Non-crystalline Nature Research Articles

Alkyl-Substituted Polycaprolactone Poly(urethane-urea)s as Mechanically Competitive and Chemically Recyclable Materials.

We report the mechanical performance and chemical recycling advantages of implementing alkyl-substituted poly(ε-caprolactones) (PCLs) as soft segments in thermoplastic poly(urethane-urea) (TPUU) materials. Poly(4-methylcaprolactone) (P4MCL) and poly(4-propylcaprolactone) (P4PrCL) were prepared, reacted with isophorone diisocyanate, and chain-extended with water to form TPUUs. The resulting materials' tensile properties were similar or superior to a commercially available polyester thermoplastic poly(urethane) and had superior elastic recovery properties compared to a PCL analogue due to the noncrystalline nature of P4MCL and P4PrCL. Additionally, monomers were recovered from the TPUU materials in high yields via ring-closing depolymerization using a reactive distillation approach at an elevated temperature and a reduced pressure (240-260 °C, 25-140 mTorr) with zinc chloride (ZnCl2) as the catalyst. The thermodynamics of polymerization were estimated using Van't Hoff analyses for 4MCL and 4PrCL; these results indicated that the propyl group in 4PrCL results in a lower practical ceiling temperature (Tc) for P4PrCL.

Synthesis and characterization of new continuous phosphate glass fibers intended for structural engineering applications: Structure/property relationships

Nowadays, phosphate glass fibers (PGF) are considered quite competitive respective to conventional glass fibers. This work focus on the development of PGF fibers intended for structural engineering applications such as composite reinforcement for building and automotive fields. For this purpose, two series of phosphate glasses based on 52P2O5-24CaO-13MgO-(11-(X+Y+Z)) K2O-XAL2O3-YF2O3-ZTiO2; (X=1; 3; 5, Y=0; 5, Z=0; 1 mol %) were processed and transformed into phosphate glass fibers by melt spinning. The resulting fibers were characterized. XRD analysis confirmed the non-crystalline nature of phosphate glasses. In addition, the substitution of K2O by Al2O3 and by the combination of Al2O3, Fe2O3 and TiO2 in the composition of phosphate glass could lead to a significant increase in fiber density from 2,16 g/cm3 to 2,80 g/cm3. The stability of the produced phosphate glass fibers was examined using two methods: weight loss at 37°C and dissolution kinetics under different pH levels (4, 7, and 12). The results showed that the chemical resistance of the PGF fibers was improved with up to 99% increase respective to the original formulation. In addition, the mechanical properties of the spinnable phosphate glass manufactured by replacing K2O oxide by Al2O3 oxide were improved, such a substitution led to a maximum tensile strength and modulus of 2668 MPa and 140 GPa, respectively. Therefore, the tensile proprieties were improved by 75% compared to the original formulation. This comparative study between phosphate glass fibers (PGF) and traditional fibers highlight similar tensile strength but combined to notable enhancements in chemical stability through cation addition, expanding their potential use in composite and biomedical materials. Finally, a correlation analysis of mechanical performances was carried out. It was observed that the results obtained using the statistical methods were consistent with the experimental data.

Influence of Milled carbon fiber MCF on mechanical and dynamic mechanical behaviour of carbon fiber fabric reinforced polymer composites

Carbon fiber reinforced polymer (CFRP) composites are widely used in engineering applications. Better understanding about the thermo mechanical properties of CFRP composites are essential for their development. Static and dynamic mechanical properties of CFRP composites can be modified by the filler materials loaded on it. This study investigates the effect of Milled Carbon Fiber (MCF) filler reinforcement on flexural and thermo-mechanical properties of CFRP composites. Fabricated composites are quasi isotropic laminates with unidirectional carbon fibers. The composite laminates were fabricated by hand lay-up technique. XRD analysis illustrates that all the processed specimens are in non-crystalline nature. Three-point bending mode is followed to evaluate the flexural and Dynamic Mechanical Analysis (DMA) tests. MCF fillers are loaded at 6 wt%, 8 wt%, 10 wt%, 12 wt% to evaluate above mentioned properties, i.e, Flexural Strength and Break strain were found from flexural analysis. Storage Modulus (E'), Loss Modulus(E’'), under varying temperature and glass transition temperature (Tg) were determined from DMA. The test results indicated that, 8 wt% of MCF filler loading improves the static and dynamic mechanical properties of CFRP composites when compared to 10 wt% and 12 wt% of MCF content.

Structural, Physical and Optical studies of Sc3+ doped Lithium Aluminum Borate glasses

Optically transparent lithium aluminum borate containing scandium glasses with composition 70B2O3 – 20Li2O – (10 – x) Al2O3 – xSc2O3 (where x= 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 in mol %) were fabricated by conventional melt quenching technique. The non-crystalline nature of the samples was monitored by X-ray diffraction and it confirms non-crystalline nature. Structure of the fabricated glasses are assessed using the Fourier transform infrared spectra. The absorption spectra of these glasses have been recorded in the wavelength range 200 nm – 1100 nm. Direct and indirect optical energy band gaps were calculated from Tauc’s plots. The physical parameters such as refractive index (RI), optical basicity and interaction parameters were determined using proper formulas to know the characteristics of fabricated glass matrix. The results obtained indicate that 0.3 mol% Sc2O3-containing BLASc glass is more suitable for w-LEDs and lasers applications.

Electronic and optical properties of Na2O doped P2O5-TeO2− CoO-ZnO glasses

The phospho-tellurite glasses, (P2O5)0.25-(TeO2)0.5-x-(CoO)0.1-(ZnO)0.15-(Na2O)x ; x = 0.15, 0.20, 0.25, 0.30 and 0.35 were prepared by melt quenching and their non-crystalline nature confirmed through XRD. Density is found decreased and molar volume increased with increase of Na2O concentration and they behaved opposite to each other. The physical parameters such as transition metal ion density, mean distance between TMIs, small polaron radius, oxygen packing density and field strength were estimated. DC conductivity was measured by following two probe method in the temperature range 303K – 633K. High temperature conductivity is explained by Mott’s small polaron hopping (SPH) model and low temperature conductivity by Mott’s VRH model. Both conductivity and activation energy are found to be increasing with Na2O content. Density of states at Fermi level are found to be of the order of 1021 to 1024 eV−1 cm−3. UV-Vis spectra were recorded for the wavelength range 200-800 nm. Optical band gap (direct and indirect) except for x=0.20 is found increased, urbach energy and refractive indexes are found decreased with Na2O concentration. Various optical parameters such as molar polarizibility, metallization criterion, reflection loss, electronic polarizability, optical transmission coefficient, dielectric constant and optical dielectric constant have been determined.

Production and Characterization of Silica from Rice Husk: An Updated Review

Rice is regarded as one of the most valuable sources which is consumed by almost fifty percent of the world’s population. Rice husk ash is a by-product substance obtained from the rice husk by thermal and chemical treatment. The non-crystalline nature of silica content in rice husk, which is converted to crystalline silica such as quartz, tridymite, and cristobalite on thermal treatment. It has been an important material which impacts not only enhances the betterment of industrialization but also protects the environment from pollution. The produced silica was characterized by various analyses such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and Thermal analysis. This review is given attention to integrating and investigating processing, properties, characterization, reactivity, and application of rice husk (RH) and rice husk silica (RHS).

Low concentration Sm3+ ions loaded zinc sodium borate glasses for solid state lighting devices

Herein, zinc sodium borate glasses containing samarium ions were fabricated using the traditional melt-quenching approach and explored using several spectroscopic and structural methods. The XRD data corroborated the host glass specimen's non-crystalline nature. Scanning electron microscopy and the energy dispersive X-ray spectroscopy method were utilized to study the morphological and homogenous attributes. The UV–Vis–NIR wavelengths of absorption showed a total of seventeen distinct Sm3+ ion peaks. The three transitions 4G5/2 → 6H9/2, 6H7/2, and 6H5/2 are evident in the PL data at wavelengths of 644, 597, and 561 nm, respectively, in the red, reddish-orange, and greenish-yellow zones. The luminescence intensity of the investigated glass specimens increases up to 0.4 mol% Sm3+ ion content thereafter reducing because of the non-radiative transfer of energy. The estimated JO intensity parameters exhibit a trend of Ω2>Ω4>Ω6. The trend of the assessed radiative parameters also demonstrated that they are sensitive to changes in the glass network. The Futchbauer-Ladenburgh theory was used to compute the emission cross-section of various transitions utilizing the radiative parameters. The 1931 CIE chromaticity coordinates assessments corroborate the reddish-orange luminescence from the fabricated glasses. The outcomes have proven that obtained BNZSmx glasses doped with low concentrations of trivalent samarium ions are well suited for reddish-orange solid-state lighting systems.

Mixed Pluronic/lecithin micelles formulation for oral bioavailability of candesartan cilexetil drug: in vitro characterization and in vivo pharmacokinetic investigations

Objective This study aimed to develop a mixed polymeric micelle formulation incorporating candesartan cilexetil (CAND) drug to enhance its oral bioavailability for the better treatment of hypertension. Methods A Box–Behnken design was utilized to optimize the CAND-incorporated mixed polymeric micelles formulation (CAND-PFLC) consisting of Pluronics (P123 and F68) and lecithin (LC). The optimized CAND-PFLC micelles formulation was characterized for size, shape, zeta potential, polydispersity index (PDI), and entrapment efficiency (%EE). An in vitro release study, ex vivo permeability investigation, and an in vivo pharmacokinetic analysis were carried out to evaluate the performance of the formulation. Results The optimized CAND-PFLC micelles formulation demonstrated a spherical shape, a particle size of 44 ± 2.03 nm, a zeta potential of −7.07 ± 1.39 mV, a PDI of 0.326 ± 0.06, and an entrapment efficiency of 87 ± 3.12%. The formulation exhibited excellent compatibility, better stability, and a noncrystalline nature. An in vitro release study revealed a faster drug release of 7.98% at gastric pH in 2 hrs and 94.45% at intestinal pH within 24 hrs. The ex vivo investigation demonstrated a significantly enhanced permeability of CAND, with 94.86% in the micelle formulation compared to 9.03% of the pure drug. In vivo pharmacokinetic analysis showed a 4.11-fold increase in oral bioavailability of CAND compared to the marketed formulation. Conclusion The CAND-PFLC mixed micelle formulation demonstrated improved performance compared to pure CAND, indicating its potential as a promising oral drug delivery system for the effective treatment of hypertension.

Effect of ambient argon pressure on the structural, optical and electrical properties of non-crystalline Se85Te3Bi12 nano-thin films

In this research work, we have synthesized non-crystalline Se85Te3Bi12 chalcogenide glasses by conventional melt quenching technique. The differential scanning calorimetry measurement of the synthesized specimen was done to confirm the glassy as well as non-crystalline nature of the bulk Se85Te3Bi12 alloy. The nano-thin films of thickness 30 nm of the synthesized sample at two different ambient argon pressures (1 Torr and 3 Torr) were made using the physical vapor condensation technique at a constant substrate temperature of 77 K using liquid nitrogen. The non-appearance of prominent peaks in the high-resolution x-ray diffractometer profile confirmed the non-crystalline nature of synthesized nano-thin films. The morphological analysis of the prepared nano-thin films using Field emission scanning electron microscopy confirmed the nanochalcogenide having particle size ranges from 30–90 nm. The Fourier transform infrared (FTIR) spectroscopy suggests the presence of moisture and carbon impurities in the prepared nano-thin films. The broad optical transmission shadow observed in the FTIR results is an essential requirement for new-generation IR systems. Based on UV-visible spectroscopy, optical parameters such as optical absorption coefficients, Urbach energy, optical band gaps, Tauc’s parameter and extinction coefficients were measured for synthesized Se85Te3Bi12 nano-thin films. The value of absorption coefficients, Tauc’s parameters, optical band gap and extinction coefficients increases with the increase of ambient argon pressure. The outcome of these studies recommends that these materials can be a preeminent candidate for photovoltaic applications. Photoluminescence spectroscopy results are accredited to the accumulation of non-crystalline nanochalcogenide particles on the substrates. DC conductivity measurements further confirm the semiconducting nature of the nanochalcogenide Se85Te3Bi12 thin films.

Green approach for conversion of hazardous red mud into an efficient transparent neutron and gamma-ray shield

Research into the eco-friendly utilization of red mud or bauxite residue (BR) is expanding globally.This study successfully incorporated BR into a family of glasses through the melt quenching technique. The family have a composition of xBR. (50-x) B2O3.25CaO.25BaO, where x = 0, 5, 10, and 15 wt%. X-ray diffraction (XRD) analysis confirmed the non-crystalline nature of the glasses. Physical properties were studied by measuring density, and microhardness was estimated using Vickers hardness (HV) tests. Differential scanning calorimetry (DSC) was used to evaluate the thermal behavior. Changes in various properties resulting from the presence of BR confirmed modifications in the glass network. The radiation shielding properties were measured for gamma and slow neutrons and calculated for fast neutrons. The results indicated that incorporating BR significantly enhanced the γ-ray shielding capacity, reduced the effectiveness of slow neutron shielding, and had minimal impact on shielding against fast neutrons. Additionally, the glasses were compared to standard radiation concrete mixes, demonstrating their superiority and high potential for use in shielding against gamma/X-ray.

Effect of addition of SiO2 and Al2O3 on the dielectric properties of basalt glasses

The present research focuses on the influence of SiO2 and Al2O3 additives on the structure and dielectric properties of basalt glasses. Upon the introduction of SiO2 and Al2O3, all the prepared basalt glasses were found to exhibit a non-crystalline nature. The initial dielectric constant of the basalt glass without the addition of SiO2 and Al2O3 was 7.893. However, as the content of SiO2 and Al2O3 increased, the dielectric constant of the basalt glasses initially decreased, but then started to rise. Remarkably, the lowest dielectric constant, achieved with the addition of 1 wt% Al2O3, was measured at 6.561. Similarly, the lowest dielectric constant, attained with the addition of 1 wt% SiO2, was recorded at 6.368. This value was lower than that produced by Al2O3 addition. These findings provide a new perspective on the dielectric properties of basalt glasses and continuous basalt fibers.

Efficient Tm3+ up-conversion in lead borophosphate glasses for visible emission

Thulium oxide (Tm2O3) doped lithium lead borophosphate glasses have been synthesised and analysed to probe their structural and luminescence properties. X-ray diffraction data confirmed the non-crystalline nature of the prepared glasses. Participation of Tm2O3 in the structure is established by the variation in density and molar volume with increasing concentration of Tm2O3. Fourier transform infrared spectroscopy revealed the various structural units present due to B2O3, P2O5 and PbO. Ultraviolet-visible near infrared absorption spectra showed peaks/bands at 466 nm (G41), 684 nm (F33), 790 nm (H43) and 1210 nm (H53), originating from ground state H63 of thulium while Ytterbium showed its characteristic peak at 978 nm. Indirect band gap, calculated from Tauc's curve showed decreasing trend with increasing concentration of Tm2O3. The other optical parameters like molar refractivity, molar polarizability, electronic polarizability and dielectric constant also showed variation with increase in concentration of Tm2O3. Judd-Ofelt parameters followed Ω2>Ω4>Ω6 trend and oscillator strengths have also been evaluated. For luminescence studies, upon 790 nm excitation, visible peaks at 454 nm, 485 nm, 529 nm, 624 nm and 665 nm were observed while at 684 nm excitation, wavelength of 542 nm and 610 nm is emitted. Excited state absorption up-conversion mechanism is responsible for the observed visible emission. Commission Internationale de I'Eclairage (CIE) chromaticity coordinates have also been calculated and coordinates lie near the white light region. Up-conversion results indicated that the prepared glasses are potential host for up-conversion and can be used in colour displays.

Investigation of the spectral characteristics of Sm3+ ions in lead borosilicate glass for photonic applications.

Different concentrations of Sm2 O3 -doped lead borosilicate glass were synthesized using a melt-quenching method and their characteristics were analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy absorption, emission, and decay curves. From the XRD patterns, the noncrystalline nature of titled glass was confirmed. The structural groups that existed in the host glass were observed from FTIR spectra. The Judd-Ofelt (JO) intensity parameters and oscillator strengths were derived from the absorption spectra and compared with various reported systems. The excitation luminescence levels of the Sm3+ ion radiative properties were further computed using the JO intensity parameters. Effective bandwidth, emission cross-sections (σe ), and several lasing properties were assessed from emission spectra and compared with other reported glass systems. The decay curves of the 4 G5/2 level of Sm3+ ion were also been measured and examined. Additionally, the colour coordinates of the Commission International de I'Éclairage chromaticity were assessed. The titled glass were suitable for visible reddish orange luminescence devices based on all obtained parameters.

Physical and electrical properties of Sm2O3 doped Boro-Zinc-Vanadate glasses

Sm2O3 doped boro-zinc-vanadate glass systems were synthesised by following the melt quenching method. XRD patterns indicated largely non-crystalline nature with few nano-crystallites. Room temperature density was measured. Molar volume and various polaron parameters were estimated. Density and molar volume are found to vary non-linearly with samarium concentration. Conductivity has been measured by two probe technique for temperature range 303K - 573K. High temperature conductivity obeyed the small polaron hopping (SPH) theory. Activation energy for conduction in the temperature regime of small polaron theory is found to vary from 0.249 eV to 0.368 eV non-linearly with Sm2O3 concentration. The conductivity data at low temperature deviated has been looked into using Mott’s VRH model and the density of states at Fermi level were determined. Shimakawa’s multiphonon tunnelling model has also been applied to the low temperature conductivity and found linearity between logarithmic conductivity, ln(σ) and logarithmic temperature ln(T) as predicted by the model. The temperature exponent values obtained from Shimakawa’s model fit are found to be in good agreement with literature. Therefore, it is concluded that at low temperature, carrier multiphonon tunnelling is the charge transport mechanism in the present glasses.

The effect of gamma radiation on structural and spectroscopic properties of lithium aluminum borate glasses doped with terbium

Spectroscopic properties of fabricated Tb2O3 doped B2O3 – Li2O – Al2O3 glasses were studied before and after gamma irradiation doses 20 kGy at the rate of 3.65 kGy/hr. Non-crystalline nature of fabricated glass matrix confirmed by XRD. The obtained results were analyzed by comparing before and after radiation with the Cobalt source to study the structural variation of the sample. The Raman spectra were recorded at room temperature from 400 to 4000 cm−1 wave number range. The photoluminescence spectra at different emission and excitation wavelengths have been recorded. The variation has been discussed with respect Tb2O3 concentration

The effect of ZnO on the structural and radiation shielding properties in borophosphate glasses

In this work, the influence of ZnO content in the structural and radiation shielding parameters of zinc borophosphate glass were studied. The glass batch was prepared by using the melt-quenching technique. The structural analyses have been carried out using XRD, Raman spectroscopy, 11B and 31P solid state MAS NMR. Density and glass transition temperature (Tg) were measurements and band gap were determined. XRD confirms the non-crystalline nature of the prepared samples. Changes in the structural characteristics with composition are associated with a replacement of BO4 by BO3 units and the replacement of PO4 phosphorous units by PO4−1 and PO4−2 units, leading to an increase of the average number of non-bridging oxygen (NBO). Density values revealed an increase of up to 43% and Tg shows reduction followed by stability with the replacement of P2O5 by ZnO. Band gap energies were measured as a function of ZnO content. Photon interaction parameters of the zinc borophosphate glasses have been investigated by the mass attenuation coefficient (MAC), half value layer (HVL), and mean free path (MFP). For radiation in the X-ray range (40 KeV), the MAC value for glass is 887% higher than for concrete and the HVL decreases almost four times, from 20 to 6 mm thickness, with the increase of ZnO content. The rise in ZnO content also improves all radiation attenuation parameters and the results reported here show that zinc borophosphate glasses present better results than ordinary concrete and is comparable to lead-based glasses. These characteristics make this glass system an excellent choice as a high-energy ionizing radiation attenuator.

Potential utility of industrially unwanted constituent under the framework of waste to wealth: Edible salt from commercial marine red seaweed Kappaphycus alvarezii (Doty) L.M. Liao

Processing of 1000 kg of fresh Kappaphycus alvarezii yielded 25 kg salt. The optical microscopy revealed non-crystalline nature, absence of geometrical pattern; while squircle aggregates with ruffled surface were evident in SEM. Caenorhabditis elegans assay confirmed its non-toxicity; while absence of Salmonella and pesticides make it safe for human consumption. Among the macro elements, ‘K' content was highest (3792.74 ± 541.23 mg 100 g−1) and ‘Ca’ was lowest (7.01 ± 1.32 mg 100 g−1); whereas among micro element ‘Fe’ was highest (6.52 ± 1.40 mg 100 g−1) and ‘Ni’ lowest (0.14 ± 0.01 mg 100 g−1). Chromium (11.5 μg g−1) was lower than a permissible daily dose, while other heavy metals (Mo, Cu, Co, Zn, As, Cd, Hg, and Pb) were below detectable level. PXRD revealed that it has only KCl Form I. The study suggested potential economic utility of seaweed salt under the framework of waste to wealth.

Study on Sm3+ ion concentration in physical, structural and optical properties of magnesium-sodium fluoroborate glasses for reddish-orange visible laser applications

The influence of Sm3+ ion concentration on physical, structural and optical properties of magnesium-sodium fluoroborate glasses were studied and analyzed. The XRD, FTIR, SEM with EDS spectra validated the non-crystalline nature, presence of functional groups, morphology and elementary analysis of the prepared glasses. The bonding parameters, oscillator strength, JO intensity parameters and radiative properties were evaluated using absorption and emission analysis. In JO intensity parameters, the lower Ω2 value implied higher symmetry and less covalency at higher Sm3+ concentration. The 4G5/2 → 6H7/2 emission transition possesses higher stimulated emission cross section (15.75 ✗ 10−22) and higher branching ratio 0.533 (βcal), 0.51 (βexp) for BMNNFS1.5 glass. The higher values of radiative parameters witnessed the suitability of prepared glasses for laser applications. Decay measurements were carried out and BMNNFS0.1 glass has higher quantum efficiency as 72%. The color coordinates (x.y) of prepared glasses lie in the reddish-orange region of the CIE diagram this confirmed the reddish-orange visible laser applications.

Investigation of gamma-rays induced defects in samarium doped BaF2-Bi2O3-Li2B4O7 Glasses

The melt quenching method was used to prepare the barium bismuth lithium tetraborate glass, which has the chemical formula BaF2-Bi2O3-Li2B4O7: Sm2O3. X-ray diffraction revealed the glass's non-crystalline nature. Prior to irradiation, four emission peaks were seen at 402 nm excitation wavelengths. Co-60 radioisotope was used to irradiate glass samples. After irradiation (3–10 kGy), peak intensities change but no modification in wavelength was noticed. Similarly, substantial variations in excitation spectra at emission wavelength 598 nm were recorded. Seven peaks (350–520 nm) were detected as being allied to the Sm3+ ion transition. Although there was a noteworthy blue shift in wavelength was recorded, it is feasible that gamma-irradiation will cause modest changes in the bond angle or bond length of certain structural groups. The fluctuations in the irradiated sample's absorbance were detected by its UV–Vis spectra, which reveal the presence of iron (Fe3+) residues in its pre-compositions. Band gap studied from UV–Vis spectra with help of Tauc’s plot, which revealed changes with gamma irradiation dose. Band gap disclose the structural rapture and band breaking due to gamma irradiation.

Spectroscopic studies of Pr3+ doped red-emitting BaO–ZnO– Li2O–P2O5 glasses for luminescent devices applications

Pr3+ doped BaO–ZnO– Li2O–P2O5 (BZLP) glass samples synthesised through melt quenching route were studied. The x-ray diffraction (XRD) confirms the amorphous non-crystalline nature of undoped and doped BZLP glass. Absorption spectra show several bands in ultraviolet, visible and infrared regions. The absorption data was used in Judd-Ofelt (J-O) theory to evaluate various radiative parameters. Three peaks are visible in the photoluminescence (PL) emission spectra with the strongest peak positioned at 604 nm for which stimulated emission cross section and quantum efficiency has been assessed. The CIE color coordinates of the samples lie in the red region. The decay time values for 604 nm emission decreased with increased Pr3+ concentration. The luminescence intensity decreased to 88.12% and 82.61% of maximum value at 423 K and 473 K respectively showing high thermal stability. These BZLP glasses can work as an effective deep red-emitting component for w-LEDs and other photonic applications.