Attenuated Total Reflection Spectroscopy Research Articles

Investigation of green functionalization of multiwall carbon nanotubes and its application in adsorption of benzene, toluene & p-xylene from aqueous solution

The presence of benzene, toluene, and p-xylene (BTX) in an aqueous media imparts harmful effects on the ecosystem. To abate these hydrophobic contaminants, adsorption with the efficient sorbent, multiwall carbon nanotubes (MWCNTs) was selected for the present research. Since the strong oxidizing agents cause the highest degree of degradation (shortening of tubes), severely affect the structural integrity of nanotubes and ultimately result in reduced sorption capacity. Therefore, the surface of MWCNTs was modified with a new combination of green dispersants (citric acid, tartaric acid, malic acid, and salicylic acid) and characterized by surface area analyzer, Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR), Raman spectroscopy, x-ray diffraction (XRD), and variable pressure field emission scanning electron microscope (VPFESEM). The incorporation of oxygen-bearing complexes over the surface of nanotubes, enhanced the surface wettability of MWCNTs that offers more active sites for the sorption process. The impact of governing factors (BTX concentration, contact time, dosage of MWCNTs, temperature, and pH) was systematically studied and optimized using RSM technique. The maximum removal efficiency of oxidized MWCNTs (O-MWCNTs) was up to 99.99% for BTX. The experimental data were best fitted to the pseudo second-order model and Langmuir isotherm models. The thermodynamic study depicted that the sorption process was spontaneous and endothermic. The sorption mechanism was quantitatively evaluated by FTIR-ATR. The successful desorption and regeneration of present surface modified MWCNTs proved the recycling capacity of the modified sorbent. Conclusively, surface modified MWCNTs presented a fast and efficient removal of BTX with the highest adsorption capacity as compared to that reported in existing literature.

Malus pumila and Juglen regia plant species mediated zinc oxide nanoparticles: Synthesis, spectral characterization, antioxidant and antibacterial studies

Zinc oxide nanoparticles derived from Malus pumila (apple) and Juglen regia (walnut) plant is an attractive area of research because of their widespread use. The use of plant material to synthesize zinc oxide nanoparticles has been considered as one of the best environmentally friendly approach. This method appears to be low-cost as compare to other conventional method of synthesis. The biosynthesized nanoparticles were characterized by Ultraviolet–visible spectroscopy (UV–visible), Fourier transform infrared spectroscopy (FT-IR), Attenuated total reflectance spectroscopy (ATR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Transmission electron Microscopy (TEM) and Dynamic light scattering (DLS). The antioxidant potential has been evaluated by 2, 2-diphenyl-1-picrylhydrazyl free radical (DPPH) assay using L-ascorbic acid as a standard. The antibacterial activity was measured by agar well diffusion method to measure the efficacy of plant species extract and extract mediated zinc oxide nanoparticles against 5 g positive bacteria namely Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), Streptococcus pyrogenes (S. pyrogenes), Corynebacterium diphtheriae (C. diphtheriae) and Corynebacterium xerosis (C. xerosis) and 3 g negative bacteria such as Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae) and Pseudomonas aeruginosa (P. aeruginosa) bacteria with standard antibiotic for gram positive (Ciprofloxacin) and gram negative bacteria (Gentamicin).

Impact of surface modification on adsorptive removal of BTX onto activated carbon

The wastewater from chemical industries encapsulates a variety of different volatile organic compounds. Among these hydrophobic pollutants, benzene, toluene and xylene (BTX) are the most harmful organic compounds. The abatement of these deleterious compounds is mandatory. The efficacy of surface modified activated carbon for the uptake of these carcinogenic moieties was analyzed. The commercial activated carbon was functionalized with green oxidizing agents. The structural properties of pristine AC (P-AC) and oxidized AC (O-AC) were analyzed by BET surface area analyzer, Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR), thermogravimetric analysis (TGA), Raman spectroscopy, X-ray diffraction (XRD), and variable pressure field emission scanning electron microscope (VPFESEM). The effect of all the variables namely contact time, temperature, pH and dose was substantially analyzed and optimized. The sorption equilibrium was quickly established within 30 min. The present sorption process conforms to pseudo 2nd order kinetic model and is controlled by intra-particle diffusion. The maximum sorption capacity was computed to be 260.78 mg/g, 263.16 mg/g, 269.55 mg/g for benzene, toluene, and p-xylene respectively, outlining that Langmuir isotherm model fits the data reasonably well as compared to that of Freundlich and D-R model. Furthermore, electrostatic interaction is the plausible mechanism for sorption of BTX onto O-AC. Thus, this mode of functionalization is regarded as the contemporary protocol with high adsorption capacity towards the uptake of BTX as compared to that of previous studies reported in literature.

Bio-based composite fibers from pine essential oil and PLA/PBAT polymer blend. Morphological, physicochemical, thermal and mechanical characterization

Biodegradable aliphatic polyesters are an alternative to reduce the use of synthetic plastic materials that cause severe damage to the environment. Formulations based on poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT), were mixed in a 60:40 ratio, adding different concentrations of pine essential oil through the use of extrusion technology to obtain biodegradable polymer fibers. Some formulations were coated with chitosan. All the elaborated fibers were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy-Attenuated Total Reflection (FTIR-ATR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and mechanical properties. The SEM studies showed that the PBAT improves the tenacity and provides greater elasticity promoting the interaction between the blends phases with fibril formation. In the FTIR-ATR analysis, compatibility between the blends was observed due to a possible interaction of the carbonyl group of PBAT with PLA. The DSC and the mechanical properties showed partial miscibility of the blends, indicating, that the plasticizing action of the essential oil gave greater mobility, flexibility, less rigidity and crystallization in the blends. A lower Young's modulus and greater elongation at break was also observed.

Poly(DL-Lactide-co-ε-Caprolactone)/Poly(Acrylic Acid) Composite Implant for Controlled Delivery of Cationic Drugs.

Poly(DL-lactide-co-ε-caprolactone)/poly(acrylic acid) implantable composite reservoirs for cationic drugs are synthesized by sequentially applying photoirradiation and liquid phase inversion. The chemical composition and microstructure of reservoirs are characterized with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and scanning electron microscopy (SEM), respectively. Drug loading and release properties are investigated using methylene blue as the drug model. Biocompatibility of reservoirs is examined through a series of in vitro tests and an in vivo experiment of subcutaneous implantation in Dark Agouti rats. Reservoirs show good ion-exchange capacity, high water content, and fast reversible swelling with retained geometry. Results of drug loading and release reveal excellent loading efficiency and diffusion-controlled release during 2 weeks. Biocompatibility tests in vitro demonstrate the lack of implant proinflammatory potential and hindered adhesion of L929 cells on the implant surface. Implants exhibit low acute toxicity and elicit a normal acute foreign body reaction that reaches the early stages of fibrous capsule formation after 7 days.

Impact of a Hyaluronic Acid-Grafted Layer on the Surface Properties of Model Silicone Hydrogel Contact Lenses

The introduction of high oxygen transmissibility silicone hydrogel lenses ameliorated hypoxia-related complications, making them the most prescribed type of contact lens (CL). Despite the progress made over the last 2 decades to improve their clinical performance, symptoms of ocular dryness and discomfort and a variety of adverse clinical events are still reported. Consequently, the rate of CL wear discontinuation has not been appreciably diminished by their introduction. Aiming to improve the interfacial interactions of silicone hydrogel CLs with the ocular surface, a biomimetic layer of hydrophilic glycosaminoglycan hyaluronic acid (HA) (100 kDa) was covalently attached to the surface of model poly(2-hydroxyethyl methacrylate- co-3-methacryloxypropyl-tris-(trimethylsiloxy)silane) (pHEMA- co-TRIS) silicone hydrogel materials via UV-induced thiol-ene "click" chemistry. The surface structural changes after each modification step were studied by Fourier transform infrared spectroscopy-attenuated total reflectance and X-ray photoelectron spectroscopy (XPS). Successful grafting of a homogeneous HA layer to the surface of the model silicone hydrogels was confirmed by the consistent appearance of N (1s) and the significant decrease of the Si (2p) peaks, as determined by low-resolution angle-resolved XPS. The HA-grafted surfaces demonstrated reduced contact angles, dehydration rate, and nonspecific deposition of lysozyme and albumin, while maintaining their optical transparency (>90%). In vitro studies demonstrated that the HA-grafted pHEMA- co-TRIS materials did not show any toxicity to human corneal epithelial cells. These results suggest that surface immobilization of HA via thiol-ene "click" chemistry can be used as a promising surface treatment for silicone hydrogel CLs.

Investigation of soil properties using different techniques of mid‐infrared spectroscopy

SummaryDiffuse reflectance spectroscopy (DRF), attenuated total reflectance spectroscopy (ATR) and Fourier transform infrared photoacoustic spectroscopy (PAS) are useful techniques that are commonly used to characterize soil properties. Here, these techniques were used to evaluate individual properties of 1456 paddy soil samples from Nanjing, China, to explore their features in the mid‐infrared range. The diffuse reflectance spectroscopy showed broad and shouldered peaks that ranged from 4000 to 500 cm−1. Attenuated total reflectance spectroscopy produced main peaks around 1000 cm−1. Fourier transform infrared photoacoustic spectroscopy spectra showed several moderate intensity peaks in the regions of 4000–2600 and 2500–500 cm−1. The effective variables (wavenumbers) were selected using an uninformative variable elimination (UVE) algorithm to predict soil pH, and soil organic matter (SOM), total nitrogen (TN) and available phosphorus (AP) contents; it used a self‐adaptive partial least squares model (SAM–PLS). The results showed that selected wavenumbers improved the accuracy of prediction for pH, and SOM, TN and AP contents. For the prediction of pH, ATR spectra showed marginally better performance than the other spectra. The DRF spectroscopy was the optimal method for SOM and TN prediction. Available phosphorus contents were predicted poorly by all three spectra. Furthermore, mid‐infrared incident light paths, absorption modes, sensing styles, as well as peak interference and the prediction model, were the main factors that affected the assessment of soil properties in the three types of spectroscopy.Highlights Soil spectra data were measured with DRF, ATR and PAS spectrometers over the range 4000–500 cm−1. A UVE algorithm was used to select effective wavenumbers from the full spectrum. The pH, SOM, TN and AP were estimated using three techniques based on a SAM–PLS model. Mid‐infrared incident light paths and absorption modes affected prediction performance of the three techniques.

Plasma resistance of addition-cure liquid silicone rubber with Ureido-attached MQ silicone resin

Ureido-attached MQ silicone resin (U-MQ) was synthesized and added into addition-cure liquid silicone rubber (ALSR) for the improvement of the plasma resistance. The morphology and chemical structure of the surface of ALSR/U-MQ after plasma treatment were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and the water contact angles (WCAs) of the surface at different recovery time were also measured. The results indicated that the surface of ALSR/U-MQ was slightly destroyed after plasma treatment, exhibiting excellent plasma resistance. Furthermore, the increasing rate of WCAs of ALSR with U-MQ kept faster than that of ALSR without U-MQ at different recovery time after plasma treatment, also demonstrating the lower destruction degree of ALSR/U-MQ. It was possible that inorganic ceramic layer was gradually formed on the surface of ALSR/U-MQ under plasma treatment, which was beneficial to protect the inner matrix from serious destruction.

Light driven PVDF fibers based on photochromic nanosilica@naphthopyran fabricated by wet spinning

Photoresponsive polyvinylidene fluoride (PVDF) fibers doped with naphthopyran-functionalized silica nanoparticles (SiO2@NPT) were successfully prepared by dry–jet wet spinning. The incorporated photochromic nanomaterials, SiO2@S1 and SiO2@S2, were previously prepared by covalent post-grafting of the silylated NPTs – 2H-naphtho[1,2-b]pyran derivatives, S1 and S2 – onto nano-sized SiO2 (15 ± 3 nm).The morphological and chemical characterization of the resulting doped fibers PVDF@SiO2@S1 and PVDF@SiO2@S2 was evaluated by scanning electron microscopy with energy dispersive spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Both PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers presented average diameters of 133 ± 8 μm and 98 ± 7 μm, respectively, and a porous outer surface. The presence of the SiO2@NPT within the fibers was confirmed through the observation of dense clusters embedded within the polymeric matrix. Furthermore, the FTIR-ATR spectra of the fibers revealed that the PVDF matrix was composed of α and β crystalline and amorphous phases.The PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers showed photoresponsive properties under UV and sunlight irradiation, exhibiting fast coloration kinetics and good optical contrast (ΔE*ab = 7.2 and 15.1, respectively), and changing from a pale orange and an off-white color to a more intense yellow-orange and purple coloration, respectively, in less than 1 min. Moreover, they showed an initial fast bleaching, losing half of their color in less than 30 min (t1/2 = 28 and 20 min for PVDF@SiO2@S1 and PVDF@SiO2@S2 fibers, respectively), but displaying a residual coloration that took 1 and 2 h to return to the initial uncolored state (t3/4 = 95 and 49 min, respectively). The PVDF@SiO2@S2 fibers presented the best photochromic performance.

Surface-Functionalized Model Contact Lenses with a Bioinspired Proteoglycan 4 (PRG4)-Grafted Layer.

Ocular dryness and discomfort are the primary reasons for the discontinuation of contact lens wear. This is mainly due to poorly hydrated contact lens surfaces and increased friction, particularly at the end of the day and can potentially cause reduced vision or even inflammation. Proteoglycan 4 (PRG4) is a mucinous glycoprotein with boundary lubricating properties, naturally found in the eye, able to prevent tear film evaporation and protect the ocular surface during blinking. Aiming to improve the interfacial interactions between the ocular surface and the contact lens, the synthesis and characterization of surface-modified model contact lenses with PRG4 is described. Full-length recombinant human PRG4 (rhPRG4) was successfully grafted onto the surface of model conventional and silicone hydrogel (SiHy) contact lenses via its somatomedin B-like end-domain using N, N'-carbonyldiimidazole linking chemistry. Grafting was assessed by Fourier transform infrared spectroscopy-attenuated total reflectance, X-ray photoelectron spectroscopy, and radioactive (I131) labeling. Surface immobilization of rhPRG4 led to model conventional and SiHy materials with improved antifouling properties, without impacting optical transparency or causing any toxic effects to human corneal epithelial cells in vitro. The surface wettability and the boundary friction against human corneal tissue were found to be substrate-dependent, with only the rhPRG4-grafted model SiHy exhibiting a reduced contact angle and kinetic friction coefficient compared to the unmodified surfaces. Hence, clinical grade rhPRG4 can be an attractive candidate for the development of novel bioinspired SiHy contact lenses, providing improved comfort and overall lens performance.

Collagen/poly(d,l-lactic-co-glycolic acid) composite fibrous scaffold prepared by independent nozzle control multi-electrospinning apparatus for dura repair

The objective of the present study was to evaluate non-woven collagen/poly(lactic-co-glycolic acid) fibrous scaffold (Col/PLGA FS) prepared by a co-electrospinning process using a novel multi syringe electrospinning system for dura repair. The morphological and mechanical properties of the fibrous scaffolds (FSs) were assessed by scanning electron microscopy (SEM) and a universal testing machine (UTM). The changes in chemical composition due to the incorporation of collagen into PLGA were determined by Fourier transform infrared spectroscopy-attenuated total reflection mode (FTIR-ATR). The biocompatibility of the FSs was also evaluated in vitro in cultures of mouse fibroblasts and in vivo by subcutaneous implantation studies in rats. SEM images of the samples showed that the fiber size distribution of Col/PLGA FS became narrow compared to that of PLGA FS due to the incorporation of collagen with small fiber diameter. The FTIR-ATR spectrum of Col/PLGA FS revealed the characteristic bands of collagen and PLGA, indicating the co-existence of two fibrous structures. The poor mechanical properties of collagen FS were improved by co-electrospinning with PLGA. In vitro L929 cell proliferation assay revealed that the cyto-compatibility of Col/PLGA FS was increased compared to that of PLGA FS. In addition, Col/PLGA FS showed increased hydrophilic properties sufficient to absorb the exudates at the interface with mild foreign body reactions. In animal studies using a traumatic brain injury (TBI) model, the incorporation of collagen induced increased macrophage chemotaxis, and the post-inflammatory reaction of these cells led to remarkable brain tissue regeneration.

Infrared absorbance spectroscopy of aqueous proteins: Comparison of transmission and ATR data collection and analysis for secondary structure fitting

Attenuated total reflectance (ATR) infrared absorbance spectroscopy of proteins in aqueous solution is much easier to perform than transmission spectroscopy, where short path‐length cells need to be assembled reproducibly. However, the shape of the resulting ATR infrared spectrum varies with the refractive index of the sample and the instrument configuration. Refractive index in turn depends on the absorbance of the sample. In this work, it is shown that a room temperature triglycine sulfate detector and a ZnSe ATR unit can be used to collect reproducible spectra of proteins. A simple method for transforming the protein ATR spectrum into the shape of the transmission spectrum is also given, which proceeds by approximating a Kramers‐Krönig–determined refractive index of water as a sum of four linear components across the amide I and II regions. The light intensity at the crystal surface (with 45° incidence) and its rate of decay away from the surface is determined as a function of the wave number–dependent refractive index as well as the decay of the evanescent wave from the surface. The result is a single correction factor at each wave number. The spectra were normalized to a maximum of 1 between 1600 cm−1 and 1700 cm−1 and a self‐organizing map secondary structure fitting algorithm, SOMSpec, applied using the BioTools reference set. The resulting secondary structure estimates are encouraging for the future of ATR spectroscopy for biopharmaceutical characterization and quality control applications.

In situ study of porous silicon thin films thermal oxidation by pulsed laser photoacoustics

Passivation is of remarkable importance for porous silicon (PSi) applications to guarantee the chemical stability of its high surface area through time. Thermal oxidation is one of the most common methods to passivate the surface of PSi. In order to better understand the oxidation process, here we performed an in situ study by using pulsed laser photoacoustics. During the thermal oxidation, the photoacoustical signal was measured each 1 °C from 70 °C to 900 °C. The measurements were analyzed by standard correlation, and the significant signal changes were related to the presence of different surface species. We have found temperatures, where the photoacoustical signal changes drastically, that can be related to the absorption and desorption of chemical species in the surface. Species identification where made through Fourier-transform infrared spectroscopy-attenuated total reflection analysis of the PSi samples, at temperatures around where these notorious modifications on the surface were observed.

Dense restructuring of amorphous silicon network induced by non-bonded hydrogen

We confirmed the presence of non-bonded hydrogens (NBHs) in hydrogenated amorphous silicon (a-Si:H) films, using a combination of multiple techniques (Rutherford backscattering spectrometry/hydrogen forward scattering, Fourier-transform infrared spectroscopy-attenuated total reflection, and thermal desorption spectrometry). The hydrogen effusion profile of an a-Si:H film with large amounts of NBHs was analyzed in detail. We report the effect of NBHs on band structure and electrical conductivity, and we present additional considerations for previous data on number density of silicon, optical bandgap, and vacancy size distribution [J. Non-Cryst. Solids 447, 207 (2016)]. The effect of NBHs on the a-Si network is explained by the “dense restructuring model”.

Biocomposites with increased dielectric constant based on chitosan and nitrile-modified cellulose nanocrystals

The motivation of the present work was the preparation of bio-based thin film nanocomposites with improved dielectric properties using modified nanocellulose and chitosan, both materials known to derive from industrial waste. Cyanoethylation of cellulose nanocrystals (CNC) was achieved through a “green” method for the first time. Then, modified CNCs were incorporated into a chitosan (Chi) matrix, obtaining a homogeneous and flexible material with higher dielectric constant due to the high dipole moment of the nitrile functional group. The value of dielectric constant rises with the content of modified CNCs, from a value of 5.5 for pure chitosan at 25 °C and 1 kHz up to a value of 8.5 for the nanocomposite with 50 wt% at the same conditions. These bio-based nanocomposites show an improvement in their dielectric properties compared to pure chitosan and chitosan/unmodified CNC nanocomposites (for which dielectric constant decreases up to 4.5 at 25 °C and 1 kHz) and can be considered for high-temperature applications. Characterization of cyanoethylated cellulose nanocrystals (CN-CNC) and nanocomposites was carried out by infrared spectroscopy (FT-IR), attenuated total reflectance spectroscopy (ATR), atomic force microscopy (AFM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and solid-state NMR and broad band dielectric spectroscopy (BDS). Tensile tests were developed for mechanical characterization.

The degree of conversion and class II cavity microleakage of different bulk fill composites placed with different restorative techniques

ObjectivesThe current study aimed to investigate the degree of conversion and microleakage of bulk fill composites placed using different restorative techniques. Materials and methodsFour types of resin composites were used: Incrementally-placed Filtek Z350 XT (INC), Filtek Bulk Fill Posterior Restorative (B), Filtek Bulk Fill Flowable (F), 3M ESPE, United States, and SonicFill (SON), Kerr, United States. For the degree of conversion (DC) test, five cylindrical samples were prepared for each group (5 mm diameter and 5 mm depth) (n = 5). Five groups, representing different material-technique combinations, were investigated: Group (INC) in which the incremental technique was used for packing Z350 composite (control), Group (B) in which Filtek Bulk Fill Posterior Restorative was placed as a one 5 mm deep increment, Group (FB-1C) in which Filtek Bulk Fill Flowable was used to fill 2 mm in the base of the mold followed by 3 mm Filtek Bulk Fill Posterior Restorative on top of it then both materials were cured simultaneously, Group (FB-2C) in which 2 mm of Filtek Bulk Fill Flowable was placed at the base of the mold and cured then the rest of the mold was filled with Filtek Bulk Fill Posterior Restorative followed by a final cure, and finally Group (SON) in which SonicFill composite was placed as a one 5 mm increment. The DC of both top and bottom surfaces of each sample was measured using Fourier-transform infrared spectroscopy-Attenuated Total Reflectance (FTIR-ATR). Forty-five extracted human premolars were used for the microleakage assessment. One or two class II slot cavities, with standardized dimensions, were prepared in each tooth. Each of the five investigated groups was represented by 11 cavities (n = 11). The cavities were filled using the same composite material-technique combinations used for the DC test. The restored teeth were thermocycled then immersed in 2% methylene blue solution for 24 h at 37 °C. Dye penetration was assessed by examining longitudinal mesio-distal sections through the restored teeth using a stereomicroscope at 25× magnification. The microleakage was scored using predetermined scoring criteria. The results were statistically analyzed. ResultsThe (INC) group showed significantly higher DC for the top surface than all bulk fill groups. No significant difference was found between the (INC), (FB-1C) and (FB-2C) groups regarding the DC of the bottom surface and the three groups had the highest DC while the (SON) group had the lowest DC values. Comparing the top and bottom surfaces of each single group, only the (FB-1C) and (FB-2C) groups showed a significant difference. No significant difference was found between the microleakage scores of the five investigated groups. ConclusionsConventional incrementally-placed composite has a higher DC compared to all bulk fill types regardless of the technique used for the bulk fill composite. The sonic-activated composite exhibits lower DC of the bottom composite surface than all other bulk fill composites. Regarding the microleakage, bulk fill composites, used with any of their possible techniques, do not perform any inferior compared to incremental composites.

An Analysis of Effect of CO2 Laser Treatment on Carbon Fibre Fabric

The colour of carbon fibre fabric is black which limits its aesthetic properties. CO2 laser has been used for cutting carbon fibres. The impact of CO2 laser treatment to modify the surface of carbon fibre fabric is investigated in this work. Different combinations of laser process parameters, i.e., pixel time (110, 120, 130, 140, 150, 160, 170, 180, 190 and 200 µs, with 10 µs intervals) and resolution (70, 80, 90 and 100 dpi (dots per inch), with 10 dpi intervals), were used for treating carbon fibre fabric surface. Since the laser process is a surface treatment, contact angle measurement was used for evaluating the wetting property imparted after laser processing. The resistivity of the laser-treated carbon fibre fabric was measured to evaluate any effect on the original electrical property of the carbon fibre fabric. Moreover, surface morphology and functionality of laser-treated carbon fibre fabric were assessed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy-attenuated total internal reflectance (FTIR-ATR), respectively. SEM assessment was to examine the physical change in the carbon fibre surface after laser processing. On the other hand, the FTIR-ATR measurement can help to evaluate the chemical change in the carbon fibre surface after laser processing.

Enhanced mid-infrared multi-bounce ATR spectroscopy for online detection of hydrogen peroxide using a supercontinuum laser

A compact multi-bounce attenuated total reflection (ATR) probe combined with a Fabry-Pérot filter spectrometer (FPFS) has been developed for detection of hydrogen peroxide used for oxidative gas scrubbing operating in the mid-infrared (MIR) spectral region. A novel MIR supercontinuum light source is employed to enhance the quantification capabilities of the sensor and is compared to a classical thermal emitter. An improvement of a factor of 4 in noise and approximately a factor of 3 in limit of detection is shown in this study allowing fast inline detection of aqueous hydrogen peroxide solutions around 0.1%.

The study of bis-chloromethyl-phosphinic acid crystal by ATR and Raman spectroscopy and X-ray diffraction

Crystals of bis-chloromethyl-phosphinic acid ((CH2Cl)2POOH) are studied by attenuated total reflection (ATR) and Raman spectroscopy supported by X-Ray diffraction. The bands recorded in the ATR and in Raman spectra have the same wavenumbers within experimental uncertainty. It is in agreement with the X-Ray diffraction results which show that the molecules in crystals form infinite chains through hydrogen bonds and there is no center of inversion. The parameters of the unit cell, the bond lengths and angles, and the distance between two oxygen atoms in hydrogen bond bridges are determined. The spectral features and the intermolecular distance between oxygen atoms are characteristic for a strong hydrogen bonded system.

Strengthening of polyacrylonitrile (PAN) fiber networks with polyamide epichlorohydrin (PAE) resin

Polyacrylonitrile (PAN) fibers are one of the most important synthetic fibers that are widely studied because of their excellent characteristics, such as good mechanical strength, chemical resistance, and good thermal stability. Polyamide epichlorohydrin resin (PAE) is a type of cross-linking strengthening resins, with abundant active groups. However, the strengthening mechanism of polyamide epichlorohydrin resin (PAE) in synthetic fiber sheet is not clear. Herein, to meet the feasibility of some synthetic fiber sheet application, PAE resin reinforced polyacrylonitrile (PAN) fiber networks (PAE/PAN hybrid networks) were successfully prepared. Fourier transform infrared spectroscopy-attenuated total reflection (FTIRATR) spectroscopic and X-ray photoelectron spectroscopy (XPS) were used to characterize the self-cross-linking process which the formation of tertiary amine group in PAE/PAN hybrid networks boosted by the self-crosslinking of PAE polymer. The hot-pressing conditions, like temperature, time, and pressure, were also optimized. By adding low amount (0.6 wt%) of PAE serving as cross linkers, the density, tensile index, tear index, and elongation were increased by 9.6, 21.0, 25.8, and 34.3%, respectively. This work suggests a promising PAN fiber enhancement strategy with outstanding mechanical properties by adding PAE resin used as excellent self-cross-linking material and may have great practical application prospects in some other synthetic fiber sheets.