Epoxy Bond Research Articles

Double affinity integrated MIPs nanoparticles for specific separation of glycoproteins: A combination of synergistic multiple bindings and imprinting effect

The selective recognition, isolation, and subsequent enrichment of target glycoproteins are becoming more and more important in clinical diagnosis. In this work, nano-sized molecularly imprinted polymers integrated double affinity (i.e. metal ion affinity and boronate affinity) (D-MIPs) were prepared for specific separation of ovalbumin (OVA). Poly(styrene-glycidyl methacrylate) nanoparticles (PSG) with epoxy bonds were firstly grafted with iminodiacetic acid (IDA) by ring-opening reaction, and then the Cu2+ was chelated to prepare PSG/IDA-Cu2+. Subsequently, imprinted OVA molecules were pre-immobilized through Cu2+ ion affinity. Finally, a surface imprinting layer was formed though the gentle self-oxidization of a kind of boronic acid ligand (i.e. 3-aminophenylboronic acid, APBA). By washing out imprinted molecules, as-prepared D-MIPs posed higher monolayer binding capacity (138.92 mg g−1) and faster capture kinetics (30 min) for OVA, when compared with single affinity integrated MIPs (S-MIPs) and non-imprinted polymers (NIPs), and the chemical adsorption dominated double affinity was the rate-determining step for whole adsorption process. The imprinting factor (IF) of OVA, horseradish peroxidase (HRP) and bovine serum albumin (BSA) by the available D-MIPs were 4.44, 2.23 and 1.47, respectively, which confirmed the better selectivity for OVA. D-MIPs performed favorable regeneration ability and a promising application in actual sample. In addition, a combination of synergistic multiple bindings and imprinting effect, as the mechanism for enhancing specific separation, was also demonstrated.

Stepwise-acid-active organic/inorganic hybrid drug delivery system for cancer therapy.

Due to the difference of pH values between normal tissues, tumor tissues and intracellular environments, DOX@MSN-CD-PEG, a stepwise-acid-active organic/inorganic hybrid drug delivery system (DDS) was reported in this article. The inorganic mesoporous silica nanoparticle (MSN) was introduced for loading of doxorubicin hydrochloride (DOX). Then organic components were applied to achieve the stepwise-acid-active intracellular drug release: MSN was capped with a β-cyclodextrine (β-CD) based host-guest system via pH-sensitive epoxy bond. Then PEG was grafted outside of the carriers through pH-sensitive benzoic imine bond. With the protection of PEG layer, the carriers were difficult cellular uptake by normal cells but could be "acid-activated" for cytophagy by cancer cells in the slightly acidic environments in tumor tissues because of the abscission of PEG. Inside the cells, the more acidic environments could further "activate" the carriers to release DOX as the leaving of the host-guest system. The fabrication processes of DOX@MSN-CD-PEG were monitored. And the stepwise-acid-active property of which was investigated by acid-triggered PEG abscission studies and in vitro drug release studies at pH 7.4 and 6.5, respectively. The in vitro cellular cytotoxicity and cellular uptake behavior were also investigated. In summary, the stepwise-acid-active hybrid DDS should be considerable for cancer therapy.

An efficient bio-based plasticizer for poly (vinyl chloride) from waste cooking oil and citric acid: Synthesis and evaluation in PVC films

Abstract In this study, a bio-based efficient plasticizer (acetylated-fatty acid methyl ester-citric acid ester, AC-FAME-CAE) for poly(vinyl chloride) (PVC) was synthesized by using waste cooking oil and citric acid as raw materials in very user-friendly approaches. Its structure was characterized by FTIR and 1H NMR. The epoxidation and ring opening reaction were investigated primarily using a GC-MS analysis. Tetrabutylammonium chloride (TBAC) was used as the catalyst of ring opening, and it dramatically accelerated the reaction process of carboxylic acid and epoxy bonds. The glass transition temperature (Tg) decreased to 26.32 °C, as determined by dynamic mechanical analysis (DMA), when 50 phr of AC-FAME-CAE was added. The mechanical and migration stabilities of PVC films with AC-FAME-CAE plasticizer were investigated using volatility and extraction tests as well as thermogravimetric analysis (TGA) and TGA–FTIR analysis. The mechanical properties of PVC films with AC-FAME-CAE plasticizer were obviously better than those of PVC films plasticized by ESO (epoxidized soybean oil) and as good as those of PVC films plasticized by DOP (dioctyl phthalate, 99%). The structure−property analysis of the AC-FAME-CAE as a PVC plasticizer confirmed that a higher molecular weight and more ester bonds could reduce the volatility and extraction loss and improve the compatibility and stability of PVC films.

Quantitative evaluation of the mechanical strength of titanium/composite bonding using laser-generated shock waves

Intense acoustic shock waves were applied to evaluate the mechanical strength of structural epoxy bonds between a TA6V4 titanium alloy and a 3D woven carbon/epoxy composite material. Two bond types with different mechanical strengths were obtained from two different adhesive reticulations, at 50% and 90% of conversion, resulting in longitudinal static strengths of 10 and 39 MPa and transverse strengths of 15 and 35 MPa, respectively. The GPa shock waves were generated using ns-scale intense laser pulses and reaction principles to a confined plasma expansion. Simulations taking into account the laser–matter interaction, plasma relaxation, and non-linear shock wave propagation were conducted to aid interpretation of the experiments. Good correlations were obtained between the experiments and the simulation and between different measurement methods of the mechanical strength (normalized tests vs laser-generated shock waves). Such results open the door toward certification of structural bonding.

Spectroscopic observation of oxygen dissociation on nitrogen-doped graphene

Carbon nanomaterials’ reactivity towards oxygen is very poor, limiting their potential applications. However, nitrogen doping is an established way to introduce active sites that facilitate interaction with gases. This boosts the materials’ reactivity for bio-/gas sensing and enhances their catalytic performance for the oxygen reduction reaction. Despite this interest, the role of differently bonded nitrogen dopants in the interaction with oxygen is obscured by experimental challenges and has so far resisted clear conclusions. We study the interaction of molecular oxygen with graphene doped via nitrogen plasma by in situ high-resolution synchrotron techniques, supported by density functional theory core level simulations. The interaction leads to oxygen dissociation and the formation of carbon-oxygen single bonds on graphene, along with a band gap opening and a rounding of the Dirac cone. The change of the N 1 s core level signal indicates that graphitic nitrogen is involved in the observed mechanism: the adsorbed oxygen molecule is dissociated and the two O atoms chemisorb with epoxy bonds to the nearest carbon neighbours of the graphitic nitrogen. Our findings help resolve existing controversies and offer compelling new evidence of the ORR pathway.

Polyethyleneimine modified bentonite for the adsorption of amino black 10B

The modified bentonite with a graft amount of 30% was prepared by polyethylenimine reacting with the epoxy bonds on the molecular of (3-Glycidyloxypropyl) trimethoxysilane and being grafted on the bentonite to remove amino black10B. The effects of pH, time, temperature and concentration on the adsorption capacity were studied. As the pH value increases from 3 to 10, the adsorption capacity decreased from 264.5 to 140.4mg/g. The adsorption process reached equilibrium at 90min when pH=3. The adsorption kinetics indicates that the adsorption process was very fast and in accordance with the secondary adsorption kinetics. The data about thermodynamic equilibrium was consistent with the Langmuir model. The adsorption process mainly depended on electrostatic attraction and hydrogen bonding and the adsorption data of Bent-PGLYMO-PEI showed that the maximum adsorption capacity reached 327.7mg/g.

Kimyasal yöntem ile indirgenmiş grafen oksit sentezi ve karakterizasyonu

More recently, graphene, having outstanding electrical, mechanical, thermal and optical properties, have become an important research topic. Reduced graphene oxide (RGO) is one of the most effective way to obtain the graphene. In this study, RGO was obtained by reduction of graphene oxide (GO) synthesized by a modified Hummers method. The transparent structures of RGO have been identified through SEM images. The ratio of carbon (C) was found to be approximately 89% by SEM/EDX analysis. It was proven by FT-IR analysis that hydroxyl, carbonyl, epoxy and alkoxy bonds in GO structure were removed from RGO structure. On the other hand, RAMAN spectroscopic studies showed that the new sp 2 structures occurred, and the amount of regular structures increased. XRD analysis indicated that d-spacing between the layers of RGO decreased from 0,83 nm to 0,36 nm due to the degradation of functional groups during the chemical process, which were formed in the oxidation process.

EXPERIMENTAL STUDY OF THE INFLUENCE OF ADHESIVE PROPERTIES AND BOND LENGTH ON THE BOND BEHAVIOUR OF NSM FRP BARS IN CONCRETE

The near-surface mounted (NSM) fibre reinforced polymer (FRP) technique is a relatively recent system for strengthening concrete structures. Bond is a key factor in its behaviour, and is affected by many factors whose influence can only be tested through experimental studies. In this study, the modified pull-out test was used to study the effect of epoxy properties and bond length on the behaviour of NSM FRP bars. Three epoxy types, two FRP materials (carbon and glass) and four bond lengths (6db, 12db, 24db and 30db) are used. The load capacity, slips at the loaded end and free end and average bond stress are all analysed. The test results indicate that the role of epoxy properties appear to be a key factor in bond performance in the NSM FRP strengthening technique, and that their effect varies depending on bond length and FRP properties.

Detecting debonding flaws at the epoxy–concrete interfaces in near-surface mounted CFRP strengthening beams using the impact–echo method

This paper discusses the feasibility of using the impact–echo method (IE method) to assess the debonding flaws at the epoxy–concrete interfaces of near-surface mounted carbon fiber reinforced polymers (NSM CFRPs). The effectiveness of NSM CFRP strengthening is influenced by whether epoxy bonds CFRP bars and existing concrete structures effectively and thoroughly, thereby mutually transmitting the stress in the reinforced zones with CFRP bars. Because of poor construction quality, aging, and deterioration, debonding occurs between epoxy and concrete surfaces, severely inhibiting the reinforcement effectiveness of NSM CFRPs. The IE method is based on the principle of stress waves and was adopted in this study as the nondestructive debonding flaw assessment technique. To clarify the characteristics of the stress wave propagation caused by impact forces on NSM CFRP structures, numerical analysis and experimental test were performed on the bar-like epoxy specimens with a cross-sectional size of 13×13mm. The types of specimens used in this study included the bar-like pure epoxy specimen, bar-like epoxy specimens containing CFRP bars, and the concrete beams containing bar-like epoxy specimens with and without CFRP bars. For the concrete beams embedded with bar-like epoxy specimens, various debonding statuses at the epoxy–concrete surfaces were considered. The numerical analysis revealed that the impact responses in the bar-like pure epoxy specimen and bar-like epoxy specimens containing CFRP bars were dominated by the first few cross-sectional modes of vibration, and the IE test verified this result. The numerical and experimental results indicated that for the concrete beams containing bar-like epoxy specimens with and without CFRP bars and without debonding flaws, the impact response spectra each featured one high-amplitude peak at the fundamental mode frequency, referred to as the dominant frequency. When debonding occurred at the epoxy–concrete interfaces of the concrete beams containing bar-like epoxy specimens with and without CFRP bars, the impact responses showed that the dominant frequencies decreased significantly. When the dominant frequencies instead increased to levels nearly equal to those of the fundamental frequencies of the bar-like epoxy specimens, the epoxy thoroughly debonded from the concrete interfaces. According to the characteristics of the aforementioned impact responses, the IE method is capable of detecting the debonding flaws at epoxy–concrete interfaces in NSM CFRP strengthening.

The ultra-precision Ud-lap grinding of flat advanced ceramics

The present study focuses on the Ud-lap grinding process and its machine-tool design aiming at ultra-precision (UP) manufacturing of advanced ceramics. Impacts of three different overlapping factors on a dressing (Ud) and three abrasive grit sizes of conventional SiC grinding wheels were analyzed on flat nanometric surface finishing of dense discs of 3Y-TZP in a ductile regime of material removal. Microhardness, contact and optical profilometry, SEM-FEG, Raman spectroscopy, XRD, and confocal epi-fluorescence were applied to characterize the ceramic material. Mechanical and electric-electronic designs of the machine-tool were developed toward the UP ceramic grinding. The design methodology was successful for supporting the achievement of all design requirements of the CNC Fiocchi Lap Grinder. The machine-tool and the Ud-lap grinding process were capable of manufacturing flat 3Y-TZP surfaces with nanometric finishing without introducing critical defects. The best finishing, Ra=60.63nm, came from the #300 grinding wheel dressed with Ud=5. A flatness deviation of 0.308μm was obtained through the #800 grinding wheel and Ud=3. Differences between theoretical and real macro and micro effects over the grinding wheels after single-point diamond dressing, epoxy bond strength, abrasive protrusion, abrasive grit size and abrasive friability play a key role in the Ud-lap grinding. There is no report of an abrasive process capable of achieving similar nanometric finishing without introducing critical defects with the same micrometric grit size and type of abrasive. The Ud-lap grinding can replace the engagement of processes such as grinding, lapping, and polishing of advanced ceramics.

Dipole-dipole interaction and its concentration dependence of magnetic fluid evaluated by alternating current hysteresis measurement

Magnetic nanoparticles (MNPs) are used as therapeutic and diagnostic tools, such as for treating hyperthermia and in magnetic particle imaging, respectively. Magnetic relaxation is one of the heating mechanisms of MNPs. Brownian and Néel relaxation times are calculated conventional theories; however, the influence of dipole–dipole interactions has not been considered in conventional models. In this study, water-dispersed MNPs of different concentrations and MNPs fixed with an epoxy bond were prepared. dc and ac hysteresis loops for each sample were measured. With respect to both dc and ac hysteresis loops, magnetization decreased with the increase in MNP concentration because of inhibition of magnetic moment rotation due to dipole–dipole interactions. Moreover, intrinsic loss power (ILP) was estimated from the areas of the ac hysteresis loops. The dependence of ILP on the frequency of the magnetic field was evaluated for each MNP concentration. The peak frequency of ILP increased with the decrease in MNP concentration. These peaks were due to Brownian relaxation, as they were not seen with the fixed sample. This indicates that the Brownian relaxation time became shorter with lower MNP concentration, because the weaker dipole–dipole interactions with lower concentrations suggested that the magnetic moments could rotate more freely.

Magnetization Reversal and Specific Loss Power of Magnetic Nanoparticles in Cellular Environment Evaluated by AC Hysteresis Measurement

The effect of intracellular hyperthermia induced by magnetic nanoparticles (MNPs) has been evaluated using a theoretical model. In this study, magnetization reversal of MNPs in the cellular environment under an AC magnetic field was evaluated on the basis of measured AC hysteresis loops. The specific and intrinsic loss powers—SLP and ILP—were also estimated from the area of AC hysteresis loops. The measured samples were a liquid sample dispersed in water, a fixed sample mixed with an epoxy bond, and a cellular sample. In the cellular environment, the rotations of particles and magnetic moments were inhibited by particle‐cell and dipole‐dipole interactions, respectively. The heat dissipation of the MNPs in the cellular environment was lower than that of the liquid and fixed samples. Moreover, the SLP in a single cell was estimated. The temperature increase of a single cell was calculated on the basis of the conventional theoretical model and the SLP measured in a single cell.

X-ray and synchrotron investigations of heterogeneous systems based on multiwalled carbon nanotubes

This paper presents the results of a complex investigation of heterogeneous systems based on multiwalled carbon nanotubes with the outer surfaces covered by iron oxide (Fe3O4) nanocoatings deposited using iron pentacarbonyl as a precursor. Investigations were performed by the methods of electron microscopy, X-ray diffractometry, and ultrasoft X-ray spectroscopy with synchrotron radiation. It was established that the formed thin coatings are continuous and nonuniform in thickness. It was shown that good adhesion of iron oxide on the multiwalled carbon nanotube surface is provided by the formation of epoxy and double carbon-oxygen bonds; in this case, the outer graphene layer of nanotubes is not destroyed and retains the hexagonal structure.

Kenaf fibre composites using thermoset epoxy and polyester polymer resins: energy absorbed versus tensile properties

Composite has been created to improve the mechanical characteristics in natural fibres such as stiffness, toughness and impact resistant. This research investigated the tensile properties and low velocity impact behaviour of the long kenaf with two different thermoset polymer resins (epoxy and polyester). The tensile properties of kenaf/epoxy and kenaf/polyester composite were studied by experiment using Instron Universal Testing Machine according to the standard ASTM D638. Tensile testing of kenaf fibres was carried out by different fibre weight percentages (10, 15, 20 and 25%).The impact test was conducted using an instrumented drop tower device at 10 J energy level according to the standard ASTM D3763. The results of this study indicated that kenaf/polyester composite has better impact absorption energy than kenaf/epoxy composite. However, the kenaf/epoxy composite has higher tensile properties than kenaf/polyester composite. This is a good indication to show that epoxy bonds better than other thermoset polymer resin.

The chlorination and chlorine resistance modification of composite polyamide membrane

ABSTRACTMembrane‐based separation technology is one of the most active separation technologies being employed in water treatment. Polyamides (PA) are widely used membrane materials because they exhibit excellent performance, such as high flux with high salt rejection, and enhanced stability against wide range of pH and temperature. Unfortunately, PA membranes exhibit extremely poor resistance to chlorine leading to increased operation costs and decreased membrane lifetime. In this study, we find new ways for prolonging membrane lifetime and reducing the operating costs by investigating the chlorination and modification of PA membranes. Varying concentrations of hypochlorite were used to chlorinate a commercial reverse osmosis membrane (BW‐30, DOW). The results showed that short‐time exposure to high concentrations of hypochlorite could cause more serious problems to membranes than long‐time exposure to low concentrations under the similar total exposure. The performance of the chlorinated membranes was recovered to some extent after treatment with NaOH solution (pH 10), indicating that the alkali treatment could initiate the reversible regeneration of chlorinated membranes. Furthermore, an industrial grade epoxy resin was used to modify the membranes to enhance the chlorine resistance via the reaction between the amide nitrogen and epoxy bond. The successful modifications were confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. Moreover, the chlorination tests showed that the modifications performed in these experiments enhanced the chlorine resistance of the membranes, especially for the membranes exposed to low concentration of chlorine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41584.

Biocompatibility and Biofunctionality of Magnetic Nanoparticles

Superparamagnetic nanoparticles are used as an imaging agent. Magnetic particle imaging (MPI) is applicable to not only diagnostics but therapy such as hyperthermia and drug delivery. Integrative therapeutic and diagnostic application is called as theranostics. In particular, magnetic relaxation is one of the most important factors for both imaging and hyperthermia treatment. The evaluation of magnetic relaxation property is necessary to design the materials and instrument applying an external magnetic field. Magnetic relaxation is characterized by two distinct modes. Brownian relaxation is occurred by rotation of the particles. Néel relaxation is induced by rotation of the magnetic moment. The mechanism of magnetic relaxation is influenced by the primary and secondary size of magnetic nanoparticles, surface coating agent, state of materials, viscosity of medium. In this study, the magnetic relaxation properties of Resovist and other commercial magnetic nanoparticles were measured at frequency of several kiro heltz up to 500 kHz and high magnetic field up to 50 Oe. The commercial iron oxide nanoparticles of both of superparamagnetic and ferrimagnetic features were used for the measurements. The hysteresis loop under an applied alternating magnetic field was measured for estimating magnetic loss and effective magnetic relaxation time. The materials were prepared in powder form, dispersed state in medium, or fixed state by agarose / epoxy bond. Magnetic nanoparticles dispersed in medium were rotated by an alternating magnetic field, and both Brownian and Néel relaxation could occur. In contrast, fixation regulated rotation of the particles and only Néel relaxation could occur. Therefore, hysteresis loop of alternating magnetic field in dispersed and fixed samples directly indicated the magnetic relaxation mechanisms of measured materials. The dependency of area of the hysteresis loop on the frequency of magnetic field indicated the effective frequency of Brownian and Néel relaxation. Relaxation time was also calculated. Experimental estimation of effective relaxation time confirms the influence of size distribution, concentration, state, surface coating agent and medium. Thus, evaluation of magnetic loss and magnetic relaxation time measured under the alternating field condition which is used for MPI is the effective method to evaluate the mechanisms of magnetic relaxation and optimum material property.

Design and Characterization of a Resistively Heated Shape Memory Polymer Micro-Release Device1

Design and Characterization of a Resistively Heated Shape Memory Polymer Micro-Release Device1

Debonding Mitigation of CFRP-Strengthened Steel Beams with Silyl-Modified Polymer and CFRP Wrap Anchorage

AbstractThis paper presents an innovative strengthening methodology for damaged steel beams with carbon-fiber-reinforced polymer (CFRP) sheets. Emphasis is placed on controlling premature CFRP debonding using an emerging material called silyl-modified polymer (SMP) in conjunction with its hybrid bond application with a conventional epoxy adhesive. The hypothesis proposed is that the low-modulus SMP addresses stress singularity along the CFRP-steel interface, while the high-modulus epoxy preserves interfacial capacity. CFRP anchorage assists the efficacy of such a hybrid bond configuration. A two-phase experimental program is conducted to evaluate the performance of various CFRP-strengthening schemes, including element- and structural-level investigations (i.e., interface and beam tests, respectively). Test results reveal that the SMP bond mitigates CFRP debonding that is commonly observed in epoxy bond. The strengthening systems employed significantly improve the flexural behavior of the test beams in ter...

Preparation and antibacterial property of the mulberry based textiles

The mulberry based textile products were prepared by means of degumming, dyeing, spinning and weaving using mulberry bark as raw materials. The structure of the mulberry based textiles was characterized by scanning electron microscope (SEM). The antibacterial property of the mulberry fibers was evaluated by means of antibacterial testing, and the antibacterial composition in the mulberry based textiles was investigated by FTIR and 13C-NMR. The results show that the mulberry based fibers, dyed fibers, yarns and fabrics with high quality can be prepared successfully by the above processes. The mulberry based textiles have excellent antibacterial property. The inhibitory rate of raw mulberry bark on Escherichia coli and Staphylococcus aureus is (67.2±3.1)% and (53.8±4.6)% respectively, and the inhibitory rate of mulberry fiber on Escherichia coli and Staphylococcus aureus is both above 80%. The inhibitory rate of the mulberry/cotton blended yarn on Escherichia coli and Staphylococcus aureus ranges from (51.7±5.1)% to (72.4±4.1)%, which has similar inhibitory rate with the mulberry/cotton blended fabric. The results of Fourier Transform-Infrared (FTIR) and 13C-nuclear magnetic resonance (13C-NMR) show that the typical functional group (hydroxyl, carbonyl, double bond and epoxy bond) exist in the composition of the mulberry fiber, which indicates that the flavones and phenolic compounds including in the mulberry fiber.

Numerical simulation of the shock spalling failure of bonded fibre–epoxy strengthening systems for metallic structures

Fibre–epoxy strengthening systems have been identified as a suitable approach for metallic structures subjected to explosive loads, to increase the structural performance of existing structures and/or create high performance hybrid structures. However, experimental studies have shown that when subjected to the blast pressures resulting from the detonation of explosives, the epoxy bond material may fail by shock spalling, substantially reducing the performance of the strengthening system. Shock spall failure involves tension fracturing of the epoxy material, resulting from tension stress waves generated as the shock wave moves through the composite structure, creating wave reflections and interactions at the constituent boundaries. The experiments investigated a limited range of blast environments due to the limitations of laboratory testing. The present study validates numerical models of the experimentally observed shock spalling failures, and then extends the models to investigate the effect of a broad range of blast environments, metal geometric and material properties, epoxy bond material properties and fibre layouts on the shock spalling failure of the epoxy bond. The numerical results are used to provide generalised considerations for the design of bonded fibre–epoxy strengthening systems for metallic structures, in the form of iso-damage curves for the spall damage and spall failure of such systems in a variety of practical blast environments.