smaller the w/b ratio and the increasing of curing age, the more is C–S–H gel and the denser SSC matrix, which is beneficial to resist water diffusion. With the addition of FA, the water penetration resistance of SSC tends to decrease overall. The addition of LC2 can reduce the macro pores obviously and promote cement hydration to generate denser hydration products (C-A-S-H, monosulfate (AFm)) to fill the macropores and free water channels of the matrix and improve the water permeability of SSC. Especially, when the replacement rate of LC2 is 25%, the water penetration depth (WPD) decreases by 55.81%, 51.08%, 48.91% during the curing age of 28 d, 56 d, and 120 d, respectively. With the higher the design compressive strength of SSC, the better is the water penetration resistance. Using the data regression analysis method, the relationship between the compressive strength and the WPD of SSC was established, and the capillary water absorption with time and w/b ratio/FA content has a good non-linear function relationship, and the correlation coefficients are greater than 0.95.