Crystalline Temperature Research Articles

In vitro degradation of fibrous bilayer poly-L-lactic acid scaffolds

Polymer degradation and mechanical properties are of paramount importance in tissue engineering. The degradation rate of polymeric scaffolds is influenced by several important material and environmental factors. In particular, the mechanical support provided by the scaffold to the surrounding tissue during tissue regeneration is critical for that it directly impacts the cell behavior through mechanical signals sensed by mechanoreceptors on the cell surface. Consequently, the principal objective of the present study was to investigate the degradation behavior of electrospun poly-L-lactic acid (PLLA) bilayer microfibrous scaffolds in pH-neutral medium. Changes in the morphology, molecular weight, crystallinity, mass loss, and thermomechanical properties of the scaffolds over an extended period were studied by scanning electron microscopy, differential scanning calorimetry, gel permeation chromatography, and tensile testing. An interplay between chain scission and orderly chain rearrangement in the polymer scaffold commenced during degradation, leading to the decrease of the molecular weight and stiffness, a constant mass loss, and an increase in crystallinity, tensile strength, and glass transition temperature, with virtually constant yield strength and melting temperature. The unchanged structure morphology and adequate matrix stiffness after prolonged degradation illuminated the potential of the bilayer PLLA scaffolds for tissue engineering and drug delivery applications. Nonetheless, modifications to the scaffold structure or surface may be required to accordingly tune the degradation rate in these applications. The experimental methodology introduced in this study can be extended to potentially investigate material degradation in other fields, such as agriculture, packaging, and disposable products.

Effect of Sn Concentration on the Structural and Thermal Properties of SnxSb20Se80−x Glasses

SnxSb20Se80−x bulk glasses were prepared using the well-known melt quenching technique, where x was taken as 7.5 at.%, 9.5 at.%, 11.5 at.% and 13 at.%. X-ray diffraction (XRD) and differential scanning calorimetery (DSC) were used to monitor the crystallinity and transition temperatures, respectively. XRD examinations showed that the 7.5 at.% and 9.5 at.% compositions were purely amorphous, while the other two compositions exhibited a crystalline structure. DSC thermograms demonstrated that 7.5 at.% and 9.5 at.% alloys had a single crystallization peak, whereas for the 11.5 at.% and 13 at.% alloys, two exothermic peaks and three peaks appeared. The glass stability and kinetics of amorphization and crystallization were studied using different approaches. The correlation between topological constraints and the dimensionality of the growth was established.

The effect of chemical crosslinking on the properties of Rotomolded high density polyethylene

AbstractIn this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general.

Translithospheric magmatic plumbing system of a late Early Cretaceous intraplate volcano in NE China: Insights from geochemistry and phenocryst composition

The magmatic plumbing systems of intraplate volcanoes are key to understanding the structure of intraplate continental crust. A late Early Cretaceous volcano in NE China provides an opportunity to reconstruct the magmatic plumbing system of an intraplate paleo-volcano. ArAr and zircon SIMS UPb dating results indicate that olivine basalts formed at 102.81 ± 0.17 Ma and hornblende andesitic rocks formed at 101.1 ± 1.1 Ma–102.84 ± 1.2 Ma. Compared with coeval olivine basalts, the hornblende andesitic rocks have lower rare earth element (REE) abundance and parallel REE patterns, indicating that the basalts and andesitic rocks have independent origins. Olivine phenocrysts only occur in the basalts and are often zoned, with cores of Fo78–86 and rims of Fo62–68, the crystalline temperatures of olivine cores are 1204–1234 °C. The plagioclases from the basalt groundmass have An = 62–63. There are two types of plagioclase phenocryst in the andesitic rocks. One has An = 62–50, the other has An = 27–34.The former is normally zoned crystals (An = 62–50 from the core to rim) with high-An rims (60–63), similar in composition to plagioclase in the groundmass of the coeval basalt. They formed at temperatures of 1140–1162 °C and pressures of 4.7–7.0 kbar, implying that they were crystallized from basaltic melt with H2O contents of 0.60–0.82 wt%. The latter is low-An phenocrysts (27–34) with high-An (∼44) rims, suggesting that they were crystallized from felsic melt and that the injection of mafic magma had happened. The orthopyroxene phenocrysts only occur in andesitic rocks and have Mg# of 80–82, and are estimated to have crystallized at 6.7–8.5 kbar, and 1206–1222 °C, implying that they were crystallized from basaltic melt. The hornblende phenocrysts in andesitic rocks are pargasite, tschermakite, magnesio-hornblende, and magnesio-hastingsite and formed at 2.4–3.5 kbar and 883–957 °C. The estimated pressure and temperature of orthopyroxene and plagioclase (An>55) phenocrysts indicate that mafic magma chambers was located at depths of over 31.0 km, whereas those of hornblende phenocrysts show that felsic magma chamber was located at 8.9–12.8 km and has H2O content of 5.8–7.3 wt%. Using these data, we construct a new model of translithospheric magmatic plumbing system for intraplate volcanoes. Mantle-derived mafic magma chamber was emplaced at the crust–mantle boundary and causes partial melting of the lower crust, which in turn produces felsic magma that would be stored in a magma chamber in the upper crust. The mafic magma chamber at the crust-mantle boundary does not crystallize in-situ, as mafic magma could occasionally rise and be repeatedly injected and mix into the felsic magma chamber in the upper crust.

The effect of modified carbon-doped boron nitride on the mechanical, thermal and γ-radiation stability of silicone rubber composites

The developing nuclear technology has increased the need for radiation-resistant and shielding materials. It is crucial to study the radiation resistance of polymers in order to prevent safety incidents brought on by the degradation of polymer performance in a nuclear environment. In this work, γ-aminopropyltriethoxy silane (KH550) was successfully grafted onto carbon-doped boron (BCN) to obtain modified BCN (BCN-KH550), then BCN-KH550 was added in silicone rubber and refined and vulcanized. The elongation at break of silicone rubber composite doped with 0.3 phr BCN-KH550 can retain (54 ± 2)% of the initial value. The addition of BCN and BCN-KH550 both increases the initial decomposition temperature of the irradiated SR. The radiation caused changes in crystallinity and glass transition temperature (Tg) were measured using differential scanning calorimetry. The difference Tg of BCN-KH550/SR0.3 before and after irradiation is 0.9 °C higher than that of SR. It is supposed that BCN protects the side group of SR during irradiation through differential thermogravimetric analysis curve and gas phase infrared spectra of the irradiation-induced gas products. BCN and BCN-KH550 can lower the hydrocarbon, CO2 and CO production by side chain breakdown in both air and nitrogen atmospheres. The presence of BCN and BCN-KH550 decrease the radiation crosslinking of SR. The outcomes demonstrate that BCN-KH550 can reduce the effects of γ-radiation crosslinking on SR by declining side chain decomposition.

Isolation and characterization of bacterial cellulose produced from soybean whey and soybean hydrolyzate

Soybean whey and soybean hydrolyzate can be used for the biotechnological production of high-value products. Herein, we isolate soybean whey (SW)-and soybean hydrolyzate (SH)-derived bacterial cellulose (BC, produced by kombucha) and characterize it by a range of instrumental techniques to reveal differences in micromorphology, crystallinity, and themal behavior. Studies have shown that the amounts of wet state BC produced from HS, SW and SH was 181 g/L, 47 g/L and 83 g/L, respectively. The instrumental analysis of BC, included SEM, AFM, FT-IR, XRD and TGA. It is shown that the FT-IR spectra of BC have a similar character, but we found differences in the micromorphology,crystallinity and thermal temperature of BC. The minimum average widths of the fibers produced from SH medium was 100 ± 29 nm. The CrI values of BC produced from SH medium was 61.8%. The maximum thermal degradation rate temperature of BC produced from SW medium was 355.73 °C. The combined results demonstrate that soybean industrial waste can be used as a cost-effective raw material for BC production.

Extrusion and characterization of recycled polyethylene terephthalate (rPET) filaments compounded with chain extender and impact modifiers for material-extrusion additive manufacturing

The continuous growth of annual production and consumption of polyethylene terephthalate (PET) is coined with increasing waste that leaks into the environment, landfills and oceans as microplastics and nano plastics fragments. Upcycling the recycled PET to make a feedstock for the fast-growing material-extrusion additive manufacturing (MEX-AM) technology can contribute to the solution and supports the concept of sustainable materials. In this work, extrudable filaments comprising recycled polyethylene terephthalate (rPET) with low-cost additives, such as pyromellitic dianhydride (PMDA) as a chain extender, styrene-ethylene-butylene-styrene terpolymer functionalized with maleic anhydride (SEBS-g-MA), a thermal modifier and toughening agent, ethylene-ethyl acrylate-glycidyl methacrylate terpolymer (E-EA-GMA), a functional reactive elastomeric impact modifier and ethylene-ethyl-acrylate (EEA), a non-reactive elastomeric impact modifier, have been fabricated using the twin-screw extruder. The optimum extrusion process parameters for producing uniform filaments of different rPET compounded formulations have been identified, this includes the extrusion die temperature of 280 °C and the screw speed of 150 ± 3 rpm. The compounded filaments are then printed into standard ASTM test specimens for thermal characterization and mechanical characterization, including glass transition and melting temperatures, crystallinity and crystallization temperature, tensile strength, tensile modulus, ductility, flexural strength, and Izod impact energy. Furthermore, the melt flow index for the filaments was measured. More significantly, the experimental data showed that compounding rPET with such additives in the reactive twin-screw extrusion process results in uniform filaments that display advantageous thermal and mechanical properties and can be used as a feedstock in the MEX-AM technology. This study suggests that compounding the recycled PET pellets with low-cost additives while extruding them into filaments for MEX-AM offers excellent potential to make high-value-added customized products from a sustainable polymer feedstock, such as prototyping, tooling, testing components or end-use internal components for small machines and cars.

Thermo-Oxidative Aging Effect on Charge Transport in Polypropylene/Ultra-High Molecular Weight Polyethylene Nanocomposites

This study investigates the impact of magnesium oxide (MgO) nanoparticles on the thermo-oxidative aging behavior of blends of polypropylene (PP) and ultra-high molecular weight polyethylene (UHMWPE). The samples, both unfilled and filled with MgO, were aged at 120 °C for varying durations of up to 672 h. The observed structural changes are not monotonic; recrystallization leads to the increased crystallinity and melting temperature of UHMWPE until 336 h. Beyond this, the consumption of the antioxidant leads to chain scission which, in turn, results in decreased crystallinity. The presence of carbonyl groups indicates chemical changes and, as such, the carbonyl index is used as an indicator of aging, with subsequent changes to charge transport. During thermal aging, the interaction between PP and UHMWPE chains at interfaces is enhanced, leading to improved compatibility and the emergence of a new single crystallization peak in PP/UHMWPE blends. Although MgO does not show evidence of elevating the crystallization temperature, implying the absence of enhanced nucleation, it acts as a compatibilizer, improving interfacial interaction compared with the unfilled blend counterparts. MgO hinders the breakage of molecular structures and impedes the diffusion of oxygen. This, in turn, results in nanocomposites filled with MgO having reduced their charge accumulation and conductivity, thus delaying the aging process compared to PP/UHMWPE blends without nanofiller.

Green modification of corn starch through repeated freeze-thaw cycles (RFTC), microwave assisted solid state acetic acid esterification (MSAE), and by dual RFTC/MSAE treatment

Freeze-thaw treatment as a green technology has been extensively applied to improve the functional properties in types of starches. The present work aimed to compare the effects of repeated freeze-thaw cycles (RFTC), microwave assisted solid state acetic acid esterification (MSAE), and their combination (RFTC/MSAE) on structural and functional properties of corn starch (NS). RFTC/MSAE treatment provided higher esterification efficiency (68.7%) for the esterified starches compared to MSAE alone (32.6%) due to raised surface area of starch granules after applying RFTC. Esterification of starch chains by using acetic acid was confirmed through FTIR (1700 cm−1) and 1H NMR (2 ppm). SEM images showed that the pores and channels were formed on granules after applying RFTC treatment, while no change in their size was observed. Also, XRD and DSC were employed to scrutinize the changes in crystalline structure of granules after applying each modification. The dual treatment decreased crystallinity, viscosity, swelling power, digestibility rate, and gelatinization temperatures, while increased amylose extent, whiteness, solubility, and paste clarity compared to those of NS. The conformity of the dual treatment with principles of green chemistry was investigated by Eco-scale methodology. Starch acetate synthesized through the dual modification can be utilized in formulation of low-calorie foods due to its highlighted features such as low digestibility rate (RS: 54.7%) and viscosity (455 cp).

Mechanical Properties, Radiation Resistance Performances, and Mechanism Insights of Nitrile Butadiene Rubber Irradiated with High-Dose Gamma Rays.

The radiation effect of materials is very important and directly related to the safety and reliability of nuclear reactors. Polymer materials, one of the indispensable materials in nuclear power equipment, must withstand the ordeal of high-energy ionizing rays. In this work, through screening different γ-ray dose irradiation conditions, we systematically and comprehensively study the changes in the structure and properties of nitrile butadiene rubber (NBR) before and after γ-ray static irradiation at a high dose rate, and master the rule and mechanism of the γ-ray static irradiation effect of these polymer materials. The mapping relationship between the macroscopic properties, microstructure, and irradiation dose of NBR is accurately characterized. With an increase in total irradiation dose, the C=C double bond reaction occurs, and the C≡N bond, C=C, and C=O participate in the hyper crosslinking reaction. The glass transition temperature (Tg) increases with the cumulative irradiation amount. With the increased total irradiation amount, the degree of rubber cross-linking increases, causing an increased crystallinity and decomposition temperature. A growing amount of gamma irradiation causes the mechanical properties of the rubber to degrade simultaneously, increasing the shore hardness while decreasing the tensile strength and ultimate elongation at break. When the cumulative amount reaches 1 MGy, the ultimate elongation at break decreases significantly. A cumulative dose of radiation resistance of 4 MGy can be achieved by the samples. This work can provide theoretical and experimental support for the long-term stability of nitrile butadiene rubber and its derivatives in nuclear radiation fields and space radiation conditions.

Poly (butylene succinate): Low-temperature nucleation and crystallization, complex morphology and absence of lamellar thickening

Melt-crystallization of poly (butylene succinate) (PBS) at largely different melt-supercooling was analyzed by X-ray scattering techniques, direct imaging using microscopy, and by fast scanning chip calorimetry, with the latter employed to achieve high melt-supercooling. Crystallization at 100 and 20 °C, representing structure formation at low and high melt-supercooling, respectively, yields lamellae with thicknesses of around 8 and 4 nm. In both cases, lamellar thickening is excluded as main mechanism of isothermal secondary crystallization, suggesting that absence of intracrystalline chain-sliding diffusion is not dependent on the absolute value of the thickness of lamellae. The wide-angle X-ray pattern of PBS crystallized at low temperature shows less and broader peaks than in case of PBS crystallized at high temperature, pointing to presence of crystal defects, and causing an enlargement of the unit cell. Secondary crystallization leads to an increase of the melting temperature, being distinctly larger (per unit annealing time) for low-temperature crystallized PBS. Since lamellar thickening is absent, and imperfection of the bulk crystal structure persists even on long-term annealing, merging of crystalline blocks and lateral crystal growth at the crystallization temperature, for explaining the observed increases of the crystallinity and melting temperature, are suggested. Though there is detected a large rigid amorphous fraction in PBS crystallized at high supercooling, vitrification only occurs continuously on cooling, after the isothermal crystallization process.

FTIR, Raman and XPS Structural Studies of Bismuth Modified Phosphosilicate Glasses for Orange-Red Lighting Sources

Bismuth-oxyfluoride glasses with the chemical composition of P2O5+NaF+SiO2+Bi2O3 (PNSiBi) have been prepared by melt-quenching method and studied their structural and thermal properties through Raman, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) and differential thermal analysis. Moreover, elemental analysis of these glasses has been performed with energy-dispersive X-ray (EDX) spectroscopy. The glass transition and crystalline temperatures of the glasses have been estimated using differential thermal analysis (DTA). The vibrational modes of these glasses have been studied through Fourier transform infrared (FTIR) and micro-Raman analysis. Elemental compositions and binding energies of the PNSiBi glasses have been explored from XPS analysis. Binding energies of PNSiBi glasses have been obtained as 100 eV for Silicon (Si2p), 132 eV for Phosphorous (P2p), 157 and 163 eV for Bismuth (Bi 4 f) and 1069.7 eV for Sodium (Na1s). The valance states and binding energies of these elements unveiled orthophosphate (PO4)2− type structure, which forms trisodium phosphate [Na3(PO4)] with sodium and fluorides of BiF3, and (PF6)−. A 1 mol% Sm2O3 doped PNSiBi05Sm01 glass unveiled robust emission among other concentrations of Bi ions proposed that PNSiBi05 glass could be an effectual host for laser and other active photonic applications.

Preparation, characterization and in vitro digestion of octenyl succinic anhydride-modified porous starch with different degrees of substitution

Octenyl succinic anhydride modified porous starch (OSA-PS) with degrees of substitution (DS) from 0.0123 to 0.0427 were prepared by aqueous phase method. From SEM, PS had a porous structure which showed a rough and corrosive surface after esterification with OSA. FT-IR revealed the characteristic peaks of OSA-PS at 1725 cm−1 and 1570 cm−1. From 1H NMR spectra, OSA-PS displayed extra chemical signal peaks at 0.85 ppm, 1.25 ppm and 1.96 ppm. These results fully demonstrated that OSA groups were successfully grafted onto PS. Furthermore, as DS increased, the specific surface area (5.6464 m2/g), pore volume (0.9959 × 10−2 cm3/g) and methylene blue adsorption capacity (24.3962 mg/g) of OSA-PS reached the maximum, while its relative crystallinity (26.8112 %) and maximum thermal decomposition temperature (291.96 °C) were the minimum. In vitro digestion studies showed that with the increase of DS, OSA-PS' contents of rapidly digestible starch and slowly digestible starch decreased from 9.06 % to 6.27 % and 28.38 % to 14.61 %, respectively. In contrast, its resistant starch had an increase in content from 62.56 % to 79.12%. The results provided an effective method for obtaining a double-modified starch with high specific surface area and anti-digestibility, thus broadening the industrial application of starch.

Starch multiscale structure and physicochemical property alterations in high-quality indica rice quality and cooked rice texture under different nitrogen panicle fertilizer applications

The starch multiscale structure, physiochemical properties, grain quality and cooked rice texture of high-quality early and late indica were analyzed under nitrogen panicle fertilizer (low panicle fertilizer, LPF; middle panicle fertilizer, MPF; high panicle fertilizer, HPF) treatments and their internal relations were investigated. Compared to the MPF treatment, the starch granules in HPF and LPF had more surface-proteins and irregular voids for high-quality early and late indica rice cultivars, respectively. Nitrogen panicle fertilization application increased amylopectin medium and long chains as well as protein content, resulting in higher relative crystallinity and gelatinization temperatures. Moderate changes in starch multistructures and physicochemical properties such as branching degree, amylopectin medium chain, and pasting viscosities derived from MPF treatment significantly improved processing, appearance qualities and cooked rice texture. Additionally, the decrease in starch branching, gelatinization temperatures, and granule uniformity along with an increase in large granules, breakdown, and △Hgel under MPF treatment were the main reasons for improving rice textural properties.

Regiospecific Incorporation of Acetylene Linker in High‐Electron Mobility Dimerized Acceptors for Organic Solar Cells with High Efficiency (18.8%) and Long 1‐Sun Lifetime (> 5000 h)

AbstractThe commercialization of organic solar cells (OSCs) requires both high power conversion efficiency (PCE) and long‐term stability. However, the lifetime of the OSCs containing small‐molecule acceptors (SMA) should be significantly enhanced. In this study, a series of planarity‐controlled is developed, high electron mobility dimerized SMAs (DSMAs) and realize OSCs with high‐performance (PCE = 18.8%) and high‐stability (t80% lifetime = 5380 h under 1‐Sun illumination). An acetylene linker with a planar triple bond is designed for dimerization of SMA units to afford the high backbone planarity necessary to achieve high crystallinity and electron mobility. To further engineer the molecular conformation and electron mobility of the DSMAs, different regioisomers of a Y‐based SMA are dimerized to yield three regioisomerically distinct DSMAs, denoted as DYA‐I, DYA‐IO, and DYA‐O, respectively. It is found that the crystallinity, electron mobility, and glass transition temperature of the DSMAs gradually increase in the order of DYA‐O, DYA‐IO, and DYA‐I, which, in turn, enhance the PCE and device stability of the resulting OSCs; DYA‐O (PCE = 16.45% and t80% lifetime = 3337 h) < DYA‐IO (PCE = 17.54% and t80% lifetime = 4255 h) < DYA‐I (PCE = 18.83% and t80% lifetime = 5380 h).

Co‐crystallization behaviors and thermo‐physical properties of SSPCM consisting of an extra low melt viscosity HDPE and paraffin waxes

AbstractShape stabilized phase change materials (SSPCMs) consisting of an extra low melt viscosity high‐density polyethylene (lv‐HDPE) and paraffin waxes (PW) were fabricated using a twin screw extruder. Thermal and mechanical properties of these composites were assessed. The latent heats (ΔH) of the SSPCMs fabricated were up to 78 J g−1. Co‐crystallization between lv‐HDPE and paraffin waxes increased with increasing wax content. Dynamic mechanical thermal analysis confirmed the paraffin wax having a higher melting point (H‐PW, Tm ranging from 56 to 58°C) plasticized the lv‐HDPE, decreasing both its crystalline content and melting temperature. Static mechanical testing, disregarding the form of deformation (tension, flexural, and compression), showed addition of paraffin waxes resulted in a diminution of all mechanical properties of lv‐HDPE, but the properties of the composites with H‐PW were good in comparison to those with a lower melting point wax (L‐PW, Tm ranging from 18 to 23°C). Evidences from Cole–Cole plots obtained from oscillatory rheology experiments showed there was no interaction between lv‐HDPE and H‐PW, inducing a heterogeneous blend in contrast to the more homogeneous lv‐HDPE/L‐PW composites.

Characterization of Bamboo Culm as Potential Fibre for Composite Development.

This study aims to evaluate how age, harvesting seasons, and culm height affect the properties of various bamboo species. The properties of bamboo fibres for composite development in Ethiopia have not been investigated so far. In this study, the properties of Y. alpina and B. oldhamii were scientifically investigated for bamboo culm structural applications and bamboo fibre composite development based on age and the harvesting season. Y. alpina was collected at Injibara and Mekaneselam which are located in east Gojjam and south wollo, whereas B. oldhamii was collected at Kombolcha which is located in south Wollo, Ethiopia. Three representatives of bamboo plants were collected in the three regions, namely from three age groups, across two harvesting months. The highest and lowest moisture content and shrinkage were measured at the ages of one year and three years, respectively, whereas basic densities were measured at the ages of three years and one year. The harvest month of November yields higher moisture content and shrinkage but lower basic densities compared to February. Yushania alpina has a higher moisture content and shrinkage but lower basic densities compared to Bamusa oldhamii. The current research demonstrates that the three-year-old groups and the harvesting month of February produce yields more suited for construction and structural purposes due to the ensuing good dimensional stability after drying. From the highest to the lowest percentage of the degree of crystallinity of the yield, it is that derived from Inj., followed by Meka., and then Kombolcha, respectively. Bamboo fibres have high powder crystals and degradation temperatures which make them suitable for composite development at two year old. Yushania alpina has a higher degree of crystallinity and degradation temperature of cellulose compared to Bambusa oldhamii.

Development of packaging based on PLA/POE/SeNPs nanocomposites by blown film extrusion method: Physicochemical, structural, morphological and antioxidant properties

The aim of the current study was to prepare a novel and biodegradable polylactic acid (PLA) film by the addition of different concentrations of polyolefin elastomer (POE; 10, 20 and 30 wt%), selenium nanoparticles (SeNPs; 1.5 wt%) and triethyl citrate (TEC) as plasticizer in order to modify physical and mechanical properties of the film. The SeNP with mean particle diameter of 170 nm was successfully prepared by using ascorbic acid and polyvinyl alcohol as the reducing and binding agent. The FT-IR results showed new chemical interactions among PLA matrix and incorporated POE and SeNPs. Tensile strength and Young’s Modulus of the nanocomposite films decreased by adding SeNPs and POE, whereas the elongation at break of the films significantly increased (p < 0.05). DSC analysis indicated that the crystallinity and melting temperature of PLA matrix were reduced by incorporation of SeNPs and POE. Swelling of nanocomposite films were significantly higher than that of neat PLA (p < 0.05). Adding SeNPs and POE, caused a notable reduction in water vapor permeability (WVP) of nanocomposite films (by 77% in the sample with 20% POE). Scanning electron microscopy (SEM) images confirmed the homogenous, uniform, and compact structure of the nanocomposites at 10% POE. Moreover, the anti-oxidant activity increased significantly with the incorporation of POE. Overall, the developed PLA/POE/SeNPs composite films can potentially be used for food packaging with enhanced barrier and mechanical properties.

Broadband dielectric behaviour and structural characterization of PVDF/PMMA/OMMT polymer nanocomposites for promising performance nanodielectrics in flexible technology advances

Characterization of broadband dielectric behaviour of polymer nanocomposites (PNCs) is vital for the exploration of efficient nanodielectrics as energy storage, flexible dielectric substrates, and insulators in a wide range of advanced electronic device technologies. Accordingly, herein, PNC films based on poly(vinylidene fluoride) (PVDF)/ poly(methyl methacrylate) (PMMA) blend matrix (80/20 wt/wt%) dispersed with 0, 2.5, 5, and 10 wt% organo-modified montmorillonite (OMMT) nanoclay are developed by state-of-the-art homogenized solution casting method. These PVDF/PMMA/OMMT compositions based flexible PNC films are characterized in detail by employing a scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) device, x-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectrometer, differential scanning calorimeter (DSC), inductance-capacitance-resistance (LCR) meter, and impedance/material analyzer (IMA). The SEM microimages, XRD traces, and FTIR spectra evidenced appreciable homogeneity and surface morphology, intercalated and exfoliated OMMT structures, and the α, β and γ-phase crystallites of the PVDF in these complex semicrystalline PNCs. The DSC thermograms confirmed a significant alteration in the melting temperature and degree of crystallinity of the PVDF crystallites with the increased amount of OMMT in the 80PVDF/20PMMA blend host matrix. The broadband dielectric dispersion spectra over the frequency range of 20 Hz−1 GHz explained the contribution of interfacial polarization in the complex dielectric permittivity at lower experimental frequencies, whereas at higher frequencies permittivity is ruled by dipolar polarization in these composites at 27 °C. The dielectric loss angle tangent and electric modulus spectra revealed an intense structural dynamics relaxation process in the upper radio frequency region. The influence of OMMT concentration on the dielectric permittivity and electrical conductivity is explored. The detailed dielectric and electrical characterization of these innovative semicrystalline composites with important structural and thermal properties revealed their immense potential as high-performance nanodielectrics for highlighting current applications of broadband frequency range electrical and electronic device technologies.

Alternative dental impression fillers made of nanorod glutinous rice flour particles through precipitation

In this work, nanorod particles were synthesized from a locally available source, glutinous rice flour, using sodium hydroxide (NaOH) through a simple precipitation process. The synthesized nanofillers were then presented as an alternative organic filler for dental impression application to support the making of a diagnostic and working model. Dynamic Light Scattering, Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy, x-ray Diffraction, Energy Dispersive Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Colorimeter were used to characterize the fillers. The particle size measurement, morphology interaction, and composition of glutinous rice flour nanorod particles were also investigated. The cell viability using 3T3L1 cells was assessed to determine the safety of nanorod particles using the MTT assay and trypan blue solution. All treated samples exhibit a change in particle morphology from polyhedral to rod. Additionally, a decrease in crystallinity, dehydration, and gelatinization temperature was observed. The functional group interacting with sodium hydroxide also changes slightly after size reduction. The samples treated with 3000 centrifugation speed without surfactant addition showed changes from the control sample’s 3931.71 nm to the smallest average width particle size of 73.26 nm with an average length of 865.15 nm. All of the treated samples with NaOH and NaOH-surfactant additions met the non-cytotoxicity acceptance criteria in the range of 73.54%–99.58%, according to the cell viability results. The incorporation of 15 wt% of the synthesized nanorod fillers resulted in a 20 μm continuous line as the impression materials specimen, yielding a satisfactory detail reproduction test result. In conclusion, nanorod particles with biocompatible properties have been successfully manufactured and can potentially be used in the future as an alternative dental impression filler materials.