FTIR TGA Research Articles

Biomass fly ash as nanofiller to improve the dielectric properties of low-density polyethylene for possible high-voltage applications

Flexible capacitive energy storage applications require polymer nanocomposites with high dielectric properties, which can be accomplished by addition of inorganic nanofillers to the polymer matrix. Low-density polyethylene (LDPE), known for its good dielectric characteristics and wide use in electrical insulation have been investigated for the desired applications. However, the improvement of its breakdown strength still continues with the use of various nanomaterials employed as nanofillers. In this study, a waste-derived material known as biomass fly ash (BFA) as a nanofiller to improve the dielectric properties of LDPE has been explored. BFA exhibits versatility in its composition with various metal oxides, making it an attractive choice as a nanofiller. The BFA-LDPE sheets were prepared using a conventional solvent mixing and subsequent hot-pressing process, incorporating BFA loadings ranging from 1 % to 4 wt%. The effects of different BFA loadings were carefully examined, and the synthesized nanocomposites were extensively characterized using various characterization methods, such as XRD, SEM, FTIR, TGA and dielectric constant measurements, to investigate the crystallographic properties, morphology, chemical composition, and thermal stability. Among all the nanocomposites, 4 wt%BFA-LDPE exhibited the highest dielectric constant, with a value of 11.58, compared to simple LDPE that had a dielectric constant of 8.33. This improvement is ascribed to the synergistic effects of different inorganic metal oxides (SiO2, MgO, and Fe2O3) present in BFA. The results showed a significant enhancement in dielectric properties, indicating that the waste-derived BFA can be purposefully applied as an effective nanofiller in the LDPE-based composites with even less than 4% loading for electrical insulating applications in future studies.

Errata and comments on “thermal decomposition of ammonium perchlorate—A TGA–FTIR–MS study: part I” [Thermochim. Acta 610 (2015) 57–68

Some errata were noticed in the calculated pre-exponential factor (A) data represented in the TGA and kinetic analysis section of the paper “Thermal decomposition of ammonium perchlorate—A TGA–FTIR–MS study: part I” [Thermochim. Acta 610 (2015) 57–68]. In the discussion, we analyse what went wrong during the determination of the pre-exponential factor and subsequently identify the correct values. The correct value of pre-exponential factor (A) for the decomposition of 250 to 300 µm size AP particles during the LTD and HTD stages is found to be 5.70 × 109 min−1 and 2.70 × 109 min−1, respectively.

Synthesis, characterization and performance evaluation of a flame retardant plasticizer for poly(vinyl chloride) derived from biobased vanillic acid

The utilization of biobased resources presents a novel approach for the development of high-performance plasticizers with exceptional flexibility. Nevertheless, the combustibility of flexible poly(vinyl chloride) (PVC) products containing high content plasticizers is frequently disregarded. The development of PVC functional plasticizers requires careful consideration of a good balance between flame retardancy, migration resistance and plasticity through molecular structure design. Currently there is a dearth of biobased plasticizers that exhibit exceptional comprehensive properties. Therefore, a novel biobased flame-retardant plasticizer (VA8-P) has been synthesized from vanillic acid and fully characterized using NMR, IR and MS. The VA8-P plasticized PVC exhibits a lower glass transition temperature and higher low temperature resistance, while its elongation at break is 1141.6% higher than unmodified PVC. Transmittance, haze, cross-sectional SEM and 2D/3D AFM all demonstrate its good optical properties and the compatibility of the plasticizer with polymer matrix. PVC plasticized using VA8-P exhibits better hydrophilicity and especially superior migration resistance than does the same polymer plasticized using DOP. The thermal stability and char residue rate for decomposition of VA8-P plasticized PVC are better than the same parameter of material plasticized with DOP. In cone calorimeter tests, VA8-P plasticized PVC showed excellent heat barrier effect. Additionally, PVC-P3 reached the UL-94 VTM-0 level in the vertical burning test. Its flame-retardant mode of action was also verified by TGA–FTIR analysis. A functional biobased plasticizer with excellent comprehensive properties has been synthesized. This material exhibits greater flexibility than many traditional flame-retardant additives and its use can be expected to improve the fire resistance of flexible PVC.

Pyrolysis of Waste Plastic to Fuel Conversion for Utilization in Internal Combustion Engine

In the present study different plastic waste materials with various types of plastics such as low-density polyethylene and polypropylene with zinc oxide catalyst have been pyrolyzed in batch tubular reactor. Waste plastics were characterized by using TGA and DTG analysis and FTIR spectroscopy. The pyrolyzed products are analyzed by standard methods to determine various parameters.

Co-combustion of municipal solid waste and hydrochars under non-isothermal conditions: Thermal behaviors, gaseous emissions and kinetic analyses by TGA–FTIR

Co-combustion of municipal solid waste (MSW) with hydrochars was proposed as an effective way for both simultaneous treatments of MSW with biomass and energy recovery. In this work, thermogravimetric analyzer coupled with Fourier transform infrared spectrometer was employed to study the (co-)combustion, gaseous emissions and combustion kinetics characteristics of MSW, hydrochars and their blends. The addition of hydrochars to MSW leads to lower burnout temperatures and the shorter combustion time. Hydrochar prepared at 200 °C (SD200) has a better co-combustion performance than hydrochars prepared at 230 (SD230) and 260 °C (SD260) in term of ignition, burnout and comprehensive combustion characteristic index, hydrochar prepared at 260 °C has a better co-combustion evenness. The addition of hydrochar to MSW changed the gaseous products emission patterns of MSW and reduced the release of CO, HCN, NO and HCl. Kissinger-Akahira-Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods were used to estimate the activation energy of MSW, SD200 and their blends, the minimum average activation energy was observed when the SD200 blending ratio was 70%, which was 75.65 kJ mol−1 by KAS and 82.12 kJ mol−1 by FWO, respectively.

Temperature-Programmed Reduction of NiO/Al2O3 by Biochar In Situ Generated from Citric Acid

The reduction of metal oxides by biochar is an important reaction for many biomass utilization technologies. This work investigated the temperature–programmed reduction (TPR) of NiO/Al2O3 by in situ generated biochar from citric acid pyrolysis. Firstly, NiO/Al2O3 was loaded with citric acid by impregnation and then heated from ambient temperature to 900 °C in a N2 flow. The process was on–line analyzed by the TGA–FTIR technique. Secondly, a series of intermediates was obtained and characterized by XRD, CHNO elemental analysis, and temperature programmed oxidation (TPO). Lastly, a control experiment of unsupported NiO was conducted to show the influence of Al2O3 support on the NiO reduction. Results showed that the whole heating process could be resolved into two parts that is citric acid pyrolysis and NiO reduction at a heating rate of 5 °C/min. The NiO reduction occurred above 400 °C with the biochar from citric acid pyrolysis as reductant. In the temperature–programmed reduction process, the Al2O3–supported NiO exhibited three reduction phases in contrast with only one reduction phase for the unsupported NiO. A hypothesis was proposed to explain this. The presence of Al2O3 support may result in different deposition sites of biochar (on NiO or on Al2O3), and consequently different reduction mechanisms.

Tetradentate copper complex supported on boehmite nanoparticles as an efficient and heterogeneous reusable nanocatalyst for the synthesis of diaryl ethers

In this work boehmite nanoparticles (BNPs) were prepared through addition of aqueous solution of NaOH to solution of Al(NO3)3·9H2O. Then, the surface of BNPs was modified by (3-chloropropyl)trimethoxysilane (CPTMS) and further tetradentate ligand (MP-bis(AMP)) was anchored on its surface. At final step, a tetradentate organometallic complex of copper was stabilized on the surface of modified BNPs (Cu(II)-MP-bis(AMP)@boehmite). These obtained nanoparticles were characterized using SEM imaging, WDX, EDS, AAS and TGA analysis, BET method, FT-IR spectroscopy, and XRD pattern. In continue, the catalytic activity of Cu(II)-MP-bis(AMP)@boehmite has been used as a much efficient, reusable and hybrid of organic–inorganic nanocatalyst in the synthesis of ether derivatives through C–O coupling reaction under palladium-free and phosphine-free conditions. Cu(II)-MP-bis(AMP)@boehmite catalyst has been recovered and reused again for several times in the synthesis of ether derivatives.

Intrinsic Strength Behavior of RAC Subjected Elevated Temperature

Environmental deterioration as a result of development has wreaked havoc on the environment and jeopardizes its sustainability. Every year, millions of tonnes of construction and demolition waste (CDW) are generated as a result of the exploitation of natural resources, particularly non-renewable resources, for building purposes. In this study, an effort is made to consider CDW as a partial replacement of coarse aggregates to obtain recycled aggregate concrete and emphasize its strength properties, thereby reducing the burden on the requirement of natural resources. While RCA is being used as structural concrete, concrete is possibility exposed to elevated temperatures, which can disintegrate the concrete. Hence strength behaviour of RAC and its strength properties at elevated temperatures are emphasized. Considering the RCA replacement ratios of 0%, 50%, and 100% and water to binder ratio of 0.27 and 0.36 for compressive strength, split tensile strength, and flexural strength, the behaviour of RAC is investigated for elevated temperature; TGA analysis and FTIR are conducted on the RAC that is arrived at by conducting optimization and beneficiated RAC is proposed as a structural concrete at elevated temperature.

Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications.

Imidazoline is a five-membered heterocycle derived by the partial reduction of one double bond of the imidazole ring. This work prepared new anion exchange membranes (AEMs) based on imidazoline quaternized polystyrene copolymers bearing N-b-hydroxyethyl oleyl imidazolinium pendent groups to evaluate the application potential for anion exchange membrane fuel cells (AEMFCs). For comparison, an imidazole quaternized polystyrene copolymer was also synthesized. The polymer chemical structure was confirmed by FTIR, NMR, and TGA. In addition, the essential properties of membranes, including ion exchange capacity (IEC), water uptake, and hydroxide conductivity, were measured. The alkaline stabilities of imidazolium-based and imidazolinium-based AEMs were compared by means of the changes in the TGA thermograms, FTIR spectra, and hydroxide conductivity during the alkaline treatment in 1 M KOH at 60 °C for 144 h. The results showed that the imidazolinium-based AEMs exhibited relatively lower hydroxide conductivity (5.77 mS/cm at 70 °C) but much better alkaline stability compared with the imidazolium-based AEM. The imidazolinium-based AEM (PSVBImn-50) retained 92% of its hydroxide conductivity after the alkaline treatment. Besides, the fuel cell performance of the imidazolium-based and imidazolinium-based AEMs was examined by single-cell tests.

Enhancing the CO2 methanation activity of γ-Al2O3 supported mono- and bi-metallic catalysts prepared by glycerol assisted impregnation

Conventional Ni/Al2O3 catalyst, currently used for COx removal in ammonia production, admits room for improvement as catalysts for application in low temperature CO2 methanation, which is the aim of this work. The Incipient Wetness Impregnation (IWI) has been replaced by Glycerol Assisted Impregnation (GAI) method and, afterwards, a secondary metal (Ru) has been co-impregnated forming a bimetallic system. The monometallic as well as bimetallic systems have been characterized by several techniques (TGA, XRD, N2-physisorption, TEM, H2-TPR, H2-TPD, STEM-EDX and operando FTIR) and tested for CO2 methanation reaction in a downflow fixed bed reactor (conditions: P =1 bar, H2: CO2 ratio = 4 and WHSV = 30,000 mL h−1 g−1). GAI method together with a reducing calcination atmosphere (20 %H2/N2) results effective to avoid the formation of large metal particles during the synthesis, especially for Ru/Al2O3 formulation. In fact, the Ru dispersion of the catalyst prepared by GAI (RuAlGAI) is around 5 times higher than that of RuAlIWI catalyst. On the other hand, NiAlGAI presents larger population of reduced particles but bigger in size than NiAlIWI catalyst, which finally provides the former with slightly higher metal surface and superior catalytic performance. By co-impregnating small amounts of Ru (0.5, 1.0 or 1.5 wt%) the Ni surface is considerably increased which, together with Ru synergistic collaboration, results in a methane yield rise from 20 to 44 % at 300 °C. The operando FTIR results show no differences in the reaction pathway with GAI preparation method and incorporation of Ru, but different evolution of reaction intermediates concentration with temperature. The bimetallic Ni-RuAl system presents much higher capacity to adsorb CO and hydrogenate the reaction intermediates (adsorbed formates and carbonyls) by dissociated H2 than its monometallic counterparts.

A study on optical and thermal properties of natural polymer-based hemicellulose compounds

Films of husks of Plantango ovate, Cydonia oblonga, Mimosa pudica, Cochlospermum religiosum were prepared, delignified without protein and cellulose content, and their optical properties were evaluated. UV-Vis, FTIR TGA analysis revealed that these natural materials have strong potential in fiber optics, contact lenses and human transplantation infrastructure applications, where there is need of efficient transparency, high thermal stability and good conductivity with minimum light absorption. These natural polymeric films possess significant direct and indirect optical band gap values and better optical conductivity than currently in use synthetic polymeric materials. The Refractive index of these films is also found high in the visible region in comparison to pure or composite metal-doped synthetic films. Urbach energy (Eu), Dispersion energy (Ed), Average oscillation wavelength (λ0), and oscillation strength(S0) of this hemicellulose based natural polymeric films were found to be appropriate for such optical materials which are green, organic, economical and compatible to human systems.

Synthesis of cassava starch-g-acrylic acid/dimethylaminopropyl methacrylamide: A new hydrogel for brine solution

A new hydrogel copolymer was synthesized via the graft copolymerization of acrylic acid (AA) and dimethylaminopropyl methacrylamide (DMAPMA) on cassava starch (CSt) in aqueous solution. FTIR, TGA–FTIR, solid-state 13C NMR, SEM analyses were used to characterize the polymer. The swelling behavior of the polymer was investigated in distilled water and in various brine solutions. The effects of CSt and the ratio of the two monomers on the water absorbency of the polymer was evaluated. CSt improved the polymer swelling properties. Both polyelectrolyte and anti-polyelectrolyte effects occurred and the polymer had good salt-resistance properties in brine solutions. Such polymers have potential applications in the absorption of ultra-high concentration brine solutions.

Torrefaction of Almond and Walnut Byproducts

While the US nut industry is growing, markets for nut by-products, particularly nutshells and tree prunings, have not kept pace. Torrefaction is a thermochemical process used to improve physicochemical properties of biomass for energy and other applications. The goal of the paper was to characterize the effects of a range of torrefaction conditions on the properties of nut by-product feedstock. The process consists of thermal treatment of biomass at a temperature between 200 and 300°C in the absence of oxygen, where final material properties of the torrefied biomass depend on the temperature, heating rate, and residence time. In general, torrefied biomass exhibits higher hydrophobicity and calorific value with reduced moisture absorption compared to untreated biomass, making it an ideal fuel source for energy applications compared to raw biomass. In this study, almond shells of soft, semi-soft, and hardshell varieties, as well as walnut shells and almond wood, were torrefied at two different temperatures (230 and 290°C) and three different residence times (20, 40, and 60 min) in order to characterize the physicochemical properties. The thermal behavior of raw and heat-treated biomass was investigated by TGA analysis, elemental analysis, pH, helium pycnometry, FTIR spectroscopy, and dynamic vapor sorption analysis.

Role of Hybrid Nano-Zinc Oxide and Cellulose Nanocrystals on the Mechanical, Thermal, and Flammability Properties of Poly (Lactic Acid) Polymer

Biopolymers with universal accessibility and inherent biodegradability can offer an appealing sustainable platform to supersede petroleum-based polymers. In this research, a hybrid system derived from cellulose nanocrystals (CNCs) and zinc oxide (ZnO) nanoparticles was added into poly (lactic acid) (PLA) to improve its mechanical, thermal, and flame resistance properties. The ZnO-overlaid CNCs were prepared via the solvent casting method and added to PLA through the melt-blending extrusion process. The composite properties were evaluated using SEM, a dynamic mechanical analyzer (DMA), FTIR TGA, and horizontal burning tests. The results demonstrated that the incorporation of 1.5% nano-CNC-overlaid ZnO nanoparticles into PLA enhanced the mechanical and thermal characteristics and the flame resistance of the PLA matrix. Oxidative combustion of CNC-ZnO promoted char formation and flame reduction. The shielding effect from the ZnO-CNC blend served as an insulator and resulted in noncontinuous burning, which increased the fire retardancy of nanocomposites. By contrast, the addition of ZnO into PLA accelerated the polymer degradation at higher temperature and shifted the maximum degradation to lower temperature in comparison with pure PLA. For PLA composites reinforced by ZnO, the storage modulus decreased with ZnO content possibly due to the scissoring effect of ZnO in the PLA matrix, which resulted in lower molecular weight.

Comparative Study on the Pyrolysis Behaviors of Pine Cone and Pretreated Pine Cone by Using TGA-FTIR and Pyrolysis-GC/MS.

Pine cone (PC) is a potential biomass energy source and is rich in nonstructural substances (NSS). To understand the impact of these NSS on the pyrolysis behavior and its products, in this study, phenol alcohol extraction was used for the separation of NSS from PC (the PC after separation of NSS was labeled as A-PC), and then thermogravimetric analysis −Fourier transform infrared and PY-gas chromatography/MS detection techniques were used to conduct a systematic comparison of the thermal degradation behaviors and kinetics parameters of PC and A-PC. Results showed that the N content of PC was higher than that of other biomass, and the activation energies of PC and A-PC generally decreased at first and then increased as the conversion rate increased. Furthermore, the activation energy of PC decreased with conversion rates in the range of 0.25–0.30, while A-PC lagged significantly behind PC. On the other hand, the maximum absorption peak of CH4 for PC was higher than that of A-PC, and the maximum absorption peak of CO2 was quite the opposite. After extracting NSS from the PC, its activation energy was significantly increased.

Tuning the product distribution during the catalytic pyrolysis of waste tires: The effect of the nature of metals and the reaction temperature

Metal catalysts based on Ni, Co, and Pd supported on SiO2 were evaluated in the catalytic pyrolysis of waste tires using pyrolysis experiments coupled to gas chromatography/mass spectrometry (Py–GC/MS) and thermogravimetric analysis coupled with Fourier Transform Infrared spectrometer (TGA–FTIR) techniques. The effect of temperature and the nature of metals on the product distribution and reaction pathways was determined. Catalytic pyrolysis promoted aromatization and cracking reactions at particularly low temperatures ca. 350 °C, leading mainly to the formation of alkenes (isoprene), aromatic terpenes (p-cymene), aliphatic terpenes (d,l-limonene), and other aromatic compounds such as benzene, toluene, and xylenes (BTX). The Pd/SiO2 catalyst was the most selective toward aromatic compounds (around 40 %), owing to its well-known hydrogenation/dehydrogenation capacity, while CC bond cleavage reactions, leading to alkenes, were more favored on the Ni/SiO2 and Co/SiO2 catalysts. In all cases, high selectivity to limonene and isoprene was observed at low temperature. Above 400 °C, no significant differences in product distribution were observed between catalyzed and uncatalyzed pyrolysis. Herein, selectivity toward high-value hydrocarbons (i.e., d,l-limonene, isoprene, BTX, and p-cymene) during the catalytic pyrolysis of waste tires was tuned by the nature of the supported transition metals (i.e., Ni, Co, Pd) and the reaction temperature (e.g., <400 °C). The results demonstrate that the use of these catalysts is a promising strategy to valorize waste tires into high added-value products.

Improved flame-retardant properties of polydimethylsiloxane/multi-walled carbon nanotube nanocomposites

The flame-retardant properties of polydimethylsiloxane (PDMS)/oxidised multi-walled carbon nanotubes (MWCNT–COOH) nanocomposite films were dispersed using a nonionic acrylate copolymer surfactant. The nanocomposite films were prepared by spin coating and characterised using SEM, quasi-elastic cold-neutron scattering, TGA–FTIR, cone calorimetry, and LOI. The PDMS/surfactant/MWCNT–COOH (PSM) nanocomposite displayed superior flame-retardant performance compared to materials containing only surfactant or MWCNT–COOH. The peak heat release rate, the peak smoke production rate, total smoke release rate, carbon monoxide, and carbon dioxide production from PSM were 42, 47, 18, 28, and 47% less than the PDMS control. The LOI results for PSM exhibited a value of 32% with respect to 25% for the PDMS. PSM suppresses the smoke emission and inhibits penetration of the air reacting with the gas volatiles of the material. These new nanocomposites provide a valuable improvement in flame-retardant capabilities by physical barrier effect compared to other PDMS polymer materials.

Polycarbonate composites with high light transmittance, haze, and flame retardancy based on a series of incomplete-cage oligomeric silsesquioxanes

A series of incomplete-cage polyhedral oligomeric silsesquioxanes (DVPOSSs) bearing vinyl groups (–CH=CH2) and phosphorus-containing groups (DOPO) have been synthesized through a hydrolytic condensation reaction. FTIR, NMR, and MALDI–TOF MS have been used to identify the structures of the DVPOSSs, which include T9, T10, and T11 cage structures. Polycarbonate (PC)/DVPOSSs composites can be achieved through simple twin-screw extrusion. The addition of DVPOSSs improves the haze of PC/DVPOSSs composites, while maintaining the high transmittance of PC control. The thermal properties and fire behavior of the PC/DVPOSSs composites have been investigated by TGA, DSC, cone calorimetry, and LOI and UL-94 tests. PC/DVPOSSs-2 and PC/DVPOSSs-4 attained a V-0 rating in 3.2-mm and 1.6-mm samples. The pyrolysis and flame-retardant mechanisms of the PC/DVPOSSs composites have been assessed on the basis of TGA–FTIR, cone calorimetry, and char layer morphology results. The main flame-retardant mechanism is that DVPOSSs induce early decomposition of the PC matrix and increase char formation, rapidly extinguishing the flame and causing an obvious reduction in heat release rate.

Synthesis and gas transport properties of hyperbranched network polyimides derived from Tris(4-aminophenyl)benzene

A series of carbon molecular sieve (CMS) membranes have been prepared for CO2/N2 separation based on the aromatic hyperbranched polyimides (HBPIs) synthesized by polymerizing 1,3,5-Tris(4-aminophenyl)benzene (TAPB) and three commercially available dianhydrides, including 1,2,4,5-benzenetetracarboxylic anhydride (PMDA), 2,3,3′,4′-Biphenyltetracarboxylic dianhydride (BPDA), 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The polymerizations were carried out at −60 °C to avoid the gelation at the critical polymerization concentration and the free-standing membranes were successfully obtained from the HBPI solution using directly solvent casting method after post thermal annealing. The hyperbranched molecules swollen, interpenetrated into the adjacent molecules and finally formed a network, when the temperature increased to 60 °C. Both the molecular entanglement and the post thermal imidization contribute to the membrane formation, without resorting to any additional crosslinking agents. The factors governing the gas separation of the HBPI membranes and the CMS ones were investigated using TGA analysis, FT-IR spectroscopy, X-ray diffraction and Raman characterization. The results confirm that the inter-chain spacing in the HBPIs provide the pathways for gas molecules crossing the membrane. The gas permeabilities of the CMS membranes have been further improved owing to the ultramicro- and micro-pores generated after pyrolyzing at 550 °C. For example, the CO2 permeability of XS13-550 significantly increased from 26.0 barrer (XS13) to 16564.4 barrer with a loss of CO2/N2 selectivity from 34.7 (XS13) to 16.6. This work provides a low-temperature process to prepare HBPI precursors without any crosslinking agents.

Ultrasonication treatment enhances MOF surface area and gas uptake capacity

It is well recognised fact that the properties of materials depend on the synthesis technique. We can use this power to change the physical and chemical properties of materials. Metal organic frameworks are porous coordination polymers that have a highly porous structure, great surface area and can be utilised for gas capturing and storage applications. Improving the surface area of MOFs has always been targeted in coordination chemistry. Synthesis reactions need mass physical forces where the mass transfer of reactants is required, and it can definitely be provided by the sonochemical synthesis approach. In this study, the very well-known MOF-2 was re-synthesised using an ultrasonication method. The prepared sample was activated under vacuum to obtain highly porous MOF crystals. All the prepared samples were fully characterized using SCXRD, PXRD, FTIR TGA, SEM-EDS and BET analysis. The results indicated highly crystalline, water stable MOF materials with a high carbon dioxide capture tendency. Moreover, it was found that sonication treatment and vacuum activation at high temperature increases the specific surface area of the prepared samples compared to MOF-2 prepared by a conventional solvothermal synthesis.