Differential Thermogravimetric Analysis Research Articles

Repercussion of Fiber Content on the Mechanical, Thermal, and Thermomechanical Properties of Natural Fibers Reinforced Thermoplastic Composites for Automotive Application

Abstract Natural fibers are becoming very popular as a reinforcement in composite materials owing to their benefits, such as low-price, lightweight, availability, and environmental friendliness. In this study, abaca fiber-reinforced polypropylene (PP) and high-density polyethylene (HDPE) composites were created with the help of the injection molding method. Prior to composite fabrication, abaca fibers were chemically treated with a 5 wt.% caustic soda (NaOH) solution to improve the bonding between the abaca fibers and the matrix and to enhance their properties. Scanning electron microscopy (SEM) was utilized to assess the fiber surface microstructures before as well as after the chemical treatment, along with the fractured surfaces of tensile specimens. The mechanical properties, such as tensile, bending, and impact strength, of abaca/PP and abaca/HDPE composites were evaluated and compared. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods were utilized to investigate the thermal behaviour of composites. Also, the dynamic mechanical analysis (DMA) method was utilized to explore the thermomechanical properties of the fabricated composites. The outcomes of the experimental findings showed that abaca/PP composite with 10 and 20 wt.% fibers is the best choice of material to be used in the automobile industry.

Biobased polymer nanocomposites prepared by in situ polymerization: comparison between carbon and mineral nanofillers

AbstractTwo series based on poly(propylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PPF-b-F-PTMO) containing carbon and mineral nanofillers that differ in shape (1D and 2D) were synthesized via in situ polymerization. The influence of the addition of the 1D-type nanoparticle, i.e., carbon nanofibers (CNFs) and halloysite nanotubes (HNTs), and the so-called 2D-type, i.e., graphene nanoplatelets (GNPs) and organoclay (C20A), on the properties of a biobased block copolymer was analyzed. The dispersion of nanoadditives in the nanocomposites was determined using a scanning electron microscope (SEM). The thermal properties were studied employing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The introduction of nanoparticles increased the crystallinity (Xc) and the mean values of tensile modulus (E) of the bionanocomposites. In turn, one observed that the decrease in the limited viscosity number (LVN) was visible along with incorporating nanoadditives. The synthesized polymer bionanocomposites reveal the mechanical properties of elastomers during mechanical testing. Moreover, the good processability of the obtained materials by injection molding combined with the comprehensive ability to change mechanical and thermal properties of PPF-b-F-PTMO by tailoring the type and content of the nanofillers can indicate their possible applications in packaging, automotive, sports, construction, and many other industries.

LDH-Indomethacin Nanoparticles Antitumoral Action: A Possible Coadjuvant Drug for Cancer Therapy

Indomethacin (INDO) has a mechanism of action based on inhibiting fatty acids cyclooxygenase activity within the inflammation process. The action mechanism could be correlated with possible anticancer activity, but its high toxicity in normal tissues has made therapy difficult. By the coprecipitation method, the drug carried in a layered double hydroxides (LDH) hybrid matrix would reduce its undesired effects by promoting chemotherapeutic redirection. Therefore, different samples containing INDO intercalated in LDH were synthesized at temperatures of 50, 70, and 90 °C and synthesis times of 8, 16, 24, and 48 h, seeking the best structural organization. X-ray diffraction (XRD), vibrational Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), spectrophotometric analysis in UV-VIS, and differential thermogravimetric analysis (TGA/DTA) were used for characterization. Our results indicate that higher temperatures and longer synthesis time through coprecipitation reduce the possibility of INDO intercalation. However, it was possible to establish a time of 16 h and a temperature of 50 °C as the best conditions for intercalation. In vitro results confirmed the cell viability potential and anticancer activity in the LDH-INDO sample (16 h and 50 °C) for gastric cancer (AGP01, ACP02, and ACP03), breast cancer (MDA-MB-231 and MCF-7), melanoma (SK-MEL-19), lung fibroblast (MRC-5), and non-neoplastic gastric tissue (MN01) by MTT assay. Cell proliferation was inhibited, demonstrating higher and lower toxicity against MDA-MB-231 and SK-MEL-19. Thus, a clinical redirection of INDO is suggested as an integral and adjunctive anticancer medication in chemotherapy treatment.

3D Confinement Stabilizes the Metastable Amorphous State of Antimony Nanoparticles - A New Material for Miniaturized Phase Change Memories?

The wet-chemical synthesis of 3D confined antimony nanoparticles (Sb-NP) at low and high temperatures is described. Using reaction conditions that are mild in temperature and strong in reducing power allows the synthesis of amorphous Sb-NP stabilized with organic ligands. Exchanging the organic ligand 1-octanethiol by iodide enabled to investigate the unusual strong stability of this metastable material through simultaneous thermal analysis combining differential scanning calorimetry and thermogravimetric analysis. Additionally, in situ high temperature powder x-ray diffraction (p-XRD) shows a significant increase in stabilization of the amorphous phase in comparison to thin layered, 1D confined Sb or bulk material. Further, it is shown with scattering-type scanning near-field optical microscopy (s-SNOM) experiments that the optical response of the different phases in Sb-NP make the distinctness of each phase possible. It is proposed that the Sb-NP introduced here can serve as a 3D-confined optically addressable nanomaterial of miniaturized phase change memory devices.

Optimising thermochemical energy storage: a comprehensive analysis of CaCO3 composites with CaSiO3, CaTiO3, and CaZrO3.

With the increasing amount of renewable energy produced, many governments and industries are pushing for the installation of battery energy storage system (BESS) solutions. Thermal batteries are systems that store heat made from various energy sources, and can be used to produce electricity upon demand. These systems are easily scalable and can be installed in cities, homes and remote locations. Thermochemical energy storage (TCES) uses the enthalpy of a chemical reaction to store and release heat through endothermic and exothermic processes, respectively. CaCO3 has been identified as an ideal TCES material as it is cheap and abundant, but maximising long-term cyclability is key to ensure battery longevity. This article investigates the addition of CaSiO3, CaTiO3 and CaZrO3 to CaCO3 in a 1 : 1 ratio to ascertain the reaction properties and cyclic capacity over time. Cycling longevity and thermodynamic properties were determined using simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC-TGA) along with the Sieverts technique, and their reaction pathway studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The low cost of the CaCO3-CaSiO3 material of $1.8 USD per kW hth suggests that if a suitable particle refinement agent were to be employed to ensure cycling longevity this material would be an excellent TCES material. Despite the CO2 cycling capacity of the CaCO3-CaZrO3 system only reducing by 16 wt% over 100 cycles, the cost of ZrO2 brings the materials cost to $30.9 USD per kW hth, making this material currently unsuitable for application. The CaCO3-CaTiO3 system showed only a 17% drop in total CO2 uptake over 100 cycles, although the cost was $11.1 USD per kW hth.

A new nanocomposite membrane based on sulfonated polysulfone boron nitride for proton exchange membrane fuel cells: Its fabrication and characterization

Sulfonated polysulfone (SPSf) polymer is an alternative raw material in producing commercially used proton exchange membranes. On the other hand, hexagonal boron nitride (hBN) is one of the additives of interest for nanocomposite PEMs. In this study, nanocomposite membranes is fabricated and characterized with SPSf and hBN nanoparticles. The degree of sulfonation of the sulfonated polysulfone is determined by titration, and sulfonic acid bonds are investigated by Proton Nuclear Magnetic Resonance (1H NMR) analysis. SPSf is dissolved with dichloromethane, and hBN nanoparticles are added. After homogenizing the prepared solution with magnetic and ultrasonic stirrers, membranes are formed using Dr. Blade. 1H NMR, Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffractometer (XRD), and Thermogravimetric Analysis (TGA) analysis are examined the morphological, thermal, and organic compound structures of the membranes. Water uptake capacity, swelling ratio, proton conductivity, oxidative resistance, and mechanical properties of the membranes are determined. The highest water uptake capacity is obtained as 40.08 % in the membrane named SPSf-3 %hBN. Using hBN additive improved swelling ratio and thermal and mechanical strength properties. The proton conductivity values of polysulfone (PSf), SPSf, SPSf-1 %hBN, SPSf-2 %hBN, and SPSf-3 %hBN membranes are determined as 2.89, 6.84, 3.57, 10.8 and 5.12 mS cm−1, respectively. As a result of the analysis, it is observed that the nanocomposite membrane structure has both amorphous and crystalline homogeneous structure.

A novel chemical pre-pyrolysis treatment of waste tyre crumbs: A viable way for low temperature waste tyre pyrolysis

Pyrolysis of tyres is a process that consumes non-renewable energy resources, and is characterised by the requirement of a significant amount of energy. For example, natural rubber and styrene-butadiene rubber require 300–350 °C and 400–450 °C, respectively, to decompose under inert nitrogen conditions. The current study aims, firstly, to reduce the temperature typically used for waste tyre crumbs pyrolysis to minimise the energy requirement of the process as well as to improve the quality of the liquid fraction of the pyrolysis product, tyre derived oil (TDO). Before pyrolysis, waste tyre crumbs were first treated with a mixture of chemicals, dried and then pyrolysed using a 40 g vertical fixed bed reactor. The results acquired from the ultimate analyser for the CHNS illustrated a decrease in carbon from 80.6 % to 57.2 % and an increment in nitrogen (from 0.4 % to 6.5 %) and oxygen (from 9.7 % to 30.2 %) in the treated tyre crumbs. FTIR results indicated that oxidation took place in the treated sample by displaying the presence of oxygenated functional groups in the spectrum, which agreed with CHNS results. The temperature was reduced drastically from a minimum of 400 °C to a minimum of 100 °C for pyrolysis, and therefore, resulting in a lower initial/starting pyrolysis temperature range of 100–115 °C. In addition, approximately 87 wt% pyrolysis yield was obtained out of 60 % pyrolysable substances in a tyre at the final temperature of 280 °C. The differential thermogravimetric analyser (DTA) was used to confirm the extent to which pyrolysis experiments took place in the feedstock by analysing the char after pyrolysis. The current study is set to improve the pyrolysis of waste tyre crumbs by significantly reducing the temperature and time of the process, which lowers the operation cost required for the tyre crumbs’ pyrolysis process.

Preparation and Screening of SRB Gel Particles Used for Deep Purification of Acid Mine Drainage

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to contaminated anaerobic environments. The research focused on elucidating the physiological characteristics and optimal growth conditions of SRB, particularly in relation to the pH level and temperature. The experimental findings reveal that the SRB exhibited a sulfate removal rate of 88.86% at an optimal temperature of 30 °C. Additionally, SRB gel particles were formulated using sodium alginate (SA) and carboxymethyl cellulose (CMC), and their performance was assessed under specific conditions (pH = 6, C/S = 1.5, T = 30 °C, CMC = 4.5%, BSNa = 0.4 mol/L, and cross-linking time = 9 h). Under these conditions, the SRB gel particles demonstrated an enhanced sulfate removal efficiency of 91.6%. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) provided further insights into the stability and properties of the SRB gel spheres. The findings underscore the potential of SRB-based bioremediation as a sustainable and efficient method for AMD treatment, offering a novel and environmentally friendly solution to mitigating the adverse effects of environmental contamination.

Core-Tunable Dendritic Polymer: A Folate-Guided Theranostic Nanoplatform for Drug Delivery Applications.

Clinical application of anticancer drugs is mostly limited due to their hydrophobic nature, which often results in lower bioavailability and lesser retention in systemic circulation. Despite extensive research on the development of targeted drug delivery systems for cancer treatment, delivery of hydrophobic therapeutic drugs to tumor cells remains a major challenge in the field. To address these concerns, we have precisely engineered a new hyperbranched polymer for the targeted delivery of hydrophobic drugs by using a malonic acid-based A2B monomer and 1,6-hexanediol. The choice of monomer systems in our design allows for the formation of higher molecular weight polymers with hydrophobic cavities for the efficient encapsulation of therapeutic drugs that exhibit poor water solubility. Using several experimental techniques such as NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform-infrared (FT-IR), and gel permeation chromatography (GPC), the synthesized polymer was characterized, which indicated its dendritic structure, thermal stability, and amorphous nature, making it suitable as a drug delivery system. Following characterizations, theranostic nanoplatforms were formulated using a one-pot solvent diffusion method to coencapsulate hydrophobic drugs, BQU57 and doxorubicin. To achieve targeted delivery of loaded therapeutic drugs in A549 cancer cells, the surface of the polymeric nanoparticle was conjugated with folic acid. The therapeutic efficacy of the delivery system was determined by various cell-based in vitro experiments, including cytotoxicity, cell internalizations, reactive oxygen species (ROS), apoptosis, migration, and comet assays. Overall, findings from this study indicate that the synthesized dendritic polymer is a promising carrier for hydrophobic anticancer drugs with higher biocompatibility, stability, and therapeutic efficacy for applications in cancer therapy.

Preparation and Screening of SRB Gel Particles Used for Deep Purification of Acid Mine Drainage.

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to contaminated anaerobic environments. The research focused on elucidating the physiological characteristics and optimal growth conditions of SRB, particularly in relation to the pH level and temperature. The experimental findings reveal that the SRB exhibited a sulfate removal rate of 88.86% at an optimal temperature of 30 °C. Additionally, SRB gel particles were formulated using sodium alginate (SA) and carboxymethyl cellulose (CMC), and their performance was assessed under specific conditions (pH = 6, C/S = 1.5, T = 30 °C, CMC = 4.5%, BSNa = 0.4 mol/L, and cross-linking time = 9 h). Under these conditions, the SRB gel particles demonstrated an enhanced sulfate removal efficiency of 91.6%. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) provided further insights into the stability and properties of the SRB gel spheres. The findings underscore the potential of SRB-based bioremediation as a sustainable and efficient method for AMD treatment, offering a novel and environmentally friendly solution to mitigating the adverse effects of environmental contamination.

Developing nanocellulose-loaded chitosan–polylactic acid biofilms for green food packaging

The food industry is considered one of the main contributors to plastic waste due to packaging. Sustainable and degradable packaging solutions are the need of the hour. Biopolymers have proved to be a promising replacement for petroleum-based polymers. The main reason is their various intrinsic properties, such as antimicrobial nature and degradability. The main objective of this study was to develop chitosan/nanocrystalline cellulose- and polylactic acid-based biofilms. The biofilms were developed using the drop-casting method. The developed biofilms were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. The performance of the biofilms was checked using mechanical, water solubility, porosity, antioxidant and antibacterial activity tests. The developed biofilms can solve the issues of environmental pollution being faced by the food packaging industry.

THE EFFECT OF BARRIER TECHNOLOGIES ON THE CHEMICAL, NUTRITIONAL, SENSORY, AND MICROBIOLOGICAL QUALITY OF ARBUTUS UNEDO L. FRUITS DURING STORAGE

Arbutus unedo L. is a widespread tree known for its nutritional and antioxidant importance. However, the utilization of its berries remains limited due to their sensitivity and damage during storage. This study aims to evaluate the effect of barrier technologies with the addition of lemon juice (Citrus limon) and bitter orange juice (Citrus aurantium) as additives on the sensory, nutritional, and microbiological quality of fruits during storage. The combined fruits exhibited a significant decrease in pH (from 5.07±0.23 to 3.45±0.34 for fruits combined with bitter orange juice and from 5.07±0.23 to 3.64±0.12 for fruits combined with lemon juice), moisture content (from 62.48±2.32 to 45.47±3.54 for fruits combined with bitter orange juice and from 62.48±2.32 to 51.4±3.12 for fruits combined with lemon juice), and showed inactivation of aerobic mesophilic bacteria compared to non-treated fruits. Differential thermogravimetric analysis (DTG, DSC) demonstrated that fruits conditioned in the presence of bitter orange juice preserved their nutritional quality (vitamins B2, B6, B9, B12, and C) under light and oxygen exposure. The combination of acidity and sweetness improved the sensory quality of the combined fruits during storage.

THE EFFECT OF BARRIER TECHNOLOGIES ON THE CHEMICAL, NUTRITIONAL, SENSORY, AND MICROBIOLOGICAL QUALITY OF ARBUTUS UNEDO L. FRUITS DURING STORAGE

Arbutus unedo L. is a widespread tree known for its nutritional and antioxidant importance. However, the utilization of its berries remains limited due to their sensitivity and damage during storage. This study aims to evaluate the effect of barrier technologies with the addition of lemon juice (Citrus limon) and bitter orange juice (Citrus aurantium) as additives on the sensory, nutritional, and microbiological quality of fruits during storage. The combined fruits exhibited a significant decrease in pH (from 5.07±0.23 to 3.45±0.34 for fruits combined with bitter orange juice and from 5.07±0.23 to 3.64±0.12 for fruits combined with lemon juice), moisture content (from 62.48±2.32 to 45.47±3.54 for fruits combined with bitter orange juice and from 62.48±2.32 to 51.4±3.12 for fruits combined with lemon juice), and showed inactivation of aerobic mesophilic bacteria compared to non-treated fruits. Differential thermogravimetric analysis (DTG, DSC) demonstrated that fruits conditioned in the presence of bitter orange juice preserved their nutritional quality (vitamins B2, B6, B9, B12, and C) under light and oxygen exposure. The combination of acidity and sweetness improved the sensory quality of the combined fruits during storage.

Bio-Based Polyurethane Networks Containing Sunflower Oil Based Polyols.

This work focused on the preparation and investigation of polyurethane (SO-PU)-containing sunflower oil glycerides. By transesterification of sunflower oil with glycerol, we synthesized a glyceride mixture with an equilibrium composition, which was used as a new diol component in polyurethanes in addition to poly(ε-caprolactone)diol (PCLD2000). The structure of the glyceride mixture was characterized by physicochemical methods, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), nuclear magnetic resonance spectroscopy (NMR), and size exclusion chromatography (SEC) measurements. The synthesis of polyurethanes was performed in two steps: first the prepolymer with the isocyanate end was synthesized, followed by crosslinking with an additional amount of diisocyanate. For the synthesis of the prepolymer, 4,4'-methylene diphenyl diisocyanate (MDI) or 1,6-hexamethylene diisocyanate (HDI) were used as isocyanate components, while the crosslinking was carried out using an additional amount of MDI or HDI. The obtained SO-PU flexible polymer films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The so-obtained flexible SO-PU films were proved to be suitable for the preparation of potentially biocompatible and/or biodegradable scaffolds. In addition, the stress versus strain curves for the SO-PU polymers were interpreted in terms of a mechanical model, taking into account the yield and the strain hardening.

Effect of immediate curing at elevated temperatures on the tensile and interfacial properties of carbon fiber-epoxy composites

Elevated temperature conditions known to improve curing from the onset and during the process of immediate curing are not available in the field, which can hinder the mechanical performance of these strengthening systems. In this study, mechanical testing and material characterization were conducted to identify the effects of subjecting nanomodified epoxy and fiber-reinforced nanomodified epoxy composites to room temperature (RT) (30 °C) and elevated temperature (110 °C) from the onset of curing. Static tensile testing and interfacial adhesion tests were conducted to evaluate the mechanical performance. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed to determine curing characteristics to inform on the immediate curing of nanomodified resins cured under the two temperature conditions. Scanning electron microscopy was performed to identify Carbon nanotube (CNT) dispersion characteristics. Overall, due to the incorporation of CNTs in epoxy, RT curing results in upto 62% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, a 51% increase in strength and 42% increase in Youngs Modulus can be observed in the nanomodified epoxy. In CFRP-epoxy composites, due to the incorporation of CNTs in the epoxy, RT curing results in upto 27% increase in strain at failure. By supplying additional energy during immediate curing with elevated temperatures, upto 133% increase in strain at failure is observed and upto 17% increase in strength is observed. CNTs incorporated in CFRP-epoxy composites demonstrated upto 50% increase in interfacial adhesion whereas supplying additional energy for their immediate curing with elevated temperatures, upto 130% increase in interfacial adhesion was observed. TGA and DSC results supported the mechanical observations and show a need for immediate curing when CNTs are used in epoxy matrices.

Chitin Nanocomposites for Fused Filament Fabrication: Flexible Materials with Enhanced Interlayer Adhesion.

In this work, we present a series of nanocomposites for Fused filament fabrication (FFF) based on polycaprolactone (PCL) and chitin nanocrystals (ChNCs). The ChNCs were synthesized by acid hydrolysis using HCl or lactic acid (LA). The approach using LA, an organic acid, makes the ChNCs synthesis more sustainable and modifies their surface with lactate groups, increasing their compatibility with the PCL matrix. The ChNCs characterization by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that both ChNCs presented similar morphologies and crystallinity, while differential scanning calorimetry and thermogravimetric analysis proved that they can bear temperatures up to 210 °C without degrading, which allows their processing in the manufacturing of PCL composites by twin-screw extrusion. Therefore, PCL composites in the form of filaments containing 0.5-1.0 wt % ChNCs were produced and used as feedstock in FFF, and standard tensile and flexural specimens were printed at different temperatures, up to 170 °C, to assess the influence of the ChNCs in the mechanical properties of the material. The tensile testing results showed that the presence of ChNCs enhances the strength and ductility of the PCL matrix, increasing the elongation at break around 20-50%. Moreover, the vertically printed flexural specimens showed a very different bending behavior, such that the pure PCL specimens presented a brittle fracture at 7% strain, while the ChNCs composites were able to bend over themselves. Hence, this work proves that the presence of ChNCs aims to improve the interlayer adhesion of the objects manufactured by FFF due to their good adhesive properties, which is currently a concern for the scientific community and the industrial sector.

Silica extraction from sodium silicate for wollastonite synthesis at low temperatures

In this study, ceramic wollastonite was prepared at low temperatures by using amorphous silica and calcium oxide powders. The amorphous silica was extracted from sodium silicate, while calcium oxide (CaO) was obtained through the calcination of calcium carbonate (CaCO3) particles. The effect of reaction temperature on the formation of wollastonite was systematically investigated. The synthesized powders were analyzed using various characterization techniques, including X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results indicate that the synthesized silica nanopowders exhibit a notable surface area, with specific surface area (SSA) values reaching 148 m²/g for samples subjected to calcination at 600°C. Furthermore, based on XRD and differential scanning calorimetry (DSC) analyses, it is evident that β-CaSiO3 forms at approximately 780°C and subsequently undergoes complete transformation into α-CaSiO3 at 1200°C. Notably, this study underscores that the utilization of amorphous silica expedites wollastonite formation at lower temperatures compared to those reported in existing literature.

Characterization and In-vitro Study of Polyethylene Glycol as Coating Material used as Drug Carriers on Coronary Stent for Treatment of Cardiac Diseases

Background: The way coronary artery disease is treated has changed dramatically with the use of coronary angioplasty and stenting. Nowadays, acute coronary syndromes brought on by coronary artery disease are frequently treated using drug-eluting stents. A review of the literature reveals that the polymer coating’s thickness affects the stent’s safety; moreover, current computational studies suggest that larger coatings increase the risk of stent deformity. Polyethylene glycol is the preferred polymer coating material for coronary artery stents.Objectives: Characterization of polyethylene glycol as a medication carrier coating for coronary stents used in cardiac disease therapyMethods: Using UV-visible spectrophotometer, differential scanning calorimetry (DSC), fourier-transform infrared (FTIR), X-ray diffraction, thermogravimetric analysis, and surface morphology, polyethylene glycol was characterized.Results: The calibration curves’ linear regression results, as revealed by the UV-visible spectrophotometer investigation, showed a significant linear association between the concentration range of 10 to 60 μg/mL for polyethylene glycol Y = 0.0354X + 0.0212 (r2 = 0.999), was found. Polyethylene glycol’s molecular miscibility, recrystallization, and phase separation were investigated using a DSC analysis. It was found that the material was physically stable because no recrystallization peaks were visible. According to the results of the thermogravimetric study, a ceramic sample cup with 4 to 6 mg of sample was heated to 400°C at a rate of 5°C every minute. Nitrogen gas was continuously supplied at a rate of 20 mL/min into the sample chamber during the analysis. The results of each batch were measured, and an average was determined. The study of surface coatings to examine the microstructure of the coatings produced both before and after the use of polymers is known as surface morphology. Within analytical imaging is the subset of surface morphology. Pure polyethylene glycol’s morphology showed broad plate-shaped structures. Additionally, a strong band is detected between 1362 and 1287 cm-1, which is comparable to the C-O stretching vibration seen in primary alcohol.Conclusion: On base of the characterization results above shows that polymers were stable and included functional groups and structures throughout a range of conditions. It is possible to use polyethylene glycol as a coating material for coronary stents.

On Tautomerism and Amphoterism: An In-Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts.

Ammeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single-crystal X-ray diffraction. In this structure, ammeline is exclusively found as its 4,6‑diamino-1,3,5-triazin-2(1H)-one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products' thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high-energy-density materials.

On Tautomerism and Amphoterism: An In‐Depth Structural and Physicochemical Characterization of Ammeline and Some of Its Salts

AbstractAmmeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single‐crystal X‐ray diffraction. In this structure, ammeline is exclusively found as its 4,6‐diamino‐1,3,5‐triazin‐2(1H)‐one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products’ thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high‐energy‐density materials.