Journal articles: 'Vinyl acetate/versatate'

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Wu, X. Q., X. M. Hong, Cajetan Cordeiro, and F. J. Schork. "Miniemulsion and macroemulsion copolymerization of vinyl acetate with vinyl versatate." Journal of Applied Polymer Science 85, no. 10 (2002): 2219–29. http://dx.doi.org/10.1002/app.10839.

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Kovalenko, Yurii, Volodymyr Tokarchuk, Svitlana Kovalenko, and Oleksandr Vasylkevych. "Identifying the influence of redispersed polymers on cement matrix properties." Eastern-European Journal of Enterprise Technologies 4, no. 6(118) (2022): 38–45. http://dx.doi.org/10.15587/1729-4061.2022.262438.

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The physical-mechanical influence and chemical effect of calcium formate, vinyl acetate/versatate, and vinyl-acrylate copolymer on the processes of solidification, hardening, and structure formation of the cement matrix were studied during the research reported here. The compositions of mixtures containing additives in the amount of 1, 3, and 5 wt % were investigated. Noteworthy is the water-holding nature of vinyl acetate/versatate and vinyl-acrylate copolymer. With the introduction of appropriate additives, an increase in working time of the mixtures is noted, which was manifested in prolonging the end time of solidification duration. Calcium formate reduced the end time of solidification duration with an increase in the content of the additive. During 28 days of hardening, a decrease in strength gain was observed with an increase in the content of the additive compared to control samples. At 1 wt % of the additive, the decline in strength on day 28 was 8.7 % for calcium formate, 13 % for versatate, and 15.5 % for vinyl-acrylate copolymer. For versatate and vinyl acrylate with the addition of 3 and 5 wt % in the mixture, the loss of strength is 23–25 % and 27–56.7 %, respectively. 5 wt % calcium formate admixture, compared to 3 wt %, on day 7 and day 28 of hardening has a higher strength index. This nature of the effect of additives is explained by the formation of polymer structures throughout the volume of the mixture with the introduction of versatate and copolymer vinyl acrylate, as well as their chemical interaction with the components of the cement binder during hydration in the formed alkaline medium. Calcium formate plays the role of both a filler and a hardening accelerator due to the introduction of an additional amount of calcium ions. The reported results can be used as a basis for continuing to study the effect of redispersed additives on the durability of cement articles, the development of new formulations for building mixtures, and their potential use in the production of concrete.

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Yurii, Kovalenko, Tokarchuk Volodymyr, Kovalenko Svitlana, and Vasylkevych Oleksandr. "Identifying the influence of redispersed polymers on cement matrix properties." Eastern-European Journal of Enterprise Technologies 4, no. 6 (118) (2022): 38–45. https://doi.org/10.15587/1729-4061.2022.262438.

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The physical-mechanical influence and chemical effect of calcium formate, vinyl acetate/versatate, and vinyl-acrylate copolymer on the processes of solidification, hardening, and structure formation of the cement matrix were studied during the research reported here. The compositions of mixtures containing additives in the amount of 1, 3, and 5 wt % were investigated. Noteworthy is the water-holding nature of vinyl acetate/versatate and vinyl-acrylate copolymer. With the introduction of appropriate additives, an increase in working time of the mixtures is noted, which was manifested in prolonging the end time of solidification duration. Calcium formate reduced the end time of solidification duration with an increase in the content of the additive. During 28 days of hardening, a decrease in strength gain was observed with an increase in the content of the additive compared to control samples. At 1 wt % of the additive, the decline in strength on day 28 was 8.7 % for calcium formate, 13 % for versatate, and 15.5 % for vinyl-acrylate copolymer. For versatate and vinyl acrylate with the addition of 3 and 5 wt % in the mixture, the loss of strength is 23–25 % and 27–56.7 %, respectively. 5 wt % calcium formate admixture, compared to 3 wt %, on day 7 and day 28 of hardening has a higher strength index. This nature of the effect of additives is explained by the formation of polymer structures throughout the volume of the mixture with the introduction of versatate and copolymer vinyl acrylate, as well as their chemical interaction with the components of the cement binder during hydration in the formed alkaline medium. Calcium formate plays the role of both a filler and a hardening accelerator due to the introduction of an additional amount of calcium ions. The reported results can be used as a basis for continuing to study the effect of redispersed additives on the durability of cement articles, the development of new formulations for building mixtures, and their potential use in the production of concrete.

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Ma, Guoyan, Le Wang, Xiaorong Wang, et al. "Preparation and Properties of Poly(vinyl acetate) Adhesive Modified with Vinyl Versatate." Molecules 28, no. 18 (2023): 6634. http://dx.doi.org/10.3390/molecules28186634.

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A series of vinyl versatate (VV10) modified poly(vinyl acetate) adhesive (HVPVAc) were prepared using soap-free emulsion polymerization. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to characterize the structure of the modified poly(vinyl acetate) latex. The effect of the VV10 content on particle size, viscosity, mechanical properties, and T-peel strength of the modified poly(vinyl acetate) was determined. No absorption peak at 1675–1500 cm−1 in the ATR-FTIR spectrum was observed as a result of the carbon-carbon double bond reacting completely. With the occurrence of -C-O-C and the disappearance of the carbon-carbon double bond in the FTIR spectrum, a more complex structure formed. The structure improves the mechanical properties. Increasing the VV10 content resulted in an increase in particle size from 63 nm to 221 nm, a steady increase in the viscosity of the HVPVAc latex, an increase in tensile strength from 7 MPa to 13.4 MPa, and a decrease in breaking elongation from 1310% to 1004%. As the VV10 content increased from 0 to 30% by weight, the T-peel strength of the HVPVAc adhesive increased from 8.35 N/mm to 18.97 N/mm, indicating improved adhesive performance.

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Wang, Xiao Feng, Tie Kun Jia, Jian Wei Li, and Xin Ai Zhang. "Effect of Admixture Additive on Properties of Polymer-Modified Lightweight Cement Mortar." Applied Mechanics and Materials 253-255 (December 2012): 417–20. http://dx.doi.org/10.4028/www.scientific.net/amm.253-255.417.

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Redispersible polymer powder of vinyl acetate and versatate copolymer (VA/Voeva) used as admixture additive, is introduced to modify lightweight cement mortar with ground granulated blast furnace slag, quartz sand and expanded perlite as aggregates. The effect of the dosage of redispersible polymer powder of vinyl acetate and versatate on the compressive and flexural strengths was investigated in details. The ratio of compressive strength to flexural strength (σc/σf ) of cement mortars varied with the variation of the dosage of redispersible polymer powder. Scanning electronic microscopy was used to investigate the internal structure of the polymer-modified lightweight cement mortar. The result showed that the toughness of the polymer-modified lightweight cement mortar was improved with the increase in the dosage of redispersible polymer powder, and the network membranous structure formed by the polymer attribute to the improvement of the toughness and flexural strengths.

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Wang, Ru, and Pei-Ming Wang. "Action of redispersible vinyl acetate and versatate copolymer powder in cement mortar." Construction and Building Materials 25, no. 11 (2011): 4210–14. http://dx.doi.org/10.1016/j.conbuildmat.2011.04.060.

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KOVALENKO, YURII, VOLODYMYR TOKARCHUK, and SVITLANA KOVALEKO. "INFLUENCE OF SULFATE ION ENVIRONMENT ON THE CEMENT MATRIX MODIFIED BY REDISPERSIBLE POLYMERS." Herald of Khmelnytskyi National University. Technical sciences 319, no. 2 (2023): 154–62. http://dx.doi.org/10.31891/2307-5732-2023-319-1-154-162.

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Injection of sulfate ions into the cement matrix with water by wet spraying due to high moist in the environment is the reason of the deterioration acceleration and durability decrease with time. The effects of introduction of redispersible polymers (RP) and calcium formate on the increasing of the durability and decreasing of the deterioration effect caused by sulfate ions on the cement matrix were studied. Vinyl-acetate/versatate, vinyl-acrylic copolymer and calcium formate were mixed into nine separate cement mixtures at a concentration of additives 1 %, 3 % and 5 % respectively. Three different sulfate ion environment were sprayed through the fog environment at high moist concentration using a salt spray device “Salt Fog Chamber”. Test results showed that different additive in different sulfate environment has various affects both on the deceleration of the structure deterioration and the reduction of the strength of cement matrix. Vinyl-acetate/versatate and calcium formate in concentrations of 1% and 3% have high stability while maintaining strength at the level of exploitational properties of the matrix. While, vinyl-acrylic copolymer at 5 % has more resistance to strength loss after 168 days of withholding in an aggressive environment compared to 1 % and 3 %. Detailed observation of the structure formation of the cement matrix at 168 days shows formation that relate both to the hydrated cement minerals and complexes of organic salts. This formation allowed at the late age of the experiment to decrease the strength loss under intensive impact of SO42– migration through the matrix due to the encapsulating of cement minerals at early ages of hydration in polymer films with RP and active early formation of Ca(OH)2 for formate. This allowed the cement matrix to retain its shape for a long periods, become more stable, reduce the washing out of soluble cement components at early ages, and reduce the content of active Ca by bonding it into semisoluble compositions that cause the decreasing of the negative effect on cement matrix by SO42–.

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França De Sá, Susana, Carolina Viana, and Joana Lia Ferreira. "Tracing Poly(Vinyl Acetate) Emulsions by Infrared and Raman Spectroscopies: Identification of Spectral Markers." Polymers 13, no. 21 (2021): 3609. http://dx.doi.org/10.3390/polym13213609.

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Vinyl emulsions started to be used by artists in paintings at least since the early 1960s, being now present in several artworks worldwide. However, different vinyl formulations can result in distinct behaviours over time, and if some artworks are currently showing a good condition, others already show damages due to the use of compositions more susceptible to degradation. For this reason, it is fundamental to identify the main components in the vinyl acetate-based (VAc-based) emulsion. This work focuses on the molecular study of VAc-based emulsions by infrared and Raman spectroscopies. It aims at deepening the knowledge on the variability of the composite formulation and on the identification of characteristic bands and spectral profiles (identified as spectral markers) for both polymer and additives. To this end, a broad set of vinyl emulsions was gathered, including reference materials, historical commercial brands in use by Portuguese artists, and commercial brands collected from industrial companies. The entire set includes vinyl homopolymers produced for the purpose of the study and known formulations of vinyl homopolymers and copolymers, with and without plasticisers, according to technical data sheets and previous studies. Furthermore, unknown formulations have been included to validate the usefulness of the identified spectral markers. This set has been studied in the form of solid films deposited in glass slides by infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) and micro-Raman spectroscopy (µ-Raman), both conducted in situ. As conclusions, the combined use of ATR-FTIR and µ-Raman proved to be very useful as different spectral markers were detected by each technique, confirming their complementarity. Besides the clear identification of vinyl acetate-based emulsions by both techniques, it was also possible to suggest spectral markers for the copolymerisation of vinyl acetate with vinyl versatate by µ-Raman, the stabilisation of the emulsion with poly(vinyl alcohol) by ATR-FTIR, and the addition of phthalates or benzoates plasticisers by both ATR-FTIR and µ-Raman.

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Kostyantyn, Кalafat, Taran Nadezhda, Plavan Viktoriia, Bessarabov Volodymyr, Zagoriy Glib, and Vakhitova Liubov. "COMPARISON OF FIRE RESISTANCE OF POLYMERS IN INTUMESCENT COATINGS FOR STEEL STRUCTURES." Eastern-European Journal of Enterprise Technologies 4, no. 10 (106) (2020): 45–54. https://doi.org/10.15587/1729-4061.2020.209841.

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Thermal destruction of fire-retardant intumescent coating of the composition of ammonium polyphosphate (APP)/melamine (MA)/pentaerythrite (PE)/titanium oxide (TiO2)/polymer, which can be applied for fire protection of steel structures, was studied. The influence of polymers of different nature – ethylene-vinyl acetate (EVA), vinyl acetate versatate (VAVV), styrene acrylates, and vinyl toluene acrylate on the processes of formation of a coke layer and fire-retardant effectiveness of appropriate coatings was determined. Chemical transformations of polymers EVA and styrene acrylate in the intumescent system of ARR/MA/PE/TiO2 in the temperature range of 200–800 °С were studied. It was established that the processes of the thermal destruction of vinyl acetate polymer are more harmonized with chemical reactions of the components of the intumescent system than similar processes for acrylate aromatic polymers. Thermal-oxidation destruction of intumescent compositions at the temperatures of 200–800 °С was explored. It was shown that basic chemical processes with polymers of EVA and VAVV begin after 300 °С and flow in the temperature range of 350–600 °С. It was found that the noticeable degradation of the carbon-phosphorus frame of intumescent compositions with styrene acrylate polymers begins at 450 °С, which is almost by 150 °С below the temperature of degradation of the compositions containing vinyl acetate binders. The conducted fire tests demonstrate that intumescent compositions with the use of acrylate aromatic polymers are more effective at the low coating thickness in ensuring the fire resistance boundary of 30 min. In order to ensure higher values of fire resistance, it is necessary to use intumescent coatings containing vinyl acetate co-polymers as the polymer component. The study of the impact of polymers of intumescent coatings on the boundary of fire resistance of steel structures has scientific and practical significance for the development of differentiated fire protection means, oriented to the given class of fire resistance. Fire-retardant intumescent compositions examined in this study can be used as the basis for the formulations of materials for fire protection of building structures under conditions of a standard fire

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Wang, Ru, Pei-Ming Wang, and Li-Juan Yao. "Effect of redispersible vinyl acetate and versatate copolymer powder on flexibility of cement mortar." Construction and Building Materials 27, no. 1 (2012): 259–62. http://dx.doi.org/10.1016/j.conbuildmat.2011.07.050.

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Abd El-Wahab, H., G. A. Meligi, M. G. Hassaan, and L. Lin. "New water-based flexographic ink based on new ter-polymer nano-particles as eco-friendly binders – Part II." Pigment & Resin Technology 49, no. 6 (2020): 473–82. http://dx.doi.org/10.1108/prt-12-2019-0111.

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Purpose The purpose of this study is to prepare, characterise and evaluate nano-emulsions of ter-polymers of various compositions as eco-friendly binders for flexographic ink industry. Design/methodology/approach Various nano-emulsions of ter-polymers were prepared based on Vinyl acetate, Vinyl Versatate, butyl acrylate, acrylic acid and acrylamide monomers by means of a conventional seeded emulsion polymerisation technique, using K2S2O8 as the initiator. The characterisation of the prepared emulsions was performed using Fourier transform infrared, thermo-gravimetric analysis, gel permeation chromatography and transmission electron microscopy. A selection of co-polymers and ter-polymers were formulated with pigments and additional ingredients, as water-based flexographic inks. The inks were characterised for their rheological properties, pH, degree of dispersion, water-resistance and colour density. Findings It was found that the low viscosity of the prepared polymers may reduce the film thickness of the flexographic inks and may also increase the spreading of the ink on the surface. As a result, stable modified poly acrylate-based latex with improved physico-mechanical properties was obtained. The prepared latexes showed improved properties such as enhanced thermal stability and better water resistance. The effect of the emulsifier type on the properties of the resulting emulsion latexes and their corresponding films were investigated. Also, as the hydrophobic monomer increases, so does the colour density and increasing the binder ratio enhances the gloss values. The improving in gloss values were obtained and provide excellent adhesion properties for both the pigment particles and the base paper. Research limitations/implications The study focusses on the preparation of new water-based ter-polymer nano-particles and their use as eco-friendly binders for flexographic ink industry. Ink formulations based on other different type emulsion polymers could also be studied to assess the applicability of the ink formulation system found for other binders. Practical implications The ink formulations developed could find use in industrial-scale printing. Originality/value Eco-friendly environment and low-cost ink formulations for printing on paper substrates are novel.

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Ding, Jian Jun, Wen Yan Zhao, Hong Yan Guan, Xuan Li, and Yi Fei Mei. "Composition Analysis of an Unknown Redispersible Powder." Key Engineering Materials 726 (January 2017): 55–59. http://dx.doi.org/10.4028/www.scientific.net/kem.726.55.

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As an important type of additive, the redispersible powder is widely applied in cement-based and gyp-based materials, so as to improve the cementing strength, impermeability, workability, hydrophobicity and so on. However, the chemical composition of the redispersible powders determines its applicability, as well as the degree of improvement to the matrix materials. In this paper, the chemical composition of an unknown redispersible powder was analyzed by several instruments. Firstly, Fourier transform infrared spectroscopy (FTIR) analysis indicated that the polymer was polymerized with monomers of vinyl esters. Secondly, pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) analysis showed the pyrolysis products were mainly acetic acid, methyl acetate and methyl versatates. Considering the pyrolysis mechanism of synthetic polymers and the results from FTIR spectra, the polymer in the redispersible powder was deduced to be the copolymer of vinyl acetate and vinyl ester of versatic acid (VeoVa), which was a monomer with a unique highly branched carbon-rich structure. Thermogravimetry (TG) analysis revealed that the powder contained 74.0% of polymer, 14.5% of calcium carbonate and 11.4% of other inorganic materials.

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Rudenko, Igor I., Oleksandr P. Konstantynovskyi, Artem V. Kovalchuk, Marharyta V. Nikolainko, and Dmytro V. Obremsky. "Efficiency of Redispersible Polymer Powders in Mortars for Anchoring Application Based on Alkali Activated Portland Cements." Key Engineering Materials 761 (January 2018): 27–30. http://dx.doi.org/10.4028/www.scientific.net/kem.761.27.

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Properties of dry mixes for anchoring application (increasing of mortars strength, adhesion, volume stability etc.) based on alkali activated Portland cement (AAPC) are influenced by different factors. One of them is application of chemical admixtures with different functionality. Adhesive properties are mainly achieved by redispersible polymer powders (RPP). The main problem in choice of RPP’s type is destruction of their molecules with ester links due to alkaline hydrolysis.The purpose of work was investigation of RPP’s molecular structure influence on properties of mortar for anchoring application based on AAPC and determination of the most effective.Efficiency of RPP based on copolymer of versatile acid ester was shown. The application of this RPP provides adhesion of 1.1 MPa and consistency of 190 mm. Positive effect of copolymer of ethylene and vinyl acetate was shown despite of partial destruction of RPP’s molecule as a result of alkaline hydrolysis of vinyl acetate at early terms of hardening. Negative effect of RPP is in decreasing of mortar strength. Thus this problem solving is decreasing of powder content to values which provide necessary physical-mechanical properties (strength, adhesion).

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Barner-Kowollik, Christopher, Thomas P. Davis, and Martina H. Stenzel. "Synthesis of Star Polymers using RAFT Polymerization: What is Possible?" Australian Journal of Chemistry 59, no. 10 (2006): 719. http://dx.doi.org/10.1071/ch06297.

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Various pathways to generate star polymers using reversible addition–fragmentation transfer (RAFT) are discussed. Similar to other polymerization techniques, star polymers can be generated using arm-first and core-first approaches. Unique to the RAFT process is the subdivision of the core-first approach into the R-group and Z-group approaches, depending on the attachment of the RAFT agent to the multifunctional core. The mechanism of the R- and Z-group approaches are discussed in detail and it is shown that both techniques have to overcome difficulties arising from termination reactions. Termination reactions were found to broaden the molecular weight. However, these side reactions can be limited by careful design of the synthesis. Considerations include RAFT and radical concentration, number of arms, type of RAFT agent and monomer. Despite obvious challenges, the RAFT process is highly versatile, allowing the synthesis of novel polymer architectures such as poly(vinyl acetate) and poly(vinyl pyrrolidone) star polymers.

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Chaname, Josef, Juan García, and Guillermo Arriola Carrasco. "Improvement of the Mechanical Properties of Structural Concrete Using Microporous Ethylene Vinyl Acetate." Revista Politécnica 53, no. 2 (2024): 17–26. http://dx.doi.org/10.33333/rp.vol53n2.02.

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Over the years, the world has tried to increase the recycling of materials, especially those of artificial origin, this in order to produce compounds that are sustainable and sustainable. Among these materials, concrete stands out as a versatile element, to which different external agents can be added; however, since many of them are not compatible with aggregates, cement or water, can cause some alterations in their mechanical performance. Therefore, the present investigation addressed the study of an artificial material called Microporous Ethylene Vinyl Acetate (MEVA), in order to evaluate its influence on the mechanical properties of structural concrete. MEVA additions were used in ranges of 5.00 %, 10.00 %, 15.00 % and 20.00 % with respect to the volume of concrete, to analyze its behavior in the mix, both in physical and mechanical properties. The results show that the workability and unit weight are affected by the increase in MEVA. Despite this, the mechanical performance showed significant increases in the compressive strength of 8.81 %, tensile of 22.86 %, flexion of 24.51 % and modulus of elasticity of 2.12 %, with the addition of 5.00 % of MEVA after 28 days. Nevertheless, at higher doses there is a reduction in said strengths. For these reasons, it is concluded that the incorporation of MEVA at 5.00 % greatly improves the mechanical properties of concrete for structural use, in relation to the theoretical design strength of 21.00 MPa.

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Wei, Jia Cheng, Xue Gang Luo, Xiao Yan Lin, and Hong Ping Zhang. "Preparation and Characterization of Polyethylene/Ethylene Vinyl Acetate Composite Non-Dropping Greenhouse Film." Materials Science Forum 724 (June 2012): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.724.237.

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For the problem it is easy for the film to generate fog and drop in greenhouse, Polyethylene/Ethylene Vinyl Acetate (PE/EVA) composite greenhouse film was prepared by co-blending and extrusion. The impact of preparation parameters and the dosage of anti-fogging and anti-dropping masterbatch on the mechanical properties and non-dropping properties of the film has been investigated by versatile mechanical testing machine, atomic force microscope (AFM), contact angle tester, water bath acceleration method. The results show that the elongation at break and tensile strength of the composite film, contact angle of water and the film have decreased after added the anti-fogging and anti-dropping masterbatch. The addition of the anti-fogging and anti-dropping masterbatch can increase the non-dropping property of the greenhouse film greatly.

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Yoshizawa, Akina, Chie Maruyama, Samuel Budi Wardhana Kusuma, et al. "Aryloxy Ionic Liquid-Catalyzed Homogenous Esterification of Cellulose with Low-Reactive Acyl Donors." Polymers 15, no. 2 (2023): 419. http://dx.doi.org/10.3390/polym15020419.

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Ionic liquids (ILs) are recyclable, non-volatile, and can dissolve cellulose, a natural polymer that is insoluble in versatile solvents. Therefore, ILs have been used to modify cellulose. However, 1-ethyl-3-methylimidazolium acetate (EmimOAc), a commercially available IL often used to dissolve and modify cellulose to prepare cellulose-based materials, causes the undesired introduction of an acetyl group derived from the acetate anion of EmimOAc onto the hydroxy group of cellulose during esterification. In this study, for cellulose esterification, we prepared aryloxy ILs as non-carboxylate-type and basic ILs, which can theoretically prevent the undesired introduction of an acyl group from the IL onto the hydroxy group of cellulose. The optimized 1-ethyl-3-methylimidazolium 2-pyridinolate (Emim2OPy) and mixed solvent system achieved rapid cellulose esterification (within 30 min) with an excellent degree of substitution (DS) value (up to >2.9) derived from the employed low-reactive vinyl esters and bio-based unsaturated aldehydes, without any undesired substituent introduction from side reactions.

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Hedir, Guillaume G., Maria C. Arno, Marvin Langlais, Jonathan T. Husband, Rachel K. O'Reilly, and Andrew P. Dove. "Poly(oligo(ethylene glycol) vinyl acetate)s: A Versatile Class of Thermoresponsive and Biocompatible Polymers." Angewandte Chemie 129, no. 31 (2017): 9306–10. http://dx.doi.org/10.1002/ange.201703763.

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Hedir, Guillaume G., Maria C. Arno, Marvin Langlais, Jonathan T. Husband, Rachel K. O'Reilly, and Andrew P. Dove. "Poly(oligo(ethylene glycol) vinyl acetate)s: A Versatile Class of Thermoresponsive and Biocompatible Polymers." Angewandte Chemie International Edition 56, no. 31 (2017): 9178–82. http://dx.doi.org/10.1002/anie.201703763.

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Chana, Jasminder, Ben Forbes, and Stuart Allen Jones. "The Synthesis of High Molecular Weight Partially Hydrolysed Poly(vinyl alcohol) Grades Suitable for Nanoparticle Fabrication." Journal of Nanoscience and Nanotechnology 8, no. 11 (2008): 5739–47. http://dx.doi.org/10.1166/jnn.2008.475.

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Poly(vinyl alcohol) (PVA) is a highly versatile synthetic polymer that is formed by full or partial hydrolysis of poly(vinyl acetate) (PVAc). A wide range of PVA partially hydrolysed grades are commercially available, but the amphiphilic grades of the polymer (30–60% hydrolysis), which probably the most interesting in terms of drug delivery, are not readily available. As a consequence few studies have assessed the application of low hydrolysis PVA polymers to form nanocarriers. The aims of this study were to synthesise amphiphilic grades of PVA on a laboratory scale, analyse their chemical properties and determine whether these grades could be used to form nanoparticles. PVA 30%, PVA 40%, PVA 50% and PVA 60% were synthesised via direct saponification of PVAc. All grades of PVA synthesised had degrees of hydrolysis close to those predicted from the stoichiometry of the saponification reaction. The PVA grades displayed <1.5% batch to batch variability (n = 3) in terms of percentage hydrolysis, demonstrating the manufacture process was both reproducible and predictable. Analysis of the polymer characteristics using 13C nuclear magnetic resonance and differential scanning calorimetry revealed that all PVA grades contained block distributions (i.e., η < 1) of vinyl alcohol monomers (η ranged from 0.33–0.45) with a high probability of adjacency calculated for the hydroxylated units (POH ranged 0.926–0.931). All the grades of PVA formed nanoparticles using a precipitation technique with a trend towards smaller particle size with increasing degree of PVA hydrolysis; PVA 30% resulted in significantly larger nanoparticles (225 nm) compared to PVA 40–60% (137–174 nm).

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Mariam George, Priyanka, and Sheeja S Varghese. "Electrospun Ocimum Sanctum Loaded Fibres With Potential Biomedical Applications – Periodontal Therapeutic Perspective." Biomedical and Pharmacology Journal 11, no. 3 (2018): 1731–36. http://dx.doi.org/10.13005/bpj/1542.

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Electro spinning is a technique that is simple, unique, cost effective and versatile. The nanofibers obtained are to be non woven with high tunable porosity and a large surface area. The parameters decide the morphology of the resultant fibers, such as tip to collector distance, viscosity of the solution, diameter of the needle. By controlling or tuning the parameters it is possible to obtain or fabricate fibers for the desired function. To establish ideal spinning parameters so as to formulate a nanoscale resorbable system for local periodontal therapy based on electro spinning of Ocimum sanctum(Tulsi) loaded resorbable Poly vinyl acetate (PVA) fibers. Ocimum sanctum (Tulsi) extract prepared was incorporated by electro spinning (HOLAMRC’S HO-SPLF4) into Poly vinyl acetate (PVA) at different concentrations (1-20%w/w). Electrospinning was performed at different paremeters: applied voltage of 13,15,20,55Kv.Tip- to- collector distance was set at 12, 22, 16-18.5cm .solution flow rate was 500µl/hr0.8ml/hr,1ml/hr,1.5ml/hr, tip diameter was 12mm,22m,0.91mm,.4mm. volume of the solutions were 2.5, 1ml, duration was of 5 or 3 hours. The fibers obtained were subjected to SEM analysis. Electro spinning of 10% concentration tulsi done under the following conditions resulted in formation of uniform and beadless fibers. Applied voltage of 13kV, tip- to- collector distance at 12cm, solution flow rate of 500µl/hr, tip diameter of 12mm, volume of 2.5ml and duration of 5hrs. SEM images revealed that the textures of all resultant samples were homogenous and free of heterogeneities or artefacts’ The study revealed that Ocimum sanctum (Tulsi) 10wt% incorporated into PVA can be electrospun into nonfibers at an applied voltage of 13kV, tip- to- collector distance of 12cm, solution flow rate at 500µl/hr, and a tip diameter of 12mm.

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Yuan, Ming, Lili Xu, Xuetao Cui, Jiaxing Lv, Panpan Zhang, and Huadong Tang. "Facile Synthesis of Ultrahigh Molecular Weight Poly(Methyl Methacrylate) by Organic Halides in the Presence of Palladium Nanoparticles." Polymers 12, no. 11 (2020): 2747. http://dx.doi.org/10.3390/polym12112747.

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A facile and versatile approach for the synthesis of ultrahigh molecular weight poly(methyl methacrylate) (PMMA) at mild conditions was developed. Certain organic halides combined with a catalytical amount of palladium nanoparticles (Pd NPs) were found to be very effective in initiating polymerizations of methyl methacrylate (MMA), methyl acrylate, vinyl acetate and other vinyl monomers. An ultrahigh molecular weight PMMA with a number-average molecular weight of 4.65 × 106 Da and a weight-average molecular weight of 8.08 × 106 Da was synthesized at 70 °C using 2-bromoisobutyric acid ethyl ester (EBiB) as an initiator in the presence of catalytical amount (10.1 ppm) of Pd NPs. A kinetic investigation found that the orders of polymerization with respect to EBiB, Pd NP and MMA were 0.23, 0.50, and 0.58, respectively. Proton nuclear magnetic resonance (1H NMR) combined with matrix-assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF) and gel permeation chromatography (GPC) were used to prove that the macromolecular chain had an end-group of EBiB residue. The electron spin resonance (ESR), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) results reveal that the reaction of EBiB with Pd NPs caused a bromo atom (Br) transfer from EBiB to Pd NPs and resulted in the generation of EBiB residue radical to initiate the polymerization of MMA and the formation of PdIIBr2 on the surface of Pd nanoparticles.

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Erdem, İlker, Şeyma Avcı, and Mehmet Fazıl Kapçı. "Ethyl vinyl acetate (EVA) composites with nanoclays and boric acid: Thermal and mechanical properties." Journal of Boron 10, no. 1 (2025): 19–34. https://doi.org/10.30728/boron.1568002.

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The polymers are widely used materials in various applications. Their flammability is a concern when the material will be facing high temperatures and/or conditions resulting in the incidence of ignition. The flame resistance of the polymers tends to be enhanced by the utilization of inorganic materials as additives. Versatile inorganic materials can be used for this purpose, e.g., ceramics (oxides, hydroxides, clays, etc.). The addition of inorganic additives could alter the mechanical properties of the polymer-inorganic composite structure, which should be considered during composite preparation as well. In this study, two different nanoclays (up to 20/100 by weight) and boric acid (BA) were added to ethyl vinyl acetate (EVA) to investigate possible enhancement in flame retardancy of the polymer. The mechanical properties were also determined for the neat polymer and polymer-inorganic composites to determine the effect of nanoclay and BA addition. The prepared nanocomposites were evaluated in terms of their chemical structures (Fourier transform infrared spectroscopy and X-Ray diffraction analysis), thermal characteristics (thermogravimetric analysis), mechanical properties (tensile test), and flammability behaviours. The NC 1.4 sample containing the highest amount of nanoclay had the longest burning time and Young’s modulus. The NC 2.3 and NC 1.3-BA samples had relatively higher stress-bearing capabilities. The addition of BA enhanced the stress-bearing capability of NC 1 containing samples and it slightly increased the burning time for NC 2 containing composites. The organic surface modifiers of nanoclays and BA addition were effective on the thermal and mechanical characteristics of the nanoclay/EVA composites.were effective on the thermal and mechanical characteristics of the nano-clay/EVA composites.

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Hero, Devid, and Gergely Kali. "New, Aqueous Radical (Co)Polymerization of Olefins at Low Temperature and Pressure." Processes 8, no. 6 (2020): 688. http://dx.doi.org/10.3390/pr8060688.

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In this communication, we describe our preliminary results for the development of a new method of ethylene and propene (co)polymerization at low pressure at room temperature, using cyclodextrin-assisted aqueous radical polymerization for the first time. For polypropylene homopolymerization, the cyclodextrin was entirely removed, and the partially soluble polymer was characterized. The purification of polyethylene was not complete, since the threaded cyclodextrins remained on the polymer chain, enhancing its solubility and enable to analyze the sample. With this environmentally benign method, polyolefines could be produced, for the first time. The estimated yield was low, and therefore the conditions should be further tuned for industrial application. This straightforward approach could also be applied to synthesize poly(ethylene-co-vinyl acetate) copolymer with an ethylene content of 20 mol% and enhanced yield. Although the procedure in this stage of research has some limitations, the theory behind can later be applied to develop new, energy-efficient, and versatile industrial processes for olefin copolymerizations for a wide range of comonomers.

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25

Grollmisch, A., U. Kragl, and J. Großeheilmann. "Enzyme Immobilization in Polymerized Ionic Liquids-based Hydrogels for Active and Reusable Biocatalysts." SynOpen 02, no. 02 (2018): 0192–99. http://dx.doi.org/10.1055/s-0037-1610144.

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Enzyme immobilization in polymerized ionic liquids (PILs) promises to be a versatile tool for simple recovery and reuse of catalysts. In this study, a raw extract of CalB was encapsulated in poly(VEImBr) and assessed with respect to solvent, temperature, amount of enzyme, leaching behavior, and reusability on the example of the kinetic resolution of rac-1-phenylethanol with vinyl acetate. This immobilization method increased the enzyme activity of the CalB raw extract in comparison to the non-immobilized enzyme. The desired product was synthesized with high enantiomeric excess (ee) and no leaching of active enzyme was observed in the experiments. The immobilization method was compared to Novozyme 435 and Lipozyme RM IM, as commercially available immobilisates. Nonpolar solvents, including n-heptane and n-dodecane, proved to be the best reaction solvents, showing nearly full conversion and high catalytic activities. The encapsulated lipase was easily recovered from the reaction mixture and reused for ten cycles.

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26

Koumura, Kazuhiko, Kotaro Satoh, and Masami Kamigaito. "Manganese-Based Controlled/Living Radical Polymerization of Vinyl Acetate, Methyl Acrylate, and Styrene: Highly Active, Versatile, and Photoresponsive Systems." Macromolecules 41, no. 20 (2008): 7359–67. http://dx.doi.org/10.1021/ma801151s.

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27

Brar, A. S., Ashok Kumar Goyal, and Sunita Hooda. "Two-dimensional NMR studies of acrylate copolymers." Pure and Applied Chemistry 81, no. 3 (2009): 389–415. http://dx.doi.org/10.1351/pac-con-08-06-01.

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High-resolution NMR spectroscopy is the most versatile, reliable, and generally acceptable technique for the determination of the microstructure of polymers. 2D NMR techniques, along with 1D NMR, have more potential to study absolute configurational assignments and sequence distribution of copolymers. Physical and chemical properties of polymers are influenced fundamentally by their microstructure. We discuss the detailed microstructure analysis of a large number of homopolymers, copolymers, and terpolymers. 2D NMR study of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), and poly(methacrylonitrile) (PMAN) is discussed in this article. In addition to homopolymers, 2D heteronuclear single-quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple-bond correlation (HMBC) study of different copolymers such as poly(methyl methacrylate-co-methyl acrylate), poly(styrene-co-methyl methacrylate), and poly(methyl methacrylate-co-methacrylonitrile) have also been reported here. This in turn helps in microstructural analysis of terpolymers such as poly(methacrylonitrile-co-styrene-co-methyl methacrylate), poly(acrylonitrile-co-methyl methacrylate-co-methyl acrylate), and poly(ethylene-co-vinyl acetate-co-carbon monoxide).

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Tardy, Antoine, Jean-Claude Honoré, Johanna Tran, et al. "Radical Copolymerization of Vinyl Ethers and Cyclic Ketene Acetals as a Versatile Platform to Design Functional Polyesters." Angewandte Chemie 129, no. 52 (2017): 16742–47. http://dx.doi.org/10.1002/ange.201707043.

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Tardy, Antoine, Jean-Claude Honoré, Johanna Tran, et al. "Radical Copolymerization of Vinyl Ethers and Cyclic Ketene Acetals as a Versatile Platform to Design Functional Polyesters." Angewandte Chemie International Edition 56, no. 52 (2017): 16515–20. http://dx.doi.org/10.1002/anie.201707043.

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30

Zhou, Bo, Xiaotian Qi, Peng Liu, and Guangbin Dong. "Development and Mechanistic Studies of the Iridium‐Catalyzed C−H Alkenylation of Enamides with Vinyl Acetates: A Versatile Approach for Ketone Functionalization." Angewandte Chemie 133, no. 38 (2021): 21094–102. http://dx.doi.org/10.1002/ange.202107331.

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Zhou, Bo, Xiaotian Qi, Peng Liu, and Guangbin Dong. "Development and Mechanistic Studies of the Iridium‐Catalyzed C−H Alkenylation of Enamides with Vinyl Acetates: A Versatile Approach for Ketone Functionalization." Angewandte Chemie International Edition 60, no. 38 (2021): 20926–34. http://dx.doi.org/10.1002/anie.202107331.

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32

Schmiedel, Volker Martin, and Hans-Ulrich Reissig. "Alkoxyallenes as Starting Materials for the Syntheses of Natural Products." Current Organic Chemistry 23, no. 27 (2020): 2976–3003. http://dx.doi.org/10.2174/1385272824666191218115731.

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Alkoxyallenes are easily available and versatile building blocks for the preparation of a variety of natural products (terpenes, polyketides, alkaloids, amino acids, carbohydrates etc.) originating from different classes. The synthetic use of the three allene carbon atoms frequently follows the “normal” reactivity pattern showing that alkoxyallenes can be regarded as special enol ethers. Additions of alcohols or amines to alkoxyallenes form vinyl-substituted O,O- or N,O-acetals that are frequently used in ring-closing metathesis reactions. This methodology delivers crucial heterocyclic units of the target compounds. Enantioselective additions provide products with high enantiopurity. Alternatively, an “Umpolung” of reactivity of alkoxyallenes is achieved by lithiation at C-1 and subsequent reaction with electrophiles, such as alkyl halides, carbonyl compounds, imines or nitrones. High stereoselectivity of the addition step can be achieved by substrate control or auxiliary control. The high diastereo- or enantioselectivity is transferred to the subsequent acyclic or cyclic products. The cyclization of primary addition products occurs efficiently under mild conditions and provides functionalized dihydrofuran, dihydropyrrole or 1,2-oxazine derivatives. These are valuable intermediates for the synthesis of a variety of heterocyclic natural products. Nazarov cyclizations or gold catalyzed rearrangements allow the synthesis of five- and six-membered carbocyclic compounds that are also used for natural product synthesis. Dedicated to Dr. Reinhold Zimmer, a pioneer of alkoxyallene chemistry, on the occasion of his 60th birthday.

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Guerrero, Palimécio G., Miguel J. Dabdoub та Adriano C. M. Baroni. "Hydroalumination of selenoacetylenes: a versatile generation and reactions of α-aluminate vinyl selenide intermediates in the highly regio and stereoselective synthesis of telluro(seleno)ketene acetals". Tetrahedron Letters 49, № 24 (2008): 3872–76. http://dx.doi.org/10.1016/j.tetlet.2008.04.072.

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34

Gong, Zheqing, and Lijun Chen. "Study on modified VAc-VeoVa10 latex prepared by soap-free emulsion polymerization." Journal of Elastomers & Plastics, October 18, 2023. http://dx.doi.org/10.1177/00952443231207969.

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Modified latex is prepared via the soap-free emulsion polymerization of ethyl acetate (VAc) and vinyl versatate (VeoVa10). DFHMA is used as modified monomers. The composite surfactants of SR-10 and ANPEO-10 are used as the composite emulsifiers. The polymerization is initiated by potassium sulfate (KPS). The structure of latex film was characterized by Fourier transform infrared spectroscopy (FTIR). The latex films were tested by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA) determinator. The particle size of the latex emulsion particle size is determined by the Zetatrac dynamic light scatter. Results show that the optimum condition of preparing the modified latex can be obtained, i.e. the amount of emulsifier is 4.0%; the mass ratio of SR-10 to ANPEO-10 is 1:1; the amount of initiator is 0.5%; the mass ratio ofVAc to VeoVa10 is 1:1; the amount of DFHMA is 5.0%. The appearance of the latex is blue and translucent with a small particle size. The conversion rate is more than 98%. Compared with the conventional latex, the hydrophobicity and heat resistance of the film have been improved. Moreover, the latex has good chemical stability and mechanical stability.

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35

Robertson, Mark, Andrew Barbour, and Zhe Qiang. "Valorization of shoe sole waste into high-performance cationic dye sorbents via sulfonation." RSC Applied Polymers, 2024. http://dx.doi.org/10.1039/d4lp00281d.

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Ethylene-vinyl acetate (EVA)-based copolymers are widely employed in various applications such as packaging, adhesives, and shoe soles due to their relatively low cost and versatile properties, which are controlled by...

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36

Itai, Massad and Ilan Marek*. "Alkene Isomerization Revitalizes the Coates–Claisen Rearrangement." January 9, 2022. https://doi.org/10.5281/zenodo.5831573.

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The [3,3]-sigmatropic rearrangement of allylic vinyl acetals, first investigated by Coates nearly four decades ago, is set apart from other variants of the Claisen rearrangement owing to the versatile monoprotected 1,5-dicarbonyl motif featured in the products. Unfortunately, the synthetically elusive nature of the substrates has thus far precluded the widespread application of this attractive transformation. Herein, we show that the key allylic vinyl acetals can be efficiently generated through alkene isomerization of their readily available regioisomeric counterparts (derived from allylic alcohols and a,b-unsaturated aldehydes), thus enabling the first systematic study of the substrate scope of this rearrangement, as well as the discovery of exceptionally mild conditions for its mediation by Lewis and Brønsted acids

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37

Michelas, Maxime, Laura Wimberger, and Cyrille Boyer. "A General Approach for Photo‐Oxidative Degradation of Various Polymers." Macromolecular Rapid Communications, July 15, 2024. http://dx.doi.org/10.1002/marc.202400358.

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AbstractThe escalating demand for plastics has resulted in a surge of plastic waste worldwide, posing a monumental environmental challenge. To address this issue, a versatile photo‐oxidative degradation method applicable to seven distinct polymer families is proposed, comprising poly(isobutyl vinyl ether) (PIBVE), poly(2,3‐dihydrofuran) (PDHF), poly(vinyl acetate) (PVAc), poly(n‐butyl acrylate) (PBA), poly(methyl acrylate) (PMA), poly(vinyl chloride) (PVC), poly(dimethyl acrylamide) (PDMA), poly(ethylene oxide) (PEO), poly(oligo(ethylene glycol) methyl ether acrylate) (PEGMEA), and even poly(methyl methacrylate) (PMMA). This method employs photo‐mediated hydrogen atom transfer (HAT) followed by oxidation to promote polymer degradation. This reaction is carried out under aerobic condition in the presence of iron trichloride (FeCl3) as a photocatalyst in combination with low‐intensity purple light irradiation. The process can degrade up to 97% of the polymer in less than 3 h. This degradation process can be easily controlled by switching the light off, which allows for precise modulation of the degradation rate, enhancing the effectiveness of the method. Overall, this method provides a sustainable method for degrading various polymer types with low energy input.

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38

Golikov, Aleksei N., Chibeom Seo, JaeHwan Lee, and Sangho Koo. "Palladium‐Catalyzed S‐Allylation of Vinyl Carbinols – Total Syntheses of Carotenoids by Julia‐Kocienski Olefination." Advanced Synthesis & Catalysis, November 15, 2023. http://dx.doi.org/10.1002/adsc.202301055.

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Palladium catalyzed S‐allylation of vinyl carbinols from ionones (or conjugated carbonyls) with 2‐mercapto‐1,3‐benzothiazole (BT‐SH) provides versatile C15 dienyl benzothiazolyl (BT) sulfides. This Pd(dppe)Cl2‐catalyzed S‐allylation is highly selective for free allylic alcohols in the presence of allylic acetates, resulting in 3‐ or 4‐acetoxy C15 dienyl BT‐sulfides suitable for xanthophyll synthesis. The corresponding C15 dienyl BT‐sulfones undergo Julia‐Kocienski olefination reactions with C10 2,7‐dimethyl‐2,4,6‐octatrienedial under mild conditions to produce carotenoids natural products. Efficient synthesis is achieved for a range of carotenoids including xanthophylls such as iso‐zeaxanthin, zeaxanthin, and lutein as well as carotenes like β‐carotene, ε‐carotene, and 9'‐Z‐phenyl‐carotene.

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Su, Zhengkang, Qinzhe Zhou, Junhong Jin, Shenglin Yang, Guang Li, and Jingjing Zhang. "Phase‐Transition‐Promoted Interfacial Anchoring of Sulfide Solid Electrolyte Membranes for High‐Performance All‐Solid‐State Lithium Battery." Advanced Science, October 22, 2024. http://dx.doi.org/10.1002/advs.202407798.

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AbstractSolvent‐free manufacturing is crucial for fabricating high‐performance sulfide‐electrolyte‐based all‐solid‐state lithium batteries (ASSLBs), with advantages including side reaction inhibition, less contamination, and practical scalability. However, the fabricated sulfide electrolytes commonly suffer from brittleness, limited ion transport, and unsatisfactory interfacial stability due to the uncontrolled dispersion of the sulfide particles within the polymer binder matrix. Herein, a “solid‐to‐liquid” phase transition strategy is reported to fabricate flexible Li6PS5Cl (LPSCl) electrolytes. The polycaprolactone (PCL)‐based binder (PLI) with phase‐transition characteristics fills the gap of LPSCl particles and tightly grafts on the particle surface via ion‐dipole interaction, bringing a thin and compact electrolyte membrane (80 µm). The simultaneously high Li‐ion conducting and electron insulating nature of PLI binder facilitates Li‐ion transport and ensures good interfacial stability between electrolyte and anode. Consequently, the sulfide electrolyte membrane exhibits high ionic conductivity (8.5 × 10−4 S cm−1), enabling symmetric and full cells with 10 and 2.5 times longer cycling life compared with that of the cells with pristine LPSCl electrolyte, respectively. The demonstrated strategy is versatile and can be extended to ethylene vinyl acetate copolymer (EVA) that also brings enhanced electrochemical performance. The thin sulfide electrolyte with high interfacial stability potentially facilitates dendrite‐free ASSLBs with high energy density.

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Elbarbary, Ahmed M., M. A. Elhady та Yasser H. Gad. "Development of Cotton Fabrics via EVA/SiO2/Al2O3 Nanocomposite Prepared by γ-Irradiation for Waterproof and Fire Retardant Applications". Journal of Inorganic and Organometallic Polymers and Materials, 30 червня 2022. http://dx.doi.org/10.1007/s10904-022-02395-w.

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AbstractDevelopment of cotton fabric (CF) properties using nanocomposites via coating method was of considerable interest for wide applications. This article aims at developing CF properties by coating treatment using ethylene–vinyl-acetate (EVA), silicon dioxide (SiO2), aluminum oxide (Al2O3) nanoparticles and γ-irradiation widely used in waterproof and flame retardant applications. EVA-based nanocomposites, EVA/SiO2, EVA/Al2O3, and EVA/SiO2/Al2O3, were synthesized by γ-irradiation and the highest gel content of 81.2–95.3% was achieved at 30 kGy. The physicochemical properties of EVA-based nanocomposites were characterized by FT-IR, XRD, DSC and SEM techniques. Usage of irradiated EVA and EVA-based nanocomposites for treatment of CF by coating technique was successfully achieved. This technique provides a simple and versatile method leading to excellent uniform and smooth surface morphology without aggregation. The weight gain, mechanical properties, thermal properties, water vapor permeability and flame-retardant properties of the modified CF were evaluated. Moreover, compared with control CF, the resistivity of water absorptivity and hydrophobic property and the thermal stability were gained. The flame retardant properties of CF samples were performed using limited oxygen index (LOI) and vertical burning flame tests. LOI percentages of CF/EVA/SiO2, CF/EVA/Al2O3 and CF/EVA/SiO2/Al2O3 increased to 25.3, 27.5, and 29.3%, respectively. Untreated CF ignited and burned rapidly after 5 s. Meanwhile, the treated CF hold flame resistance properties and the burning time prolonged to 25 s. The results of the treated CF providing revealed hydrophobic and protective capability of the fabrics from being destroyed by burning, and support their further use in waterproof and flame retardant applications of fabrics.

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Guerrero, Palimecio G. Jr, Miguel J. Dabdoub та Adriano C. M. Baroni. "ChemInform Abstract: Hydroalumination of Selenoacetylenes: A Versatile Generation and Reactions of α-Aluminate Vinyl Selenide Intermediates in the Highly Regio- and Stereoselective Synthesis of Telluro(seleno)ketene Acetals." ChemInform 39, № 35 (2008). http://dx.doi.org/10.1002/chin.200835164.

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Journal articles on the topic 'Vinyl acetate/versatate'

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