Fourier Transform Infrared Spectrometer Research Articles

Preparation of the fluorinated graphene/epoxy resin anti-corrosion composite coating

In order to enhance the corrosion resistance of epoxy resin (EP) coating system, we put forward a facile approach to prepare hydrophobic fluorinated graphene (FG) filler for the EP coating by one-pot hydrothermal reaction in this work. Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact angle measuring instrument and scanning electron microscopy (SEM) were employed for the FG characterization. The SEM images of fracture morphology revealed that FG uniformly dispersed in epoxy resin matrix. Additionally, the excellent water resistance and the lower coefficient of friction of FG/EP coating was confirmed through the water absorption test and friction and wear test machine. The electrochemical impedance spectroscopy (EIS) demonstrated that the impedance value at the low frequency (|Z|0.01Hz) of 0.50 wt% FG/EP was 3.49 × 107 Ω·cm2 after being immersed in 3.5 wt% NaCl solution for 60 days, which was about 2 orders of magnitude higher than that of the pure EP coating (4.74 × 105 Ω·cm2). The 0.50 wt% FG/EP coating exhibited the superior anti-corrosion performance due to the FG with the two-dimensional sheet structure, uniform dispersion and hydrophobicity properties.

Hyperthermia and biological investigation of a novel magnetic nanobiocomposite based on acacia gum-silk fibroin hydrogel embedded with poly vinyl alcohol

The design and synthesis of biocompatible nanostructures for biomedical applications are considered vital challenges. Herein, a nanobiocomposite based on acacia hydrogel, natural silk fibroin protein, and synthetic protein fibers of polyvinyl alcohol was fabricated and magnetized with iron oxide nanoparticles (Fe3O4 MNPs). The structural properties of the hybrid nanobiocomposite were investigated by essential analyses such as Fourier Transform Infrared Spectrometer (FTIR), Field emission scanning electron microscopy (FE-SEM), and X-ray powder diffraction)XRD(analyses, Thermogravimetric and Differential thermogravimetric analysis (TGA-DTG), Vibrating-sample magnetometry (VSM), and Energy Dispersive X-Ray Analysis (EDX). The biological activities and functional properties of the prepared magnetic nanobiocomposite were studied. Results proved that this nanobiocomposite is non-toxic to the healthy HEK293T cell line. In addition, the synthesized nanobiocomposite showed an approximately 22 % reduction in cell viability of BT549 cells after 72 h. All results confirmed the anti-cancer properties of nanobiocomposite against breast cancer cell lines. Therefore, the prepared nanobiocomposite is an excellent material that can use for in-vivo application. Finally, the hyperthermia application was evaluated for this nanobiocomposite. The SAR was measured 93.08 (W/g) at 100 kHz.

Synthesis and Characterisation of Cellulose Acetate/Polyethylene Glycol Membrane from Pineapple Hump by Phase Inversion Method

Cellulose is a natural polymer contained in growing fibres, such as pineapple fibres. Cellulose can be modified into cellulose acetate, a modified polymer that can be used in the synthesis of a cellulose acetate/polyethylene glycol (CA/PEG) membrane. The phase inversion method was used in this study to produce CA/PEG membranes. Variations in polyethylene glycol (PEG) concentration with a ratio of 1:1 to cellulose acetate, where variations in PEG concentrations used are 2%, 5% and 8%. Acetone and dimethylformamide are used as organic solvents. Membrane morphological analysis using scanning electron microscopy (SEM) and functional group analysis using a Fourier transform infrared (FTIR) spectrometer were performed for membrane characterisation. The result of the synthesis of the CA/PEG membrane is in the form of a thin white layer. The characterisation results of the FTIR spectrometer showed the vibration of the carbonyl bond at wavenumber 1729 cm−1 and the vibration of the hydroxyl bond torque at the wave number 648 cm−1, where the vibration intensity decreased with each addition to the concentration. The results of SEM characterisation show that the increase in PEG concentration increases the percentage porosity of the membrane. The membranes with 2%, 5% and 8% PEG have porosity percentages of 51.54%, 68.70% and 73.50%, respectively. As the membrane with 2% PEG has the lowest percent porosity, it has more potential in removing or filtering solutes from a fluid.

Estimated of Pomegranate Peel Waste for Biosorption of Cu (II) & Pb(II) Ions From Aqueous Solutions

This study intends to explore the waste natural materials’ adsorption capability. The use of pomegranate peels was investigated to see the chances of eradicating Pb(II) and Cu(II) ions from the aqueous solutions. Adsorption capability was evaluated using batch adsorption experiments, which also evaluated the impact of solution pH and initial metal concentration. The ideal biosorption conditions included a pH of 6.0, a dose of 0.1 g of biomass, and an equilibrium duration of 90 minutes. The adsorption data fit in a way that was comparable to the isotherm models by Freundlich and Langmuir. Pomegranate peel (PGP) was tested for its affinity and adsorption capability. Based on the values of the separation factor (RL) and Freundlich constant (n), it seems that the metal ions were taken up onto biosorbents in a preferred manner. According to this study's conclusions, the equilibrium data suit the Freundlich and Langmuir isotherms rather nicely. According to correlation coefficient data, the maximal sorption capacity of the produced pomegranate peel is 5000 mg/g. The Fourier Transform Infrared Spectrometer (FTIR), Energy Dispersive X-ray Spectrometer (EDX), and Scanning Electron Microscope (SEM) were utilised in the characterisation examinations. As a result, distinct aggregates formed on the surface of the biosorbent. In the characterisation experiments, an energy-dispersive X-ray spectrometer (EDX) and a scanning electron microscope (SEM) were employed. Different aggregates developed on the biosorbent surface as a result of contact with metal ions. On the surface of the biosorbent, distinct aggregates formed as a result of interaction with metal ions. Either via complexation or electrostatic attraction, the metal ions attached themselves to the biosorbents' active sites.

Insight into influence of degradation metabolism of Firmicutes on the microstructure of anthracite coal

Promoting the permeability of deep, low-permeability coal seams through biological means is currently a research hotspot for enhancing the efficiency of coalbed methane extraction. In this study, we selected anthracite coal from Sihe Mine for microbial anaerobic degradation culture experiments. The effects of adding functional microorganisms on the microstructure of anthracite coal were analyzed by high-throughput sequencing of samples before and after the cultivation and microcharacterization experiments of coal samples. The results showed that the maximum methane migration during the period of biodegradation reached 0.640 mL/g coal, and the cumulative migration of the whole cycle was as high as 1.318 mL/g coal. 16S rRNA high-throughput sequencing results indicated that the bacterial community structure had undergone significant succession after the biodegradation experiments, and that the Firmicutes represented by Bacillus(82.41% of the total) occupied the dominant niche. Metabolic pathway analysis based on Kyoto Encyclopedia of Genes and Genomes (KEGG) database showed that the degradation of aromatic compounds by microorganisms appeared to be significantly enhanced by the addition of nitrogen sources. Also, the relative abundance of a number of key metabolic enzyme genes capable of catalyzing the oxygen-containing functional groups into the structure of the coal molecule and the de-cyclization reaction were increased. Fourier Transform Infrared Spectrometer (FTIR) experiments revealed that biodegradation stimulated by nitrogen source reduced the aromaticity of coal by 59.62% and enhanced the hydroxyl functional group content by 1.822 times. Mercury pressure and low-temperature nitrogen adsorption experiments showed that the micropore pore volume of the treated coal decreased by 34.09%, and the macropore pore volume accounted for an increased 168.28%, with an average pore size increment of 60.72 nm. Therefore, the nitrogen source can stimulate Firmicutes on the degradation of polycyclic aromatic hydrocarbon and increase the content of oxygen-containing functional groups, which might promote the development of pores in coal and make the difficult-to-desorption methane migrates rapidly. This study investigated the effect of nitrogen source on the degradation of coal by Firmicutes. This will help improve the efficiency of gas extraction and ensure the safety of coal mine production.

Идентификация цефалоспориновых антибиотиков с использованием ИК-спектроскопии и хемометрических алгоритмов

The use of mid-field infrared spectroscopy in combination with chemometric algorithms for the identification of cephalosporin antibiotics in the form of injectable powders is demonstrated. III generation cephalosporins have been selected as objects of the study: ceftriaxone, ceftazidime, cefotaxime, which are widely used in pharmaceutical practice. IR spectra of the medical preparations have been recorded using an FT-801 Fourier transform IR spectrometer with an attenuated total reflection (ATR) attachment. The results have been processed in the Microsoft Excel computer package with the XLSTAT add-in using the principal component analysis (PCA), the k-means method and agglomerative hierarchical clustering (AНC). It has been shown that using these algorithms it is possible to identify the studied cephalosporin antibiotics from different manufacturers. In the PCA method, points corresponding to samples are located in separate quadrants depending on the nature of the antibiotic. The k-means method has been used to divide antibiotics into classes; differences are also visible in the classes themselves, depending on the manufacturer. The clearest separation of cephalosporins is observed when data are presented using the AHC method in the form of a dendrogram.

Antibacterial and Antibiofilm Potential of Chlorophyllin Against Streptococcus mutans In Vitro and In Silico.

Streptococcus mutans is a leading causative agent of dental caries and exerts pathogenicity by forming biofilms. Dental caries continues to be a significant public health issue worldwide, affecting an estimated 2.5 billion people, showing a 14.6% increase over the past decade. Herein, the antibacterial potential of Chlorophyllin extracted from Spinacia oleracea was evaluated against biofilm-forming S. mutans via in vitro and in silico studies. The antimicrobial activity of chlorophyllin extract against S. mutans isolates was tested using the agar well diffusion method. Chlorophyllin extract was also tested against biofilm-forming isolates of S. mutans. Chlorophyllin was docked with the antigen I/II (AgI/II) protein of S. mutans to evaluate its antimicrobial mechanism. The chemical structure and canonical SMILES format of Chlorophyllin were obtained from PubChem. Additionally, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) analyses of Chlorophyllin were performed using ADMETlab 2.0 to assess its pharmacokinetic properties. An agar well diffusion assay revealed that all S. mutans isolates were susceptible to Chlorophyllin extract and showed a variety of inhibition zones ranging from 32 to 41 mm. Chlorophyllin reduces the biofilm strength of four isolates from strong to moderate and six from strong to weak. The antibiofilm potential of Chlorophyllin was measured by a reduction in the number of functional groups observed in the Fourier Transform Infrared Spectrometer (FTIR) spectra of the extracellular polymeric substance (EPS) samples. Chlorophyllin showed binding with AgI/II proteins of S. mutans, which are involved in adherence to the tooth surface and initiating biofilm formation. The ADMET analysis revealed that the safety of Chlorophyllin exhibited favorable pharmacokinetic properties. Chlorophyllin stands out as a promising antibacterial and antibiofilm agent against biofilm-forming S. mutans, and its safety profile highlights its potential suitability for further investigation as a therapeutic agent.

Optimal development and performance evaluation of electrolytic graphene oxide synergistic all-solid waste cementitious grouting material

The low-carbon and friendly alkali-activated cementitious (AACM) grouting material has a broad application potential in the field of grouting engineering due to its excellent workability and higher early strength and is expected to replace cement grouting material in the future. In this study, an AACM grouting material using electrolytic graphene oxide (EGO) synergistic ground granulated blast-furnace slag (GGBS)-fly ash (FA)-rice husk ash (RHA) solid waste was proposed. The optimal ratio was 0.025 % EGO, 8.13 % FA, 26.6 % RHA, and 65.27 % GGBS, which determined by the Analytic Hierarchy Process (AHP), Entropy Weight Method (EWP), and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) methods. A systematic evaluation of the mechanical properties and impermeability of the proposed AACM grouting material was conducted by macro experiments (compressive strength, flexural strength and permeability) and micro experiments (XRD, SEM-EDS, Fourier Transform Infrared Spectrometer (FTIR) and Thermogravimetry Analysis (TG)). The results show that the increment of compressive strength and flexural strength for AACM grouting material with 0.025 % EGO compared to the cement water-glass grouting material were 161.2 % and 2.9 %, respectively, at 7-day. While the permeability coefficient compared to AACM grouting material without EGO decreased by 43.9 %. The XRD results show that the EGO reduced the intensity of AACM grouting material diffraction peaks, and FTIR analysis reveals that EGO increased the visibility of O-C-O characteristic peaks. These confirmed that EGO could enhance the degree of alkali activation reaction. The TG results indicate that the addition of EGO promoted the formation of carbonates, which strengthen the mechanical properties of AACM grouting material. The SEM-EDS results demonstrate that EGO increased the Ca/Si ratio, promoted the formation of highly polymerized hydration products.

Heat and mass transfer visualisation of an exothermic acid-base microfluidic reactor using infrared thermospectroscopy

ABSTRACT Here, a microfluidic reactor that is transparent in the mid-wave infrared spectrum with an effective path length of 38 µm is developed for characterisation via operando Fourier-transform Infrared (FTIR) thermospectroscopy. This imaging technique couples an infrared (IR) camera with an FTIR spectrometer to quantify heat and mass transfer in the exothermic acid-base reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH). The absorbance fields of the reaction are used to simultaneously derive the molar concentration fields of the reactants (HCl and NaOH) and products (sodium chloride [NaCl]) at the microscale through a linear inverse method. The heat generated at the reaction interface is visualised through a thermal field captured from the measured proper emission. Concentration and thermal fields are then compared to an advection-diffusion model for validation. The results proposed in this work present a refined contactless calorimetry process for characterising the heat and mass transport in an acid-base reaction. Further refinement of this work will enable accurate and non-invasive measurements for the enthalpy of reaction in chemical reactions.

Fabrication of a macro-micro porous structure on PEEK surface by ultrasound-assisted sulfonation

A multiscale porous surface can significantly improve the osseointegration of biomedical implants, but it cannot be facilely achieved on the Poly-ether-ether-ketone (PEEK) surface. In this work, a macro-micro porous structure was prepared on the PEEK surface by ultrasound-assisted sulfonation. The surface morphologies, chemical compositions, functional groups, surface roughness, and wettability of the porous structures at different sulfonation times were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectrometer (FTIR), laser scanning confocal microscope (LSCM), and contact angle measurement, respectively. The results demonstrate that a macro-micro porous structure is formed on the PEEK surface, with macropore sizes ranging from 50 to 250 μm and micro-sized pore sizes ranging from 0.2 to 1.5 μm. Moreover, the results of in vitro cellular experiments demonstrate that the macro-micro porous structure can promote cell adhesion and proliferation of BMCSc. The formation mechanism of the multiscale porous structures has also been discussed. This novel approach may provide a simple and effective strategy for surface modification of PEEK to improve its mechanical and biological response.

Reinforcing biomimetic cementitious composites by aligned hierarchical carbon fibers

Cementitious composites reinforced by carbon-based fibers of varied length scales still face limitations of a single dimension, anisotropic alignment, smooth surface, or poor dispersion. In this study, we developed a bioinspired, hierarchical reinforcing structure that enables multiscale coupling of mechanical properties and directional fiber alignment, significantly improving the load-bearing capacity of cementitious composite. The aligned hierarchical reinforcing structure was synthesized by grafting CNTs onto microscale CFs-COOH via an esterification reaction and a nozzle-injected technique. Parameters for synthesizing the CNTs grafted aligned CF (ACF-CNTs) were optimized considering oxidation solutions, grafting techniques, CNTs geometry, and CNTs concentrations. The chemical bond between CF and CNTs was examined by Laser Raman Spectrometer (LRS), Fourier Transform Infrared Spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS), respectively. Results indicate that CNTs are uniformly and densely grafted onto CF via ester linkage, forming a hierarchical reinforcing structure. Mechanical measurements show that 1 wt% ACF-CNTs results in a maximum flexural strength of 34.76 MPa and a maximum improvement of 297.12 % (compared to plain cement paste) in the biomimetic cementitious composites. Analysis based on fiber alignment, interface transition zone, and failure mode of CF-CNTs/CNTs suggests that multiscale coupling of mechanical properties and directional fiber alignment are the main reinforcing mechanisms.

Assessment of selenium-enriched deactivated probiotic yeast efficiency in patulin detoxification in apple juice

Patulin (PAT) contamination in fruits, particularly apples and their products, poses a significant health hazard. This research aimed to eliminate PAT from simulated juice solution and actual apple juice using live and ultrasonically deactivated (D) probiotic yeasts, specifically Saccharomyces cerevisiae (S.c) and Saccharomyces boulardii (S.b) yeasts enriched with selenium (Se). The Se-enriched yeasts were analyzed using various techniques including Fourier transform infrared spectrometer (FT-IR), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and Inductively coupled plasma–optical emission spectroscopy (ICP-OES). The study assessed the effects of yeast type, contact time (2–18 h), ultrasound treatment, and initial concentration of PAT (50–150 μg.L−1) on PAT adsorption. The most effective treatment involved the Se-S.b-D yeast strain, with an initial PAT concentration of 50 μg.L−1 for 10 h, exhibiting notable toxin removal percentages in both the apple juice simulator (98.27% reduction equivalent to 49.135 μg.L−1) and real apple juice (87.19%). The detoxification outcomes were consistent with pseudo-second-order kinetic and Langmuir isotherm models, indicating that Se-S.b-D is a biocompatible and low-cost strain with high efficiency to remove PAT in aqueous solutions.

Investigation of kinetics, reaction mechanisms, thermodynamics, and synergetic effects in co-pyrolysis of wood sawdust and linear low-density polyethylene using the thermogravimetric approach.

This study focused on investigating thermal degradation behaviors, kinetics, reaction mechanisms, synergistic effects, and thermodynamic parameters of wood sawdust (WSD), linear low-density polyethylene (LLDPE), and their blends (LW1:3, LW1:1, and LW3:1) during co-pyrolysis in a thermogravimetric analyzer (TGA). Thermal behavior exhibited a LW1:3 blend (25 wt.% LLDPE) showing significant mass loss at lower temperatures (150 to 300°C) compared to the individual feedstocks, such as 150 to 400°C and 300 to 520°C for WSD and LLDPE, respectively. The iso-conversional methods (KAS, FWO, and FM) were used to determine the kinetic parameters (Ea and A), and the activation energy drop was highest for the LW1:3 blend. According to the master plots, the third-order reaction (O3), nucleation (P2/3), and diffusional model (D4) were the predominant reaction mechanisms for the co-pyrolysis of the LW1:3, LW1:1, and LW3:1 blend, respectively. The thermodynamic parameters demonstrate that a small amount of plastic addition into WSD can improve the reactivity of the blend, shorten the reaction time, and cause less energy-intensive reactions. The values of ΔH, ΔG, and ΔS also confirmed the co-pyrolysis process's spontaneity and endothermic nature. The Fourier transforms infrared spectrometer (FTIR) spectra of raw feedstock, blends, and their biochar revealed some of the peaks were shifted, the intensity was reduced, and disappearance can happen when the temperature was increased. Using the experimental and theoretical/predicted activation energies, the parity chart illustrates the synergistic effects of co-pyrolysis of different blends, and the LW1:3 blend has a favorable synergistic impact. These results could be helpful in process optimization and designing an effective reactor system for co-pyrolysis.

γ-Cyclodextrin-metal organic framework as a carrier for trans-N-p-coumaroyltyramine: A study of drug solubability, stability, and inhibitory activity against α-glucosidase.

γ-Cyclodextrin-based metal-organic frameworks (γ-CD-MOF) were successfully synthesized using the solvent diffusion method and applied as carriers for trans-N-p-coumaroyltyramine (N-p-t-CT, NCT) to study the solubability, stability, sustained release and inhibitory activity against α-glucosidase. The solubilization effect of γ-CD-MOF on N-p-t-CT was performed using impregnation (NCT@CD-MOF-1) and co-crystallization (NCT@CD-MOF-2) methods. X-ray diffraction, scanning electron microscope (SEM), fourier transform infrared spectrometer (FTIR), and N2 adsorption/desorption were used to characterize the MOFs before and after loading NCT. The results showed that NCT@CD-MOF-2 had a better solubability for N-p-t-CT, 145.03μg/mg of drug loading capacity could be achieved, and the solubility of NCT@CD-MOF-2 in water was 366 times higher than free N-p-t-CT. In addition, the stabilities of N-p-t-CT under temperature, UV light and pH conditions were greatly improved after encapsulation in γ-CD-MOF. Furthermore, NCT@CD-MOFs had a sustained release of N-p-t-CT over an extended period in vitro due to the primary encapsulation in pore structures. Notably, γ-CD-MOF loaded with N-p-t-CT showed superior inhibitory activity against α-glucosidase compared to free N-p-t-CT. Cytotoxicity studies demonstrated that NCT@CD-MOF-2 had low toxicity in vitro and perfect biocompatibility with HL-7702 cells, and γ-CD-MOF could reduce the toxicity of free N-p-t-CT at higher concentrations.

Investigate Performance of ATGF nanocomposite based on guar gum polymer for adsorption of Congo Red dye and alpha lipoic acid drug from wastewater: study kinetics and simulation

AbstractIn this study, the synthesized nanocomposite novel arginine/thiourea/guar gum/ferrite (ATGF) adsorbent was evaluated for the adsorption of alpha lipoic acid (ALA) and Congo Red (CR) from wastewater. The synthesized nanocomposite was examined by Brunauer–Emmett–Teller theory (BET), Termal gravimetric analysis (TGA), Fourier transform infrared spectrometer (FT‐IR), field emission scanning electron microscopy (FE‐SEM), X‐ray Diffraction (XRD), Vibrating sample magnetometer (VSM), and energy dispersive X‐ray (EDX). For the removal of ALA and CR from aqueous solution, the capacity of the nanocomposite was investigated by working on a series of experiments such as the effect of adsorbent dose, initial concentration, contact time, pH and temperature. The adsorption kinetics of these two pollutants were investigated using pseudo‐first‐order and pseudo‐second‐order velocity equations. The nanocomposite kinetics follow pseudo‐second‐order. Langmuir and Freundlich isotherms were investigated. The results show that the Langmuir isotherm model gives the maximum adsorption capacity of ALA as 96.93 mg g−1 and of CR as 229.34 mg g−1 on the nanocomposite. © 2024 Society of Chemical Industry.

Preparation of halogen-free flame retardant curing agent and its application in epoxy resin

9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-N-Aminoethylpiperazine (DOPO-AEP), a phosphorus and nitrogen intumescent flame retardant curing agent was prepared by using acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. The structure of the flame retardant curing agent DOPO-AEP was analyzed Fourier Transform Infrared Spectrometer (FTIR), Nuclear Magnetic Resonance (NMR) and Electrospray Ionization Mass Spectrometry (ESI-MS), and the synthesis method of the target product was determined. In addition, the content of char residue was determined by thermogravimetric analyzer, and its thermal properties were comprehensively explored, and based on the obtained results, the curable epoxy resin was selected to prepare DOPO-AEP/EP flame retardant composites. According to the amount of DOPO-AEP added product, different proportions of DOPO-AEP/EP flame retardant composites were prepared, and the actual impact of flame retardant properties and mechanical properties of epoxy resin in different proportions was explored. When the content of DOPO-AEP is 35%, the limiting oxygen index of DOPO-AEP/EP reaches 29.9, which has a significant increase compared with the limiting oxygen index of pure epoxy resin of 19.8, but compared with the content of DOPO-AEP of 30%, the limiting oxygen index of DOPO-AEP/EP is 28.7, and there is no significant increase change. Comprehensive analysis shows that when the component content of DOPO-AEP is 30%, the flame retardant system has a tensile strength of 29.0 MPa, an impact strength of 4.5Kj/m2 and a flexural strength of 73.9 MPa, and its limiting oxygen index is as high as 28.7, and the comprehensive performance of the system is the best. By testing the surface morphology of the flame retardant composites after combustion by SEM, it was found that a dense char layer was formed on the surface of the epoxy resin cured char residue and foamed obviously, indicating that the flame retardant curing performance of DOPO-AEP was good.

Preparation of Poly(Styrene-co-Acrylonitrile)-Grafted Attapulgite via Simultaneous Reverse and Normal Initiation Atom Transfer Radical Polymerization (SR&NI ATRP) and Its Effect on Polycarbonate/Acrylonitrile-Butadiene-Styrene Terpolymer Ternary Composites

To further improve the comprehensive properties of polycarbonate/acrylonitrile–butadiene–styrene terpolymer blends (PC/ABS), in this work, styrene–acrylonitrile copolymer [P(St-co-An)] was grafted on the surface of attapulgite particles (ATP) by simultaneous reverse and normal initiation ATRP (SR&NI ATRP) to yield ATP@P(St-co-An) hybrid particles. Then a series of PC/ABS/ATP@P(St-co-An) composites were prepared via the melt blending method. The effects of ATP@P(St-co-An) content on the morphological, mechanical, thermal and rheological properties of the composites were investigated in detail. The core-shell ATP@P(St-co-An) hybrid particles with the polymer layer thickness of 20-40 nm were synthesized successfully according to the results of X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The improvement in mechanical properties, reduced glass transition temperature (T g) difference between PC and ABS and micromorphology changes of the composites proved the compatibilization, strengthening, and toughening effect of the ATP@P(St-co-An). Compared with the PC/ABS blend, with strength and toughness of 50.8 MPa and 56.3 kJ/m2, when the ATP@P(St-co-An) content was 4 wt%, a reasonable balance (85.8 MPa and 86.2 kJ/m2) between strength and toughness was achieved with substantially enhanced thermal stability. Moreover, the composite showed more remarkable non-Newtonian behavior, and its processability was also improved. We believe this work provides an effective approach to optimize the compatibility and comprehensive properties of PC/ABS blends.

Ultrasound-assisted extraction of polysaccharides from Ginkgo biloba: Process optimization, composition and anti-inflammatory activity

Plant derived polysaccharides can enhance immune function in the human body, effectively prevent diseases, and reduce the probability of bacterial infections. Ginkgo crude polysaccharide (GCP) was obtained from Ginkgo biloba by ultrasonic-assisted hot water extraction. Our data showed that the best extraction conditions of GCP were as follows: extraction temperature 80 °C, ultrasonic time 35 min, extraction time 3 h, and solid‒liquid ratio 1:30. Fourier transform infrared spectrometer (FT-IR) data showed that this polysaccharide might be an acidic polysaccharide with a carboxylic acid ring structure. Further studies implied that GCP was mainly composed of glucose, galacturonic acid, rhamnose, galactose and arabinose, accounting for 39.45 %, 25.01 %, 15.40 %, 11.94 % and 4.25 %, respectively. 0.1, 1 and 10 mg/mL GCP reduced the release of inflammatory factors in RAW264.7 cells via inhibition of the nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) signalling pathway. GCP was separated into five components with different molecular weights by an ultrafiltration membrane. Our data showed that GPa with a molecular weight ≥100 kDa was the main component of GCP. 1 mg/mL GPa, GPb, GPc and GPd had anti-inflammatory activities, and 1 mg/mL GPa had the best anti-inflammatory activities. Our results preliminarily reveal the elements and biological activity of GCP, which will provide a reference for the development of Ginkgo biloba.

Investigating the impact of different cleaning techniques on bond strength between resin cement and zirconia and the resulting physical and chemical surface alterations.

To evaluate the effect of cleaning methods and thermocycling on the micro-tensile bond strength between resin cement and contaminated zirconia and to characterize the physicochemical alterations at the zirconia surface resulting from contaminants and subsequent application of cleaning methods. Thirty-two alumina air-abraded zirconia blocks were divided into eight groups: (i) uncontaminated control followed by methacryloyloxydecyl dihydrogen phosphate (MDP) primer (G-Multi Primer) application (CON). In groups ii-viii, the blocks were contaminated with saliva and silicone disclosing agents, followed by cleaning as follows: (ii) MDP primer applied, followed by contamination (GMP1); (iii) MDP primer applied before and after contamination (GMP2); (iv) cleaning with alumina air-abrasion (APA); (v) cleaning with sodium hypochlorite (NaOCl); (vi) cleaning with Ivoclean (IVC); (vii) cleaning with ZirClean (ZC); and (viii) cleaning with Katana Cleaner (KC). After cleaning, the zirconia blocks in groups iv-viii were applied with MDP primer. The blocks in each group were cemented together with resin cement (G-Cem Linkforce). Subsequently, each bonded zirconia block was sectioned using a water-cooled diamond saw into microsticks (1×1×9 mm3). Micro-tensile bond strength was measured after either 24h or 10,000 thermal cycles (n = 20/subgroup). Data were analyzed using two-way analysis of variance (ANOVA), followed by one-way ANOVA, and Tukey's post-hoc test. The contact angle measurements, energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FTIR) spectrometer were used for physiochemical evaluation. After 24h of water storage, the highest bond strength was observed in the CON, NaOCl, APA, and GMP2 groups. After thermocycling, the bond strength significantly decreased in all groups except the GMP2 group, which maintained the highest bond strength. Commercial ceramic cleaning agents (IVC, ZC, and KC groups) exhibited lower bond strengths than the CON groups in both aging conditions. The application of MDP primer before and after contamination is a promising cleaning protocol for removing saliva and silicone disclosing agent contaminants from zirconia surfaces. This approach achieved the highest bond strength and maintained it even after artificial aging through thermocycling.

Corrosion resistance of polymer-modified hardened cement paste and phosphoric acid-activated metakaolin geopolymer in carbonic acid solution

Corrosion resistance of hardened Portland cement paste (HCP), polymer-modified hardened cement paste (PHCP) and phosphoric acid-activated metakaolin (PMK) geopolymers in carbonic acid solution was comparatively evaluated by multiple techniques of thermogravimetry (TG), energy dispersive spectrometer (EDS), fourier transform infrared spectrometer (FTIR), inductively coupled plasma optical spectrometer (ICP), microindentation and compressive tests. The incorporated polymer kinetically slows down the corrosion process of Portland cement paste as the carbonation depth of PHCP is lower than those of HCP characterized by all techniques. Meanwhile, the addition of polymer slightly hinders leaching of substances from HCP by blocking the pores. Despite the increase of elastic modulus, decreases of compressive strength of both HCP and PHCP samples caused by carbonation are observed probably due to the generation of microcracks and uneven brittleness across the section. PHCP presents less mechanical loss after carbonation treatment than HCP. PMK geopolymer samples soaked in deionized water and carbonic acid solution have comparatively identical results of TG, EDS, FTIR and mechanical measurements, indicating that the PMK geopolymer is highly resistant to carbonic acid, thanks to its inherent acidic nature. In addition, the leaching amount of PMK geopolymer in carbonic acid solution is also much less than the HCP and PHCP.