Polyvinyl Acetate and Vinyl Acetate-Ethylene Hybrid Adhesive: Synthesis, Characterization, and Properties

The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.

Efficient and selective upcycling of waste polylactic acid into acetate using nickel selenide

The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.

Regulating the Localization of Intumescent Flame Retardant for Improving the Flame Retardancy of Ethylene-vinyl Acetate Copolymer Using Polyamide 6 as a Charring Agent

Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.

A comparative study for petroleum removal capacities of the bacterial consortia entrapped in sodium alginate,sodium alginate/poly(vinyl alcohol),and bushnell haas agar

The purpose of this study was to identify and compare the degradation efficiencies of free and entrapped bacterial consortia(Staphylococcus capitis CP053957.1 and Achromobacter marplatensis MT078618.1)to different polymers such as Sodium Alginate(SA),Sodium Alginate/Poly(Vinyl Alcohol)(SA/PVA),and Bushnell Haas Agar(BHA).In addition to SA and SA/PVA,which are cost-effective,non-toxic and have different functional groups,BHA,which is frequently encountered in laboratory-scale studies but has not been used as an entrapment material until now.Based on these,the polymers with different surface morphologies and chemical compositions were analyzed by SEM and FT-IR.While the petroleum removal efficiency was higher with the entrapped bacterial consortia than with the free one,BHA-entrapped bacterial consortium enhanced the petroleum removal more than SA and SA/PVA.Accordingly,the degradation rate of bacterial consortia entrapped with BHA was 2.039 day^(-1),SA/PVA was 1.560,SA was 0.993,the half-life period of BHA-entrapped bacterial consortia is quite low(t_(1/2)=0.339)compared with SA(t_(1/2)=0.444)and SA/PVA(t_(1/2)=0.697).The effects of the four main factors such as:amount of BHA(0.5,1,1.5,2,2.5,3 g),disc size(4,5,6,7,8 mm),inoculum concentration(1,2.5,5,7.5,10 mL),and incubation period on petroleum removal were also investigated.The maximum petroleum removal(94.5%)was obtained at≥2.5 mL of bacterial consortium entrapped in 2 g BHA with a 7 mm disc size at 168 h and the results were also confirmed by statistical analysis.Although a decrease was observed during the reuse of bacterial consortium entrapped in BHA,the petroleum removal was still above 50%at 10th cycle.Based on GC-MS analysis,the removal capacity of BHA-entrapped consortium was over 90%for short-chain n-alkanes and 80%for medium-chain n-alkanes.Overall,the obtained data are expected to provide a potential guideline in cleaning up the large-scale oil pollution in the future.Since there has been no similar study investigating petroleum removal with the bacterial consortia entrapped with BHA,this novel entrapment material can potentially be used in the treatment of petroleum pollution in advanced remediation studies.

Nutrient Release Characteristics of Vinyl Chloride-Vinyl acetate Copolymers Coated SlowRelease Nitrogen Fertilizer and Its Effect on Soil Mineral Nitrogen

[Objective] The aim was to explore release characteristics of vinyl chlo- ride-vinyl acetate copolymer controlled-release N fertilizer and the effects on minerat nitrogen in soils. [Method] Vinyl chloride-vinyl acetate copolymer and hydroxyl-modi- fied VCNAc were taken as coating materials to prepare slow release fertilizer. Nutri- ent release characteristics of VC/VAc slow release fertilizer was evaluated by water immersion method and the effects of VC/VAc slow release fertilizer on mineral ni- trogen were researched by pot experiment. [Result] The release periods of VC-VAc controlled-release urea and hydroxyl-modified VC/VAc coated urea were 60 and 50 d, respectively. Furthermore, the content of ammonium nitrogen reached the peak on the 30th d and the content of nitrate nitrogen reached the peak on the 60th d in soils in treatments with VCNAc and hydroxyl-modified VC/VAc; the content of nitrate nitrogen rose again on the 120th d in the treatment with VC/VAc. In terms of wheat yield, different treatments showed insignificant differences and rice yield in the treatment with VCNAc was significantly higher than that in the treatment with hy- droxyl-modified VCNAc （P〈0.05）. [Conclusion] The release days of slow controlled- release fertilizer vary upon pot experiment method and water immersion method. Slow controlled-release fertilizer is not suitable for monoculture, due to long fertilizer efficiency, but multiple cropping would be optimal for its role to be fully exploited.

SYNTHESIS OF POLY(VINYL ACETATE)-INTERCALATED GRAPHITE OXIDE BY AN IN SITU INTERCALATIVE POLYMERIZATION

Graphite oxide, a pseudo-two-dimensional solid in bulk form, was synthesized from natural graphite powder by oxidization with KMnO4 in concentrated H2SO4. The poly(vinyl acetate)-intercalated graphite oxide nano-composite was prepared by an in situ intercalative polymerization reaction, in which n-octanol-graphite oxide intercalation compounds were first obtained, vinyl acetate monomer was then dispersed into the interlayer of modified graphite oxide, followed by thermal polymerization of the monomer. It was experimentally shown that the c-axis space of poly(vinyl acetate)-intercalated graphite oxide was increased to 0.115 nm, which suggested there existed a monolayer of poly(vinyl acetate) chain between the layers of graphite oxide. The nanocomposite was also characterized with thermal analysis and FT-IR spectrometry.

Polyvinyl acetate/poly(amide-12-b-ethylene oxide) blend membranes for carbon dioxide separation

In this paper,blend membranes from polyvinyl acetate(PVAc)and block copolymer poly(amide-12-b-ethylene oxide)(Pebax1074)are prepared by solution casting and solvent evaporation method.Although they are homogeneous on a macro-scale,the observations from DSC and SEM indicate micro-phase separation for PVAc/Pebax1074 blend membranes.With the increase of Pebax1074 content,gas permeabilities of CO2,H2,N2and CH4all increase greatly.PVAc/Pebax1074 blend membranes with high PVAc content are appropriate for CO2/CH4separation.The temperature dependence of gas permeability is divided into rubbery region and glassy region.The activation energies of permeation in rubbery region are smaller than those in glassy region,and they all decrease with increasing Pebax1074 content.For N2,H2and CH4,their gas permeation properties are mainly influenced by the dual-mode sorption and hydrostatic pressure effect.But for CO2,its permeability increases with the increase of pressure due to CO2-induced plasticization effect,which is more obvious for PVAc/Pebax1074 blend membranes with high PVAc content.

SYNTHESIS OF POLYMERIC β-CYCLODEXTRIN SUPPORTED BY CROSSLINKED POLY(ACRYLAMIDE-co-VINYLAMINE)AND ITS CATALYSIS OF THE HYDROLYSIS OF p-NITROPHENYL ACETATE

Polymeric β-cyclodextrin (β-CD) supported by crosslinked poly(acrylamide-co-vinylamine) was synthesized as anartificial analog of hydrolytic enzyme and its catalysis of the hydrolysis of p-nitrophenyl acetate (p-NPA) was theninvestigated. The result showed that the polymer-supported β-CD could accelerate the hydrolytic reaction of p-NPA morequickly than β-CD itself and crosslinked poly(acrylamide-co-vinylamine) alone. The acceleration rate of the polymer-supported β-CD was about 10 times as fast as that of free β-CD in 0.01 mol/L phosphate buffer (pH 7.4) containing 32%DMSO at 37±0.1℃ when the molar amount of β-CD units in the polymer was equal to that of free β-CD in the experiments.The enhanced acceleration of thc polymer-supported β-CD should be ascribed to the cooperative contribution of theinclusion effect of β-CD ring and the nucleophilic effect of amino groups on the polymeric support.

The Effect of Polyvinyl Acetate Polymer on Reducing Dust in Arid and Semiarid Areas

Because the large areas of Iran are on arid and semiarid belt of the world, it has many problems due to windstorms. Wind storms cause dust and haze due to a mass of fine sand or silt soil elevated in the atmosphere. It makes heart disease-cardiovascular and respiratory and so is detrimental for the children. These have plagued the residents and so lives of them are disrupted every so often. In this research, the subject soil stabilization using adherence of poly vinyl acetate polymer as a way to reduce the production of dust is defined for prone area. In this paper, the effect of poly vinyl acetate polymer on silt soil has been studied. In this study the samples were uncompacted particles of soil with different amount of water-solvated polymer (0, 5, 10, 15, 20, 25, 30 grams per meter squared) poured over them. These samples are kept in experimental environment for 7 days. After ensuring complete dryness, their stabilities are tested against wind flow with 20 m/s speed. Results showed that adding more polymers to soil would considerably increase its particles’ stabilities. This stability is due to positive reaction of polymer with soil particles. The effect of this stability is maintained during sample drying time in the lab and the soil maintains its characteristics during testing. The best results are obtained for 20 grams polymer per meter squared, where caused an increase in stability to about 15 times that of the soil without polymer.

PHOTOCOPOLYMERIZATION OF MALEIC ANHYDRIDE AND VINYL ACETATE IN TETRAHYDROFURAN~*

The copolymerization of maleic anhydride and vinyl acetate in tetrahydrofuran was studied. Results show that the maximum copolymerization rate is in 0.6 mole fraction of maleic anhydride, indicating the involvement of maleic anhydride-tetrahydrofuran charge transfer complex in the chain initiation process. ESR study provides collateral evidence for the formation of maleic anhydride radical and tetrahydrofuran radical.

Sound Absorption Properties of Discarded Feathers/Ethylene Vinyl Acetate Copolymer Thermoplastic Composite Materials

The discarded feathers / ethylene vinyl acetate copolymer( EVA) thermoplastic composite materials was obtained with discarded feathers as reinforced material and EVA powders as matrix material by hot pressing method. Sound absorption properties were studied by changing mass ratio of discarded feathers and EVA,thickness of composite materials,hot pressing pressure and hot pressing temperature. It was found that the sound absorption properties of composite materials were good when the mass ratio of discarded feathers and EVA was 1: 1,thickness of composite materials was 30 mm,hot pressing pressure was 8 MPa,and hot pressing temperature was 80 ℃. Under the optimum conditions,the effect of composite density on sound absorption property was analyzed. In a certain range,the sound absorption property was enhanced with the decrease of the composite density.When the composite density was 0. 1g /cm^3, the maximum absorption coefficient was 0.96. Finally,the capillary theory was used to calculate the maximum sound absorption coefficient of discarded feathers / EVA thermoplastic composite materials. The good agreements of experimental results and calculated results proved the validity of the theoretical models.

Bifurcation control and eigenstructure assignment in continuous solution polymerization of vinyl acetate

The major difficulty in achieving good performance of industrial polymerization reactors lies in the lack of understanding of their nonlinear dynamics and the lack of well-developed techniques for the control of nonlinear processes, which are usually accompanied with bifurcation phenomenon. This work aims at investigating the nonlinear behavior of the parameterized nonlinear system of vinyl acetate polymerization and further modifying the bifurcation characteristics of this process via a washout filter-aid controller, with all the original steady state equilibria preserved. Advantages and possible extensions of the proposed methodology are discussed to provide scientific guide for further controller design and operation improvement.

Radiation grafting of poly(vinyl acetate) onto wheat straw and properties of the product

Poly(vinyl acetate)(PVAc) was grafted onto wheat straw by γ-irradiation to improve the compatibility between wheat straw and high-density polyethelene(PE).The grafting was proved by Fourier transform infrared(FTIR) spectroscopy. The compact structure of wheat straw was loosened because the chemical bonds and crystalline structure were destructed by the γ-rays. The modified wheat straw needed less energy for thermal transition, as revealed by differential scanning calorimetry(DSC).Thermal analysis revealed that grafted PVAc acted as a protective barrier for the wheat straw and leads to an increase in maximum pyrolysis temperature. The crystallite size of grafted wheat straw decreased to 5.33 nm from 5.63 nm before irradiation. There were holes in melted form appeared on the surface of the grafted wheat straws.Both the grafted PVAc and irradiation are beneficial to lower the torque of wheat straw/PE melts and improve its mechanical properties by 36%. Possible mechanism of irradiation grafting was proposed.

Graft co-polymerization of maleic acid and vinyl acetate onto poly(vinylidene fluoride) powder by pre-irradiation technique

Binary monomers of maleic acid and vinyl acetate are grafted onto poly(vinylidene fluoride) (PVDF) powder by pre-irradiation induced graft polymerization technique in emulsion solution. The co-grafting of binary monomers is successfully proved by FT-IR spectroscopy analysis. The influences of the absorbed dose, reaction temperature, reaction time, total concentration of monomers, and feed ratio of binary monomers on the degree of grafting are investigated. The thermal property of grafted PVDF powder was characterized by differential scanning calorimetry (DSC) and thermo-gravimetry analysis (TGA).

RADICAL DESORPTION IN EMULSION POLYMERIZATION OF VINYL ACETATE

In the present paper a model equation for calculating the radical desorption rate constant,k0,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluating k0 were determined.Effects of reaction temperature,emulsifier concentration,initiator con-centration,monomer conversion and phase ratio on k0 were studied.It indicates that the desorptionof radicals from latex particles to aqueous phase must be taken into account in the modelling ofemulsion polymerization for the monomers with higher hydrophilicity such as vinyl acetate.

PHOTOCOPOLYMERIZATION OF MALEIC ANHYDRIDE AND VINYL ACETATE

The charge-transfer complex of maleic anhydride and vinyl acetate was copolymerized under UV light. The chain composition and structure of the copolymer were analyzed with conductometry and NMR, and the chain sequence was determined as alternating. The copolymerization rates at different feed ratios, temperatures and in different solvents were investigated, giving evidence to the very active involvement of the CT complexes in the copolymerization. Terpolymerization with acrylonitrile also showed that the complex mechanism was a proper one for this system.

COMPATIBILITY IN POLYMER BLENDS OF POLY (VINYL ACETATE) AND POLY (METHYL METHACRYLATE)STUDIED BY NMR

Compatibility of poly (vinyl acetate) (PVAc) with poly (methyl methacrylate) (PMMA) mixtures has been studied by using nuclear magnetic relaxation, differential scanning calorimeter and small-angle X-ray scattering techniques. The nuclear magnetic relaxation time T_1's were measured as a function of composition in blends of PMMA and PVAc prepared from chloroform solution. The results show that the system is miscible for casting from chloroform solution.

Synthesis of poly (vinyl acetate) oligomersand their phase behavior in supercritical carbon dioxide

Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.

Microwave Synthesis of Inulin Acetate as Potential Bio- Based Additive for Poly(Vinyl Chloride)

The paper presents the findings of an experimental study on the microwave synthesis (MW) of inulin acetateand its possible application as bio-additive in poly(vinyl chloride) (PVC). The obtained inulin acetate has beenidentified and characterized by spectroscopic methods. Advantages of the MW compared with the conventionalsynthesis were defined. In order to evaluate possible application of the product as bio-based additive forpolymers, effect of the inulin ester on PVC behavior and characteristics has been investigated by differentialscanning calorimetry (DSC) and deformation upon extension. Experimental results show that in concentrationrange up to 30.0 wt. % the inulin ester influences positively the properties of PVC causing effect similar toplasticizing one. At concentration over 30 wt.% the ester shows more specific behavior, which will be furtherinvestigated. Conclusions about potential application of MW synthesized inulin acetate as bio-based additive forPVC have been drawn.

ION CONDUCTION AND ELECTROCHROMIC BEHAVIOR OF POLY[VINYL VIOLOGENACETATE-CO-OLIGO(OXYETHYLENE)METHACRYLATE]

A novel kind of polymeric solid electrolyte,PVAEO_16,which possesses both ion conduction and electrochromic characteristics,was synthesized.Its anion conductivity was 1.9× 10^(-6)S·cm^(-1)(25℃).PVAEO_(16)—based ECD could display reversibly the color of yellow and bluish violet over 1.7 V.The color—changing response time was 0.6 s and 1.3 s(±2.0V),re- spectively.The storage time of bluish violet under open circuit was more than 16 hours.