Resin Phase Research Articles

Gas-Free Continuously Regenerated Impurity Removal Device for Ion Chromatography.

A gas-free continuously regenerated-anion impurity removal device (CR-ARD) is described for ion chromatography (IC). It is a sandwiched configuration consisting of three channels. The central eluent channel is isolated from two outer regenerant channels by stacked anion exchange membranes (sAEM) and a bipolar membrane (BPM) plus stacked cation exchange membranes (BPM-sCEM), in which the anion exchange side of BPM is facing the central channel. The sAEM side is an anode with respect to the cathode of the BPM-sCEM side. The central channel is packed with strongly basic anion exchange resins in hydroxide form. The application of an electrical voltage to the device causes enhanced water splitting at the interface of BPM to occur and the potential drives the hydroxide ions through the resin phase toward the anode, thereby enabling continuous regeneration of the resin and avoiding any off-line regeneration. Meanwhile, nonhydroxide anionic impurities (basically carbonate) are transported toward the anode through the sAEM. It does not produce gas in the eluent channel, and no degasser is required afterward. It shows a strong ability to remove anionic impurities, as indicated by effective removal of 5 mM CO32- injected sample plug (25 μL, 125 pmol) or continuous removal of 600 μM KNO3 solution at 1 mL/min (10 nmol/s) over 300 min. Much improved peak integration at the gradient mode and a higher signal-to-noise ratio at the isocratic mode can be achieved by CR-ARD. To our knowledge, this is the first account of gas-free CR-ARD.

Preliminary design of recyclable epoxy asphalt: Regeneration feasibility analysis and environmental impact assessment

AbstractEpoxy asphalt is a construction material for pavement structures and has been widely used due to excellent durability and longevity characteristics. Although the asphalt phase could be compensated after epoxy asphalt aging, the epoxy resin phase cannot be regenerated at high value due to irreversible covalent cross‐links, resulting in reclaimed epoxy asphalt pavement (epoxy RAP) being employed as aggregate. In this paper, with consideration toward its nonrenewable characteristic, a recyclable epoxy asphalt is designed preliminarily based on the reversible principle of dynamic covalent bonds, thus focusing on the principle of circular economy and reducing environmental impact. The molecular design of recyclable epoxy asphalt was conducted to justify it theoretically. An environmental impacts assessment is used to analyze energy consumption and carbon footprint caused by using reclaimed recyclable epoxy asphalt pavement (recyclable epoxy RAP) in asphalt mixture manufacturing. The analysis of molecular design showed the feasibility of recyclable epoxy asphalt regeneration. And the mixture containing recyclable epoxy RAP could reduce the emission of GHGs by 34% compared with the epoxy RAP, although the consumption of energy is approximate. Based on molecular design and environmental impacts evaluation, the sustainability of recyclable epoxy asphalt is verified.

Low-Temperature Performance of Asphalt Mixtures Modified by Microencapsulated Phase Change Materials with Various Graphene Contents

Microencapsulated phase change materials (PCMs) added to conventional ones can store excessive heat energy and reduce thermal stresses. In this study, melamine–formaldehyde resin phase change microencapsulated PCMs, with different contents of graphene (CG), were added to asphalt mixtures, in order to reduce their low-temperature cracking, induced by thermal stresses. Low-temperature and heat-conducting/storing performance of the obtained mixtures was examined via beam bending tests, semi-circular bending low-temperature performance tests, thermal conductivity tests and volume-specific heat capacity tests. Besides, the prepared asphalt mixtures’ water stability and high-temperature stability values were obtained via freeze-thaw splitting and wheel tracking tests. The low-temperature performance of PCM-modified asphalt mixtures was evaluated via their bending strain energy densities, with one of the PCM-modified asphalt mixtures, namely CGMFPCM3, synthesized by the authors, was 1.7 times higher than that of the common asphalt mixture. Although the dynamic stability of all three PCM-modified mixtures was deteriorated by 68, 50, and 20% compared to the common one, that of CGMFPCM3 still complied with the standard requirement. Thermal conductivity and volume-specific heat capacity of the asphalt mixture at 278.15 K was enhanced by 5 and 43%, respectively, after adding CGMFPCM3. It is recommended for reducing the temperature variation-induced cracking in the asphalt pavement. Thermal conductivity and volume-specific heat capacity can be used for evaluating the temperature-regulating performance of asphalt mixtures.

DFT, MD simulations and experimental analysis of adsorptive complexation and isotope separation of gadolinium ion with macrocyclic crown ether embedded polymeric resin

Di-benzo-18-crown-6 ether (DB18C6) functionalized polymethyl acrylic acid (PMA) resin was synthesized after screening by employing density functional theory (DFT) and molecular dynamics (MD) simulations for the enrichment of gadolinium isotopes, Gd-155 and Gd-157. Batch adsorption and column chromatography studies were performed at various pH, gadolinium ion concentration and temperatures to check its efficacy and validation of theoretical approach. The adsorption capacity of gadolinium ion with the PMADB18C6 resin was found to be quite modest with a value of 1.128 mg/g. Both MD simulations and adsorption experiments confirm the Temkin type of adsorption isotherm. The positive entropy change along with the positive enthalpy change indicates that sorption of the Gd3+ ion with PMADB18C6 is entropy driven process. From the chromatography experiments, the lighter isotope (Gd-155) is seen to be depleted in the breakthrough volume samples which specify that the resin phase is depleted with heavier isotope (e.g Gd-160) contrast to natural Gd composition. The separation coefficient (ε) for Gd155/158, Gd156/158, Gd157/158, Gd155/160 and Gd157/160 isotopic pairs were found to be 1.67 × 10−3, 2.65 × 10−3, 5.40 × 10−4, 3.18 × 10−3 and 1.87 × 10−3 respectively. The experimental isotopic separation factor corroborates the DFT findings. Further, both DFT and MD simulations confirm the experimentally observed endothermic complexation of Gd3+ ion with PMADB18C6 resin. The present findings employing combined DFT, MD simulations and experimental approaches are expected to benefit in the fundamental understanding of molecular complexation based isotope separation and design and development of future gadolinium isotopic enrichment technologies using chemical exchange methods.

Isolation and characterization of anti-tumor compounds from ethyl acetate extract of Rumex japonicus houtt roots and their cytotoxic effects

To isolate and characterize anti-tumor compounds through nuclear magnetic resonance (NMR) spectroscopy of ethyl acetate extract of R. japonicus Houtt root and their cytotoxic effects were evaluated in terms of measuring inhibition of growth of three cancer cell lines: human hepatoma cells (HepG2), cerebral glioma cells (U251) and ovarian carcinoma cells (SK-OV-3/DDP). The roots of R. japonicus Houtt were extracted with ethanol, and partitioned with petroleum ether, dichloromethane and ethyl acetate, respectively. The ethyl acetate extract was separated chromatographically using macroporous resin, positive and negative phase silica gel and high performance liquid chromatography. The structures of isolated compounds were elucidated by nuclear magnetic resonance (NMR) spectral data. Ten compounds were isolated form the ethyl acetate extract of R. japonicus roots. Their structures were determined as emodin (1), chrysophanol (2), aloe emodin (3), physcion (4), quercetin (5), resveratrol (6), β-sitosterol (7), 3β-acetoxy-28-hydroxyurs-12-ene (8), sucrose (9) and dibutyl phthalate (10). Among of them, compounds 1, 3, 4, 6 and 8 exhibited highly significant (p<0.05) cytotoxicities against HepG2 to a certain extent. Compounds 3-6 exhibited moderate cytotoxicities against U251 with IC50 values of 19.8, 23.5, 23.8 and 17.8 µM, respectively. Compounds 1, 2 and 7 also exhibited cytotoxicities against U251 to a certain extent with IC50 values of 48.3, 50.1 and 85.3 µM, respectively. Compounds 1-6 exhibited moderate cytotoxicities against (SK-OV-3/DDP) with IC50 values of 62.8, 64.2, 31.3, 61.0, 47.4 and 42.0 µM, respectively.

Evaluation of Releasability Between Molding Resin and MAX Phase Ceramics

Evaluation of Releasability Between Molding Resin and MAX Phase Ceramics

Effect of epoxy resin content and conversion rate on the compatibility and component distribution of epoxy asphalt: A MD simulation study

Molecular dynamics simulation technology was introduced into the characterization of epoxy asphalt performance, to display the reaction process between the epoxy resin and curing agent in epoxy asphalt clearly and explore the influence of epoxy resin content and conversion rate on the epoxy asphalt performance containing thermodynamic, compatibility, component distribution and diffusion. The reaction between the epoxy resin and curing agent was realized through Perl script, and epoxy asphalt molecular dynamics models with different resin content (25%, 45%, and 65%), and various conversion rates were prepared. Results demonstrated that the addition of epoxy resin enhanced the low-temperature performance of epoxy asphalt, but the increase in conversion rate played a negative impact on low-temperature performance. The CED and solubility parameter were synergistically affected by the epoxy resin content and conversion rate. Furthermore, the raise in the content of epoxy resin was the main reason for enhancing the compatibility between epoxy resin and asphalt. Therefore, the reasonable control of the resin content and conversion rate was beneficial to enhance the stability of the epoxy asphalt system and improve the compatibility between the resin phase and the asphalt phase. 25%-EA and 45%-EA were considered as asphalt phase materials. Aggregation behaviors exhibited between asphaltenes, and adsorption behaviors presented between epoxy resin and asphaltene. With the increase of conversion rate, the adsorption behavior gradually disappeared. 65%-EA belonged to the resin phase material, and the aggregation between asphaltenes was diminished. In addition, the epoxy resin without conversion reaction had the smooth diffusion behavior in epoxy asphalt.

Analysis of UV-Assisted direct ink writing rheological properties and curing degree

In this research, the relationship between the viscosity and curing degree of an acrylate-based resin under UV light was investigated by UV-rheometer and photo-DSC. The influences of different material compositions were studied with single-factor analysis. Viscosity and heat flow measurements were carried out to identify the relative states of the curing and to evaluate the material curing behavior by quantitative analysis. Different intensities were used to observe the effects on viscosity and curing degree. The findings of this work reveal the correlation between the relative curing degree and viscosity, which is divided into two parts depending on the light intensity. The correlated curve follows second-order polynomial under higher intensities, while the lower intensity follows a Gauss distribution. From the results, the relative curing degree is estimated by observing the viscosity of the resin system during the process. The critical curing degree was also determined to identify the resin phase transfer from the liquid to solid.

Lifetime health monitoring of fiber reinforced composites using highly flexible and sensitive MXene/CNT film sensor

In this paper, lifetime health monitoring of composites was conducted, included manufactured monitoring and structural health monitoring. A thin film sensor composed of multi-walled carbon nanotubes (MWCNTs) and MXene was developed through simple mixing and spray vacuum filtration. This highly flexible and susceptible MXene/CNT film sensor can be embedded in polymer composites to monitor the phase change of the resin and the determination of the gel point during the preparation of the composite in real-time. The MXene/CNT film sensors were embedded and arrayed in fiber-reinforced composites, which can be used for resin curing monitoring, then continued structural health monitoring. Experimental results show that the MXene/CNT film sensor embedded in the composite laminates can effectively capture the change of the resin phase, that characterized by resistance. MXene/CNT films have a good ability to respond to changes in the resin state. The gel point of resin obtained from the MXene/CNT film sensor is 134 °C, which is consistent with 137 °C from the DMA results. The accurate gel point can optimize the curing system and improve the quality of composite products. Then the tensile, bending, and fatigue tests of fiber-reinforced composite laminates embedded with MXene/CNT film sensors were carried out. MXene/CNT film sensor can keep good response and response consistency for a long time. As a novel sensor, the MXene/CNT film sensor has the advantages of high response sensitivity, solid real-time performance, and long service time. The MXene/CNT film sensor has great potential to establish and optimize manufacturing processes and to improve the cure quality of fiber-based resin composites. This sensor can be used to follow the entire life cycle of a composite from fabrication till end-of-life.

Extraction chromatography based separation of zirconium(IV) from simulated high-level liquid waste using N,N-di-octyl-2-hydroxyacetamide impregnated amberlite XAD-7 resin

Selective separation of zirconium(IV), from the simulated high-level liquid waste solution containing uranium(VI) and trivalent lanthanides, during reprocessing of fast reactor metal fuel was studied by extraction chromatography using N,N-di-octyl-2-hydroxyacetamide (DOHyA) impregnated on to Amberlite XAD-7 resin. The extraction behavior of Zr(IV), Nd(III) and U(VI) with varying concentrations of nitric acid was explored using a solvent impregnated resin with different compositions of DOHyA in XAD-7 [10, 20, 30, 40 and 50 (w/w) %]. The resin exhibited faster kinetics with more than 99 % recovery of Zr(IV) and with an apparent Langmuir adsorption capacity of ∼54 mg.g−1of Zr(IV) on to the resin phase. Quantitative (> 99%) and selective extraction of Zr(IV) with minimum loading of other trivalents and uranium was observed during column chromatography. Results of the study showed that Zr(IV) can be selectively separated in presence of trivalent lanthanides and U(VI).

Highly efficient plutonium scavenging by an extraction chromatography resin containing a tetraaza-12-crown-4 ligand tethered with four diglycolamide pendent arms

An efficient extraction chromatography resin, containing tetraaza-12-crown-4 functionalized with four diglycolamide moieties, was evaluated for the separation of plutonium. This chromatography resin yielded very large distribution coefficients for Pu4+ (>105) in 0.5 – 6 M HNO3 feed solutions. Various physicochemical properties such as sorption kinetics, Pu4+ sorption mechanism, and its sorption capacity were investigated. The sorption kinetics, following a pseudo-second-order model, showed that about 10 minutes of equilibration was sufficient for >99.9% sorption of Pu4+. The sorption of Pu4+ on the resin followed the Langmuir monolayer model, which was confirmed by a theoretical calculation based on the kinetic model. The Pu4+ sorption on the resin was driven by a large exothermic enthalpy change (ΔH = −31.4±2.2 kJ/mol) and a positive entropy change (ΔS = 224±15 J/mol/L). The resin could sorb a maximum of 12.1±0.8 mg of Pu per gram of resin, which is equivalent to 1:2 metal/ligand complex on the resin. The Pu4+ from the resin phase was completely stripped with 0.5 M oxalic acid. A possible application of this resin for the separation / pre-concentration of Pu4+ was successfully demonstrated in the column mode.

Removal mechanism of CFRP by laser multi direction interaction

A heterogeneous simulation model considering carbon fiber and resin phase about laser ablation of carbon fiber reinforced composite (CFRP) was established by ANSYS firstly. Then the ablation process of CFRP by short pulse laser was simulated and the mechanism of laser scanning direction on heat affected zone (HAZ) was studied. Lastly, the validity of the model was verified by experiments. The results show that the width of the heat affected zone increases with the angle between the laser scanning direction and the carbon fiber laying direction, while the fracture length of the carbon fiber increases firstly and then decreases. The split line is 45°, which also indicates the existence of the optimal scanning direction and has a certain guiding significance for the cutting of CFRP.

Study on the mechanism of inhomogeneous microdamage in short-pulse laser processing of carbon fiber reinforced plastic

In this article, a micro-heterogeneous material simulation model with carbon fiber and resin phase about laser ablation on carbon fiber reinforced plastic (CFRP) is established by Ansys. The ablation process of CFRP by nanosecond ultraviolet laser is simulated, and the mechanism of pulse energy and spot spacing on the heat-affected zone (HAZ) is studied, then the process parameters are optimized with the goal of HAZ size and processing efficiency, and finally the validity of the model is verified by experiments. It is found that the residual gradient and the width of the radial HAZ increase with the increase of the spot spacing, and the width of the axial HAZ decreases slightly with the increase of the spot spacing, which indicates the existence of the optimal spot spacing. Second, the ablation depth increases with the increase of the pulse energy, and the carbon fiber retains a relatively complete degree of exposure when the pulse energy is low, which has a certain guiding significance for the cleaning and bonding of CFRP.

Boron Removal from Aqueous Solutions by Strong Base Anion-exchange Resin Batch and Column Experiments

Borate ion exchange capacity of Purolite NRW600 strong base anion resin in hydroxide form and mixed bed NRW600+NRW100 ion exchange was investigated with static experiments. Anion exchange resin was saturated with 0.1–45 g/dm3 concentration boric acid solution in a static mixer at 20, 30, 40 and 50 °C at 150 rpm for 24 hours. Remaining borate content of saturation solutions was deter-mined with ion chromatography and ICP-OES. The amount of fixed borate as borate anions increased with the saturation borate concentration as well as in case of simple anion exchange as in case of mixed bed.Column sorption-elution study was carried out by using strong base anion exchange resins (Purolite NRW600 and Amberlite IRN78). Resins in hydroxide and in chloride forms were saturated in column with 5–40 g/dm3 boric acid solution in excess. The resin was then eluted with 200 cm3 salt free water with 5 cm3/min at 25 °C and then eluted by 1 mol/dm3 sodium-sulfate solution with 5 cm3/min. The effluent was collected and analyzed for borate content by titrimetric method. In chloride form the resin adsorbed and released much less borate. Effective borate and polyborate sorption needs hydroxide ions in resin phase.

Weakly Hydrated Anion Exchangers Doped with Cu2O and Cu0 Particles-Thermogravimetric Studies.

Hybrid ion exchangers (HIXs) containing fine Cu2O and Cu0 particles were subjected to thermal analysis in order to determine their hygroscopic water content (with regard to their anomalously low porosity) and to determine the effect of the oxidation state of the copper atom in the deposit on the thermal properties of composite materials. Commercially available anion exchangers, Amberlite IRA 900Cl (macroreticular, M) and Amberlite IRA 402OH (gel-like, G), were used as supporting materials. M/Cu2O, G/Cu2O, M/Cu and G/Cu, containing 4.3–8.4 wt% Cu, were subjected to thermal analysis under respectively air and N2. TG/DTG curves revealed that dry M/Cu and G/Cu contained as little as 7.2% and 4.3% hygroscopic water, while M/Cu2O and G/Cu2O contained respectively 10.6% and 9.4% (Cu0 was a stronger water repellent than Cu2O). The oxidation state of the copper atom in the deposit was found to affect the amount of the forming char, and also Cu0 was found to contribute to the formation of more char than in the pyrolysis of the pure resin (the anion exchanger with no copper deposit). Under air the two kinds of particles transformed into CuO, while under N2 metallic copper and char (from the resin phase) made up the solid residue. This means that in the pyrolysis of the HIXs the inorganic phase participated in char formation and it also transformed itself (undergoing reduction when possible). The above findings provide a basis for in-depth research aimed at the innovative use of copper-containing HIXs and at obtaining usable composite materials with a designed (organic-inorganic) composition.

Purification of 89Sr from FBTR irradiated Yttria target by extraction chromatography using HDEHP impregnated XAD-7 resin

Abstract 89Sr is used in bone pain palliative care of cancer patients and the same is being produced presently via the 89Y(n, p)89Sr reaction by irradiating yttria target in Fast Breeder Test Reactor (FBTR). An efficient separation method was standardized for the removal of bulk yttrium target by extraction chromatography using di(2-ethylhexyl) phosphoric acid (HDEHP) impregnated on XAD-7 resin. In the present paper, the extraction behavior of Sr(II) and Y(III) was studied as a function of the concentration of nitric acid in the aqueous phase and concentration of HDEHP in the resin phase. The separation of Sr(II) and Y(III) was standardized using the above resins and the method was subsequently applied satisfactorily for the removal of yttrium from the dissolver solution of FBTR irradiated yttria pellet towards the purification of 89Sr. A baseline separation of 89Sr and Y was achieved. Leaching and breakthrough capacity studies were evaluated for the resins and it was established that the stability and capacity of the resins were satisfactory. The breakthrough capacity was found to be 12 mg Y(III) per gram of the HDHEP resin whereas the leaching studies established that the resins are stable for multiple cycle of operations.

Cavitation erosion behavior of nickel foam/polyurethane co-continuous composite

The cavitation erosion behavior of Ni foam/polyurethane (PU) co-continuous composites under different experimental conditions was investigated using an ultrasonic vibration cavitation erosion device. Experimental results showed that the Ni foam metal skeleton structure had severe effects on the cavitation resistance of the composites. The composites with thick metal arris and large pore size exhibited good resistance to cavitation erosion. Stress waves had greater influence on the cavitation erosion behavior of composites than micro-jets. In a synergistic way of buffering stress wave in the resin phase and absorbing stress waves in the metal phase, the composites could exhibit better cavitation resistance than pure PU.

Sorption Recovery of Lanthanum, Iron, Aluminum, and Calcium Ions from Phosphoric Acid

Sorption recovery of lanthanum, iron(III), aluminum, and calcium ions from phosphoric acid solutions with MTC 1600 macroporous sulfonic cation exchanger under dynamic conditions was studied. Calcium suppresses the sorption of lanthanum and other elements; in its presence, the dynamic exchange capacity of the sorbent for lanthanum decreases from 53.5 to 11.8 mg g–1, and that for iron and aluminum tends to zero. In elution of lanthanum and calcium ions from the resin phase with an ammonium nitrate solution, the maximal concentration of the ions was 5.5 and 9.5 g L–1, respectively. The ratio of the calcium and lanthanum ions in the eluate is 2 times higher than that in the initial phosphoric acid solution.

Size-Controlled Transformation of Cu2O into Zero Valent Copper within the Matrix of Anion Exchangers via Green Chemical Reduction.

Composite materials containing zero valent copper (ZVC) dispersed in the matrix of two commercially available strongly basic anion exchangers with a macroreticular (Amberlite IRA 900Cl) and gel-like (Amberlite IRA 402OH) structure were obtained. Cu0 particles appeared in the resin phase as the product of the reduction of the precursor, i.e., copper oxide(I) particles previously deposited in the two supporting materials. As a result of a one-step transformation of preformed Cu2O particles as templates conducted using green reductant ascorbic acid and under mild conditions, macroporous and gel-type hybrid products containing ZVC were obtained with a total copper content of 7.7 and 5.3 wt%, respectively. X-ray diffraction and FTIR spectroscopy confirmed the successful transformation of the starting oxide particles into a metallic deposit. A scanning electron microscopy study showed that the morphology of the deposit is mainly influenced by the type of matrix exchanger. In turn, the drying steps were crucial to its porosity and mechanical resistance. Because both the shape and size of copper particles and the internal structure of the supporting solid materials can have a decisive impact on the potential applications of the obtained materials, the results presented here reveal a great possibility for the design and synthesis of functional nanocrystalline solids.

A Study to Investigate the Mechanical Properties of Recycled Carbon Fibre/Glass Fibre-Reinforced Epoxy Composites Using a Novel Thermal Recycling Process

Manufacturing-based carbon fibre-reinforced polymer (CFRP) and glass fibre-reinforced polymer (GFRP) wastes (pre-consumer waste) were recycled to recover valuable carbon fibres (CFs) and glass fibres (GFs), utilising a novel thermal recycling process with a cone calorimeter setup. The ideal conditions to recycle both the fibres occurred at 550 °C in atmospheric pressure. The processing time in the batch reactor to recycle CFs was 20–25 min, and to recycle GFs it was 25–30 min. The recovery rate of the recycled CFs was 95–98 wt%, and for GFs it was 80–82 wt%. Both the recycled fibres possessed a 100–110 mm average length. The resin phase elimination was verified by employing scanning electron microscopy (SEM). Furthermore, the fibres were manually realigned, compression moulded at room temperature, and cured for 24 h by a laminating epoxy resin system. The newly manufactured CFRP and GFRP composites were continuous (uniform length from end to end), unidirectionally oriented (0°), and non-woven. The composites were produced in two fibre volumes: 40 wt% and 60 wt%. The addition of ≈20 wt% recycled CFs increased the tensile strength (TS) by 12%, young modulus (YM) by 34.27% and impact strength (IS) by 7.26%. The addition of ≈20 wt% recycled GFs increased the TS by 75.14%, YM by 12.23% and the IS by 116.16%. The closed-loop recycling approach demonstrated in this study can effectively recycle both CFRP and GFRP manufacturing wastes. Preserving the structural integrity of the recycled fibres could be an advantage, enabling recycling for a specified number of times.