Vinyl Chloride-vinyl Acetate Copolymer Research Articles

Microplastics in sediments and fish from the Red Sea coast at Jeddah (Saudi Arabia)

Environmental contextMillions of tons of plastic debris are present in the marine environment. This study addresses the issue of microplastics in nearshore sediment and fish sampled from the Saudi coastal waters of the Red Sea. The results show that the sediments of all analysed stations contained microplastics, and microplastic particles were detected in almost half of the 140 sampled fish. AbstractThe amounts of microplastics in sediment samples obtained from four stations along the Jeddah coast were shown to range from not detected to 119particleskg−1 wet sediment. Four classes of microplastic particles in the sediment, that is, fragments, granules, foams and fibres, were characterised by fluorescence microscopy. Microplastics of various forms and sizes were also identified in 44% of the 140 sampled fish (6 local species) in amounts ranging from not detected to 30 microplastic particles per individual. Polyethylene terephthalate and vinyl chloride-vinyl acetate copolymers were the dominant polymer types in the sediment samples identified by Fourier-transform infrared spectroscopy (FTIR) analysis, while polystyrene, polyethylene and polyester were the dominant polymer types detected in fish. FTIR analysis showed that the most detected fibres were made of polyester. The results of this study emphasise that microplastic pollution represents an emerging threat to the marine environment of the Red Sea. The results of this study provide useful background information for further investigations and provide an accurate overview of the microplastics distribution in the marine environment of the Saudi Red Sea.

Contribution to the Study of Fungal Attack on Some Plasticized Vinyl Formulations

The objective of this study was to develop new vinyl flooring formulations with increased resistance to fungi and microorganisms attack, by using plasticizers having a chemical composition different from that of common di-ethylhexyl phthalate (DOP). It is suspected that during the vinyl flooring life service, the attack of fungi and microorganisms leads to the degradation of DOP and the release of some volatile organic compounds (VOC). For this reason the new materials were formulated with plasticizers having chemical composition different of that of DOP i.e.: diethyleneglycol dibenzoate (2–45), tricresyl phosphate (Lindol) and phenol alkylsulphonic ester (Mesamoll). For the same reason in the new flooring formulations the vinyl polymer, vinyl chloride-vinyl acetate copolymer (VC-VAc), was partially replaced with lignin (L) a natural polymer and major component of wood and vascular plants. Besides its other functions in wood, L imparts resistance to the most microorganisms attack. An organosolv lignin Alcell lignin (AL) was utilized as partial replacement of VC-VAc copolymer. The influence of the new plasticizers, as well as the influence of the partial replacement of VC-VAc copolymer with L on the resistance of the new formulations to fungal attack was evaluated following a standard procedure given in ASTM G 21–2002 “Determining Resistance of Synthetic Polymeric Materials to Fungi”. The evaluation has been undertaken for controls (formulated without AL) and blends (formulated with 20 parts AL) specimens. Test specimens were inoculated with a mixture of five fungi. Following 28 days of incubation at 28°C and 95% relative humidity, the specimens were examinated visual and under the microscope and rated for fungal growth. Weight loss, changes in mechanical properties and changes in glass transition temperature due to the effect of biodeterioration were also determined. Although each plasticizer has a specific resistance to hydrolysis due to differences among ester groups, the visible effects of fungal attack, in formulations without AL, is similar for all plasticized controls, with the exception of formulations incorporating diethyleneglycol dibenzoate (2–45) in which a higher degree of biodegradation was always present. Based on the weight loss of specimens formulated without AL, their resistance to fungal attack can be rated as follows: $$\hbox{Lindol} > \hbox{Mesamoll} \ge \hbox{DOP}> 2-45$$ . The same rating is applicable for blend specimens. The results have demonstrated that each particular AL-plasticizer-additives formulation has its specific mechanism of biodegradation.

Effect of compatibility of PVC/P2 alloy system on membrane structure and performance.

The effects of the secondary polymer component (P(2)) on poly(vinyl chloride) (PVC)/P(2) alloy membrane structure and performance were systematically investigated. A series of P(2) with varying compatibility with PVC used in this study included vinyl chloride-vinyl acetate copolymer (VC-co-VAc); copolymer of vinyl chloride, vinyl acetate-maleic anhydride copolymer (VC-co-VAc-co-MAL); isobutylene-maleic anhydride copolymer (IB-co-MAL); poly(methyl methacrylate) (PMMA); poly(vinylidene dichloride) (PVDC); and styrene-acrylonitrile copolymer (SAN). Alloy membranes were prepared by means of solution blending-phase inversion technique. On the basis of our experimental results, the compatibility of PVC/P(2) was proved to be the most critical factor affecting the alloy membrane structure and performance. Systems with good compatibility, such as PVC/VC-co-VAc, are more suitable for preparing membranes with small pore size; whereas systems with partial compatibility, such as PVC/PMMA, are more favored for the formation of large-pore membranes.

China produces its first vinyl chloride-vinyl acetate copolymer resin

China produces its first vinyl chloride-vinyl acetate copolymer resin

Hydroxyapatite precipitation on a carboxylated vinyl chloride-vinyl acetate copolymer

The kinetics of crystal growth of hydroxyapatite [Ca5(PO4)3OH, HAP], the thermodynamically most stable calcium phosphate phase, on a commercially available carboxylated (1%) vinylchloride (83%) vinyl acetate (13%) copolymer was investigated at relatively low ionic strength, at 37 °C and pH 7.4. Stable supersaturated solutions were seeded with HAP seed crystals as reference and with the polymer in powder form. Well defined induction times preceded the growth of HAP on the polymeric substrate. The induction times measured were inversely proportional to the solution supersaturation. The rates of crystallization both on HAP and on the polymer were measured at conditions of constant supersaturation. HAP growth took place on both substrates and the parabolic dependence of the rates of crystal growth on the relative solution supersaturation suggested a surface diffusion controlled mechanism. The rates of HAP crystal growth on the polymeric substrate were found to depend on the amount of the seed material suggesting selective overgrowth of HAP. A possible explanation for this selectivity is the development of active growth sites through the formation of surface complexes of the calcium ions with the dissociated carboxyl groups.

Miscibility behaviour of blends of a thermoplastic polyester polyurethane with vinyl polymers

AbstractA method based on the intrinsic viscosities of transfer has been used to predict miscibility of polymer blends. This method has been applied to study the change in the phase behaviour of a microphase separated polyester polyurethane (PSPU) on blending with polyvinyl chloride (PVC), polyvinyl acetate (PVAc) and a vinyl chloride‐vinyl acetate copolymer (VCVAc). The PVC/PSPU blends are found to exhibit complete miscibility over the entire composition range. PVAc/PSPU blends show immiscibility while VCVAc/PSPU blends show partial miscibility. Thermal analysis and scanning electron microscopic studies of the blend films have confirmed the results evaluated on the basis of the viscosity method.

Values of Bethe–Bloch stopping power parameters for Vyns (vinylchloride–vinylacetate copolymer) extracted from stopping power measurements with 0.55–1.75 MeV protons and 1.03–3.22 MeV alpha particles

Recent transmission-type measurements of the stopping powers of Vyns (a vinylchloride–vinylacetate copolymer) for 0.55–1.75 MeV protons and 1.03–3.22 MeV alpha particles have been analyzed in terms of modified Bethe–Bloch stopping power theory in order to extract values of the parameters known as the mean excitation energy ( I) and Barkas-effect parameter ( b). The weighted average value of I thus established, 110.8 eV, exceeds the prediction based on linear additivity by some 3%, and the weighted average of b, 1.54, agrees very well with expectations. The results of this analysis are compared with those from a previous similar study of another material having essentially the same average atomic number and atomic weight but quite different atomic composition, called Kapton.

Compatibility of Poly(vinyl chloride-vinyl acetate)/Polyester-based Polyurethane Blends

The compatibility of poly(vinyl chloride-vinyl acetate) copolymer (P(VC-VA)) with thermoplastic polyurethane elastomers (TPU) was studied using Fourier transform infrared spectroscopy, optical microscopy and solubility parameters. The Gibbs free energy of mixing for the polymer-solvent system was calculated. The mechanical studies show that decrease in the P(VC-VA)/TPU ratio decreases the tensile strength.

Conducting polymer composites: Polypyrrole and poly(vinyl chloride-vinyl acetate) copolymer

Composites of a polypyrrole (PPy) and poly(vinyl chloride-vinyl acetate) copolymer (PVC-PVA) were prepared both chemically and electrochemically. An insulating polymer was retained in the blend and the thermal stability of the polymer was enhanced by polymerizing pyrrole into the host matrix in both cases. The composites prepared electrochemically gave the best results in terms of conductivity and air stability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 667–671, 1997

A Viscometric Study of the Miscibility Behaviour of Poly(N-Vinyl Pyrrolidone) Blends

The miscibility behaviour of blends of poly(N-vinyl pyrrolidone) (PVP) with poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and vinyl chloride–vinyl acetate (VCVAc) copolymer has been investigated on the basis of a viscometric approach. PVP is found to be miscible with PVC over the entire composition range, as is evident from the high values observed for the intrinsic viscosity of transfer. This is further supported by the single glass transition temperature observed in differential scanning calorimetry studies of the blend films. Blends of PVP with VCVAc copolymer exhibit microphase separation which is shown clearly in the scanning electron micrographs of the films. PVAc/PVP blends show interaction only at low PVAc contents, but in general are immiscible. © of SCI.

Stopping powers of 200–3000 keV 4He and 550–1750 keV 1H ions in Vyns

Stopping powers for Vyns (vinylchloride-vinylacetate copolymer) were measured both for 4He ions in the range 200–3000 keV and for 1H ions in the range 550–1750 keV using the transmission technique. A detector model is used for the energy calibration to improve the accuracy of the stopping power curve for 4He ions in the low energy region. The estimated uncertainty in the stopping power values is ∼1.5% for 4He ions and ∼2% for 1H ions. A comparison is made between a parametrization of the present data and several parametrizations of the stopping power found in the literature. The stopping power values closest to the present experimental data for 4He ions are obtained by adding elemental stopping powers using Bragg's rule. For this the experimental values for the Cl stopping power reported earlier should be used. The charge state scaling, sometimes used to take account for phase-state effects, is not appropriate for Vyns. For 1H ions, the parametrization closest to our data is that of Janni from 1982.

Ultrafiltration membranes made of vinyl chloride-vinyl acetate copolymer

This paper presents the results of investigations concerning the formation, structure and transport properties of tubular ultrafiltration membranes made of copolymer vinyl chloride-vinyl acetate (Winicet, Poland). A method of tubular membrane formation by the phase-inversion method has been worked out. To prepare the casting solution, dimethylformamid was used as the solvent, and water as the non-solvent. The compactness of the membranes can be controlled by changing the concentration of polymer in the casting solution, the gelation temperature and by using polyethlene glycol as an additive to the casting solution. The porosity of the membranes was determined by means of electron microscopy, the bubble-point method and nitrogen adsorption/desorption method. The obtained membranes are asymmetrical and the macroporous sublayer has a finger-like structure. The pore size distribution of the skin has a rather narrow character. The transport-separation properties of the membranes were determined by measuring the water flux and retention coefficient of water soluble macromolecules and colloids.

Phase behavior of blends of vinyl chloride-vinyl acetate copolymers with polymethacrylates

The phase behavior of blends of vinyl chloride-vinyl acetate copolymers with poly(methyl methacrylate) (PMMA) and poly(n-butyl methacrylate) (PnBMA), was examined as a function of the vinyl acetate (VAc) content in the copolymer. From the variation of cloud points with the copolymer composition, segmental contact energy parameters X ij 's for various monomeric unit pairs have been estimated by using a copolymer model based on Patterson's equation of state theory. It was found that the segemental interaction of VAc with MMA and VC is attractive in each case, indicating that PVAc is miscible with PMMA and PVC

Fluorescence probe for microenvironments: effect of solvent vapour on the properties of vapour-swollen polymers

The effect of solvent vapour on the properties of vapour-swollen vinyl chloride-vinyl acetate ( 83 17 ) copolymer has been studied by a fluorescence probe, a p- N, N-dialkylaminobenzylidenemalononitrile derivative ( 1). Results show that the fluorescence quantum yield ( Ф f ) of 1 in vinyl chloride-vinyl acetate ( 83 17 ) matrix decreases by a factor of ≈ 10, an indication of the increase in free volume or in polymer chain mobility, upon vapour swelling. The variations of Ф f observed in various swollen matrices, which correlate only with the density of the swelling solvent, indicate that there is a profound vapour effect on the properties of swollen polymer. A density effect on the mobility of polymer chains in swollen polymer is proposed.

Hydrodynamic and thermodynamic properties of vinyl chloride-vinyl acetate copolymer solutions

The Mark-Kuhn-Houwink constants have been determined by viscometric and light scattering methods for polyvinylacetate and the vinyl chloride-vinyl acetate copolymers. The equilibrium flexibility parameters of the polymers have been examined. The products examined were found to be flexible polymers. The hydro- and thermodynamic properties of the macromolecules largely depend on the VAc concentration in the copolymers.

Compositional sequence distribution, cotacticity, and second-order Markov statistics in vinyl chloride-vinyl acetate copolymers

Compositional sequence distribution, cotacticity, and second-order Markov statistics in vinyl chloride-vinyl acetate copolymers

Effect of pressure and temperature on the secondary relaxation in vinyl chloride-vinyl acetate copolymer films by the PSD and TSD current techniques

A relaxation in the glassy state has been observed in the poled vinyl chloride-vinyl acetate copolymer film by using the piezo-stimulated (PSD) as well as the thermally stimulated depolarisation (TSD) current techniques. The observed relaxation peak has also been studied as a function of poling temperature, field and the applied pressure. The relaxation time is a linear function of pressure and temperature, whereas the displacement coefficient of the peak with temperature and pressure is quite small and the ratio of the Delta V*/Vm is less than unity. The PSD results agree fairly well with those calculated by analysing the TSD current peak.

Molecular motion studies in VC:VAc copolymer thin films

Abstract Depolarization current characteristics of vinyl chloride-vinyl acetate (VC:VAc) copolymer thin films were studied as a function of the polarizing field EP (96.25 × 105-2.25 × 106 V/m), time tp (7.20 × 103—5.04 × 104 sec), and the temperature of polarization Tp (305—425 K). Three relaxation processes at 340, 412, and 460 K were observed with activation energies U of 0.59, 1.01, and 1.37 eV, respectively. The peak at 340 K is associated with orientation of the dipoles of the main polymer chain; that at 412 K is attributed to ionic movements in the amorphous region of the VC:VAc copolymer film and that at 460 K is attributed to the space charge polarization, the space charge being the resultant of injected charge carriers from the electrodes and the already present carriers. The peaks at 340 and 412 K shift toward higher temperatures and their U increase with increase of tp and Tp. This is attributed to a distribution of relaxation times and activation energies and suggests that these two peaks are complex in nature and cannot be represented by a discrete level of activation energy having a single relaxation time. The calculated values of dielectric loss ϵ” from the TSD spectra are in good agreement with those determined from the DC measurements.

The effect of the character of grains on the course of plasticization and properties of plasticized PVC and plasticized vinyl chloride-vinyl acetate copolymers. Part. V. Changes in the morphological structure of plasticized PVC during gelation

The effect of the character of grains on the course of plasticization and properties of plasticized PVC and plasticized vinyl chloride-vinyl acetate copolymers. Part. V. Changes in the morphological structure of plasticized PVC during gelation

Analysis of copolymer surfaces by surface reactions and XPS

The adsorption of polar groups at the polymer melt/mould interface is detected by chemical analysis. Vinyl alcohol groups and vinyl acetate groups (after hydrolysis) react with heptafluoro-butanoic acid chloride to attach a fluorine-containing molecular group to the surface. By measuring fluorine and other elements with XPS the surface composition is determined. On a gold substrate vinyl alcohol groups are adsorbed in a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol. If a vinyl chloride-vinyl acetate copolymer is compression moulded against gold, the polymer surface energy is increased by adsorption of vinyl acetate groups. Subsequent relaxation, after removal of the substrate, leads to slow desorption of vinyl acetate groups. At the interface of the vinyl chloride-vinyl acetate copolymer with nickel or aluminium the polymer is oxidized.