Integral Procedural Decomposition Temperature Research Articles

Thermal, mechanical property and flame retardant analysis of bio-based rigid polyurethane foam modified with expandable graphite

As an energy-efficient building material, rigid polyurethane foam (RPUF) has attracted attention. However, there are still great challenges in how to easily prepare RPUF materials with good mechanical properties, flame retardant properties, thermal insulation and other properties. In the current work, expandable graphite (EG)-modified lignin-based polyol (RPUF) was prepared by a one-step method. Thermogravimetric analysis was used to study the pyrolysis of modified foams under nitrogen conditions. It was found that the RPUF-4 with an EG of 10 wt% had the highest the apparent activation energy (E), integral procedural decomposition temperature (IPDT), initial temperature and residue rate. And RPUF-4 also had excellent thermal insulation properties. In addition, RPUF-4 exhibited excellent flame retardancy and smoke suppression properties (peak heat release rate (RHRR), total heat release rate (THR) and Ds were 65.46 %, 23.92 % and 45.94 % lower than those of the unadded RPUF, respectively). At the same time, RPUF-4 also had good mechanical properties and energy absorption properties. These results will lay the foundation for the development and application of RPUF in the field of building insulation.

Improved mechanical, magnetic and radiation shielding performance of rubbery polymer magnetic nanocomposites through incorporation of Fe3O4 nanoparticles

The current research investigates the impact of magnetite (Fe3O4) nanoparticles (3–12 wt%) on the properties of rubbery polymer nanocomposites fabricated via melt blending method. The tensile and impact properties were improved at an optimal 6 wt% Fe3O4, revealing a good interfacial interaction. Fe3O4 enhanced the thermal stability, as evidenced by the increased integral procedure decomposition temperature up to 26 %. Fe3O4 increased residual and saturated magnetization the most at 6 wt% loading. The gamma-ray shielding properties were explored with energy ranging from 0.2835 to 2.506 MeV, and effectively at low energies. Increased Fe3O4 content correlated positively with linear attenuation coefficient (LAC), enhancing radiation shielding but reducing neutron shielding. At 0.2835 MeV, the LAC values increased up to 0.12431 cm−1 for 12 wt% Fe3O4, while the fast neutron removal cross-section values decreased from 0.10427 cm−1 to 0.08548 cm−1. These findings highlight the multifunctional potential of Fe3O4-incorporated nanocomposites in radiation shielding applications.

Thermal Degradation Kinetic Study of Expanded Perlite‐Modified Butadiene Rubber Composites

AbstractMineral–rubber composites based on phosphorylated butadiene rubber (PhBR), including pure expanded perlite (EP) and modified phosphorylated expanded perlite (PhEP) as fillers, are developed. The process involves forming PhBR and its composites—EP/PhBR and PhEP/PhBR—through the oxidative chlorophosphorylation (OxCh) reaction. An in‐depth comparative analysis is conducted on the thermal destruction of the PhBR matrix and the EP/PhBR, and PhEP/PhBR composites. The thermogravimetric (TG)/differential thermogravimetry (DTG) analyses reveal three stages of thermal degradation for the PhBR matrix and both composites, highlighting the notable effects of EP and PhEP in the second and third stages of the degradation process. In comparison, the PhEP/PhBR composite exhibits reduced weight loss, the highest integral procedural decomposition temperature (IPDT) value, and a lower Tmax on the DTG curve, compared with the EP/PhBR composite and the PhBR matrix. The mechanism of the thermal destruction reaction and the kinetic parameters Ea and A are calculated using the model‐fitting Coats–Redfern method.

Synthesis, Characterization, Isoconversional Analysis and Degradation Kinetics of Novel Acetate Coated Hydroxyethyl Starch: A New Candidate as a Drug Carrier

The hydroxethyl starch (HES) is very trending biopolymer in biomedical field. In recent research we have successfully synthesized a novel ester of HES, i.e., HES-acetate by acetylation of HES followed by investigation of its thermal behavior. The successful acetylation of HES was confirmed by Fourier Transform Infrared (FTIR) and Proton-Nuclear Magnetic Resonance (1H NMR) spectroscopic techniques. Thermal stability and thermal degradation kinetics of HES-acetate were investigated by thermo-gravimetric analysis. Flynn–Waal–Ozawa model was fitted to the thermal data to find the values of thermodynamic triplet (ΔS, ΔG and ΔE). Energy of activation (Ea) values of the major thermal degradation steps were found to be 242.85 and 287.17 kJ mol–1 for HES and HES-acetate, respectively. The order of degradation, integral procedural decomposition temperature (IPDT) and index of intrinsic thermal stability (ITS) were also taken into account. The results of the thermal analysis reveal that the HES-acetate gained significant thermal stability as compared to that of HES. This benign polysaccharide-based material was investigated for its potential in drug release studies by taking caffeine as a model drug. HES-acetate-based matrix tablets showed sustained release behavior of the drug indicating its potential for the development of oral delivery systems for sustained drug release.

Development of nanostructured green divalent manganese‐coordinated polyurea

AbstractThe work presented here reports the greener synthesis of polyurea (GPUa) via in‐situ solvent‐free precipitation polymerization of toluene diisocyanate (TDI) (used as monomer) and water. The divalent manganese [Mn(II)] ions were incorporated into GPUa to form Mn(II)‐GPUa to enhance its applicability. The structure of GPUa and Mn(II)‐GPUa was validated by Fourier‐transform infrared and proton nuclear magnetic resonance spectral techniques. The morphology along with the elemental analysis of GPUa and Mn(II)‐GPUa was assessed by X‐ray diffraction analysis and field emission scanning electron microscopy along with energy‐dispersive X‐ray spectroscopy. Thermal degradation behavior and stability of GPUa and Mn(II)‐GPUa were investigated by thermo‐gravimetric, differential thermal, differential scanning calorimetry, and integral procedure decomposition temperature analysis. Furthermore, the batch adsorption method was used to examine the adsorption behavior of Mn(II)‐GPUa. The study's results indicated that Mn(II)‐GPUa might be used as an eco‐friendly, thermally stable material and adsorbent, making it suitable as an effective dye adsorbent for wastewater treatment. The current work is aligned with Green chemistry principles (Principles 1, 2, 3, 4, 5, 6, 8, and 12).

Thermal Degradation Behavior and Mechanism of Organosilicon Modified Epoxy Resin

AbstractOrganosilicon modified epoxy resin is one of the most widely used ablative coating matrices in the whole aerospace industry. However, most research focuses on the final effect of organosilicon modification, while systematic studies on thermal degradation behavior and mechanism of organosilicon modified epoxy resin are rarely reported. In this work, a heat‐resistant epoxy resin (ES231) is prepared through the condensation reaction between epoxy resin and methylphenyl organosilicon intermediate. The TGA test results show that the integral procedural decomposition temperature (IPDT), the thermal residual weight at 800 °C (R800), and decomposition temperature range all improve under both N2 and air atmospheres after modification. The functional groups variation of polymers and the generated volatile segments during the degradation process are measured by FTIR, TG‐IR, and TG‐MS to investigate the thermal degradation mechanism in detail. Meanwhile, the composition and microstructure of the solid residue after thermal degradation are also systematically studied by SEM, XPS, and Raman spectroscopy. It is expected that this work can provide some theoretical basis and new ideas for designing new heat‐resistant epoxy resin.

"COMPARATIVE ISOCONVERSIONAL THERMAL ANALYSIS AND DEGRADATION KINETICS OF SALVIA SPINOSA (KANOCHA) SEED HYDROGEL AND ITS ACETATES: A POTENTIAL MATRIX FOR SUSTAINED DRUG RELEASE"

The present study deals with the isolation and modification of Salvia spinosa hydrogel (SSH) to investigate its thermal degradation profile. The SSH was modified chemically to its acetylated derivative (ASSH-1–4) with DS 1.05-2.79. After characterization by Fourier transform infrared (FTIR) and solid-state CP/MAS 13C-NMR spectroscopic techniques, both SSH and ASSH-4 were subjected to thermogravimetric analyses (TG) by the isoconversional method, i.e., the Flynn-Waal-Ozawa (FWO) and the Kissinger methods. TG curves showed that both SSH and ASSH-4 exhibited two-step degradation. The energy of activation (Ea) for each degradation step was calculated by fitting thermal degradation data to the FWO method, revealing greater stability of ASSH-4 than that of SSH. Analysis by Kissinger’s method revealed the second and one and a half order of thermal degradation (n) for SSH and ASSH-4, which also evidenced that ASSH-4 is more stable than SSH. The values of the thermodynamic triplet (ΔH, ΔG and ΔS) were calculated from thermal data. Positive values were found for ΔG, which showed the non-spontaneous nature of thermal degradation of SSH and ASSH-4. The values of integral procedural decomposition temperature (IPDT) and intrinsic thermal stability (ITS) for SSH and ASSH-4 were found comparatively greater than those of many other commercially available materials of the same kind, which revealed the higher stability of both materials. SSH, as a benign polysaccharide-based material, was also assessed for its utility in drug release studies, taking caffeine as a model drug. The SSH matrix-based tablet formulation (SSHC) showed a sustained release behavior of the drug in preliminary studies.

Thermal stability and non‐isothermal kinetics of poly(ethyl cyanoacrylate) nanofibers

AbstractA thermogravimetric study of poly(ethyl cyanoacrylate) nanofibers was carried out at five heating rates with a linear increase in the temperature in a nitrogen atmosphere. The data provided by the thermogravimetric study were used to evaluate the kinetics of the degradation process using three isoconversional methods. Considering that the kinetic parameters of the process depend on the reaction mechanism, various approaches were applied in order to determine the most probable mechanism function. In this respect, the mechanism of thermal degradation of poly(ethyl cyanoacrylate) is a phase boundary reaction with cylindrical symmetry (F0.5 function) as demonstrated by the z(α) master plots method, iso‐temperature method and isoconversional method. On their basis, the values of the kinetic triplet (Ea, A and the shape of the most appropriate f(α) function) of the process were obtained, and subsequently the thermodynamic functions of the activated complex formation were calculated. The thermal stability of the polymer was predicted according to the integral procedure decomposition temperature. © 2022 Society of Chemical Industry.

Development of Antibacterial Xanthan/Chitosan Biguanidine Hydrochloride Polyelectrolyte Complexes Decorated with Eco-friendly Prepared Silver Nanoparticles

Background: Novel eco-friendly silver nanocomposites of xanthan/chitosan biguanidine hydrochloride polyelectrolyte complexes were successfully prepared. Methods: Silver nanoparticles (AgNPs) were formed through an insitu eco-friendly reduction by the non-toxic polysaccharides without the usage of toxic reagents. FTIR confirmed the successful preparation of the nanocomposites while XRD confirmed the presence of AgNPs with face-centered cubic structures. TEM confirmed the homogeneous distribution of AgNPs with an average size of 14.1 nm. SEM was used to study the surface morphology of the nanocomposites while the energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of AgNPs. Results: Thermogravimetric analysis showed that the thermal stability was improved in the presence of AgNPs as detected from the calculated integral procedure decomposition temperature. Antibacterial activity against different bacteria species was significantly improved upon increasing the content of AgNPs. Conclusion: Due to their interesting properties, the prepared polyelectrolyte complexes and their AgNPs nanocomposites could be employed potentially in many biomedical applications like drug delivery.

Roles of Small Polyetherimide Moieties on Thermal Stability and Fracture Toughness of Epoxy Blends.

Bisphenol A diglycidyl ether (DGEBA) was blended with polyetherimide (PEI) as a thermoplastic toughener for thermal stability and mechanical properties as a function of PEI contents. The thermal stability and mechanical properties were investigated using a thermogravimetric analyzer (TGA) and a universal test machine, respectively. The TGA results indicate that PEI addition enhanced the thermal stability of the epoxy resins in terms of the integral procedural decomposition temperature (IPDT) and pyrolysis activation energy (Et). The IPDT and Et values of the DGEBA/PEI blends containing 2 wt% of PEI increased by 2% and 22%, respectively, compared to those of neat DGEBA. Moreover, the critical stress intensity factor and critical strain energy release rate for the DGEBA/PEI blends containing 2 wt% of PEI increased by 83% and 194%, respectively, compared to those of neat DGEBA. These results demonstrate that PEI plays a key role in enhancing the flexural strength and fracture toughness of epoxy blends. This can be attributed to the newly formed semi-interpenetrating polymer networks (semi-IPNs) composed of the epoxy network and linear PEI.

Thermal Stability, Smoke Density, and Flame Retardance of Ecotype Bio-Based Flame Retardant Agricultural Waste Bagasse/Epoxy Composites.

In the study, agricultural waste bagasse was used as a bio-based flame retardant for reducing the flammability of epoxy. Specifically, an interpenetrating network (IPN) was formed through a ring opening reaction between the hydroxyl functional group of bagasse and the epoxy group of triglycidyl isocyanurate (TGIC), forming Bagasse@TGIC. Next, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) was mixed with Bagasse@TGIC, inducing a reaction between the active hydrogen of DOPO and the epoxy group of TGIC, ultimately forming Bagasse@TGIC@DOPO with an IPN structure. Finally, the novel flame retardant was added to epoxy to create a composite. The integral procedural decomposition temperature (IPDT) of pure epoxy is 619 °C; after the introduction of the 30 wt% flame retardant, the IPDT of the resultant composite material increased to 799 °C, greatly increasing the thermal stability by 29%. After the addition of the Bagasse@TGIC@DOPO flame retardant, the limiting oxygen index increased from 21% for the pure epoxy to 29% for the composite, and the UL-94 rating improved from failing rating for the pure epoxy and V-0 rating for the composite. The Raman spectrum indicated that the addition of Bagasse@TGIC@DOPO IPN substantially increased the biochar yield during the burning process, increasing thermal stability. These results confirmed that the epoxy/Bagasse@TGIC@DOPO composite had substantial flame retarding effects.

A Study on Circular Economy Material Using Fish Scales as a Natural Flame Retardant and the Properties of Its Composite Materials

Fish scales (FSs) are fishery wastes that can cause environmental pollution. This study aimed to solve this environmental problem. FSs were used as a flame retardant for polymer materials, making them valuable. Fish scales were combined with a commercial flame retardant, ammonium polyphosphate (APP), through synergistic effects to reduce the amount of commercial flame retardant. The use of FSs conforms to the concept of a circular economy and lowers costs by reducing the consumption of APP. Thermogravimetric analysis (TGA), integral procedural decomposition temperature (IPDT), pyrolysis kinetics, limiting oxygen index (LOI), the Underwriters Laboratories 94 (UL94) flammability test, scanning election microscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy were used to determine the thermal properties, flame retardant properties, flame retardant mechanism, char morphology, and composition of the composites. The TGA results indicated that the addition of 40% flame retardant raised the char residue from 16.45 wt.% (pure EP) to 36.07 wt.%; IPDT from 685.6 °C (pure EP) to 1143.1°C; LOI from 21% (pure EP) to 30%; and UL94 classification from fail (pure EP) to V-0. These results suggest an increase in char residue, which indicates better protection of the polymer matrix material. The improvements in IPDT, LOI, and UL94 classification, which indicate greater thermal stability, lower flammability (from flammable to fireproof), and higher flammability rating (from fail to V-0), respectively, suggest that the composite material has favorable thermal properties and is less inflammable.

Short alkyl chain length ionic liquid as organic modifier in polypropylene/clay nanocomposite: a thermal comparative study

The most common polymeric nanocomposites are constituted of organically-modified clays. Generally, these organic modifiers are based on quaternary ammonium salts. These systems have as disadvantage the low thermal resistance of its modifiers under processing. Ionic liquids (IL) with different molecular structures can be used as organic modifier in lamellar clays-based polymeric nanocomposites, being promising not only to increase interactions between the nanoclay and the matrix, but also to increase the thermal resistance. In this study, polypropylene-based/montmorillonite nanocomposites were compared from two different organic modifiers. The use of short alkyl chain length imidazolium-based IL as montmorillonite modifier was investigated in terms of the thermal stability when compared to the usual quaternary ammonium salt surfactant. Integral procedure decomposition temperature was employed to determine the effect of these two different organoclay modifiers in PP-nanocomposites. The activation energy for these samples was calculated using Flynn–Wall–Ozawa (FWO) method. It was also used the multiple linear regression analysis to calculate the activation energy in order to evaluate the accuracy of this method when applied to nanocomposites.Article HighlightsShort length alkyl group in ionic liquid was able to improve the thermal stability of PP-based nanocomposite.IPDT methodology is more realistic to evaluate the thermal stability of ionic liquid-based nanocomposite.MLR methodology was efficient to assess the entropic contribution associated to polymer-clay interactions, inter-lamellae spaces and interface morphology.

Preparation, characterization and testing of flame retardant cotton cellulose material: flame retardancy, thermal stability and flame-retardant mechanism

It is significant to treat cotton fabrics with flame retardant, which can effectively protect them from damage in the fire. A novel reactive flame retardant coating, ammonium salt of N,N-dimethylene-piperazine-(methylphosphonic acid) (ASNDP), was prepared and employed to enhance the anti-burning effect of pure cotton fabrics. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectrum were used to analyze the chemical composition of the synthesized ASNDP. The combustion behavior and anti-burning performance of coated cotton fabrics were fully investigated with using cone calorimetry test, limited oxygen index (LOI) test and vertical flammability test. The total heat release value of the sample coated with ASNDP (450 g/L) decreased to 3.7 ± 0.1 MJ/m2 and the LOI value of the sample with a weight gain of 17.4 ± 0.3% raised to 29.5 ± 0.1%. The thermal and thermo-oxidative stability of coated cotton fabrics were researched with thermogravimetric analysis. The integral procedural decomposition temperature (IPDT) value of coated cotton fabrics in nitrogen atmosphere increased from 610.1 to 1402.8 °C, which proved that ASNDP inhibited the thermal degradation of fiber unit by promoting the growth of the char layer. Besides, the morphological structure of uncoated and coated samples before and after combustion was characterized by scanning electron microscopy. It can be observed that the fiber skeleton of the coated cotton fabrics was evenly distributed and remained intact after combustion. The conclusion was that ASNDP endowed cotton fabrics with good flame retardancy, and effectively performed the flame-retardant effect in both gas phase and the condensed phase. A novel phosphorus–nitrogen synergistic flame retardant containing multiple reactive groups was successfully synthesized and applied to improve the flame retardancy and thermal stability of pure cotton fabrics.

Comparative isoconversional thermal analysis of Artemisia vulgaris hydrogel and its acetates; a potential matrix for sustained drug delivery

Artemisia vulgaris hydrogel (AVH) was acetylated (AAVH) and characterized by FTIR, CP/MAS 13C-NMR spectroscopic techniques and thermogravimetric analysis. Flynn–Waal–Ozawa model was used to investigate thermal degradation kinetics. Energy of activation (Ea) values of first and major thermal degradation steps were found to be 128.14 and 116.85 kJmol−1 for AVH and AAVH, respectively. Thermodynamic triplet, order of degradation reaction, integral procedural decomposition temperature (IPDT) and comprehensive index of intrinsic thermal stability (ITS) were also taken into account. In vitro caffeine release from AVH-based matrix tablets indicates potential of AVH for the development of oral delivery systems for sustained drug release.

Novel biocompatible and antimicrobial supramolecular O-carboxymethyl chitosan biguanidine/zinc physical hydrogels

Zinc crosslinked supramolecular hydrogels from O-carboxymethyl chitosan biguanidine were successfully prepared. The structures of the prepared hydrogels were verified by 1H NMR, FTIR and XRD. FE-SEM verified the porous structure of hydrogels especially at high contents of Zn2+ ions. The integral procedure decomposition temperatures calculated from TGA curves showed that the thermal stability was increased upon increasing the content of Zn2+ ions. Cytotoxicity assays confirmed that the amounts of Zn2+ ions released from hydrogels were below the toxic level towards a breast cancer cell line (MCF-7). The prepared hydrogels exhibited a significant microbial inhibition towards different species of bacteria and fungi, particularly at high Zn contents. Based on the obtained interesting data, the prepared zinc/O-carboxymethyl chitosan biguanidine could be used in drug delivery and biomedical applications.

Structural and Thermal Characterization of Castor Oil Based Unsaturated Polyester Resin

In the present study, unsaturated polyester resins based on castor oil was synthesized. Structure elucidation of the synthesized unsaturated polyester resin was done by FTIR and 1H NMR spectroscopy. Thermogravimetric analysis was used to evaluate the thermal stability of cured unsaturated polyester resin. Thermogram plot was further utilized to calculate various other parameters such as statistic heat-resistant index (Ts) and the integral procedural decomposition temperature (IPDT). Comparable properties with respect to commercial resins were reported for the synthesized polymers

Magnetic, Thermal and Electrical Transport Properties of o-Substituted Polyanilines Encapsulated with Fe2O3 Nanoparticles

Poly(2-nitroaniline), poly(2-nitroaniline)-Fe2O3 and poly(2-methylaniline)-Fe2O3 nanocomposites synthesized by in situ chemical oxidative polymerization technique were characterized by XRD, thermal (TGA and DTA) and FTIR & UV-visible spectroscopic techniques. The thermal stability was confirmed by the integral procedural decomposition temperature (IPDT) and oxidation index (OI) calculations. The electrical conductivity and dielectric properties were also investigated. At low frequency region, the dielectric constant decreases with increase in frequency due to electrical relaxation process. At high frequencies, dielectric constant is independent of frequency. At low frequency, there was strong frequency dispersion of permittivity and above 3 Hz, a frequency independent behaviour in permittivity was observed. The materials exhibit ferromagnetic behaviour.

Effect of silanized sisal fiber on thermo-mechanical properties of reinforced epoxy composites

An effective method was adopted to improve the thermo-mechanical properties of the epoxy composite by functionalization of the sisal fiber. Initially, a neat sisal fiber was acetylated with molar solution of acidic mixture (0.5:1 of HNO3:H2SO4) that removed the content of lignin and hemicellulose and increased the crystallinity of the sisal fiber. The acetylated sisal ( a-sisal) fiber was further treated with 3-aminpropyltriethoxy silane to graft the silanol moieties on sisal fiber. The functionalization of the sisal fiber with 3-aminpropyltriethoxy silane exhibits the strong interaction with epoxy, resulting in homogenous dispersion of the sisal fiber in epoxy. The composite possesses great enhancement in thermal and mechanical properties. The tensile strength in functionalized sisal epoxy composite ( CP-f-Sisal) was significantly enhanced up to 23% in comparison to non-functionalized sisal epoxy composite ( CP-n-Sisal) by adding 15 wt.% of the sisal fiber. In addition, the functionalized sisal epoxy composite ( CP-f-sisal) shows better thermal stability as compared to non-functionalized sisal epoxy composite ( CP-n-sisal). Similar results are attributed by investigating the kinetics of thermal stability parameters that include activation energy and integral procedure decomposition temperature.

A novel strategy for enhancing the flame resistance, dynamic mechanical and the thermal degradation properties of epoxy nanocomposites

In this study, aiming at improving the flame resistance of bisphenol-A epoxy resin (EP), a novel self-assembled montmorillonite-multiwalled carbon nanotube (MMT-MWCNT) was designed and prepared by using triethylenetetramine (TETA) as grafting agent. The chemical component, structure and morphology of the MMT-MWCNT and its corresponding EP nanocomposites were well characterized. It was disclosed that the MMT was intercalated or exfoliated by the grafted MWCNT, and the MWCNT could be better distributed with the presence of MMT as well. The flame resistance analysis revealed that as compared with the pure EP, the peaks of heat release rate (HRR), smoke production rate (SPR) and carbon monoxide release rate (CORR) of EP/MMT-MWCNT decreased by 7.4%, 26.3% and 13.9%, respectively. The time to ignition (TTI) of EP nanocomposites showed increase compared to pure EP, especially for EP/MMT-MWCNT with an increase by 65.9%. The activation energy (Ea) and the integral procedural decomposition temperature (IPDT) of the EP/MMT-MWCNT based on TGA were found to be 9.7% and 14.1% higher than those of EP, respectively. Furthermore, the EP/MMT-MWCNT exhibited superior mechanical performance against the EP, that is the storage modulus and loss factor of EP/MMT-MWCNT were increased by 21.5% and decreased by 34.2%, respectively. This novel self-assembled MMT-MWCNT performed advantage over simply mixing MMT and MWCNT in enhancing the flame resistance, dynamic mechanical and the thermal degradation properties of EP.