Diglycidyl Ether Of Bisphenol A Research Articles

The adsorption modeling of bisphenol A derivatives on the surface of carbon materials

A carbon nanotube and a graphene surface with bisphenol A derivatives have been simulated in the DFT framework using periodic boundary conditions. Such compounds are components of epoxy diane resins, which are important composite materials for aircraft structures. The simulation results allow one to state that the use of the specialized exchange-correlation functional Berland and Hyldgaard developed to account for weak Van der Waals interactions is preferable to DFT-D2 method. We observed that the energy of complexes formation depends on the orientation of the functional groups of diglycidyl ether of bisphenol A and determines by whether the surface of the carbon material is flat, like graphene, or curved, like nanotubes. It was found that the strongest binding is observed for nanotubes with a diameter of 1 nm, for which the energy of complex formation is 65 % lower than for the complex of diglycidyl ether of bisphenol A on graphene with the same orientation of functional groups relative to the surface. On the curved outer surface of the nanotubes, the ester derivatives form a greater variety of non-covalent interactions in accordance with the QTAIM analysis of electron density and the energy of complexes formation is lower.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China

Despite high production and usage, little is known about exposure to bisphenol diglycidyl ethers (BDGEs) and their derivatives in pregnant women and fetuses. In this study, we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China. Bisphenol A bis (2,3-dihydroxypropyl) glycidyl ether (BADGE·2H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether (BADGE·HCl·H2O), and bisphenol F diglycidyl ether (BFDGE) were the major BDGEs, with median concentrations of 0.57, 4.07, and 1.60 ng/mL, respectively, in maternal serum, and of 3.58, 5.61, and 0.61 ng/mL, respectively, in cord serum. The transplacental transfer efficiencies (TTEs) were estimated for BDGEs found in samples, and median values were in the range of 0.98 (BFDGE) to 5.91 (BADGE·2H2O). Our results suggested that passive diffusion plays a role in the placental transfer of BADGE·HCl·H2O and BFDGE, whereas several mechanisms contribute to the high accumulation of BADGE·2H2O in cord serum. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers, especially those related to liver injuries, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and adenosine deaminase (ADA) (P < 0.05). To our knowledge, this is the first study to report the occurrence of BDGEs in paired maternal–fetal serum samples and provide new insights into prenatal and fetal exposures. The newly discovered TTEs in maternal–fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body, ultimately adding to a more significant comprehensive risk evaluation.

Improved thermal conductivity of epoxy resins using silane coupling agent‐modified expanded graphite

AbstractA silane coupling agent was used to modify the surface of expanded graphite (EG), which was subsequently used as a thermally conductive filler to fabricate diglycidylether of bisphenol‐A (DGEBA)/EG composites with high thermal conductivity via hot blending and compression‐curing processes. The surface characteristics of silane coupling agent‐modified EG (Si@EG) were characterized by a variety of analytical techniques. The effects of the Si@EG content on the thermal conductivity, thermal stability, impact strength, and morphology of the DGEBA/Si@EG composites were investigated. The results revealed that the addition of 80 wt.% Si@EG increased the thermal conductivity of the composites from 0.17 to 10.56 W/m K, which was 61.1 times higher than that of pristine DGEBA. The initial decomposition temperature of the composite containing 80 wt.% Si@EG was 60.6°C higher than that of pristine DGEBA. The impact strength of the composites decreased from 2.0 to 0.87 kJ/m2 when the Si@EG content increased from 0 to 80 wt.%. The scanning electron microscopy images of the fractured surfaces revealed that the EG sheets in the DGEBA matrix formed a continuous thermally conductive path at high Si@EG contents.

A bio-based intrinsically flame-retardant epoxy vitrimer from furan derivatives and its application in recyclable carbon fiber composites

The recycling of carbon fiber reinforced polymer composites (CFRPCs) is difficult because the thermosetting matrix is insoluble and does not melt. To overcome this problem, a furan-derived epoxy resin (HMF-GAN-EP) was synthesized from 5-hydroxymethylfurfural and cured with a furan-based curing agent (DIFFA). The cured HMF-GAN-EP/DIFFA system showed excellent flame retardancy (UL-94 V-0 and LOI of 40%). The glass transition temperature, tensile strength, and tensile modulus of the cured HMF-GAN-EP/DIFFA system were approximately 234 °C, 67 MPa and 2273 MPa, respectively, all of which were higher than those of the diglycidyl ether of bisphenol A (DGEBA)-type epoxy thermosets cured by 4,4′-diaminodiphenylmethane (DDM) (151 °C, 56 MPa and 1744 MPa). The cured HMF-GAN-EP/DIFFA system could dissolve in a mixed solution of THF:HCl (8:2, v/v), making it possible for the recycling of carbon fibers from CFRPCs.

Molecular dynamic study on modulating the interfacial thermal conductivity of carbon fiber/epoxy interfaces

Chemical functionalization of carbon fiber surface is a widely used strategy to improve the out-of-plane thermal conductivity of carbon fiber reinforced plastics (CFRPs) for structural and space applications. However, determining the ‘right ligand’ to achieve this objective is a difficult problem. Molecular dynamics (MD) simulations are performed in this study to characterize the effect of different chemical ligands on the interfacial thermal conductivity (Ki) of carbon fiber/epoxy composites. The carbon fiber is modeled as graphene layers, diglycidyl ether of bisphenol F (EPON862) and diethyl toluene diamine (DETDA) are used as epoxy and crosslinker in MD simulations. The carbon fiber is functionalized with different types of small (amine and carboxylic) and large (aniline, single-chain para-amine surface grafted molecules (SGM), and double-chain meta-amine SGM) functional groups with varying degrees of functionalization. When the carbon and the neighbouring epoxy molecules are bridged by relatively larger ligands, that are capable of large fluctuations in their end-to-end distances, we observe a very effective reduction in the thermal resistance that otherwise exists between base carbon and the epoxy matrix.

Degradation of vinyl ester resin and its composites via cleavage of ester bonds to recycle valuable chemicals and produce polyurethane

Vinyl ester resins (VER) and its composites are widely used in chemical industry and municipal engineering. However, its dense three-dimensional network structure makes its degradation and recycling a great challenge. Herein, a novel, efficient and green degradation system gamma-valerolactone (GVL)–H2O/p-toluene sulfonic (PTSA) was developed to degrade VER and its composites. VER was completely degraded in the GVL-H2O/PTSA at 210 °C and 0.6 MPa. By combing SEM-EDS, IR, NMR, GPC and MALDI-TOF-MS analysis, it was clarified that VER swelled well in GVL, allowing the transfer of PTSA and H2O through the resin matrix. The ester bonds in VER were cleaved via hydrolysis with H2O catalyzed by the sulfonic acid of PTSA, and high value-added polymer products, i.e., copolymer of styrene and methacrylic acid (SMAA) and bisphenol-A diglycidyl ether (DGEBA), were recycled, which accounted for ca. 87.0 wt% of raw VER. DGEBA can be recycled to prepare a new PU material. The GVL-H2O/PTSA system was also effective for degrading UPR and VER-containing composites. This work provides a practical strategy for chemical degradation and recovery of thermoset VER resins.

Malleable and recyclable thermoset network with reversible β‐hydroxyl esters and disulfide bonds

AbstractBy combining bifunctional diglycidyl ether of bisphenol A (DGEBA) and trifunctional tris(4‐hydroxyphenyl) methane triglycidyl ether (TMTE) epoxy monomers, along with 4,4′‐dithiodibutyric acid (DTDBA) as a carboxylic acid, a variety of novel reprocessable and recyclable thermoset polymers are synthesized. The crosslinked network structures with different crosslinking densities are produced by changing the mixing ratio between DGEBA and TMTE, resulting in changes in mechanical and thermal properties of the final products. The stress relaxation and self‐healing experiments confirmed that all of these polymeric materials have covalent adaptable networks in their microstructures and perform reversible transesterification processes inside a polymer network. These thermoset polymers are completely decomposed in solution by disulfide‐thiol reduction of DTDBA with reversible cleavage or coupling capability in the presence of reducing agent, allowing chemical recycling capability into the thermoset polymer network.

Mechanically robust, hydrothermal aging resistant, imine-containing epoxy thermoset for recyclable carbon fiber reinforced composites

Imine compounds have been proved to possess great potential in the design and preparation of sustainable epoxy thermosets. However, it is still a great challenge to develop imine-containing hardener with definite structure due to the randomness of condensation reaction between aldehydes and primary amines. Herein, a novel amine hardener containing imine bond is synthesized successfully by selecting 4-imidazole formaldehyde and 3-aminobenzylamine as raw materials. The asymmetric structure of raw material can avoid uncontrollable reaction and ensure that this hardener possesses definite chemical structure. Due to high activity of hardener, the resultant epoxy thermosets with high cross-linked density exhibit excellent thermostability and fine hydrothermal aging resistance. Furthermore, such thermosets show good mechanical properties (tensile strength of ∼76 MPa), which are comparable to that of commercial Diglycidyl Ether of Bisphenol A epoxy resin cured by 4,4-Diaminodiphenyl methane. More interestingly, increasing the equivalent ratio of active hydrogen to epoxy can introduce more dynamic covalent C=N linkage into the cross-linked network, thus the epoxy thermoset further achieves the decomposition within 3 h and the corresponding composite laminates also are recycled efficiently under mild condition. This work demonstrates the feasibility and potential of preparing high-performance degradable epoxy thermoset and corresponding recyclable composites based on well-designed imine-containing hardener.

Synthesis of a bio-based and intrinsically anti-flammable epoxy thermoset and the application of its carbonized foam as an efficient CO2 capture adsorbent

The production of multifunctional carbon foams from biomass has attracted great interest due to the increasing awareness of green and sustainable development. Here, we report a bio-based epoxy thermoset prepared by curing a furan-derived di-functional epoxy monomer (5-hydroxymethyl-2-furaldehyde (HMF)-3, 5-diamino-1,2,4-triazole (GU)-EP) with a furan-derived curing agent, 5,5′-methylenedifurfurylamine (DFA). For comparison, the cured commercial diglycidyl ether of bisphenol-A was used as a thermoset epoxy resin. Due to its unique structure rich in aromatic and nitrogenous structures, the cured HMF-GU-EP/DFA thermoset possessed exceptional charring ability. This fully bio-based epoxy thermoset had a very high char yield (55.8 wt%) at 800 °C under nitrogen, while the cured diglycidyl ether of bisphenol-A/4, 4′-diaminodiphenylmethane was only 13.6 wt%. Due to this excellent carbonization ability, the cured HMF-GU-EP/DFA was carbonized at 700 °C to obtain a carbon foam as a CO2 absorbent. The Brunauer–Emmett–Teller surface area and total pore volume were measured to be 472 m2/g and 0.22 cm3/g, respectively. The amounts of CO2 adsorbed with this carbon foam were 4.72 and 2.15 mmol/g at 273 and 298 K, respectively. In conclusion, this study provides a bio-based, strong and rigid, inherently flammable, and highly carbonizable epoxy thermoset and the potential application of its carbonized foam as an efficient adsorbent for CO2 capture.

L-Arginine as Bio-Based Curing Agent for Epoxy Resins: Temperature-Dependence of Mechanical Properties.

The precise characterization of new bio-based thermosets is imperative for the correct assessment of their potential as matrix material in fiber-reinforced polymer composites. Therefore, the mechanical properties of diglycidyl ether of bisphenol a (DGEBA) cured with l-arginine were investigated to determine whether the bio-based thermoset possesses the required mechanical properties for application as a matrix material. The cured thermoset is called Argopox. The mixture of amino acid and epoxy resin was prepared via three-roll milling and cured in the presence of an urea-based accelerator. The tensile, compression, flexural and toughness properties of Argopox were characterized at T=−40 ∘C, 22 ∘C and 80 ∘C to determine the temperature-dependence of the thermoset’s mechanical properties in its service temperature range. The glass transition temperature Tg was analyzed via dynamic mechanical analysis (DMA) and is approximately 119 ∘C. The tensile, compression and flexural strength at 22 ∘C are about 56 MPa, 98 MPa and 85 MPa, respectively. The critical stress intensity factor KIC and fracture energy GIC at 22 ∘C are roughly 1.1 MPam0.5 and 510 Jm−, respectively. Consequently, Argopox possesses mechanical properties that reach performance levels similar to that of materials which are already used as matrix for fiber reinforced composites.

Biomass-based epoxy resin derived from resveratrol with high temperature resistance and intrinsic flame retardant properties

Preparing biomass-based epoxy resin with high temperature resistance and flame retardancy is still an appealing yet challenging task. Now, a high-temperature resistant and flame-retardant resveratrol-based epoxy (RESEP) has been synthesized through a facile one-step method. The structure of RESEP was established using FTIR and NMR spectroscopy. RESEP and petroleum-based epoxy diglycidyl ether of bisphenol A (DGEBA) were each cured with 4,4-diaminodiphenyl methane (DDM) to prepare RESEP/DDM and DGEBA/DDM. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile testing, thermogravimetric analysis (TGA), thermogravimetric analysis-infrared spectroscopy (TG-IR), scanning electron microscopy (SEM), limiting oxygen index (LOI) and the UL-94 vertical burning test were used to systematically evaluate the properties of RESEP and RESEP/DDM. The glass transition temperature (Tg) of RESEP/DDM is 335 ℃, which is significantly higher than that of DGEBA/DDM (168 ℃). In addition, RESEP/DDM displays good thermogravimetric performance and flame retardancy. Typically, it displays a UL-94 V-0 rating, an LOI value was as high as 31.8%, and a char yield as high as 38.6% (800 ℃). The results reported indicate the possibility of preparing biomass-based epoxy resin with high temperature resistance, flame retardancy and mechanical properties, which is potential to be utilized in the fields of electronics and aerospace.

Aspects of halloysite nanotubes integration in epoxy nanocomposites: Curing kinetics and deformation mechanism

AbstractThe curing kinetics of diglycidyl ether of bisphenol A epoxy resin using amine‐based hardener in the presence of halloysite nanotubes (HNTs) are investigated by performing isothermal and dynamic differential scanning calorimetry measurements, followed by a detailed analysis of the experimental data via the kinetic free method and three common model‐based analysis. Kamal and Sourour model gave the best fit for the experimental data and thus, was further modified by Williams–Landel–Ferry diffusion control equations to calculate the diffusion constants near the glass transition temperature (Tg). The optimized model is used to find the curing kinetics parameters of epoxy/HNTs nanocomposites, and those finding are further validated and explained by performing rheometric measurements. Noncatalytic and autocatalytic curing reactions and diffusion constants are all functions of the amount of HNTs. HNTs shift the curing reaction slightly toward higher temperatures and promote etherification reactions, leading to an increase in the curing enthalpy, as extra bonds will be formed between HNTs and epoxy resin during the polymerization. The combination of acceleration and inhibition mechanisms dictates the complex kinetics of the reactions at high concentrations of HNTs, while the produced local topology of the polymeric network depends highly on HNTs weight ratio. Furthermore, to investigate the mechanical performance of the prepared nanocomposites under flexural loads, three points bending tests are performed in both modes, dynamic and static, followed by a fractography analysis of the fractured surfaces. The mechanical properties have improved by the addition of pristine HNTs without compromising the Tg of the polymer. This study provides a set of observational relationships between various chemical interactions during polymerization and the final topology and performance of the polymer, which in turn aims to bridge the gap in the literature between the curing kinetics of epoxy/HNTs nanocomposites and the performance of these nanocomposites under various thermal and mechanical stresses.

A nanoscale adhesion mechanism of cement-epoxy interface under varying moisture conditions: A molecular dynamics study

The epoxy-concrete interface is a critical phase in a bonded system, such as FRP-bonded to a concrete structure. The effectiveness of this bond is generally affected by the presence of moisture at the interface. In this paper, a nanoscale adhesion mechanism of the epoxy-cement interface under moisture variations was studied using molecular dynamics (MD) modeling. The epoxy-cement interface was first modeled by representing calcium silicate hydrate (C–S–H), and diglycidyl ether of bisphenol-A (DGEBA) resin. The surface moisture was simulated by inserting different layers of water. In addition, the macroscopic pull-off adhesion test was performed to validate the MD findings, where the latter provided an explanation for the observed macroscopic behavior. The results indicated that the interatomic and intermolecular forces across the interface at dry and relatively low moist systems are mainly due to the van der Waals (vdW) interactions. However, at relatively higher moisture content, the electrostatic interaction becomes more significant, which is responsible for the degradation process in the adhesion energy. Further, the increase in the debonding work was mainly caused by an increase in the adhesion between the C–S–H and water molecules at the interface where the latter forms hydrogen bonds with the substrate (i.e., C–S–H).

Investigation of mechanical and thermal characteristics of epoxy/graphene oxide nanocomposites by molecular dynamics simulation

This study examined the thermal stability (TS) and mechanical properties (MP) of the simulated Diethyl-toluene-diamine (DETDA) and Diglycidyl ether bisphenol A (DGEBA) matrices/graphene oxide nanosheet (GON) samples. This study was performed by molecular dynamics simulation (MDS). Physical values such as stress–strain curve, order parameter, and atomic length extension are examined at different ratios of GON and initial pressures (IP). Increasing the atomic ratio of GON increases the slope of the stress–strain curve. Thus, Young's modulus (YM) increases in atomic structures. Increasing the GON atomic ratio up to 5 % optimizes interatomic interactions and increases the order parameter. Also, by increasing the atomic ratio of GON from 1 to 5 %, the atomic length extension decreases from 11 to 8 Å. Also, the effect of the IP on the TS and MP of the sample was examined. As the IP increments, the slope of the stress–strain curve increases from 2.91 to 3.55 GPa. These studies show that the order parameter has a downward trend in increasing the IP from 1 to 5 bar and decreases from 0.48 to 0.4 as the IP increases. Also, the effects of IP on the length change of the simulated sample have a decreasing trend after 10 ns. The atomic length decreases from 11 Å to 10 Å by increasing the IP from 1 bar to 5 bar.

The effect of cross-linker structure on interfacial interactions, polymer dynamics and network composition in an epoxy-amine resin

Understanding interactions at the polymer / metal oxide interface is central to improving the performance lifetime of corrosion resistant coatings, where network polymers commonly form via step growth mechanisms in the presence of pigments. Here we employ a holistic analytical approach encompassing ATR-FTIR, DSC and molecular dynamics simulations to consider how crosslinker structure affects adsorption and incorporation into the network, using a stoichiometric mixture of diglycidylether of bisphenol-A (DGEBA) with m-xylylenediamine (MXDA) cured in the presence of hematite (Fe2O3) and goethite (FeOOH) powders. We find that the rigid MXDA molecule has two distinct binding modes on both hematite and goethite, and that synergistic hydrogen bonding modes observed on goethite limit interconversion between the two. Moreover, we find that binding persists in fully cured composite samples, determining the levels of residual amine. In contrast to previously reported results using triethylenetetramine (TETA) crosslinkers, however, we find that the Tg of composite specimens is independent of added hematite and goethite volumes. Molecular dynamics simulations demonstrate this is due to electrostatic binding between the cationic Fe sites and electronegative heteroatoms in MXDA. This renders both amine functionalities unavailable for incorporation into the network and hence, unlike TETA, MXDA adsorption does not determine polymer dynamics.

The Physicochemical Characterization of New "Green" Epoxy-Resin Hardener Made from PET Waste.

“Green” thermally stable hardener was synthesized from a PET waste. The rigid molecular linear structure of the new hardener suggests that it will provide the polymer matrix with the necessary physical and mechanical characteristics. It also allows the expectation that cured matrix based on this hardener can provide increased toughness. New hardener was used as a curing agent for three epoxy resins—tetraglycidyl methylenedianiline (TGDMA, 111–117 EEW), diglycidylether of bisphenol A (DGEBA, 170-192 EEW) and solid epoxy resin (SER)—with a medium molecular weight (860–930 EEW) based on DGEBA. The mixtures were found to have the highest Tg for the DGEBA resin, and high of that for TGDMA and SER. According to the DMA analysis for two cured matrices, the hardener proved to be no worse than the standard ones, and made it possible to obtain cured matrices with excellent mechanical properties, which allows us to hope for further application of new hardener cured epoxy matrices in appropriate composite materials at high temperatures.

Study on the synthetic mechanism of monodispersed polystyrene-nickel composite microspheres and its application in facile synthesis of epoxy resin-based anisotropic conductive adhesives

Monodispersed polystyrene-nickel (PS-Ni) composite microspheres were used to enhance the conductivity of epoxy-based anisotropic conductive adhesive (ACA) for the first time. Specifically designed PS-Ni composite microspheres were used as conductive elements to construct anisotropic conductive arrays. The surface microstructure and morphology of the prepared PS-Ni composite microspheres were tuned by controlling the implementation method of electroless plating and concentration of Ni precursor. The structural composition, thermal properties, and electrical properties of PS-Ni composite microspheres were analyzed. In addition, diglycidyl ether of bisphenol-A (DGEBA) epoxy resin and low molecular weight polyamide resin were used as the matrix resin and curing agent, respectively. The optimal process parameters were employed and predicted based on the curing kinetics. A simple strategy was developed for the preparation of anisotropic conductive binders (viz. PS-Ni/EP-ACAs) via physical doping by addition of terminal carboxyl-terminated butadiene acrylonitrile (CTBN) copolymer and additives. PS-Ni/EP-ACAs exhibited satisfactory anisotropic electrical properties in fabricated components due to submicron structures composed of PS-Ni composite microspheres with excellent integrated properties in the anisotropic conducting array. Therefore, the theoretical concept and fabrication mean proposed in this study showed great potential and practical application in large-scale ACAs preparation.

L-Arginine as a Bio-Based Curing Agent for Epoxy Resins: Glass Transition Temperature, Rheology and Latency

The need for sustainable practices in the processing chain of fiber-reinforced thermosets has led to the development of bio-based epoxy resins and curing agents. As a contribution to sustainable composites, this study focuses on the glass transition temperature (), viscosity and latency of diglycidyl ether of bisphenol a (DGEBA) cured with l-arginine in the presence of a urea-based accelerator. These characteristics are decisive features for application as a matrix in fiber-reinforced polymer composites produced via prepreg technology in which low viscosity and sufficient latency, meaning low reactivity of the one-component system, are necessary. The homogeneous mixture of amino acid and epoxy resin was prepared via three-roll milling. Two formulations, Argopox-1 with 1 accelerator and Argopox-2.5 with accelerator, were prepared and parts of each formulation were stored at 22 °C and −18 °C, respectively. Both formulations were tested via differential scanning calorimetry (DSC) and small amplitude oscillatory shear rheology (SAOS) after 0 d, 30 d, 60 d, 90 d and 180 d of storage to determine the influence of accelerator weight fraction, storage temperature and storage period on the glass transition temperature of the uncured resin system , and their viscosity. The of the thermosets is about 100 °C. The DSC and SAOS measurements show that the of Argopox-1 shifts about 5 °C in 60 d, while its viscosity is still low enough to be processed in a prepreg production line. Furthermore, Argopox-1 is storable for at least 180 d at −18 °C without significant changes in its and viscosity. Consequently, Argopox-1 possesses a sufficiently high and adequate latency, as well as a low viscosity for application as prepreg matrix material.

Human dietary exposure to bisphenol-diglycidyl ethers in China: Comprehensive assessment through a total diet study

Despite the widespread use of bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE) in various consumer products as protective plasticizer, studies on human dietary exposure to these compounds are scare. In this study, nine bisphenol diglycidyl ethers (BDGEs) including BADGE, BFDGE, and seven of their derivatives were determined in the Chinese adult population based on composite dietary samples collected from the sixth (2016–2019) China total diet study (TDS). Contamination level of nine BDGEs was determined in 288 composite dietary samples from 24 provinces in China. BADGE·2H2O and BADGE are the most frequently detected and BADGE·2H2O presented the highest mean concentration (2.402 μg/kg). The most contaminated food composite is meats, with a mean ∑9BDGEs of 8.203 μg/kg, followed by aquatic products (4.255 μg/kg), eggs (4.045 μg/kg), and dairy products (3.256 μg/kg). The estimated daily intake (EDI) of ∑9BDGEs based on the mean and 95th percentile concentrations are 121.27 ng/kg bw/day and 249.71 ng/kg bw/day. Meats, eggs, and aquatic products are the main source of dietary exposure. Notably, beverages and water, alcohols were the main contributors of dietary exposure to BADGE and BADGE·2H2O, followed by animal-derived foods. Dietary exposure assessment demonstrated that human dietary BDGEs do not pose risks to general population based on the mean and 95th percentile hazard index with < 1. This is the first comprehensive national dietary exposure assessment of BDGEs in Chinese general population.

Novel efficient method of chemical upcycling of waste poly(ethylene terephthalate) bottles by acidolysis with adipic acid under microwave irradiation

In this work, for the first time, the reaction of post-consumer poly(ethylene terephthalate) (PET) bottles with adipic acid (AA) under microwave (MW) irradiation without catalyst was investigated. An efficient procedure to isolate various materials was proposed, namely the excess adipic acid, terephthalic acid, and novel oligo(ethylene adipate-co-terephthalate) (OEAT) with carboxylic end groups. The structure of OEAT was confirmed by FTIR, 1H-NMR, and ESI-MS. OEAT is a mixture of oligomers, containing co-oligomers of ethylene adipate and terephthalate, and nonreacted adipic acid. An explanation of the mechanism of the reaction was proposed through a concerted six-member ring formation including an O-alkyl fission process. Adipic acid and terephthalic acid were recovered and used as basic materials. OEAT was used for curing diglycidyl ether of bisphenol-A (DGEBA) resin and applied as a coating material. This upcycling method of PET showed high atom efficiency and high isolated yield reaction.