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Showing papers on "Vinyl acetate published in 2017"


Journal ArticleDOI
TL;DR: Electroactive shape recovery experiments exhibited that depending on the applied voltage, temporary shapes in each region of sample can be either individually or simultaneously recovered and PLA/PVAc/graphene nanocomposite blends demonstrated excellent thermally and electrically actuated triple-shape memory effects besides their remarkable dual- shape memory behavior.
Abstract: This work aimed to develop a facile and broadly applicable method for fabricating multistimuli responsive triple-shape memory polymers (SMPs). Hence, herein the SMPs were prepared through the simple physical blending of two commercially available biopolymers, poly(lactic acid) (PLA) and poly(vinyl acetate) (PVAc), in the presence of robust and conductive graphene nanoplatelets. Interestingly, atomic force microscopy observations and thermal analyses revealed that the presence of nanofillers led to phase separation and appearance of two well-separated transition temperatures in the blend of these two miscible polymers. Consequently, shape memory results showed that the unfilled blend of PLA/PVAc with a single thermal transition can only show moderate heat triggered dual-shape memory behavior. While, PLA/PVAc/graphene nanocomposite blends demonstrated excellent thermally and electrically actuated triple-shape memory effects besides their remarkable dual-shape memory behavior. In addition, electrical conductivity of the blend was enhanced by ∼14 orders of magnitude in the presence of graphene. More interestingly, electroactive shape recovery experiments exhibited that depending on the applied voltage, temporary shapes in each region of sample can be either individually or simultaneously recovered.

78 citations


Journal ArticleDOI
TL;DR: In this article, an in-situ polymerization combined with chemical grafting modification method for preparing polyvinyl alcohol-grafted graphene oxide/Polyvinyl Alcohol (PVA-g-GO/PVA) nanocomposites was reported.

52 citations


Journal ArticleDOI
TL;DR: A versatile method for the surface tailoring of cellulose nanocrystals (CNCs) based on the reactivity of vinyl ester molecules toward the accessible hydroxyl groups located at the surface of the nanoparticles is proposed.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated one-shot copolymerization of vinyl ether with acrylates or vinyl esters in the presence of an aluminum-based Lewis acid and azo-initiator in toluene at 20 °C.

50 citations



Journal ArticleDOI
TL;DR: In this article, a nano-SiO2-based pour-point depressant (PPD) was used in copolymers of ethylene and vinyl acetate (EVA) with various Vinyl Acetate contents.
Abstract: Nanohybrid pour-point depressants (PPDs) were prepared by organically modified nano-SiO2 in copolymers of ethylene and vinyl acetate (EVA) with various vinyl acetate contents. The effects of nanohybrid PPDs on the cold-flow properties of 25 wt % wax model oil were evaluated. The crystallization behavior and crystal morphology of the model oil at low temperatures were also observed using polarized optical microscopy. The results indicated that the co-crystallization and dispersion effects of EVA on wax crystals are the key factors in determining the heterogeneous nucleation effect of the nanohybrid PPDs. The vinyl acetate content in EVA strongly affects the compatibility between the modified nanosilica and EVA. As a result, the selection of an appropriate EVA according to the oils used and the compatibility factor is important. In this work, EVA (VA = 32%)/modified nano-SiO2 composite PPD [N-SiPPD(32)] provided the best cold-flow improvement for the model oil when doped at 500 ppm. The pour point of the mo...

44 citations


Journal ArticleDOI
TL;DR: This work demonstrates structure-controlled thermal transitions, conjugation to human lysozyme through the retained end-group, and shows that this class of polymers can uniquely be copolymerized with 2-methylene-1,3-dioxepane (MDO) to generate polymers in which the degradability and cloud point can be independently tuned to create materials that display the same cloud point but degrade differently.
Abstract: Polymers with a thermally triggered phase transition are important in the design of materials for biological applications, where their behavior can be used to trigger release or (dis)assembly events. Despite their advantages, a system with tunable thermal response, end-group reactive sites, low toxicity, and controlled main-chain degradability has not been realized, yet this would be a significant advance. The versatile new poly(oligo(ethylene glycol) vinyl acetate)s are presented with excellent control over their molecular properties obtained through RAFT/MADIX polymerization. Furthermore, we demonstrate structure-controlled thermal transitions, conjugation to human lysozyme through the retained end-group, and moreover show that this class of polymers can uniquely be copolymerized with 2-methylene-1,3-dioxepane (MDO) to generate polymers in which the degradability and cloud point can be independently tuned to create materials that display the same cloud point but degrade differently.

41 citations


Journal ArticleDOI
TL;DR: In this article, the degradability of nanocomposites of poly(lactic acid) (PLA) containing cellulose nanocrystals (CNCs) were examined by FESEM, AFM, FT-IR, DSC and tensile tests.
Abstract: Nanocomposites of poly(lactic acid) (PLA) containing cellulose nanocrystals (CNCs) were prepared by dispersion of CNCs in aqueous poly(vinyl acetate) (PVAc) emulsion followed by melt extrusion with PLA. Functionalization of PVAc by radical grafting of glycidyl methacrylate (PVAc-GMA) was carried out during PVAc polymerization by using ammonium cerium (IV) nitrate as the initiator. The morphology, phase interactions, thermal and mechanical properties and degradability in composting of blends (PLA/PVAc, PLA/PVAc-GMA) and nanocomposites (PLA/PVAc/CNC, PLA/PVAc-GMA/CNC) containing 3 wt% CNC were examined by FESEM, AFM, FT-IR, DSC and tensile tests. The study of degradability demonstrated that the disintegration rate of PLA/PVAc-GMA/CNC in soil was higher than that of PLA/PVAc/CNC, likely because the epoxy groups of GMA accelerated the biodegradation rate through the formation of radicals.

38 citations


Journal ArticleDOI
TL;DR: Soft, peelable organogels from 40% hydrolyzed poly(vinyl acetate) (40PVAc) and benzene-1,4-diboronic acid (BDBA) are developed to be effective at softening and removing deteriorated coatings from water-sensitive works of art and delicate surfaces.
Abstract: We have developed soft, peelable organogels from 40% hydrolyzed poly(vinyl acetate) (40PVAc) and benzene-1,4-diboronic acid (BDBA). The organic liquids gelated include dimethyl sulfoxide, dimethylformamide, tetrahydrofuran, 2-ethoxyethanol, and methanol. The rheology of these soft materials can be tuned by altering the concentration of the polymer and/or crosslinker. Insights into the mechanisms leading to gelation were obtained from 1H NMR experiments, fluorescence measurements, and studies comparing properties of materials made from BDBA and phenylboronic acid, a molecule incapable of forming covalent crosslinks between the polymer chains. These organogels can be easily peeled off a surface, leaving no residue detectable by UV–vis spectroscopy. They are demonstrated to be effective at softening and removing deteriorated coatings from water-sensitive works of art and delicate surfaces. They have the needed characteristics to clean topographically complex surfaces: good contact with the surface, easy remo...

36 citations


Journal ArticleDOI
TL;DR: Through controlling the dissolution environment by predissolving a polymer, PVP or PVP-VA, which can interact with the crystal surface to alter its dissolution properties, improved solubility, and dissolution rates of F FA-TP CO and FFA-NIC CO have been demonstrated.
Abstract: Effects of three polymers, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and copolymer of vinylpyrrolidone/vinyl acetate (PVP-VA), on the dissolution behavior of the cocrystals of flufenamic acid with theophylline (FFA-TP CO) and nicotinamide (FFA-NIC CO) were investigated at multiple length scales. At the molecular level, the interactions of crystal surfaces with a polymer were analyzed by observing etching pattern changes using atomic force microscopy. At the macroscopic scale, dissolution rates of particular faces of a single crystal were determined by measurement of the physical retreat velocities of the faces using optical light microscopy. In the bulk experiments, the FFA concentration in a dissolution medium in the absence or presence of a polymer was measured under both sink and nonsink conditions. It has been found that the dissolution mechanisms of FFA-TP CO are controlled by the defect sites of the crystal surface and by precipitation of the parent drug FFA as individual crystals in th...

36 citations


Journal ArticleDOI
TL;DR: It was shown that the results of time-consuming long-term stability tests can be correctly predicted via thermodynamic modeling with PC-SAFT.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the production of cellulose esters under homogeneous conditions using 1,5-diazabicyclo[4.3]non-5-ene acetate ([DBNH][OAc]) as solvent.
Abstract: Cellulose acetate is widely used in films, filters, textiles, lacquer and cosmetic products. Herein we demonstrate the production of cellulose esters under homogeneous conditions using 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc]) as solvent. The reagents have been chosen such that the system is recyclable, i.e. by-products are low boiling and easy to remove. It is demonstrated that cellulose acetate can be synthesized with different degree of substitution (DS) values, and that some commonly used acylation regents, like vinyl carboxylates react well without additional base catalyst. Low to high DS values are possible with good recovery of high purity ionic liquid (IL). A linear correlation method of two separate methods, IR and 31P NMR, is proposed to reliably assess the DS of the products. The recyclability of the solvent is demonstrated by acetylating cellulose with isopropenyl acetate to high degree and regeneration into water. After regeneration of cellulose acetate from the IL with addition of water, the residual water was entrained using n-butanol to minimize hydrolysis of [DBNH][OAc], to allow for high recovery and high purity of the ionic liquid. Thus, an overall scheme for batch cellulose acetylation and recovery of [DBNH][OAc] from aqueous solutions is proposed.

Journal ArticleDOI
TL;DR: In this paper, the potential for the adsorption of cationic dyes was investigated by the combination of electrospinning method and in-situ polymerization and its potential for adaption was investigated.
Abstract: In this paper, hydroxylated α-Fe 2 O 3 nanofiber was synthesized by the combination of electrospinning method and in-situ polymerization and its potential for the adsorption of cationic dyes was investigated. The vinyl acetate monomer was polymerized onto the surface of α-Fe 2 O 3 nanofiber and subsequently it was hydrolyzed in an alkaline solution to convert the acetate group to hydroxyl group. The optimized condition of polymerization was reported. The characteristics of nanofiber were investigated by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscope (FE-SEM), energy-dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET). The FTIR result confirmed successful polymerization of vinyl acetate and generation of hydroxyl group on the surface. Microscopic analyses revealed that the modified nanofiber has a long continuous structure because of attaching the adjacent silanol group of nanofibers. Also, decreasing in the total surface area of nanofiber was detected by BET analysis. Furthermore, the influence of parameters affecting on dye removal such as adsorbent dosage, initial dye concentration and pH was investigated. The mechanism and rate of adsorption were evaluated by different adsorption isotherm and kinetic models. Non-linear regression was used to determine the best fit model for each system. To do this, three error functions were applied to predict the optimum model. It was found that the adsorption of dyes onto hydroxylated nanofiber is based on Langmuir isotherm and pseudo-second-order kinetic model.

Journal ArticleDOI
TL;DR: In this article, reversible addition-fragmentation chain transfer (RAFT) copolymerization was used to prepare copolymers of N-isopropyl acrylamide (NIPAM) and vinyl acetate (VAc) with mole fractions of NIPAM ranging from 0.1 to 0.6 and targeted degrees of polymerization of 100 and 250.

Journal ArticleDOI
TL;DR: In this paper, a well-defined poly(N-vinylcaprolactam-co-vyl acetate) thermoresponsive particles physically crosslinked by means of hydrophobic interactions were synthesized by polymerization-induced self-assembly.

Journal ArticleDOI
Bo Yao1, Lu Wang1, Fei Yang1, Chuanxian Li1, Yansong Zhao 
TL;DR: In this paper, four poly(octadecyl acrylate-vinyl acetate) (POA-VA) PPDs with different VA molar fractions were first synthesized; then, the performance of the four PPD-3 on Dingbian waxy crude oil was investigated by experiments and mesoscopic dynamic simulation.
Abstract: Polar moieties of the conventional polymeric pour point depressants (PPDs) greatly influence the PPDs’ performance on waxy crude oil. However, the influencing mechanism of the polar moieties on the PPD’s performance is not clear. In this paper, four poly(octadecyl acrylate-vinyl acetate) (POA-VA) PPDs with different VA molar fractions were first synthesized; then, the performance of the four PPDs on Dingbian waxy crude oil was investigated by experiments and mesoscopic dynamic simulation. The experimental results show that the crystallization ability of the PPDs deteriorates with increasing VA molar fraction, while the performance of the PPDs first increases and then decreases with the increase of VA molar fraction. At a moderate VA fraction 25 mol %, the PPD-3 shows the best performance in decreasing the WAT, pour point, and viscosity of the crude oil. The simulation results correlate well with the experimental data and confirm that (a) the addition of the PPDs inhibits the transformation of wax molecule...

Journal ArticleDOI
TL;DR: In this article, the effects of the blend morphology and selective localization of multiwall carbon nanotubes (MWCNTs) on the dielectric properties were systematically investigated, and the results showed that when the blend exhibits sea-island morphology accompanying MWCNT selective localization in island droplets, the die-lectric constant was increased to 1200@100 Hz with addition of 5 wt % MWC NTs.
Abstract: In this work, multiwall carbon nanotubes (MWCNTs) were melt compounded with a poly(ethylene vinyl acetate)/thermoplastic polyurethane (EVA/TPU) blend to prepare EVA/TPU/MWCNT blend nanocomposites. The effects of the blend morphology and selective localization of MWCNTs on the dielectric properties including dielectric constant and loss were systematically investigated. The results show that when the blend exhibits sea–island morphology accompanying MWCNT selective localization in island droplets, the dielectric constant was increased to 1200@100 Hz with addition of 5 wt % MWCNTs; in addition, the growth of dielectric loss is suppressed and the values of dielectric loss always remain around 1 with varying the loading of MWCNTs. Furthermore, based on the investigations of rheological percolation testing, morphological observation, and selective localization, the microcapacitor model was evoked to explain the underlying mechanism for the improvement of the dielectric constant for the blend with sea–island mo...

Journal ArticleDOI
TL;DR: In this article, the incorporation of cellulose nanoparticles in poly(ethylene-co-vinyl acetate)-EVA foams was studied, and the effect of a chemical treatment by acetylation on the cellulose fibber was observed, that is, the use of hydrophilic and hydrophobic cellulose nanofibers in EVA foams.
Abstract: Cellulose nanofibers are promising materials in the development of polymeric foams, because they act as heterogeneous nucleation sites for the growth of cells during foaming. In this research, we studied the incorporation of cellulose nanoparticles in poly(ethylene-co-vinyl acetate)-EVA foams. The foams were produced with different fiber contents. We observed the effect of a chemical treatment by acetylation on the cellulose fibber, that is, we evaluated the use of hydrophilic and hydrophobic cellulose nanofibers in EVA foams. The main results indicate that with the addition of only 1% of cellulose nanofibers, cell density significantly reduces when compared with the pure EVA foams. On the other hand, by increasing the cellulose content, the agglomeration of nanofibers also increases, which results in heterogeneous cell sizes. The same phenomenon was observed in the foams produced with acetylated cellulose nanofibers, regardless of the fiber content used. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44760.

Journal ArticleDOI
TL;DR: NMR relaxometry and SAXS measurements both show that the apolar EPM-g-furan precursor contains phase-separated polar clusters and that cross-linking with polar bismaleimide occurs in these clusters.
Abstract: Diels–Alder chemistry has been used for the thermoreversible cross-linking of furan-functionalized ethylene/propylene (EPM) and ethylene/vinyl acetate (EVM) rubbers. Both furan-functionalized elastomers were successfully cross-linked with bismaleimide to yield products with a similar cross-link density. NMR relaxometry and SAXS measurements both show that the apolar EPM-g-furan precursor contains phase-separated polar clusters and that cross-linking with polar bismaleimide occurs in these clusters. The heterogeneously cross-linked network of EPM-g-furan contrasts with the homogeneous network in the polar EVM-g-furan. The heterogeneous character of the cross-links in EPM-g-furan results in a relatively high Young’s modulus, whereas the more uniform cross-linking in EVM-g-furan results in a higher tensile strength and elongation at break.

Journal ArticleDOI
TL;DR: Remarkably, from a feed containing >50% molar VAc content, poly(VAc-alt-MAF-TBE)-b-PVAc block copolymers are produced via a one-pot synthesis and may provide access to a wide range of new polymer materials.
Abstract: Organometallic-mediated radical polymerization (OMRP) has given access to well-defined poly(vinyl acetate-alt-tert-butyl-2-trifluoromethacrylate)-b-poly(vinyl acetate) and poly(VAc-alt-MAF-TBE) copolymers composed of two electronically distinct monomers: vinyl acetate (VAc, donor, D) and tert-butyl-2-trifluoromethacrylate (MAF-TBE, acceptor, A), with low dispersity (≤124) and molar masses up to 57 000 g mol−1 These copolymers have a precise 1:1 alternating structure over a wide range of comonomer feed compositions The reactivity ratios are determined as rVAc = 001 ± 001 and rMAF-TBE = 0 at 40 °C Remarkably, from a feed containing >50% molar VAc content, poly(VAc-alt-MAF-TBE)-b-PVAc block copolymers are produced via a one-pot synthesis Such diblock copolymers exhibit two glass transition temperatures attributed to the alternating and homopolymer sequences The OMRP of this fluorine-containing alternating monomer system may provide access to a wide range of new polymer materials

Journal ArticleDOI
TL;DR: In this paper, a polyurethane/polyvinyl chloride-co-vinyl acetate (PU/PVCA) blend RO membranes were synthesized in four different ratios 90/10, 80/20, 70/30, 60/40.

Journal ArticleDOI
TL;DR: In this paper, a controlled copolymerization of perfluorohexylethylene (PFHE) and vinyl acetate (VAc) copolymers with different compositions was explored.
Abstract: Designing novel polyfluoropolymer architectures is attractive for the development of new applications, such as advanced coatings, purification membranes, or materials for energy. Nevertheless, controlling the radical polymerization of fluoroalkenes is very challenging due to the high reactivity of the propagating fluorinated macroradicals. This study aims at exploring the controlled copolymerization of perfluorohexylethylene (PFHE) and vinyl acetate (VAc) in order to prepare a range of well-defined statistical poly(PFHE-stat-VAc) copolymers with different compositions. Cobalt-mediated radical polymerization demonstrated to be active at 40 °C starting from an alkylcobalt(III) initiator, and copolymers with a fluorinated monomer content as high as ca. 80 wt % were successfully prepared. Reactivity ratios were determined to be rVAc = 0.18 and rPFHE = 0 at 40 °C and emphasized a clear tendency for alternation. Unprecedented PFHE/VAc containing block copolymers were also prepared via a single-step approach or ...

Journal ArticleDOI
TL;DR: A distinctive hydration water structure in the nonthrombogenic polymer, intermediate water (IW), was observed in the hydrated PMePVE by differential scanning calorimetry analysis, and the non thrombogenicity of PMepVE is considered to be brought about by the presence of IW.

Journal ArticleDOI
TL;DR: In this paper, vapor-grown carbon nanofiber/poly(ethylene-co-vinyl acetate) nanocomposites were systematically and explicitly investigated through combined analytical techniques.
Abstract: Vapor-grown carbon nanofibers were filled into poly(ethylene-co-vinyl acetate) through solution mixing to achieve electrical-active two-way shape memory. The vapor-grown carbon nanofiber/poly(ethylene-co-vinyl acetate) nanocomposites were systematically and explicitly investigated through combined analytical techniques. Experimental results showed an increase in crystallization temperature (Tc) and a decrease in melting temperature (Tm) as the vapor-grown carbon nanofiber concentration in the nanocomposites increased. This result indicates that carbon nanofibers can act as nucleating agents during crystallization but may hinder the formation of thermodynamically stable crystals. The nanocomposites had a higher modulus but a lower strength than pure poly(ethylene-co-vinyl acetate). In two-way shape memory testing, a decrease in reversible strain and shape recovery occurred in the nanocomposites. Nevertheless, obvious two-way shape switching was observed in all samples during cyclic heating and cooling. The...

Journal ArticleDOI
TL;DR: In this article, the reliability of the LLE experimental data was validated by the Bachman and Hand equations, which were fitted by the activity coefficient models of nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) and calculated values were in agreement with the experimental tie-line data.
Abstract: Liquid–liquid equilibria (LLE) experimental data for the systems of vinyl acetate + acetic acid/ethanol + water were determined at temperatures of 298.15 and 308.15 K and pressure of 101.3 KPa. The reliability of the LLE experimental data was validated by the Bachman and Hand equations. The LLE data of the two systems were fitted by the activity coefficient models of nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC), which the calculated values were in agreement with the experimental tie-line data. Meanwhile, the parameters of the two equations were also determined. Moreover, the distribution coefficients and selectivity values for the two systems were obtained from the ternary LLE data.

Journal ArticleDOI
TL;DR: A genomic DNA library of Acinetobacter hemolyticus was constructed, and a novel esterase (EstK1) was identified, and the whole-cell catalyst of EstK1 displayed high transesterification activity to produce cinnamyl acetate in nonaqueous systems.
Abstract: Cinnamyl acetate has a wide application in the flavor and fragrance industry because of its sweet, balsamic, and floral odor. Up to now, lipases have been mainly used in enzyme-mediated synthesis of cinnamyl acetate, whereas esterases are used in only a few cases. Moreover, the use of purified enzymes is often a disadvantage, which leads to increases of the production costs. In this paper, a genomic DNA library of Acinetobacter hemolyticus was constructed, and a novel esterase (EstK1) was identified. After expression in Escherichia coli, the whole-cell catalyst of EstK1 displayed high transesterification activity to produce cinnamyl acetate in nonaqueous systems. Furthermore, under optimal conditions (vinyl acetate as acyl donor, isooctane as solvent, molar ratio 1:4, temperature 40 °C), the conversion ratio of cinnamyl alcohol could be up to 94.1% at 1 h, and it reached an even higher level (97.1%) at 2 h.


Journal ArticleDOI
TL;DR: The strategy proposed in the present work is an important step onward in terms of sustainability because the long-chain vinyl ester can be synthesized from a renewable and biobased source, and the toxic and corrosive chemicals commonly employed for cellulose esterification are avoided.

Journal ArticleDOI
TL;DR: In this paper, a pre-exponential factor of 1.35 × 107 L mol−1 s−1 and an activation energy of 20.4 kJmol−1, with 95% confidence ellipsoids for the parameters also presented.
Abstract: Propagation rate coefficient values, kp, reported by several groups for radical polymerization of bulk vinyl acetate are critically evaluated. All data are obtained by the combination of pulsed-laser polymerization and subsequent polymer analysis by size exclusion chromatography, as recommended by the IUPAC Working Party on Modeling of Polymerization Kinetics and Processes. Although a small (≈15%) increase in kp is observed as laser pulse repetition rate is increased from low (25–100 Hz) to high (300–500 Hz) values, all of the data fulfill the required consistency criteria and thus are combined into a benchmark set covering the temperature range of 5–70°C. The data are fitted well by an Arrhenius relation resulting in a pre-exponential factor of 1.35 × 107 L mol−1 s−1 and an activation energy of 20.4 kJ mol−1, with 95% confidence ellipsoids for the parameters also presented.

Journal ArticleDOI
TL;DR: This study may contribute to environment-friendly synthesis of phenethyl ester based on optimal conditions, and enzyme reusability for high conversion of Phenethyl acetate.