Through Thermal Gravimetric Analysis Research Articles

Arone-containing cyclomatrix-type polyphosphazene hybrid microspheres for epoxy resin: Enhancing fire safety and mechanical properties

Arone-containing cyclomatrix-type polyphosphazene hybrid microspheres (PZK) were synthesized to enhance both the fire safety and mechanical performance of epoxy resin (EP). The chemical structure and micro-morphology of PZK were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy, and X-ray photoelectron spectroscopy. Subsequently, PZK was employed in fabricating EP thermosets. Thermal properties of the PZK modified EP thermosets were comprehensively assessed through thermalgravimetric analysis (TGA) and dynamic mechanical analysis. The results indicate that PZK endowed EP with enhanced char yield and storage modulus, attributed to its exceptional thermal stability and distinctive microsphere structure. Additionally, with only a 1.5% loading of PZK, EP achieved a UL-94 V-1 rating during vertical flame testing, accompanied by an increased limiting oxygen index of 28.3%. Additional analysis with a cone calorimeter demonstrated that the addition of PZK markedly reduced the peak heat release rate, total heat release, fire growth rate, and total smoke production of EP, indicating notable efficacy in suppressing heat and smoke release. Char residue and pyrolysis products were analyzed using SEM, TG-FTIR, and pyrolysis gas chromatography-mass spectrometry, revealing that PZK effectively inhibits the release of combustible gases from EP during thermal decomposition. The expected generation of Ph—O• radicals from arone units in PZK suggested a gaseous free radical trapping mechanism. The phosphazene framework played a crucial role in forming condensed-phase char due to its exceptional thermal stability. Consequently, PZK exhibited a typical biphasic flame-retardant mechanism for EP. Notably, the study observed that the introduction of PZK simultaneously enhances the tensile strength, flexural strength, and modulus of EP, with a particularly significant improvement observed in impact strength. This research expands the scope of investigation into the preparation and flame-retardant application of cyclomatrix-type polyphosphazene hybrid microspheres in polymers.

1,3‐Diynes as Precursors for the Synthesis of Triazene‐ and Diethylaniline‐Bearing Push‐Pull NLOphores

AbstractWithin the scope of this study, a total of eight new NLOphores of the D‐π‐A‐π‐D type have been synthesized. This was achieved by applying click‐type [2+2] cycloaddition‐retroelectrocyclization reactions of unsymmetrical 1,3‐diynes with well‐known electron‐deficient alkenes, TCNE, and TCNQ. Furthermore, essential insights into the optical properties of the synthesized NLOphores were obtained from comparisons with four model compounds synthesized separately within this study. The thermal stability of the NLOphores was assessed through thermal gravimetric analysis (TGA). NLOphores synthesized using two distinct electron‐deficient alkenes exhibit low energy absorption bands covering most of the visible region with λmax values ranging from 466 nm to 723 nm. Theoretical studies, including time–dependent density functional theory (TD‐DFT) investigations, frontier orbital visualizations, and electrostatic potential maps, have been utilized to further investigate the intramolecular charge transfer properties of chromophores. The NLO responses of the chromophores were determined through DFT calculations. It is worth noting that the average polarizability and first hyperpolarizability values (α(tot)=106.392–159.709×10−24 esu; β(tot)=387.552–417.359×10−30 esu) obtained from these calculations show significant promise compared to literature data.

UV-curable Schiff base-containing polymeric adsorbent for selective and efficient removal of Au(III) from aqueous solutions

UV-curable polymeric adsorbent was prepared using a diacrylate-functionalized hydrazone-oxime monomer (DAFHOM), trimethylolpropane triacrylate (TMPTA), and trimethylolpropane tris(3-mercaptopropionate) (TMPTP) through UV-initiated thiol-ene click reaction. Initially, a novel hydrazone-oxime-based Schiff base ligand was synthesized and modified with diacrylate functionality to prepare the UV-curable polymeric adsorbent. The structures of DAFHOM and the resulting polymeric adsorbent were confirmed using Fourier Transform Infrared Spectroscopy (FTIR) analysis. Additionally, the thermal behavior of the UV-cured adsorbent was investigated through thermal gravimetric analysis (TGA), which revealed that the adsorbent exhibited good stability and did not degrade at room temperature. The adsorption performance of the UV-curable polymeric adsorbent for Au(III) from aqueous solutions was studied under various experimental conditions, including pH, contact time, and initial metal concentration. The UV-curable polymeric adsorbent demonstrated effective and selective Au(III) adsorption from aqueous solutions. The findings indicated that removing Au(III) from water solutions positively correlated with pH, particularly within the pH range of 0.5–2.5. However, the efficiency declined when the pH exceeded 1.5. Among the various adsorption isotherm models investigated, the Langmuir model was found to be the most suitable for describing the behavior of the adsorbent. The maximum adsorption capacity of the adsorbent for Au(III) was determined to be 30.06 mg/g. In batch experiments, the UV-curable adsorbent displayed promising selectivity towards Au(III), even in the presence of competitive ions such as Cu(II), Pb(II), and Cd(II).

Potential Use of Melamine Phytate as a Flame-Retardant Additive in Chicken Feather-Containing Thermoplastic Polyurethane Biocomposites.

Using waste materials such as chicken feathers (CF) and biobased flame-retardant additives including melamine phytate (MPht) has become an effective approach for environmentally friendly and sustainable production in recent years. This study explores the flame retardant effectiveness of MPht in thermoplastic polyurethane (TPU)-based biocomposites containing CF. The characterizations of the composites are performed through thermal gravimetric analysis (TGA), limiting oxygen index (LOI), vertical UL-94 (UL-94 V), and mass loss calorimetry (MLC) tests. According to the test results, the highest UL-94 V rating of V0, a LOI value of 29.4%, and the lowest peak heat release rate (pHRR) (110 Kw/m2) and total heat evolved (THE) (39 MJ/m2) values are obtained with the use of 20 wt % MPht. It is demonstrated that MPht acts as an effective flame-retardant filler through the formation of intumescent char in the condensed phase and flame dilution in the gas phase.

Probing the Electro-Chemical and Thermal Properties of Polyaniline/MWCNT Nanocomposites

The tremendous interest for robust, clean energy storage devices to comprehend the growing needs of modern gadgets has led to exploration of materials having unprecedented electrochemical and interfacial properties. Here, the present study deals with the synergistic effects of multi walled carbon nanotubes and polyaniline nanocomposites on the electro-chemical and thermal properties for wide-range of applications. The microstructural, structural, and optical characterizations have been evaluated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectrophotometry. The thermal stability of the product was also studied through thermal gravimetric analysis (TGA) and the room temperature electrical conductivity was also measured. An exceptional enhancement in thermal stability and conductivity has been observed apparently due to interfacial properties of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs). Further, in present study we are going to report a comparative analysis of thermal and electrical properties of PANI/MWCNT nanocomposites with different loadings of MWCNTs. The room temperature conductivity as calculated for 1%, 2%, 4% and 8% MWCNT loading is around 2.019, 3.075, 4.48, 8.73 S/cm respectively. The mechanism for thermal and electrical enhancements in PANI-coated MWCNT nanocomposites is also expounded.

Vulcanization, compounding, thermo-mechanical properties and surface morphology of montmorillonite nanoclay based nitrile rubber nanocomposites

Remarkable importance has been bestowed upon polymer nanocomposites over the last few decades. Recently high-performance nanocomposites based on organic polymer/inorganic fillers have provided a new platform to the investigators in scientific and industrial aspects because of their unique and excellent properties. The main challenge lies in efficient dispersion and alignment of nanoclay into polymer matrix. The nanocomposites provided superior thermo-mechanical properties i.e., flexibility, light weight, good processability with comparatively low cost and several applications in field such as automobile, electrical, safety, and aerospace. The present investigation is devoted on the development of nitrile rubber nanocomposites reinforced with montmorillonite (MMT) nanoclay and other vulcanization and compounding additives like dicumyl peroxide, zinc oxide, stearic acid, di-octyl-phthalate, antioxidant, curing agents etc., and this also study investigated the effect of MMT nano-clay of loading 1, 3, 5 parts per hundred rubber (phr) on the thermo-mechanical properties and morphological aspects of nitrile rubber. Nanocomposites samples were prepared through vulcanization and compounding method using two roll mills, followed by compression moulding. The results revealed that 5 phr content of MMT nanoclay in the nitrile rubber matrix gives the highest tensile strength, tensile modulus and elongation at break according to ASTM standard and thermal stability carried out through thermal gravimetric analysis (TGA). The modification in various properties can be attributed to better interfacial adhesion between nanoclay and rubber matrixes examined by scanning electron microscopy (SEM).

Enhancing the Antioxidant, Antibacterial, and Wound Healing Effects of Melaleuca alternifolia Oil by Microencapsulating It in Chitosan-Sodium Alginate Microspheres

In this study, antibacterial and antioxidant molecules-rich Melaleuca alternifolia oil (tea tree oil (TTO)) loaded chitosan (CS) based nanoemulsions (NEMs) were prepared and encapsulated by sodium alginate (SA) microsphere for antibacterial wound dressing. CS-TTO NEMs were prepared by oil-in-water emulsion technique, and the nanoparticle tracking analysis (NTA) confirmed that the CS-TTO NEMs had an average particle size of 89.5 nm. Further, the SA-CS-TTO microsphere was confirmed through SEM analysis with an average particle size of 0.76 ± 0.10 µm. The existence of TTO in CS NEMs and SA encapsulation was evidenced through FTIR analysis. The XRD spectrum proved the load of TTO and SA encapsulation with CS significantly decreased the crystalline properties of the CS-TTO and SA-CS-TTO microsphere. The stability of TTO was increased by the copolymer complex, as confirmed through thermal gravimetric analysis (TGA). Furthermore, TTO was released from the CS-SA complex in a sustained manner and significantly inhibited the bacterial pathogens observed under confocal laser scanning microscopy (CLSM). In addition, CS-TTO (100 µg/mL) showed antioxidant potential (>80%), thereby increasing the DPPH and ABTS free radicals scavenging ability of SA-CS-TTO microspheres. Moreover, CS and SA-CS-TTO microsphere exhibited negligible cytotoxicity and augmented the NIH3T3 cell proliferation confirmed in the in vitro scratch assay. This study concluded that the SA-CS-TTO microsphere could be an antibacterial and antioxidant wound dressing.

Terahertz for the detection of the oil bearing characteristics of shale

Studying the trace organic matter (OM) in shale is of great significance to develop exploration plans for shale oil and gas exploration. Due to the low OM content, currently there are significant limitations in determining shale trace OM characteristics. This paper reports the analysis of the pyrolyzation products of shale using THz time-domain spectroscopy (THz-TDS) technology combined with pyrolyzation technology, based on the sensitivity of THz to organic and mineral differences. The THz parameters, including the time delay and amplitude of the THz peaks, were extracted to describe the pyrolyzation of shale. In the first-stage of pyrolyzation, the THz response does not change significantly in the range of < 300 °C. In the second stage of 300–700 °C, the THz parameters in the second stage decrease or increase sharply because the OM gradually decomposes. In the third stage, in the high temperature from 700 to 1000 °C, minerals such as calcite decompose. In addition, a turning point between organic matter decomposition and mineral reactions occurs at 700 °C, which helps to identify organic matter and minerals More importantly, the THz parameter can reflect a rate of change of up to 41%, which is far higher than the 4.1% rate of mass change during the pyrolyzation stage at 300–700 °C. Based on verification through thermal gravimetric analysis (TGA), mass spectroscopy (MS), X-ray diffraction (XRD), and scanning electron microscopy (SEM), we believe that the use of the THz combined with pyrolyzation technology method is practical for characterizing the organic matter in shale.

Characterizing Electrochemical and Thermal Properties of VDF Blended 3M PFSA Ionomer with Chemically Bonded Polyoxometalate Additives

Proton exchange membranes (PEMs) are considered as the most promising material for fuel cell automobile applications due to their high proton conductivity and power density. The radical attacks with peroxide formation cause lower durability, which is a major challenge to further commercialize fuel cell vehicles. Cerium and manganese cations and oxides have been implemented as radical scavenging agents to overcome the challenge from radical attacks. However, the additives tend to not stay on the initial location but move during the operation due to migration and diffusion. The migration results in cluster formation and eventually the additives may dissolve and leave the membrane system. Our previous work modifying commercial fluroelastomers with chemically bonded polyoxometalate resulted in a membrane with radical scavenging properties while inhibiting additive clustering. Advancement in PEM durability with additives has implications not only for the light-duty fuel cell vehicles but also for medium and heavy-duty vehicles applications, which would aid the widespread of commercialization of fuel cell vehicles.This work focuses on characterizing the blended perfluorinated sulfonic acid (PFSA) ionomer membrane with the chemically bound radical scavenger to enhance the durability of the membrane. Proton conductivity of the membrane was characterized under controlled relative humidity and temperature with electrochemical impedance spectroscopy (EIS). Ionic Exchange capacity of two or more proton conductive sites was measured using titration method. Correlation between water uptake and membrane properties is discussed and measuring using dynamic vapor sorption (DVS). Thermal stability was investigated through thermalgravimetric analysis (TGA).

Synthesis of glutamate intercalated Mg-Al layered double hydroxides: influence of stirring and aging time

An Mg-Al layered double hydroxides (LDHs) intercalated by glutamate ions (Glu/LDH) was obtained using co-precipitation processing. The influence of stirring and aging time on LDH morphology was investigated. The morphology of LDH was characterized by means of XRD, FT-IR, FE-SEM and XPS. The thermal stability, pore volume and specific surface area were probed through thermal gravimetric (TG) analysis and automatic specific surface area analyzer, respectively. The results showed that the stirring and aging time had an insignificant influence on the interlayer distance of Glu/LDH; while it had a critical impact on the crystallinity degree of the Glu/LDH structure. TG analysis designated that the thermal stability of glutamate ion intercalated in LDH layers was higher than that of glutamate ion before intercalation. Glu/LDH exhibited the best adsorption performance at a stirring and aging time of 12 h. A schematic molecular structure model of Glu/LDH was proposed.

Application of self-heating graphene reinforced polyvinyl alcohol nanowires to high-sensitivity humidity detection

In this study, we measured the performance of self-heating conductive conjugated polyvinyl alcohol, (PVA)/graphene (G) composite nanofibers in the detection of environmental humidity. PVA-G polymer nanocomposite fibers were electrospun together from suspensions of PVA and varying concentrations of pristine G sheets. The extent of graphene dispersion in the nanocomposite fibers were characterized via Raman and transmission electron microscopy (TEM) analysis. Where the main content of C and O elements in composite nanofibers were obtained from the energy dispersive (EDX) spectra and EDX mapping results. Thermal characteristics and structural morphology were then investigated through thermal gravimetric analysis (TGA), and focused ion beam scanning electron microscopy (FIB-SEM) & laser scanning confocal microscopy (LSCM), respectively. Applied voltages (0−10 V) to the PVA-G polymer nanocomposite fibers under varying conditions of humidity were investigated. With increasing concentration of G, increased sensitivity to relative humidity could be observed through the proportional changes in resistance. In addition, at PVA-G concentrations at 6%, the tested humidity sensor remained highly responsive while operating at low temperatures of 60 °C and with minimal power consumption.

A laboratory study of a novel bio-based nonionic surfactant to mitigate clay swelling

This study reports the applicability of quillaja saponin (QS) as a vigorous and environmentally friendly shale swelling inhibitor. QS is a natural surfactant, which is extracted from herbal sources. The inhibition strength of this surfactant was assessed through various experiments, such as sedimentation, inhibition, filtration, particle size, Scanning Electron Microscope (SEM) images, and cutting recovery. Data obtained from these tests illustrated that QS greatly inhibits clays from swelling. The optimal concentration for QS in this intend was 10 g/L. Compatibility of this surfactant with other common additives was also investigated, which showed that it is totally compatible. Finally, the potential inhibition mechanism was assessed through thermal gravimetric analysis (TGA), zeta potential, and contact angle measurement experiments. Surface coating, and wettability alteration of clay particles to the oil-wet state was recognized as the most probable mechanism.

Bilayer adsorptive ceramic membranes supported cage-like mesoporous silica for hexavalent chromium removal: Experimental and DFT studies

In this study, an adsorptive ceramic membrane coated by new layer of cage-like mesoporous silica SBA_16 which was modified with 3-aminopropyltriethoxysilane (APTES) was employed to remove (Cr (VI)) ions from aqueous solution. The morphologies and physiochemical properties of SBA_16 and modified SBA_16 (NH2-SBA_16) adsorbents as well as adsorptive membranes were characterized through thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), N2 adsorption-desorption isotherms, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The adsorption isotherm data perfectly was fitted to Langmuir isotherm model and the adsorption capacity value of NH2-SBA_16 for Cr (VI) at pH of 2.5 was 61.9 mg/g. The experimental kinetic data agreed with pseudo-second-order model. The dynamic filtration test in dead-end system was utilized to evaluate the efficiency of ceramic membranes in hexavalent chromium removal. The modification of ceramic membrane (CM2) resulted in an excellent Cr (VI) removal (100 %) for permeate stream. Aminopropyl grafting on the ceramic membrane significantly enhanced the permeate flux from 56 L/m2h to 85.6 L/m2h. Density functional theory (DFT) calculations have been performed and the adsorption energy of Cr (VI) on NH2-SBA_16 was obtained 131.25 kJ/mol.

Synthesis of reduced octadecyl isocyanate-functionalized graphene oxide nanosheets and investigation of their effect on physical, mechanical, and shape memory properties of polyurethane nanocomposites

Herein, two sets of shape memory polyurethane (PU) nanocomposites comprising 3 and 1 wt% of reduced graphene oxide and reduced octadecyl isocyanate-functionalized graphene oxide nanosheets (named as RGO and R (GO-ISO), respectively) were fabricated by solution casting approach. Fourier transform infrared (FTIR) analysis verified linking of octadecyl isocyanate to GO nanosheets via addition reaction of NCO groups with OH and COOH groups and formation of urethane and amide functionalities. The grafting content was determined through thermal gravimetric analysis (TGA), which was about 15 wt% of R (GO-ISO) nanosheets. The appropriate dispersion of R (GO-ISO) nanosheets compared to R (GO) nanosheets in PU was studied by field emission scanning electron microscopy (FE-SEM). Additionally, better distribution level of R (GO-ISO) nanosheets caused PU/R (GO-ISO) nanocomposites to possess greater modulus and lower elongation at break than PU/RGO nanocomposites. Moreover, PU/R (GO-ISO) nanocomposites showed greater shape memory fixities, due to more effective stress transfer of R (GO-ISO) nanosheets than that of RGO nanosheets.

Thermal analysis on the component interaction of asphalt binders modified with crumb rubber and warm mix additives

This study investigated the interaction among different components of asphalt binders collectively modified with crumb rubber and warm mix additives through thermal gravimetric analysis (TGA) and differential scanning calorimeter (DSC) testing. The modified binders were divided into two parts for analysis purpose, namely the extracted crumb rubber modifier (CRM) by removing all asphalt components and the separated binder system by removing insoluble CRM particles. The main findings of this study include that: (1) the interaction between CRM and base asphalt was a component exchange process, i.e., natural rubber and styrene-butadiene rubber were released from CRM and blended with asphalt molecules; (2) wax-based warm mix additives penetrated into CRM during the mixing process; (3) the incorporation of warm mix additives especially the wax-based additives, promoted the component exchange between rubber and asphalt.

Multifunctional polyester fabric using a multicomponent treatment

In this study, multifunctional polyester fabrics with the features of self-cleaning, water and stain repellency, and thermal stability were prepared utilizing a multicomponent system. To this end, both unmodified and alkaline-hydrolyzed modified fabrics were treated with nano TiO2/citric or maleic acid/sodium hypophosphite/polysiloxane and triethanolamine via a pad-dry-cure method. Surface morphology and color variation of the samples were studied utilizing field emission scanning electron microscopy (FESEM) and CIE-Lab system, respectively. Also, energy-dispersive X-ray (EDX) analysis indicated the content of Ti, P and Si on the surface of fabrics. Thermal stability of the specimen was scrutinized through thermal gravimetric analysis (TGA) and char yield. Both hydrolysis treatment and silicone softener increased the uptake of the nanoparticles. Also, in a comparison between the utilized carboxylic acids, citric acid demonstrated superior features. Generally, the treated fabrics showed desirable self-cleaning and stain repellency with some enhanced thermal stability.

Thermal and Flammability Properties of Polypropylene Filled Rice Bran/Sepiolite Composite

Polypropylene that consist of different loading of rice bran (RB) (0wt%, 10wt%, 20wt%, 30wt%, 40wt%) and sepiolite (SEP) (0phr, 1phr, 2phr, 3phr, 4phr, 5phr) were prepared by twin-screw extruder followed by compression moulding. The effect of RB and SEP loading on the thermal properties and flammability properties were studied through thermal gravimetric analysis (TGA) and UL94 horizontal burning test (UL94HB) respectively. The result from TGA revealed that RB content at 40%wt and SEP content at 4phr showed good thermal stability. The sepiolite used for flammability properties had improved the flammability matrix; however, the amount of SEP use in this study is not enough to improve the flammability of PP/RB composite.

Thermal and combustion behavior of polyethersulfone-boehmite nanocomposites

In this paper, we report a thorough study on the thermal stability and fire behavior of polyethersulfone (PES) filled with 2 wt% nano-sized aluminum oxide hydroxide particles (boehmite). The nanocomposite was prepared through melt compounding technique in a co-rotating twin screw extruder. The obtained morphology of the composite was studied by scanning electron microscopy (SEM) coupled with elemental analysis, proving that an even distribution of sub-micron boehmite particles was obtained. PES shear modulus, measured by DMA, is increased by 30% in the boehmite nanocomposite. Thermal stability of the produced materials was studied through thermal gravimetric analysis (TGA), whereas the combustion behavior through cone calorimeter and vertical burning (UL-94) tests. Cone calorimeter results show that a significant overall flame retardant effect was observed due to the presence of boehmite nanoparticles, which could not be detected by UL-94 fire scenario where neat PES is already top ranked V0.

A durable flame retardant for cellulosic fabrics

A novel halogen- and formaldehyde-free flame retardant named Neo-FR was synthesized and applied to cellulosic fabrics. The chemical structure of the flame retardant was characterized by Fourier-transform infrared spectroscopy (FTIR). The flame retardant performance was evaluated by Limiting oxygen index (LOI) and vertical flammability tests. The results indicated that the flame retardant had excellent flame retardancy and durability for cellulosic fabrics. The surface morphology of treated fibre and fibre char residue were observed through scanning electron microscope (SEM). The SEM graphs demonstrated that the Neo-FR system played intumescent flame retarding mechanism on cotton fibre. The thermal property of the flame retardant treated cotton fabric was investigated through thermal gravimetric analysis (TGA). The results indicated that char residue of the treated fabrics was about 36.5%, which was much higher than that of untreated fabric. The mechanical properties such as tensile strength and elongation of the cotton samples treated with Neo-FR system were much less affected than those treated by a commercial durable flame retardant agent (Pyrovatex CP New). The laundering test results show that the Neo-FR system is a durable flame retardant for cellulosic fabrics.

Syntheses, structure, reactivity, and thermal properties of epoxy–imide resin cured by phosphorylated triamine

A new phosphorylated epoxy–imide polymer was obtained using diimide–diepoxide (DIDE) cured with tris(3-aminophenyl)phosphine oxide (TAPO). In addition, compositions of the synthesized diimide diepoxide (DIDE), Epon 828, and DEN 438 with common curing agents, e.g., 4,4′-diaminodiphenyl ether (DDE) and 4,4′-diaminodiphenylsulfone (DDS), were compared as to curing reactivity and heat and flame retardation with that of tris(3-aminophenyl)phosphine oxide. The reactivities of those curing agent toward the three kinds of epoxy resins, as measured by differential scanning calorimetry (DSC), were in the order DDE > TAPO > DDS. Through thermal gravimetric analysis (TGA), the thermal and flame resistances of epoxy were confirmed in this study as capable of being significantly improved through introduction of imide and phosphorus groups into the epoxide structure. © 1996 John Wiley & Sons, Inc.