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Poly(vinyl acetate) (PVAc) adhesive is often used in the wood industry because it can be rapidly cured at room temperature to produce a high bonding strength. However, PVAc is a linear polymer susceptible to thermal creep, so it will fail to bond in high temperature and humidity environments. In this study, the hot water resistance of PVAc adhesive is improved by introducing lignin with a complex structure to construct multiple cross‐linked networks with a high cross‐link. However, due to the large steric hindrance, the reactivity of lignin hydroxyl groups is low. In the process of preparing adhesive, alkali lignin is hydroxymethylated to improve its reactivity, and then 4,4′‐diphenylmethane diisocyanate is used as a cross‐linker to construct interpenetrating and semi‐interpenetrating polymer networks. The hydroxymethylation occurs through the reaction of formaldehyde with lignin under alkaline conditions. Optimal reaction conditions include a reaction ratio of 0.20, a reaction temperature of 80°C, and a reaction time of 3.5 h. On those conditions, the bonding strength of the lignin‐based PVAc adhesive reaches 1.8 MPa after hot‐water treatment. Therefore, the lignin‐based hot water‐resistant PVAc adhesive has shown good application potential in high temperature and humidity environments. [ABSTRACT FROM AUTHOR]

BACKGROUND: The present work describes the facile, fast and economic base‐catalyzed acylation of benzenediols with vinyl acetate. The Hirshfeld surface analysis of benzene‐1,4‐diol O,O′‐diacetate is also described. NaOH, KOH and K2CO3 were the bases used for the catalysis of the acylation of benzene‐1,x‐diols (x = 2, 3, 4) with vinyl acetate to obtain the corresponding O,O′‐diacetyl derivatives. RESULTS: The yields were quite good, up to 99% under solvent‐free conditions. This method represents an alternative 'green' process for the preparation of O‐acetyl derivatives of hydroxyaryls. The benzene‐1,4‐diol O,O′‐diacetate crystal structure was obtained and described using Hirshfeld surface analysis. A noticeable contribution of the C⋯H contacts is shown (16.7%), despite the insignificant area of the Hirshfeld surface occupied by the carbon atoms (9.4%). By using two‐dimensional fingerprint plots, it was proved that C⋯H contacts were due to the presence of π‐stacking. The O⋯H contacts (41.4%) were the most numerous ones, relating mainly to typical hydrogen bonds (de + di ≈ 2.6 Å). The high saturation of the C⋯H and O⋯H contacts (enrichment ratios (E) = 1.30 and 1.36, respectively), despite their smaller contribution to the overall surface as compared to the H⋯H contacts (E = 0.84), is shown. CONCLUSION: The novelty of this work is the development of a method based on an inexpensive, safe and easy‐to‐use catalyst (K2CO3). This method is fast with high yields. Besides, it may be used for acylation at an industrial scale. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Immobilization is a key enabling technology in applied biocatalysis that facilitates the separation, recovery, and reuse of heterogeneous biocatalysts. However, finding a consensus immobilization protocol for several enzymes forming a multi‐enzyme system is extremely difficult and relies on a combinatorial trial‐and‐error approach. Herein, we describe a protocol in which 17 different carriers functionalized with different reactive groups are tested in a 96‐well microtiter plate to screen up to 21 immobilization protocols for up to 18 enzymes. This screening includes an activity and stability assay to select the optimal immobilization chemistry to achieve the most active and stable heterogeneous biocatalysts. The information retrieved from the screening can be rationalized using a Python‐based application CapiPy. Finally, through scoring the screening results, we find the consensus immobilization protocol to assemble an immobilized four‐enzyme system to transform vinyl acetate into (S)‐3‐hydroxybutyric acid. This methodology opens a path to speed up the prototyping of immobilized multi‐enzyme pathways for chemical manufacturing. [ABSTRACT FROM AUTHOR]

A large amount of toxic smoke and heat generated by the combustion of ethylene vinyl acetate copolymer (EVA) poses a significant threat to human fire escape evacuation. This work aims to use γ -ray to prepare e-MXene@Ag hybrid flame-retardant materials by the method of in-situ reduction, and EVA composites are prepared by melt blending to reduce the smoke and toxic gases produced during combustion significantly. Compared with pure EVA, the total heat release, total smoke release, and the production rate of CO and CO2 produced by the combustion of EVA composite with 1 wt% e-MXene@Ag1.0 decreased by 30.3%, 33.3%, 18.2%, and 20.1% respectively. The fire hazard reduction of EVA composite materials was due to the physical barrier, catalytic carbonization and adsorption of the e-MXene@Ag1.0 hybrid. In addition, e-MXene@Ag1.0 can also further increase the mechanical properties of EVA composites due to its own 'multi-contact point limit structure'. [ABSTRACT FROM AUTHOR]

The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO2 nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO2 and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO2 act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman's isoconversional method. The Avrami's modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO2 nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO2. [ABSTRACT FROM AUTHOR]

This review focuses on summarising the studies on transition metal catalysed transfer vinylation of alcohols using vinyl ethers and vinyl acetate as vinylating agents. Mercury, palladium, iridium and gold catalysts are discussed herein. Selected examples from publications and patents are given for the purpose of analysing functional group tolerance towards the methodology. In addition, mechanistic pathways are described. [ABSTRACT FROM AUTHOR]

Highlights Polymer nanocomposite films of poly(ethylene‐co‐vinyl acetate) (EVA) with different concentrations of nickel oxide (NiO) nanoparticles (NPs), produced by an open two‐roll mill mixing method. Structural characterization using Fourier transform infrared (FTIR), UV–visible spectroscopic studies and x‐ray diffraction (XRD) analysis showed elevated peak intensity for composites confirming good polymer‐filler interaction, optical clarity and improved crystallinity. Morphological analysis by field emission scanning electron microscopy (FE‐SEM) and high‐resolution transmission electron microscopy (HR‐TEM) revealed the structural regularity of nanocomposites (NCs). Augmented thermal stability, evident from thermogravimetric analysis (TGA) with increased decomposition temperature was corroborated by an increase in glass transition temperature (Tg) detected through differential scanning calorimetry (DSC) analysis. Dielectric constant and alternating current (AC) conductivity values increased with temperature, filler content and frequency. Composites containing 7 wt% NiO showed significant enhancements in mechanical properties compared to EVA, with tensile strength increasing by 122%, tear strength by 179.9%, and impact strength by 111.9%. EVA/10 wt% NiO composite exhibited the highest hardness increase of 11.9%, while elongation at break decreased by 8% for the same composition. The experimental results suggest that EVA/NiO nanocomposite films can be employed as promising alternatives for flexible dielectric substrates for optoelectronic devices. A series of EVA/NiO NCs were prepared and characterized. Enhanced optical property, thermal stability and Tg. Possess excellent electrical properties. Mechanical strength and impact resistance of EVA was greatly enhanced. A promising material for flexible energy storage applications. [ABSTRACT FROM AUTHOR]

Sol LeWitt, a pioneer of conceptual art, created during his career over 1350 wall drawings, including the Wall Drawing #736 (1993) at the Center for Contemporary Art Luigi Pecci in Prato (Prato, Italy). The painting, executed by Andrea Marescalchi and Antony Sansotta under LeWitt's instructions, features a grid of coloured rectangles obtained by overlapping different layers of inks. During a 2021 restoration by the Wall Paintings and Stuccoes Department of the Opificio delle Pietre Dure (Firenze, Italy), an in-depth investigation of the composition and the materials used by LeWitt's assistants in producing Wall Drawing #736 was performed. A multi-analytical approach entailing Raman spectroscopy, high-performance liquid chromatography coupled to diode array and high-resolution mass spectrometry, gas chromatography–mass spectrometry (GC–MS), and pyrolysis coupled with GC–MS was applied. Our results revealed the use of animal glue, shellac resin, paraffin wax, linseed oil, and various organic pigments. The binder in the preparation layer was identified as poly(vinyl acetate), while poly(n-butyl methacrylate) was determined as a fixative. This research provided valuable insights into LeWitt's techniques. The acquired knowledge on the paint technique is highly relevant in supporting conservators in restoration and consolidating the many wall drawings produced exploiting the same technique all over the world. [ABSTRACT FROM AUTHOR]

Highlights Due to the exceptional flame retardancy, environmental protection, cost‐effectiveness, and ease of processing, halogen‐free flame‐retardant polyethylene (PE) composites are attracting wide attention. However, the addition of halogen‐free flame retardants usually leads to significantly decreased mechanical properties of PE composites, which greatly limits its application. Herein, we report a halogen‐free flame‐retardant PE/ethylene‐vinyl acetate copolymer composite (PE/EVA) with excellent flame retardancy and mechanical properties by combining compatibilizer, crosslinking agent, and carbon fiber. The presence of compatibilizer not only improves the compatibility of halogen‐free flame retardants and matrix, but also interacts with the crosslinking agent to form a cladding structure on the surface of carbon fiber. The enhanced interaction between carbon fiber surface and matrix then results in significantly enhanced flame retardancy and mechanical properties of the composite. Specifically, adding 4 phr compatibilizer, 0.5 phr crosslinking agent, and 10 phr carbon fiber will lead to the halogen‐free flame‐retardant PE/EVA composite with a UL‐94 V‐1 level, limiting oxygen index of 27.1, and an increased tensile strength by 84.02% reaching 19.12 MPa. Moreover, further carbon fiber surface modification can further enhance the flame retardancy of the composite probably due to a synergistic flame‐retardant effect caused by the surface modified nitrogen and silicon elements. As a result, the composite achieves UL‐94 V‐0 level and the limiting oxygen index of 27.7 with well‐retained high tensile strength of 15.19 MPa. This work provides a practical strategy for enhancing the flame retardancy and mechanical property of PE‐based composite simultaneously. Compatibilizer interacts with crosslinking agent to form a cladding structure on the surface of carbon fiber. Crosslinking agent promotes the formation of chemical bonds between modified carbon fiber, compatibilizer, and matrix. Carbon fiber surface modification can enhance the flame retardancy of the composite due to the synergistic flame‐retardant effect. [ABSTRACT FROM AUTHOR]

The polymer/nano-inorganics composite microsphere possesses excellent application prospects, but it is difficult to resolve the problem of the aggregation of nano-inorganic particles in polymer and the affinity between inorganics and polymer matrix. In this study, the preparation and characterization of polystyrene (PS)/ethylene vinyl acetate copolymer (EVA)/CaCO3 microspheres fabricated via a novel phase inversion emulsion process are described. By this one-pot method, the PS/EVA/CaCO3 microspheres are obtained by firstly converting styrene monomer containing EVA and nano CaCO3 into droplets dispersed in water with help of emulsifiers and a following polymerization. Because the inorganic nanoparticles are ultrasonically dispersed in liquid monomer mixture before the polymerization, the aggregation of nano-inorganic particles could be prevented to a great extent. The EVA is designed to enhance toughness of polystyrene matrix and increase the affinity between polymer and inorganic particles. The morphological structure of PS/EVA/CaCO3 microspheres is that nano CaCO3 particles are embedded both in the interior and on the surface of the microspheres. The micro-sized PS/EVA/CaCO3 microspheres showed a significantly improved mechanical property and a better heat resistance. This technique also offers the possibility for fabricating many kinds of new and useful polymer/inorganic microspheres with tailored performance by using special monomers and inorganic particles. [ABSTRACT FROM AUTHOR]

Liquid carbon dioxide (LCO2) or supercritical carbon dioxide (ScCO2) can be used as an important solvent medium for preparing polymer particles through dispersion polymerization. However, based on the weak solvent characteristics of CO2, the development of stabilizers used in dispersion polymerization has always been an important challenge. These stabilizers are progressing toward the low‐cost, pollution‐free, and simple synthesis routes, et al. In this research, pentaerythritol tetra (3‐mercaptopropionate) (PTMP) is used to control the homopolymerization or copolymerization of vinyl acetate (VAc)/vinyl propionate (VPr), the homopolymers or copolymers with thiol group are synthesized by the one‐pot method. These homopolymers or copolymers are used as the stabilizers to stabilize the dispersion polymerization of N‐vinyl‐2‐pyrrolidone (NVP) in ScCO2. The results show that the structural unit proportion of the stabilizers, the concentration of stabilizers or 2, 2´‐azobis(isobutyronitrile) (AIBN), and the time interval for dispersion polymerization have significant impacts on the conversion percentage of NVP and the molecular weight of polymers. The maximum conversion percentage of NVP can get to 95%, and the molecular weight of poly(N‐vinyl‐2‐pyrrolidone)(PNVP) can reach 22.3 kPa. SEM analysis indicates that the PNVP obtained has regular spherical characteristics. [ABSTRACT FROM AUTHOR]

Biodegradable starch-based composite material with bactericidal properties was obtained in this work. The material is promising as environmentally safe food packaging. Native potato starch was modified by graft polymerization of vinyl acetate. The synthesis was carried out in the presence of ammonium persulfate in the alkaline medium under a temperature change mode from 70 to 80 °C. The grafting efficiency was 82% at 91, 5% conversion rate of vinyl acetate. The product of the synthesis is a homogeneous dispersion with an average particle size 2.2∙10–5 cm. The composition and chemical structure of Starch-g-PVAc copolymer were confirmed by extraction, IR spectroscopy and gel permeation chromatography. The films poured from copolymer solution are characterized by 24 MPa of breaking stress and 2.2% of strain. A copolymer-based composition with bactericidal properties was developed by introducing polyhexamethylene guanidine chloride. The composition is biodegradable. Biodegradation of the films under the action of mold fungus Aspergillus niger occurred by 96% in 28 days. The composite based on Starch-g-PVAc + PHMG-ch is promising for use in packaging, cleaning of water environment from contaminants, in medical applications. [ABSTRACT FROM AUTHOR]

The current work objects to fabricate poly(methylmethacrylate)/poly Vinyl Acetate/tetrabutylammonium iodide/milled multiwalled carbon nanotubes polymer composites, PMMA/PVAc/TBAI/x wt% milled MWCNTs, as future blends to utilize in the optoelectronic field. The structure and morphology of the formed blends were investigated using X-ray diffraction and scanning electron microscope techniques. The impact of MWCNTs amount on the linear and non-linear optical and emitted colors behavior of PMMA/PVAc/TBAI was studied. The transmittance reached its minimum value of 11–28% when the blend was loaded with 0.55 wt% MWCNTs. The lowest direct (4.49 eV) and indirect (4.30, 2.11) eV optical band gaps were obtained as the percentage of MWCNTs became 0.55 wt%. Due to the presence of MWCNTs, the refractive index of PMMA/PVAc/TBAI increases in the visible range. The highest values of εr and εi were obtained when the concentration of MWCNTs attained 0.55 wt%. Except for the blend doped with x = 0.22 at a lower wavelength range, all three non-linear optical parameters for PMMA/PVAc/TBAI polymer composites improved with increasing amounts of MWCNTs. The I–V properties and the conduction mechanism of all blends are investigated. In conclusion, the results showed that PMMA/PVAc/TBAI/x wt% milled MWCNTs polymer composites are promising polymer materials with remarkable optical and electric properties that could be used in different fields such as solar cells, photonic crystals, Bragg gratings and photocatalytic applications. [ABSTRACT FROM AUTHOR]

Covalent cross-linked hydrogels based on chitosan and poly(maleic acid-alt-vinyl acetate) were prepared as spherical beads. The structural modifications of the beads during the preparation steps (dropping in liquid nitrogen and lyophilization, thermal treatment, washing with water, and treatment with NaOH) were monitored by FT-IR spectroscopy. The hydrogel beads have a porous inner structure, as shown by SEM microscopy; moreover, they are stable in acidic and basic pH due to the covalent crosslinking. The swelling degree is strongly influenced by the pH since the beads possess ionizable amine and carboxylic groups. The binding capacity for Cu2+ ions was examined in batch mode as a function of sorbent composition, pH, contact time, and the initial concentration of Cu2+. The kinetic data were well-fitted with the pseudo-second-order kinetic, while the sorption equilibrium data were better fitted with Langmuir and Sips isotherms. The maximum equilibrium sorption capacity was higher for the beads obtained with a 3:1 molar ratio between the maleic copolymer and chitosan (142.4 mg Cu2+ g−1), compared with the beads obtained using a 1:1 molar ratio (103.7 mg Cu2+ g−1). The beads show a high degree of reusability since no notable decrease in the sorption capacity was observed after five consecutive sorption/desorption cycles. [ABSTRACT FROM AUTHOR]

The core–sheath bi‐polymeric scaffold has been proven as an encouraging material based on the requirement of scaffolds. This study aims to prepare electrospun core–sheath scaffolds by using acid‐soluble collagen (ASC) as core material and poly(lactic acid) (PLA) or PLA‐g‐VAc as sheath material to get the most in combination from a hydrophilic and a hydrophobic polymer. ASC is extracted from waste Tilapia fish skin conserving the triple helix structure of the α1 (130 kDa) chain, and a α2 (120 kDa) chain cross‐linked with the β (280 kDa) chain confirmed by amino acid profile, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. PLA‐g‐VAc is prepared by grafting vinyl acetate (VAc) onto the PLA chain using benzoyl peroxide as the initiator. FT‐IR, 1H NMR, and 13C NMR of PLA‐g‐VAc reveal that grafting occurs between the double bond of VAc and the methine group of PLA. The morphology of the scaffolds is determined by the field emission scanning electron microscope. FT‐IR, thermogravimetric analysis, differential scanning calorimetry, XRD, and water contact angle measurements are used for further characterization of scaffolds. In vivo, cytotoxicity analysis on the Vero cell line exposes that scaffolds are biocompatible. Application of scaffolds to the surgically produced wounding of skin in a rat model followed by histological assay indicates the enhanced properties of core–sheath scaffolds rather than the single polymeric scaffolds. [ABSTRACT FROM AUTHOR]

The applicability of a fluidically heated spinning disk apparatus (SDA) was tested for investigating the influence of the tangential velocity on the deposition of particulate material systems, in particular on latex particles. First, the SDA was characterized for particle fouling investigations with micro glass beads as a model system, then, a first series of tests was carried out with a real material system, a vinyl acetate/Versa 10 copolymer. Experiments were performed for a duration of 1 h and a tangential velocity up to 0.3 m s−1. The fouling process was characterized by the local fouling layer thickness and the calculated local mass‐based fouling resistance. A decrease in fouling resistance along the radius of the rotating disk as a function of the tangential velocity was observed. [ABSTRACT FROM AUTHOR]

In actual production processes, pure ethyl vinyl acetate (EVA) foams have a high shrinkage rate, and the foaming matrix is prone to plastic deformation, even causing the collapse of bubbles. This limits the further application of EVA foams. In this study, we incorporated styrene butadiene rubber (SBR) and butadiene rubber (BR) into EVA to improve the mechanical properties and dimensional stability of EVA composite foams without sacrificing their low-density characteristics of low density. We used a melting index meter, rotorless vulcanizing meter and dynamic mechanical analysis (DMA) to characterize the changes in viscosity and energy storage modulus of the composite matrix. Scanning electron microscopy (SEM) was used to study the microscopic morphology of foams. The mechanical properties test results showed that the addition of SBR reduced the density of EVA/SBR/BR composite foams, and the addition of BR improved the mechanical properties and dimensional stability of the foams. By combining the advantages of both, the density of products is comparable to pure EVA, the tensile strength and the compressive strength are increased by 11% and 6.3% relative to pure EVA, respectively. [ABSTRACT FROM AUTHOR]

Microwave-absorbing materials are widely used for electromagnetic interference shielding and stealth technology. However, most existing materials are heavy, rigid, and expensive, limiting their practical applications. Therefore, there is a need to develop new materials that are flexible, lightweight, and cost effective. This study aimed to synthesize and characterize a novel ternary composite material based on polyaniline (PAni), carbon nanotubes (CNTs), and graphene nanoplatelets (GNPs) in an ethylene-vinyl acetate (EVA) copolymer matrix. PAni-based ternary composites were prepared by in situ polymerization of aniline in toluene dispersion of CNT/GNP hybrids and EVA. The microwave absorption properties were evaluated using a vector network analyzer in the frequency range of 8.2–18 GHz. The presence of as little as 0.8 wt% of CNT/GNP hybrid with appropriate mass ratio increased the conductivity by more than four orders of magnitude compared to the EVA@PAni blend. The minimum reflection loss corresponded to -40.55 dB at 16.31 GHz for the system containing CNT/GNP = 0.3:0.7, whereas those with CNT/GNP = 0.0:1.0 and 0.7:0.3 presented the widest effective absorption bandwidths (RL < (10 dB), covering almost the entire Ku-band. Due to the excellent flexibility, low weight, and high microwave absorption performance, these composites are potential candidates for microwave absorption applications. [ABSTRACT FROM AUTHOR]

Rubber concrete (RUBC) is an innovative eco-friendly material, but its weak internal interfaces and pores lead to reduced mechanical properties. This study compares the modification effects of ethylene-vinyl acetate copolymer (EVA), nano-calcium carbonate (Nano-CaCO3), and silane coupling agent (KH560) on the rubber-cement interface in RUBC to improve its mechanical properties. Macroscopic tests showed that all three modification methods improved RUBC’s compressive, shear, and flexural properties to varying degrees. Under the same conditions, RUBC modified with KH560 and Nano-CaCO3 outperformed EVA-modified RUBC in terms of mechanical performance. Microscopic tests (SEM, XRD, FTIR) indicated that KH560 and Nano-CaCO3 significantly increased cement gel formation, with KH560 notably enhancing the rubber-cement interface bonding. Molecular dynamics simulations showed that EVA, Nano-CaCO3, and KH560 increased interaction energy at the interface by forming more hydrogen bonds. However, KH560 formed stronger chemical bonds with C-S-H gel through Si-O-Si bonds. This study provides experimental and theoretical support for engineering applications aimed at enhancing RUBC’s mechanical properties through multiscale analysis. [ABSTRACT FROM AUTHOR]

This study prepared modified alkali-activated slag repair materials by incorporating an ethylene-vinyl acetate copolymer emulsion (EVA). Sulfate attack tests, shrinkage tests, scanning electron microscopy, and mercury intrusion porosimetry tests were conducted to examine the durability and microstructural features of the alkali-activated slag repair materials. The experimental results demonstrated that adding EVA can enhance the shrinkage and strength of alkali-activated slag mortar, but that the materials exhibit poor resistance to sulfate attack. Optimizing the ratio design can yield alkali-activated cementitious materials with high strength, good durability, high bonding strength, and low shrinkage. This can reduce brittleness and increase the shrinkage rate of the material's defects, which has significant implications for subsequent fracture repair. The image of the microstructure showed that the section of alkali-activated slag paste is smooth and exhibits polymer emulsion filling gaps in the amorphous cementitious material. A connection between fibrous filaments on the cross section of the matrix crack enhances the strength of the material. The proportion of microcracks is increased and material strength is decreased after sulfate attack. [ABSTRACT FROM AUTHOR]

The swelling step of polymer particles or beads with blowing agents and monomers is one of the factors that directly affect the performance properties of expandable core–shell particles, including morphology, composition, and expansion degree. In this regard, the present work investigated the effect of swelling agents on polypropylene (PP) beads. Swelling agents were used to perform swelling tests in both bulk and suspension media at different temperatures and stirring rates. Additionally, a mass transfer model was implemented to predict the swelling degree at the analyzed experimental conditions. The obtained results indicated the important effect of temperature on swelling in both bulk and suspension tests. Among the investigated swelling agents, higher rates of PP beads swelling were observed when styrene was employed (~80 wt%), when compared to methyl methacrylate (~20 wt%), vinyl acetate (~9 wt%), and acrylonitrile (~6 wt%). Moreover, it seems that the stirring rate does not exert a considerable influence on the swelling rates, indicating that swelling is controlled by thermodynamic constraints and particle properties. Finally, experimental results showed that the final saturation concentration of the swelling agent can be reached before 1 hour of swelling, indicating that the swelling kinetics can be much faster than the polymerization kinetics. Highlights: The effects of non‐conventional swelling agents on PP were investigated.The swelling presented a fast dynamic behavior.The swelling dynamics was controlled by the solubility of the swelling agent.The highest swelling degree was obtained with styrene. [ABSTRACT FROM AUTHOR]

Heat shrink sleeves (HSS) are multilayer polymers that provide corrosion resistance for welding joints of steel pipes. Within the HSS structure, the adhesive layer is a blend of components, such as ethylene vinyl acetate (EVA) and linear low‐density polyethylene (LLDPE). In this study, a systematic approach was employed to investigate the effect of the rheology and blend composition of the maleic anhydride‐modified EVA and maleic anhydride‐modified LLDPE (EVA‐g‐MA/LLDPE‐g‐MA) adhesive layer, prepared by melt processing, on its adhesion properties. Various characterization techniques were employed to investigate the local morphology of the prepared blends at different zones. Peel strength tests were used to characterize the adhesion strength of the prepared adhesives. Our findings demonstrate that the local distribution of EVA‐g‐MA within LLDPE‐g‐MA plays a crucial role in the adhesion strength of the adhesive. The results show that the adhesion strength enhanced by nearly 45% as the composition of EVA‐g‐MA at the surface went up by 20%, shifting the failure location from the epoxy/adhesive interface to the bulk of the adhesive layer. Our hypothesis of the decrease of EVA‐g‐MA intrachain bonding and increase in the EVA‐g‐MA free chain amount in the presence of LLDPE‐g‐MA to improve the adhesion properties was corroborated through our calorimetry results where the relative EVA‐g‐MA crystallinity decreased as LLDPE‐g‐MA was introduced to the blend. The findings of our study highlight the importance of rheological behavior and blend composition in obtaining optimized performance of adhesives within the HSS structure. Highlights: Compression molding of EVA‐g‐MA/LLDPE‐g‐MA induces a layered morphology.Local distribution EVA‐g‐MA/LLDPE‐g‐MA components influence their adhesion.EVA‐g‐MA at the interface improves the adhesion of EVA‐g‐MA/LLDPE‐g‐MA.LLDPE‐g‐MA suppresses the EVA‐g‐MA crystallinity.EVA‐g‐MA/LLDPE‐g‐MA composition affects adhesion at different temperatures. [ABSTRACT FROM AUTHOR]

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We systematically examine the influence of varying temperature (T) over a large range in model poly(vinyl acetate) gels swollen in isopropyl alcohol. The theta temperature Θ, at which the second virial coefficient A2 vanishes, is found to be equal to within numerical uncertainty to the corresponding high molecular mass polymer solution value without cross-links, and we quantify the swelling and deswelling of our model gels relative to their size at T = Θ, as customary for individual flexible polymer chains in solutions. We also quantify the "solvent quality" dependence of the shear modulus G relative to G(T = Θ) and compare to the gel swelling factor, α. We find that all our network swelling and deswelling data can be reduced to a scaling equation of the same general form as derived from renormalization group theory for flexible linear polymer chains in solutions so that it is not necessary to invoke either the Flory–Huggins mean field theory or the Flory–Rehner hypothesis that the elastic and mixing contributions to the free energy of network swelling are separable to describe our data. We also find that changes of G relative to G(T = Θ) are directly related to α. At the same time, we find that classical rubber elasticity theory describes many aspects of these semi-dilute solution cross-linked networks, regardless of the solvent quality, although the prefactor clearly reflects the existence of network defects whose concentration depends on the initial polymer concentration of the polymer solution from which the networks were synthesized. [ABSTRACT FROM AUTHOR]

AbstractThis work aims to add an epoxy-ended co-monomer to polyvinyl acetate (PVAc) emulsion adhesive-based wood adhesive to improve its resistance to heat and moisture. Here, glycidyl methacrylate (GMA), vinyl neodecanoate (VeoVa), and vinyl acetate (VAc) emulsion copolymers have been created and evaluated as wood adhesives. To prepare the emulsion-based adhesive samples, a polyvinyl alcohol (PVA) solution, aluminium chloride solution, preservatives, and a plasticizer are added. Following that, the poly(VAc–VeoVa–GMA) based adhesive sample is compared with the VAc, VeoVa, and methyl methacrylate (MMA) (poly(VAc-VeoVa-MMA)) co-polymer-based adhesive. Tensile shear strength of wood joints under dry and wet conditions was tested in compliance with EN 204-205 standard to assess the adhesives’ performance. The EN 14257 standard, which defines the shear stress of wood joints at 80 °C, was used to assess the heat resistance of the wood adhesives. Tests on the hardness of films confirmed the results of differential scanning calorimetry, which indicated that the glass transition temperature in the GMA-based adhesive was significantly higher than in the MMA-based adhesive. After 6 h of bonding, EN 204 shows that the tensile shear strength of a GMA-based adhesive increased by 15.56% in a dry environment, by 16.67% in a wet environment and 37.84% heat resistance when compared to a co-polymer-based adhesive based on MMA. The approach that was developed provides a simple and useful way of developing adhesives with enhanced heat, water, and bonding strength resistance. [ABSTRACT FROM AUTHOR]

Three-layer glue-free composite filmss ba,sed on a PP/EVA/ela,stomer blending,sy,stem were prepared through melt blending and ca,st co-extrusion using EVA a,s an adhe,sive layer and different easterners a,s a compatibilizer for the PP core layer and adhesive layer. The resultant blending system was analyzed by means of mechanical tessts, rheological tessts, and sscanning electron microsscopy, and the propertiess of the compossite filmss were inve,stigated. The ressuta indicated that there wa,s an optimal bonding effect on paper when using the EVA containing 18 wt% vinyl acetate. The PBE easterner exhibited a more ssignificant improvement in the mechanical properties* than POE. The glass transition temperature of PP and EVA increased gradually with an increase in the PBE content, and meanwhile the curvature of Cole-Cole also increased gradually, indicating that the compatibility between PP and EVA became better and better. When the content of PBE in the EVA adhesive layer was; 30 wt%, the tensile sstrength of the composite films; reached a maximum value of 29 MPa. The adhesive strength of the composite films with paper reached at maximum value of 9 N/15 mm at a PBE content of 20 wt%. The core layer and adhesive layer cannot be peeled off for the compossite filmss at a PBE content of 25 wt%. The compossite filmss are robust without delamination in thiss ca,se. The optimal loading of PBE in the adhe,sive layer wa,s determined to be 25 wt%. [ABSTRACT FROM AUTHOR]

This document discusses the development of an efficient method for the kinetic resolution of ¿-allenols using a commercially available immobilized lipase, Lipozyme TL-IM. The study found that the method had high enantioselectivity, with an S-factor of over 1000. The researchers also found that the method was compatible with a wide range of substrates, including those with electron-withdrawing and electron-donating groups on the benzene ring. This method provides a valuable approach for synthesizing chiral oxycycles. [Extracted from the article]

In this research, by using different rheometric methods, the temperatures of phase transition for upper critical solution temperature phase diagram of polyethylene (PE) and poly(ethylene‐co‐vinyl acetate) (EVA) blends and filled systems with organically‐modified nanoclay (ONC) were measured. Since the PE/EVA‐based mixtures are widely applied in the film and foam industries, the evaluation of the phase behavior of these mixtures is of great importance. Microscopic observations show that ONC nanoparticles have a compatibilization role on the biphasic microstructure of PE/EVA. ONC nanoparticles have a remarkable impact on the viscoelastic properties of the EVA phase, leading to a reduction in the asymmetry of the viscoelastic properties of the two polymeric phases. The findings of this work focused on the isochronal dynamic temperature sweep tests on the well‐mixed and phase‐separated nanofiller‐filled systems with different cooling/heating rates indicated that these series of experiments did not have the necessary efficiency to determine the phase separation boundary and spinodal temperatures in thermodynamically equilibrium conditions. By using Han plot and dynamic temperature sweep tests at the minimum possible heating rate, 0.25 K/min, it was proved that by adding nanoparticles to PE/EVA blends, the area of well‐mixed region of the phase diagram did not show a significant increment. The pinning effects of nanoparticles on the polymeric chains and correspondingly, the reduction of molecular dynamics mainly affect the phase separation phenomenon. [ABSTRACT FROM AUTHOR]

For obtaining flame retardant, oil resistance, high strength, and softness EVA/POE‐g‐MAH composites for cables, multifunctional modified magnesium hydroxide (MH‐KH570), and aluminum hydroxide (ATH‐KH570) were prepared by grafting γ‐(methacryloyloxy) propyltrimethoxysilane (KH570) onto the surface of MH and ATH. The successful grafting was confirmed by Fourier‐transform infrared spectrometer, scanning electron microscope, thermogravimetric analysis, and contact angle test. The hydrophobicity of MH and ATH was enhanced and the decompose time was extended, called the "sustained release" effect. The ethylene‐vinyl acetate copolymer (EVA)/maleic anhydride grafted polyolefin elastomer (POE‐g‐MAH) composites containing 62.5 wt% the mixture of MH‐KH570 and ATH‐KH570 in a 1:1 mass ratio was prepared. The vertical combustion test, limited oxygen index (LOI), and cone calorimetry proved the flame retardancy performance of the EVA/POE‐g‐MAH composites were enhanced, because of the homogeneous dispersion and the "sustained release" effect of MH‐KH570 and ATH‐KH570. The vertical combustion and LOI reached V‐0 and 38.1%. Importantly, the "crosslinking" effect of MH‐KH570 and ATH‐KH570 further enhanced the tensile strength after the composites crosslinked, and reached 19.9 MPa. In a word, a simple method for preparing flame retardant EVA/POE‐g‐MAH composites with high tensile strength was provided. [ABSTRACT FROM AUTHOR]

While extensive research has focused on understanding the degradation mechanisms of Poly(vinyl acetate) (PVAC) paint under different environmental conditions, limited attention has been paid to the long-term stability of PVAC-based white glues, especially when used in artworks. This study investigates the accelerated degradation, under simulated photoaging, and isothermal treatment of a commercial PVAC-based white glue considered representative of this class of materials used in contemporary artworks to predict its durability and assess its behavior in art objects. Through accelerated aging experiments and comparison with natural aging observed in artworks, the study reveals the formation of chromophores and the release of plasticizers as key processes; in particular, the progressive darkening was considered an early indicator of degradation processes, before structural changes could be detected by FTIR or NMR spectroscopies. The plasticizer loss induces an increase in glass transition temperature, from 7 °C to temperatures higher than room temperature, affecting the adhesive's cohesive strength and contributing to the detachment of materials in artworks. The findings underscore the importance of preventive conservation measures to mitigate degradation issues in PVAC-based artworks. [ABSTRACT FROM AUTHOR]

The oxidation of sec‐alcohols is a common reaction in organic chemistry. We report a biocatalytic approach for oxidizing racemic (hetero)aromatic sec‐alcohols to the corresponding ketones. The reaction relies on employing freeze‐dried E. coli cells containing a recombinant variant of an alcohol dehydrogenase deduced from Lactobacillus kefir (E. coli/Lk‐ADH Prince) and vinyl acetate as an in situ acetaldehyde surrogate as oxidant. Biooxidations of a set of 20 racemic (hetero)aromatic alcohols were carried out in the presence of a catalytic amount of NADP+ cofactor, the biocatalyst, and vinyl acetate in an aqueous medium to generate the corresponding ketones with up to >99 % conv. Preparative scale (1.0 mmol; 100 mM in 10 mL) reactions led to obtaining ketones in the 56–83 % isolated yield range. [ABSTRACT FROM AUTHOR]

The deposition process during emulsion polymerization can be classified as both particulate and reaction fouling, but a deeper understanding of the deposition mechanism, especially in combination with the polymerization process, is lacking. Here, a more in‐depth understanding of the deposition mechanism is sought by investigating the fouling formation of a Vinyl acetate and Versa 10 copolymer on a heated stainless steel surface during emulsion polymerization. Its deposition behavior is also compared with the behavior of an already reacted polymer. All possible influencing factors are investigated separately, and the fouling is quantified by the mass based fouling resistance and the fouling layer composition. The fouling rates of both experimental approaches (ongoing reaction versus already reacted polymer) are used to determine the fraction of reaction fouling along the reaction pathway. The solids content and the driving temperature difference are identified as the main factors influencing fouling formation. The deposited material is composed of latex particles and emulsifier with particle size and number depending on the respective equilibrium composition of the fluid phase. The reaction fouling rate is correlated with the proportion of free initiator radicals and the amount of dissolved monomer in the aqueous phase. [ABSTRACT FROM AUTHOR]

The following paper presents a study of water dispersion obtained by emulsion co-polymerization of acrylic, methacrylic and vinyl monomers with the use of surfactants. Water dispersions of copolymers used in the production of paints intended for painting surfaces of steel metals and aluminum and its alloys were selected. They were synthesized by ethyl acrylate, butyl acrylate, acrylic acid, methyl methacrylate, methacrylic acid, acrylic acid amide, 2-hydroxyethylacrylate, glycidyl methacrylate, vinyl acetate and 1-ethyl-1-ethylpropylcarbamate (VeoVa 10). The investigated dispersion properties were considered in three groups. It turned out that the dispersions in which the copolymer had the lowest crystallinity temperature and were built of units having hydroxyl, carboxyl or amide groups were characterized by the most favorable properties. The hardness and weight of the membranes changed the least in the case of copolymers consisting of many units with functional groups. [ABSTRACT FROM AUTHOR]

Amongst water-based emulsion adhesives, polyvinyl acetate (PVAc) emulsion is majorly employed in the non-structural bonding of interior or exterior furniture and joinery industries. However, PVAc emulsion requires plasticizers, which inherently have challenges resulting in deteriorating thermal and mechanical properties. Hence, the present work focuses on formulating a plasticizer-free adhesive by copolymerizing vinyl acetate with butyl acrylate (BA). The physical, thermal, and mechanical properties of BA-incorporated adhesives were analyzed by viscosity, pH, water contact angle, pencil hardness test of films, and differential scanning calorimetry. Optimizing strategy by varying the content of BA was evaluated. The shear strength of the samples on the wood specimen was verified in dry conditions at various intervals, and in wet conditions as per EN 204 standard. The viscosity of the adhesives exhibited a positive shift, as the concentration BA increased. The hardness of PVAc films was also altered positively by the addition of BA. Water contact angle measurement unveiled the hydrophobic nature of BA incorporation. The performance of the newly formulated adhesive tested on dry conditions showed enhanced tensile shear strength, and the values were maximum for 1 wt. % BA sample. Tensile shear strength value measured at dry conditions after 7 d of drying displayed an increment of ∼5.5% on 1 wt. % BA sample, compared to pristine adhesive. Analysis at wet conditions also corroborated enhanced performance with BA incorporation. Hence by optimizing the content of BA, a new concept of PVAc emulsion adhesive without any plasticizer can be formulated, with enhanced water resistance and performance. [ABSTRACT FROM AUTHOR]

Poly[(3‐hydroxybutyrate)‐co‐(4‐hydroxybutyrate)] (P34HB), poly[(butylene succinate)‐co‐(butylene furandicarboxylate)] (PBSF) and poly(vinyl acetate) (PVAc) were melt‐blended to prepare P34HB/PBSF/PVAc blends with improved ductility. The thermal properties, mechanical properties, rheological properties and morphology of the blends were systematically studied. The addition of PBSF promoted the melt crystallization of P34HB. The temperatures at 5% weight loss of the blends were higher than that of P34HB. The surface of the blends was investigated using scanning electron microscopy. The surface of P34HB was very smooth, but the surfaces of the blends were rough. PVAc can increase the compatibility between P34HB and PBSF. Compared with P34HB, the elongation at break of the blends was increased to 219.1%. © 2024 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Commercially available polyvinyl alcohol (PVA) stabilized polyvinyl acetate (PVAc) emulsion adhesives produce affordable, colourless gluelines with an extremely durable connection to various types of wood. At room temperature, the adhesive solidifies as a result of water evaporation. Plasticizers are required for the PVAc emulsion; however, they have drawbacks that affect their mechanical and thermal properties. On the other hand, they demonstrate limited strength at high relative humidity and high temperatures and are neither heat- nor moisture-resistant. The goal of the present research is to develop a plasticizer-free glue by copolymerizing vinyl acetate (VAc), vinyl neodecanoate (VeoVa), and methyl methacrylate (MMA) with butyl acrylate (BA). The sample with BA is also put together with PVA solution, aluminium nitrate, and preservatives, and it is tested with the copolymer sample without BA. The viscosity, pH, water contact angle, scratch resistance of the films, and differential scanning calorimetry measurements were used to analyse the physical, thermal, and mechanical properties of adhesives containing BA. The shear strength of the samples on the wood specimen was evaluated in dry and wet conditions in accordance with EN 204-205. The viscosity of the adhesives increased as the BA concentration increased. The hardness of the adhesive films was adversely impacted by the addition of BA. The hydrophobic properties of the BA addition were confirmed through measurements of the water contact angle. The tensile shear strength value evaluated under dry conditions after 6 h of drying demonstrated a 9.5% increase on the 1 wt% BA sample in comparison to pristine glue. Analysis of performance in wet situations also showed that BA addition improved performance. By adjusting the amount of BA, a novel water-resistant crosslinked emulsion adhesive without any plasticizer can be developed with enhanced water resistance and performance. The technique used to increase the wood adhesive's resistance to moisture was affordable, plasticizer-free, and environmentally safe. [ABSTRACT FROM AUTHOR]

Co(III)-catalysed site-selective C8-allylation and vinylation of isoquinolones with allyl acetate and vinyl acetates has been accomplished. The oxo group of isoquinolone has been utilised as an inherent directing group. Based on preliminary mechanistic studies, a plausible mechanism for the developed reaction has also been delineated. Broad substrate scope with good to excellent yields and post-synthetic transformations of allylated and vinylated isoquinolines highlight the importance of the reaction. [ABSTRACT FROM AUTHOR]

The unregulated metallic deposition and continuous cracking of the fragile solid electrolyte interphase are considered the critical barriers that compromise the cyclability of lithium metal batteries (LMB), especially under low N/P ratio (<3) pairing modes. Herein, an ultra‐thin (5 µm), lightweight (0.25 mg cm−2), and moisture‐proof interfacial layer composed of the high‐entropy alloys (denoted as HEAs) and interweaved carbon nanotubes (CNTs) scaffold is constructed to modify the current collector, moreover, the thermally‐induced Li22Si5 alloy blended with the hydrophobic ethylene‐vinyl acetate copolymer (EVA) is infiltrated into the scaffold pores as the moisture‐proof cation reservoir. The HEA@CNT/Li22Si5@EVA interfacial layer not only maximizes the Li‐utilization degree with minimal voltage divergence in symmetric cells but also compensates for irreversible Li depletion in the pouch‐format anode‐less models. As the HEA@CNT/Li22Si5@EVA‐Cu substrate paired with the LiNi0.8Mn0.1Co0.1O2 cathode in a 200 mAh prototype, the phase evolution of oxide cathode and efficient Li utilization at the anode substrate can be real‐time monitored by the transmission‐mode operando X‐ray diffraction. This interfacial layer strategy affords multifunctionality to enable the LMB prototyping without excessive Li abuse. Consequently, cycling endurance and the balanced energy densities (420.1 Wh kg−1) are obtained on the whole cell. [ABSTRACT FROM AUTHOR]

Isomerization Metathesis (ISOMET) reaction is an emerging tool for "open loop" chemical recycling of polyethylene to propylene. Novel, latent N‐Alkyl substituted Cyclic(Alkyl)(Amino)Carbene (CAAC)–ruthenium catalysts (5a‐Ru, 3b‐Ru – 6c‐Ru) are developed rendering "inverted" chemical structure while showing enhanced ISOMET activity in combination with (RuHCl)(CO)(PPh3)3 (RuH) double bond isomerization co‐catalyst. Systematic investigations reveal that the steric hindrance of the substituents on nitrogen and carbon atom adjacent to carbene moiety in the CAAC ligand have significantly improved the catalytic activity and robustness. In contrast to the NHC‐Ru and CAAC‐Ru catalyst systems known so far, these systems show higher isomerization metathesis (ISOMET) activity (TON: 7400) on the model compound 1‐octadecene at as low as 3.0 bar optimized pressure, using technical grade (3.0) ethylene. The propylene content formed in the gas phase can reach up to 20% by volume. [ABSTRACT FROM AUTHOR]

In the forefront of advanced materials, ultra-high molecular weight (UHMW) polymers, renowned for their outstanding mechanical properties, have found extensive applications across various domains. However, their production has encountered a significant challenge: the attainment of UHMW polymers with a low dispersity (Ɖ). Herein, we introduce the pioneering technique of ultrasound (US) initiated polymerization, which has garnered attention for its capability to successfully polymerize a multitude of monomers. This study showcases the synthesis of UHMW polymers with a comparatively low Ɖ (≤ 1.1) within a remarkably short duration (~ 15 min) through the amalgamation of emulsion polymerization and high-frequency ultrasound-initiated polymerization. Particularly noteworthy is the successful copolymerization of diverse monomers, surpassing the molecular weight and further narrowing the Ɖ compared to their respective homopolymers. Notably, this includes monomers like vinyl acetate, traditionally deemed unsuitable for controlled polymerization. The consistent production and uniform dispersion of radicals during ultrasonication have been identified as key factors facilitating the swift fabrication of UHMW polymers with exceptionally low Ɖ. Ultra-high molecular weight (UHMW) polymers exhibit exceptional mechanical properties and have found extensive applications, however, it remains challenging to produce them with a low dispersity. Here, the authors develop ultrasound-initiated copolymerization of diverse monomers, generating UHMW polymers with low dispersity within 15 min. [ABSTRACT FROM AUTHOR]

This investigation introduces the first estimation of ternary reactivity ratios for a butyl acrylate (BA), 2-methylene-1,3-dioxepane (MDO), and vinyl acetate (VAc) system at 50 °C, with an aim to develop biodegradable pressure-sensitive adhesives (PSAs). In this study, we applied the error-in-variables model (EVM) to estimate reactivity ratios. The ternary reactivity ratios were found to be r12 = 0.417, r21 = 0.071, r13 = 4.459, r31 = 0.198, r23 = 0.260, and r32 = 55.339 (BA/MDO/VAc 1/2/3), contrasting with their binary counterparts, which are significantly different, indicating the critical need for ternary system analysis to accurately model multicomponent polymerization systems. Through the application of a recast Alfrey–Goldfinger model, this investigation predicts the terpolymer's instantaneous and cumulative compositions at various conversion levels, based on the ternary reactivity ratios. These predictions not only provide crucial insights into the incorporation of MDO across different initial feed compositions but also offer estimates of the final terpolymer compositions and distributions, underscoring their potential in designing compostable or degradable polymers. [ABSTRACT FROM AUTHOR]

The degradation behaviors of the encapsulant and the imbedded additives significantly determine the reliability of solar modules. Nevertheless, a link between the degradation of the encapsulant, including the additive interactions, and the longevity of the overall module is rarely established until now. Herein, mini‐modules containing ethylene‐vinyl acetate copolymer (EVA) as encapsulant are subject to damp heat (DH) or ultraviolet (UV) weathering based on IEC 61215. Macroscopically, the degradation under both weathering types characterized by I–V measurements and electroluminescence (EL) measurements is diverging in dependence on the used stressor. Using electron paramagnetic resonance and orbitrap mass spectrometry, it is shown that deacetylation of the EVA occurs significantly for both types of weathering. In the case of DH, however, the mechanism of action of the UV stabilizer is hindered, so that strong encapsulant degradation is observed despite a lower energy input in comparison with UV. Furthermore, the produced acetic acid under DH weathering leads to the observed reduction in EL, an increase in series resistance, and, a reduction of the performance of the modules. The work carried out shows that the degradation of the solar modules is strongly dependent on the behavior of the UV stabilizer. [ABSTRACT FROM AUTHOR]

A new strategy was developed to build a CO2-philic/hydrophilic surfactant by combining the common free radical polymerization and the grafting modification technology, and a brush polymer was synthesized with poly(vinyl acetate)(PVAc) based copolymer as the CO2-philic group (as the main chain) and the methoxy poly(ethylene glycol) (mPEG) as the hydrophilic part (as the branched chain) (PVAc-g-mPEG). The CO2-philic ability can be controlled by adjusting the chain length of the CO2-philic fragment. The results indicate that PVAc-g-mPEG has excellent surfactant activity, and can emulsify the CO2/H2O system to obtain the CO2-in-water (C/W) high interval phase emulsion (HIPE 80%, v/v), which can remain stable for more than 20 h. If using the monomers/crosslinking agent solution instead of water, the highly porous monolithic materials will be obtained after the continuous phase is polymerized. In this paper, polyacrylamide (PAM) and poly(acrylamide/diethyl aminoethyl methacrylate) (PADM)-based porous monolithic materials were prepared. These materials were used to remove bovine serum albumin (BSA, as the model matter) from the solution, and the results indicated that PAM-based porous monolithic materials had almost no enrichment capacity for protein, while PADM-based porous monolithic materials can adsorb BSA up to 129.3 mg/g. [ABSTRACT FROM AUTHOR]

Considering the essence of high electron density of ligands, frameworks with high electron donating groups are important in the transition-metal catalytic systems. As benzhydrol groups have been investigated for their beneficial electronic effects, a novel homo-dinuclear Ni (II) catalyst based on benzhydrol-substituted ligand was synthesized, characterized, and used for ethylene polymerization. The catalyst was further examined and compared with its mononuclear analogue. The maximum activity for the polymerization was then obtained at molar ratio of Al/Ni: 1500/1, polymerization temperature of 15 ℃ and the monomer pressure of 1.5 bar within 5 min of the polymerization which was 2.64 × 106 g mol−1Ni h−1. Effects of cocatalyst type (e. g., modified methylalumoxane (MMAO), triisobutylaluminum (TiBA), and triethylaluminum (TEA)) in the polymerization were also investigated wherein MMAO outperformed in terms of the greatest activity. As the polymerization temperature elevated, the polyethylene (PE) microstructure changed from crystalline into amorphous form, while both of the activity of the catalyst and the Viscosity Average Molecular Weight ( M ¯ v) of the obtained polymer were diminished. With regard to increasing of ethylene pressure in the reactor (up to 4 bars), the M ¯ v increased and reached to the maximum value of 1.44 × 106 g mol−1. The catalyst was also active in the presence of the long-chain α-olefin monomers, such as 1-hexene and 1-octene, the comonomers. The co-monomer addition decreased crystallinity of the polymer (from 25 to 15%) and led to higher branching density of the obtained copolymers. [ABSTRACT FROM AUTHOR]

In this work, self-reinforced composite of recycled polyester (rPET) fibers/recycled poly (ethylene terephthalateco-1,4-cylclohexy-lenedimethylene terephthalate) (rPETG) was prepared by internal mixing and molding press, in which rPET fibers were modified according to the previous method. The effects of compatibilizers including polyethylene-octene grafting glycidyl methacrylate (POE-g-GMA) and ethylene vinyl acetate grafting maleic anhydride (EVA-g-MAH) on the toughness of the composites were studied, respectively. The results showed that POE-g-GMA had better toughening effect on composite than EVA-g-MAH, the POE-g-GMA not only increased the toughness of rPET fibers/rPETG composite but also maintained the strength of composite at a high level. The impact strength of modified rPET fibers/POE-g-GMA/rPETG composite was found to increase by 910%. And, the bending strength and tensile strength were improved by 34.7% and 22.2%, respectively. DSC and SEM results indicated that with an increase in POE-g-GMA content, the degree of crystallinity of rPET fibers/POE-g-GMA/rPETG decreased, bonding between the fibers and matrix became tight, which improved the stress transfer ability between the matrix and the fibers. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the performance of bio-based lubricants (BBL), namely, palm mid-olein (PMO) enriched with an antioxidant agent, tertiary-butylhydroquinone (TBHQ) and a viscosity improver, ethylene-vinyl acetate (EVA), in journal bearing (JB) applications. Design/methodology/approach: Samples of the BBL were prepared by blending it with TBHQ and EVA at various blending ratios. The oxidative stability (OS) and viscosity of the BBL samples were examined using differential scanning calorimetry and a viscometer, respectively. Meanwhile, their performance in JB applications was evaluated through the use of a JB test rig with a 0.5 length-to-diameter ratio at various operating conditions. Findings: It was found that the combination of PMO + TBHQ + EVA demonstrated a superior oil film pressure and load-carrying capacity, resulting in a reduced friction coefficient and a smaller attitude angle compared to the use of only PMO or VG68. However, it was observed that the addition of TBHQ and EVA to the PMO did not have a significant impact on the minimum oil film thickness. Practical implications: The results would be quite useful for researchers generally and designers of bearings in particular. Originality/value: This study used PMO as the base stock, and its compatibility with TBHQ and EVA was investigated in terms of its OS and viscosity. The performance of this treated BBL was evaluated in a hydrodynamic JB. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2023-0363/ [ABSTRACT FROM AUTHOR]