Differential Scanning Calorimetry Research Articles

"Dissolve-on-Demand" 3D Printed Materials: Polymerizable Eutectics for Generating High Modulus, Thermoresponsive and Photoswitchable Eutectogels.

Solvent-free photopolymerization of vinyl monomers to produce high modulus materials with applications in 3D printing and photoswitchable materials is demonstrated. Polymerizable eutectic (PE) mixtures are prepared by simply heating and stirring various molar ratios of N-isopropylacrylamide (NIPAM), acrylamide (AAm) and 2-hydroxyethyl methacrylate (HEMA). The structural and thermal properties of the resulting mixtures are evaluated by 1D and 2D NMR spectroscopy as well as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). UV photocuring kinetics of the PE mixtures are evaluated via in situ photo-DSC and photorheology measurements. The PE mixtures cure rapidly and display storage moduli that are orders of magnitude greater than equivalent copolymers cured in an aqueous medium. The versatility of these PE systems is demonstrated through the addition of a photoswitchable spiropyran acrylate monomer, as well as applying the PE formulation as a stereolithography (SLA)-based 3D printing resin. Due to the hydrogen-bonding network in PE systems, 3D printing of the eutectic resin is possible in the absence of crosslinkers. The addition of a RAFT agent to reduce average polymer chain length enables 3D printing of materials which retain their shape and can be dissolved on demand in appropriate solvents. This article is protected by copyright. All rights reserved.

Thermal behavior of Sicilian clay-based geopolymers

AbstractGeopolymers have been recently proposed for restoration of built heritage to substitute traditional mortars. Local materials and industrial wastes from the Italian region Sicily showed their potential as low-cost aluminosilicate sources for the preparation of geopolymers. Here, a set of Sicilian clays was studied by Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), and its mineralogical composition was evaluated by X-ray diffraction (XRD). The raw materials were used to prepare geopolymers by alkaline activation with or without the addition of silicate. The thermal degradation profile of the final materials was studied by TGA and compared with that of the precursors, and the energetics of dehydration were investigated by DSC. Two statistical analyses (made by Principal Component Analysis) were performed on the TG data of raw materials and geopolymers and on the TG data of geopolymers and their mineralogical composition, respectively. The last analysis in particular showed a correlation between the mineralogical composition of the materials and the samples' thermal properties. Additional studies of samples subject to accelerated aging by UV irradiation and exposure to acetic acid vapors highlighted the different effects of these two agents on the samples’ stability. Graphical abstract

Comparison of Sucrose and Trehalose for Protein Stabilization Using Differential Scanning Calorimetry.

The disaccharide trehalose is generally acknowledged as a superior stabilizer of proteins and other biomolecules in aqueous environments. Despite many theories aiming to explain this, the stabilization mechanism is still far from being fully understood. This study compares the stabilizing properties of trehalose with those of the structurally similar disaccharide sucrose. The stability has been evaluated for the two proteins, lysozyme and myoglobin, at both low and high temperatures by determining the glass transition temperature, Tg, and the denaturation temperature, Tden. The results show that the sucrose-containing samples exhibit higher Tden than the corresponding trehalose-containing samples, particularly at low water contents. The better stabilizing effect of sucrose at high temperatures may be explained by the fact that sucrose, to a greater extent, binds directly to the protein surface compared to trehalose. Both sugars show Tden elevation with an increasing sugar-to-protein ratio, which allows for a more complete sugar shell around the protein molecules. Finally, no synergistic effects were found by combining trehalose and sucrose. Conclusively, the exact mechanism of protein stabilization may vary with the temperature, as influenced by temperature-dependent interactions between the protein, sugar, and water. This variability can make trehalose to a superior stabilizer under some conditions and sucrose under others.

Symmetrical liquid crystalline dimers containing azo and azomethine linkages: synthesis, characterisation, mesomorphic study and DFT studies

ABSTRACT In the current study, one new series of symmetrical liquid crystalline homologous series of dimers with a rigid aromatic core with azo and azomethine group were synthesized using an ether-linking group. Several spectroscopic methods, including FT-IR, 1H-NMR, 13C-NMR and elemental analysis, were used to describe the synthesised dimers. The differential scanning calorimetry (DSC) and polarised optical microscopy (POM) were used to assess their mesomorphic properties. The results showed that the number of methylene spacers significantly affected the thermal properties of the synthesized dimers. To ascertain photophysical behaviour, UV-visible spectroscopy was employed. All the dimers of the present series show excellent enantiotropic nematic mesophase. The relationships between structure and its mesogenic property, the effects of various flexible spacers, the mesophase ranges, and the photo-isomerization of liquid crystalline dimers were all investigated. DFT study was carried out to gain a better understanding of structural features.

Thermosensitive and mucoadhesive gels containing solid lipid nanoparticles loaded with fluconazole and niosomes loaded with clindamycin for the treatment of periodontal diseases: a laboratory experiment

BackgroundPeriodontal diseases may benefit more from topical treatments with nanoparticles rather than systemic treatments due to advantages such as higher stability and controlled release profile. This study investigated the preparation and characterization of thermosensitive gel formulations containing clindamycin-loaded niosomes and solid lipid nanoparticles (SLNs) loaded with fluconazole (FLZ), as well as their in vitro antibacterial and antifungal effects in the treatment of common microorganisms that cause periodontal diseases.MethodsThis study loaded niosomes and SLNs with clindamycin and FLZ, respectively, and assessed their loading efficiency, particle size, and zeta potential. The particles were characterized using a variety of methods such as differential scanning calorimetry (DSC), dynamic light scattering (DLS), and Transmission Electron Microscopy (TEM). Thermosensitive gels were formulated by combining these particles and their viscosity, gelation temperature, in-vitro release profile, as well as antibacterial and antifungal effects were evaluated.ResultsBoth types of these nanoparticles were found to be spherical (TEM) with a mean particle size of 243.03 nm in niosomes and 171.97 nm in SLNs (DLS), and respective zeta potentials of -23.3 and -15. The loading rate was 98% in niosomes and 51% in SLNs. The release profiles of niosomal formulations were slower than those of the SLNs. Both formulations allowed the release of the drug by first-order kinetic. Additionally, the gel formulation presented a slower release of both drugs compared to niosomes and SLNs suspensions.ConclusionThermosensitive gels containing clindamycin-loaded niosomes and/or FLZ-SLNs were found to effectively fight the periodontitis-causing bacteria and fungi.

Synergistic Effect of PBz/Epoxy/PCLA Composite Films with Improved Thermal Properties

Polybenzoxazines (PBzs) are advanced forms of phenolic resins that possess many attractive properties, including thermally induced self-curing polymerization, which produces void-free polymer products without any by-product formation. They also possess a high Tg (glass transition temperature) and thermal stability, but the produced materials are brittle in nature, due to which the final form of their application is very difficult. Hence, in this paper, an attempt has been made to overcome the brittleness of PBz by blending it with epoxy and ε-caprolactam (CPLA) to produce free-standing PBz/Epoxy/PCLA (polycaprolactam) films. The curing process between the three components (i.e., Bzo, epoxy, and caprolactam) was monitored using differential scanning calorimetric (DSC) analysis. The results show that there is no appreciable shift in curing the exotherm observed, except a slight shift in the curing process. However, the heat liberated during the exotherm (ΔH) decreases drastically from 121 to 84 J/g, indicating that the content of benzoxazine is very important as it is involved in the polymerization process through oxazine ring-opening. The morphological studies analyzed using SEM and AFM analyses indicate that there was no observable phase separation up to 30 wt.% of CPLA loading, whereas a higher CPLA content of 50 wt.% causes agglomeration and leads to distinctive phase separation. Moreover, the thermal stability of the composite film, PBz/Epoxy/PCLA30, is also increased with a 10% degradation temperature, T10, of 438 °C, when compared with an PBz/Epoxy film. From the obtained results, it is evident that the formation of a composite film through the melt blending process could produce a tough and thermally stable film without sacrificing individual properties.

Design and fabrication of 3D-printed gastric floating tablets of captopril: effect of geometry and thermal crosslinking of polymer on floating behavior and drug release

The present study aims to investigate the potential of the 3D printing technique to design gastroretentive floating tablets (GFTs) for modifying the drug release profile of an immediate-release tablet. A 3D-printed floating shell enclosing a captopril tablet was designed having varying number of drug-release windows. The impact of geometrical changes in the design of delivery system and thermal cross-linking of polymers were evaluated to observe the influence on floating ability and drug release. Water uptake, water insolubilization, Differential Scanning Calorimetry (DSC), and Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) were performed to assess the degree of thermal cross-linking of polyvinyl alcohol (PVA) filament. The 3D-printed GFT9 was considered the optimized gastric floating tablet that exhibited >12 h of total floating time with zero floating lag time and successfully accomplished modified-drug release by exhibiting >80% of drug release in 8 h. The zero-order release model, with an r2 value of 0.9923, best fitted the drug release kinetic data of the GFT9, which followed a super case II drug transport mechanism with an n value of 0.95. The optimized gastric floating device (GFT9) also exhibited the highest MDT values (238.55), representing slow drug release from the system due to thermal crosslinking and the presence of a single drug-releasing window in the device.

Glucose-stabilized polyvinyl acetate homopolymer-based wood adhesive: synthesis and characterization

The purpose of this work was to study the synthesis and characterization of an adhesive based on a glucose stabilized polyvinyl acetate homopolymer. Vinyl acetate monomer was stabilised onto liquid glucose using emulsion polymerization, and polymerization happened using potassium persulfate as an initiator. Here, the effects of adding liquid glucose as a stabiliser for adhesives were studied. Therefore, the current research examines whether liquid glucose, introduced at weight-based concentrations of 0.5% and 1.0%, is suitable as a colloid to produce PVAc adhesives for wood. By measuring viscosity, pH, contact angle, differential scanning calorimetry (DSC), and the pencil hardness test of films, the effect of adding liquid glucose as a colloid on physical, thermal, and mechanical properties was investigated. The shear strength of the PVAc homopolymers applied to wood using emulsions with varied liquid glucose concentrations was measured using a universal tensile machine. As the concentration of liquid glucose increased, the viscosity of the adhesives also considerably increased. Water resistance significantly rose when liquid glucose content increased, as was found by measuring the water contact angle. The use of liquid glucose increased the hardness of PVAc films, which was supported by the glass transition temperature. According to EN 204-205, the tensile shear strength with 1.0% of liquid glucose increased by 63.88% and 45.67%, respectively, over a pristine sample after 6 h of bonding in a dry environment and 24 h in a wet environment. The study’s overall conclusion highlights the higher adhesion capability of PVAc emulsion-based adhesives stabilized by liquid glucose.

Synthesis, crystal structure and properties of YB2C2

ABSTRACT YB2C2 is a novel ultra-high temperature ceramic material with high damage tolerance. In this work, the synthesis mechanism, crystal structure, electronic structure, elastic properties and thermal shock resistance of YB2C2 were systematically investigated through experiments and calculations. It was determined by differential scanning calorimetry with the heating rate of 10°C/min that YB2C2 was formed by the reaction of YB2C and C at about 1202°C, and became the main phase at 1450°C. The space group of YB2C2 was determined to be P4/mbm by X-ray diffraction, transmission electron microscopy, Rietveld refinement and first-principles calculations for the first time. The lattice constants are a = b = 0.5351 nm and c = 0.3561 nm. The atom positions are as follows: Y is located at 2a (0, 0, 0), B is located 4 h (0.133, 0.633, 0.5) and C is located at 4 h (0.662, 0.162, 0.5). The chemical bonding of YB2C2 displayed sharp anisotropy, with strong B-C bond within the B2C2 nets, and weak Y-B/Y-C bond between Y atom layers and B2C2 nets. Additionally, YB2C2 exhibited abnormal thermal shock resistance when the thermal shock temperature exceeded 800°C, with the residual flexural strength at 1300°C being more than 70% of the strength at room temperature.

Incorporation of Inclusion Complexes in the Dissolvable Microneedle Ocular Patch System for the Efficiency of Fluconazole in the Therapy of Fungal Keratitis.

Fluconazole (FNL) is one of the first-line treatments for fungal keratitis as it is an effective broad-spectrum antimicrobial commonly administered orally or topically. However, FNL has a very low water solubility, limiting its drug formulation, therapeutic application, and bioavailability through tissues. To overcome these limitations, this study aimed to develop FNL inclusion complexes (FNL-IC) with cyclodextrin (α-cyclodextrin, sulfobutylether-β-cyclodextrin, and hydroxypropyl-γ cyclodextrin) and incorporate it into a dissolvable microneedle (DMN) system to improve solubility and drug penetration. FNL-IC was evaluated for saturation solubility, Fourier transform infrared spectroscopy, differential scanning calorimetry, in vitro release, minimum inhibitory concentration, minimum fungicidal concentration, and time-killing assay. DMN-FNL-IC was evaluated for mechanical and insertion properties, surface pH, moisture absorption ability, water vapor transmission, and drug content recovery. Moreover, ocular kinetic, ex vivo antimicrobial, in vivo antifungal, and chorioallantoic membrane (HET-CAM) assays were conducted to assess the overall performance of the formulation. Mechanical strength and insertion properties revealed that DMN-FNL-IC has great mechanical and insertion properties. The in vitro release of FNL-IC was significantly improved, exhibiting a 9-fold increase compared to pure FNL. The ex vivo antifungal activity showed significant inhibition of Candida albicans from 6.54 to 0.73 log cfu/mL or 100-0.94%. In vivo numbers of colonies of 0.87 ± 0.13 log cfu/mL (F2), 4.76 ± 0.26 log cfu/mL (FNL eye drops), 3.89 ± 0.24 log cfu/mL (FNL ointments), and 8.04 ± 0.58 log cfu/mL (control) showed the effectiveness of DMN preparations against other standard commercial preparations. The HET-CAM assay showed that DMN-FNL-IC (F2) did not show any vascular damage. Finally, a combination of FNL-IC and DMN was developed appropriately for ocular delivery of FNL, which was safe and increased the effectiveness of treatments for fungal keratitis.

Fabrication of mechanical durable novolac matrix composites with recycled and cost-effective candle-soot nano particles

Novolac matrix composites are crucial due to their exceptional resistance to heat, chemicals, and mechanical stress. These advanced materials find applications in aerospace, electronics, and automotive industries, providing high-performance solutions for components requiring superior durability and reliability. In this context, the microstructure, thermal, phase, and mechanical properties of the composites obtained as a result of the recycling-oriented reinforcement of the waste candle-soot (CS) reinforcement at the rate of 1 wt% to the pure novolac (PN) and shaping with the hot press method were examined in detail at first time in the literature. While microstructural properties and fracture mechanisms were investigated by scanning electron microscopy (SEM), thermal properties were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results obtained provided critical findings as the composite hardness, tensile strength, and flexural strength values were 3.28, 2.47, and 3.21 times higher than PN, respectively. CS-reinforced novolac composites made a significant contribution to the literature by introducing a novel and eco-friendly approach to enhance material properties. Their use as a filler material provided insights into sustainable novolac composites, offering potential applications in various industries, such as electronics and aerospace, with improved mechanical and thermal properties.

Effect of Accumulative Roll Bonding Cycles and Postprocessing Heat Treatment Temperature on Shape Memory Properties of Cu–Al–Ag Alloys

Herein, Cu/Al/Ag‐layered composites with two silver powder concentrations (2 wt% and 3 wt%) are fabricated with the aid of accumulative roll bonding (ARB). The ARB‐ed samples are heat treated at different temperatures (750, 850, 950, and 1050 °C), times (30, 45, and 60 min), and cycles (1–9 cycles) to produce Cu–Al–Ag shape memory alloys. The samples are characterized by X‐ray diffraction, scanning electron microscope, and electron backscattering diffraction. Phase transformation temperatures are measured by differential scanning calorimetry. Strain recovery and shape memory behavior are evaluated by bending and tensile tests, respectively. The results indicate that alloys containing 2 wt% Ag, rolled till 9 cycles, heat treated at 950 °C for 60 min, and samples with 3 wt% Ag, fabricated by 9 cycles, annealed at 850 °C for 60 min show maximum β martensite phase amount. The strain recovery ratios of the first and second samples are 71.7% and 71.2%, respectively. Additionally, the tensile test shows that the residual plastic strain and the recovered strain for the first sample with 2 wt% Ag are equal to 0.7% and 3.0%, respectively. These results for the second sample with 3 wt% Ag are 1.2% and 3.4%, respectively.

Biopolymer-Based Hydrogel Incorporated with Naproxen Sodium and Lidocaine Hydrochloride for Controlled Drug Delivery

Sodium hyaluronate (HA) is a natural polysaccharide. This biopolymer occurs in many tissues of living organisms. The regenerating, nourishing, and moisturizing properties as well as the rheological properties of HA enable its application in the pharmaceutical industry as a carrier of medicinal substances. The aim of this work was to assess the release of naproxen sodium (Nap) in the presence of lidocaine hydrochloride (Lid) from the biopolymer-based hydrogels and to determine the respective kinetic parameters of this process. The possible interaction between the HA polysaccharide carrier and the selected drugs was also investigated. Three hydrogels containing Nap and Lid with different concentrations of the biopolymer were prepared. The release of Nap was studied by employing USP apparatus 5. The infrared study and differential scanning calorimetry analysis of physical mixtures and dried formulations were performed. The highest amount of Nap was released from the formulation with the lowest concentration of the biopolymer. The most representative kinetic model that described the dissolution of Nap was obtained through the Korsmeyer–Peppas equation. The release rate constants were in the range of 1.0 ± 0.1 × 10−2 min−n–1.7 ± 0.1 × 10−2 min−n. Lid did not influence the dissolution of Nap from the formulations tested; however, in the desiccated samples of assessed formulations, the interaction between the polysaccharide and both drugs was observed.

Exploring the Effectiveness of Carboxymethylated and Crosslinked Albizia procera Gum in Diltiazem Hydrochloride Matrix Tablets: A Comparative Analysis.

This study investigates the efficacy of modified Albizia procera gum as a release-retardant polymer in Diltiazem hydrochloride (DIL) matrix tablets. Carboxymethylated Albizia procera gum (CAP) and ionically crosslinked carboxymethylated Albizia procera gum (Ca-CAP) were utilized, with Ca-CAP synthesized via crosslinking CAP with calcium ions (Ca2+) using calcium chloride (CaCl2). Fourier Transform (FT) IR analysis affirmed polymer compatibility, while differential scanning calorimetry (DSC) and X-ray diffraction (XRD) assessed thermal behavior and crystallinity, respectively. Zeta potential analysis explored surface charge and electrostatic interactions, while rheology examined flow and viscoelastic properties. Swelling and erosion kinetics provided insights into water penetration and stability. CAP's carboxymethyl groups (-CH2-COO-) heightened divalent cation reactivity, and crosslinking with CaCl2 produced Ca-CAP through -CH2-COO- and Ca2+ interactions. Structural similarities between the polymers were revealed by FTIR, with slight differences. DSC indicated modified thermal behavior in Ca-CAP, while Zeta potential analysis showcased negative charges, with Ca-CAP exhibiting lower negativity. XRD highlighted increased crystallinity in Ca-CAP due to calcium crosslinking. Minimal impact on RBC properties was observed with both polymers compared to the positive control as water for injection (WFI). Ca-CAP exhibited improved viscosity, strength, controlled swelling, and erosion, allowing prolonged drug release compared to CAP. Stability studies confirmed consistent six-month drug release, emphasizing Ca-CAP's potential as a stable, sustained drug delivery system over CAP. Robustness and accelerated stability tests supported these findings, underscoring the promise of Ca-CAP in controlled drug release applications.

Variation in amylose content in three rice variants predominantly influences the properties of sushi rice

AbstractSushi rice is a ready-to-eat traditional Japanese dish seasoned with vinegar, sugar and salt that has gained popularity worldwide. There are many rice cultivars grown in the world which vary in their cooking, sensory, and processing quality. The aim of this study was to analyse chemical, physical, and functional properties of three rice varieties (Vietnamese, Italian, and Australian) to determine their suitability for sushi rice production. Rice was cooked using industry norms and vinegar was then added; samples with no vinegar were prepared for comparison. The rice was stored during 5 days at 4 °C after cooking for texture profile analysis and samples were taken on day 1 and day 5. Flour composition as well as amylose content, gelatinisation properties using differential scanning calorimeter, pasting properties using Rapid Visco Analyser, water absorption capacity (WAC), oil absorption capacity (OAC) and swelling power of extracted starch were determined. Results showed that the amylose content (16.51 to 21.37%) had a large impact on the functional and quality characteristics of the rice variants including texture, pasting, gelatinisation and WAC properties. Australian starch showed the highest amylose content, setback viscosity, final viscosity, pasting temperature and lowest gelatinisation temperature. The lower amylose content and gelatinisation temperature contributed to a softer texture in the Vietnamese rice samples over life. The added vinegar aided in keeping the texture soft during the shelf-life of the rice. Since sushi rice is usually prepared with vinegar, Italian and Vietnamese rice are better candidates for sushi rice based on their lower hardness after 5 days of storage when compared to the Australian variety.

Experimental consideration of the effects of calcium lignosulfonate and tannic acid on the flammability and thermal properties of polylactide composites

The purpose of this study was to determine the quantitative and qualitative effects of the form of natural phenolic compounds (NPCs) on the decomposition of polylactide (PLA) under different measurement conditions. For this purpose, thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), and pyrolysis-combustion flow calorimetry (PCFC) analyses were carried out not only on individual raw materials like calcium lignosulfonate (BX), tannic acid (TA), BX chemically modified with TA (BMT), but also on PLA/BX, PLA/TA, and PLA/BMT composites with 3, 6, and 9 wt.% of filler. Moreover, the work checked whether to obtain satisfactory results it is necessary to carry out chemical modification lasting many hours, or whether simple physical mixing of ingredients (TABX) is enough, e.g. in proportions 1:2, 2:4, 3:6. The results of these analyses showed that TA is neither a good flame retardant nor a highly swelling material, but when combined with BX physically or chemically, it can produce an interesting synergistic effect. This work proves that chemically obtained BMT hybrid material allows to reduce flammability by 30 % compared to PLA which cannot be achieved by physically mixing these components in a polymer melt. On the other hand, the addition of TABX is sufficient to achieve a good thermal stabilization effect under processing conditions.

Impact of thermal soil treatment on heavy metal mobility in the context of waste management.

Thermal soil treatment is a well-established remediation method to remove organic contaminants from soils in waste management. The co-contamination with heavy metals raises the question if thermal soil treatment affects heavy metal mobility in soils. In this study, four contaminated soils and a reference sample were subjected to thermal treatment at 105°C, 300°C and 500°C for 7 day. Thermogravimetry and differential scanning calorimetry were used to understand the reactions, and resulting gases were identified by Fourier-transformed infrared spectroscopy. Treated and untreated samples were characterised by X-ray diffraction (XRD) and electron microprobe analysis and subjected to pH-dependent leaching tests, untreated samples additionally by X-ray-fluorescence (XRF) and inductively coupled plasma mass spectroscopy (ICP-MS). Leachates were analysed using ICP-MS and ion chromatography. Maximum available concentrations were used for hydrogeochemical modelling using LeachXS/Orchestra to predict leaching control mechanisms. Leaching experiments show that thermal treatment tends to decrease the mobility at alkaline pH of Pb, Zn, Cd, As and Cu, but to increase the mobility of Cr. In the acidic to neutral pH range, no clear trend is visible. Hydrogeochemical modelling suggests that adsorption processes play a key role in controlling leaching. It is suggested that the formation of minerals with a more negatively charged surface during thermal treatment are one reason why cations such as Pb2+, Zn2+, Cd2+ and Cu2+ are less mobile after treatment. Future research should focus on a more comprehensive mineralogical investigation of a larger number of samples, using higher resolution techniques such as nanoscale secondary ion mass spectrometry to identify surface phases formed during thermal treatment and/or leaching.

The hemp-reinforced polypropylene composite: Effect of the alkaline and coupling agents treatment

The hemp-reinforced polypropylene composite was produced by the twin-screw extrusion in the presence of polypropylene-graft-maleic anhydride (PP-g-MA) and silane as coupling agents and subsequence by the compression molding. The hemp fiber was obtained by sodium hydroxide treatment prior to the twin-screw extruder. The PP/Hemp composite was analyzed using a universal testing machine, scanning electron microscope, differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy. The mechanical properties of the PP/MA/Hemp demonstrated a better result than that of PP/Si/Hemp in most hemp contents. The SEM images of the PP/MA/Hemp exhibited excellent interfacial bonding in PP/MA/Hemp30 without fiber pullouts. However, the fiber breakage and some fiber pullout with gaps around the fiber of PP/Si/Hemp indicate the poor bonding of the PP matrix. The functional group of the PP/Hemp composite showed the –OH cellulose result peak of the reaction between hemp fibers and polypropylene.

Crystallization of KDP in the presence of 4-nitro benzoic acid, L-ornithine hydrochloride and terephthalic acid

The present study is to investigate the optical, thermal and SHG properties of grown potassium dihydrogen phosphate (KDP) crystals using slow evaporation method in the presence of 4-nitro benzoic acid, l-Ornithine Hydrochloride and Terephthalic acid. Powder crystal XRD studies confirm their structure as that of KDP. The presence of functional groups has been tested and confirmed by FTIR. UV–visible spectral analysis - Differential Reflectance Studies (DRS) is used to examine the optical properties of pure and doped KDP crystals within the wavelength range of 200–800 nm and also evaluate the band gap, refractive index, extinction coefficient and optical conductivity of the grown crystals. Thermal properties of grown crystal are analysed by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Second harmonic generation test is carried out for the grown crystals to analyse nonlinear optical (NLO) properties.

New Hydrophilic Matrix Tablets for the Controlled Released of Chlorzoxazone

The modified release of active substances such as chlorzoxazone from matrix tablets, based on Kollidon®SR and chitosan, depends both on the drug solubility in the dissolution medium and on the matrix composition. The aim of this study is to obtain some new oral matrix tablet formulations, based on Kollidon®SR and chitosan, in order to optimize the low-dose oral bioavailability of chlorzoxazone, a non-steroidal anti-inflammatory drug of class II Biopharmaceutical Classification System. Nine types of chlorzoxazone matrix tablets were obtained using the direct compression method by varying the components ratio as 1:1, 1:2, and 1:3 chlorzoxazone/excipients, 20–40 w/w % Kollidon®SR, 3–7 w/w % chitosan while the auxiliary substances: Aerosil® 1 w/w %, magnesium stearate 0.5 w/w % and Avicel® up to 100 w/w % were kept in constant concentrations. Pharmaco-technical characterization of the tablets included the analysis of flowability and compressibility properties (flow time, friction coefficient, angle of repose, Hausner ratio, and Carr index), and pharmaco-chemical characteristics (such as mass and dose uniformity, thickness, diameter, mechanical strength, friability, softening degree, and in vitro release profiles). Based on the obtained results, only three matrix tablet formulations (F1b, F2b, and F3b, containing 30 w/w % KOL and 5 w/w % CHT, were selected and further tested. These formulations were studied in detail by Fourier-transform infrared spectrometry, X-ray diffraction, thermogravimetry, and differential scanning calorimetry. The three formulations were comparatively studied regarding the release kinetics of active substances using in vitro release testing. The results were analyzed by fitting into four representative mathematical models for the modified-release oral formulations. In vitro kinetic study revealed a complex mechanism of release occurring in two steps of drug release, the first step (0–2 h) and the second (2–36 h). Two factors were calculated to assess the release profile of chlorzoxazone: f1—the similarity factor, and f2—the factor difference. The results have shown that both Kollidon®SR and chitosan may be used as matrix-forming agents when combined with chlorzoxazone. The three formulations showed optima pharmaco-technical properties and in vitro kinetic behavior; therefore, they have tremendous potential to be used in oral pharmaceutical products for the controlled delivery of chlorzoxazone. In vitro dissolution tests revealed a faster drug release for the F2b sample.