Alcohol Copolymer Films Research Articles

Biological Evaluation of a Laminin–Apatite–Polymer Composite for Use in Skin Terminals

An ethylene-vinyl alcohol copolymer (EVOH) film with a laminin–apatite composite layer on its surface showed improved adhesion and compatibility to living epithelial tissue compared to untreated EVOH film. This result can be attributed to the good biocompatibility of apatite and the cell-adhesion activity of the laminin on the EVOH surface. This composite material, consisting of laminin, apatite, and EVOH, is considered a promising material for skin terminals to prevent epidermal downgrowth.

Hydrophobic properties of ethylene–vinyl alcohol copolymer treated with plasma source ion implantation

AbstractThe industrial use of ethylene–vinyl alcohol copolymer (EVOH) film is limited because it is easily degraded by moisture. The plasma source ion implantation (PSII) technique with CF4 or CH4 gas was used for the EVOH film to improve the surface hydrophobic properties. Variables examined in implantation were ion energy (0–10 keV), treatment time (5 s–5 min), and ion species. The hydrophobic properties of EVOH films were greatly enhanced after a CF4 PSII treatment, as evidenced by an increased contact angle from 66° to above 100° at ‐5 keV, and remained relatively unchanged during the period of 28 days. X‐ray photoelectron spectroscopy, atomic force microscopy, and O2 permeability were used to characterize the surface properties of EVOH films treated with PSII. The improved hydrophobic properties were closely related to the formation of fluorine‐containing functional groups such as CF, CF2, and CF3 on the modified surface. The percentage distribution of carbon functional groups supports the role of CF2 and CF3 groups in surface modification. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2069–2075, 2004

暮らしの中のガス透過膜とガスバリア膜 ガスバリア性フィルム包材・ＰＥＴボトルの技術動向

Gas-barrier property is a most important factor for food packaging. Now polyvinylidene chloride (PVDC) resins are still in wide use as gas-barrier films. However, PVDC resins as packaging materials have been declining in face of various environmental problems they pose. Under these circumstances, ethylene vinyl alcohol co-polymer (EVOH) films, polyvinyl alcohol (PVA) -coated polypropylene films, MXD6 nylon resins, and silica-or alumina-coated PET films are becoming the mainstream for gas-barrier purposes.Recently, various types of oxygen scavengers have been developed and applied as active packaging materials. PET bottles having oxygen barrier or scavenging properties are now used for plastic beer bottles in Europe and United States. EVOH and MXD6 nylon are used as the oxygen barrier materials. As the oxygen scavenging materials, the blend of MXD6 nylon and cobalt salt are used for PET bottles.In Japan, oxygen scavenging PET bottles are used for plastic tea bottles.

Oxygen permeability and free volume hole size in ethylene–vinyl alcohol copolymer film: temperature and humidity dependence

Relationship between oxygen permeability and free volume hole size evaluated from ortho-positronium lifetime in ethylene–vinyl alcohol copolymer (EVOH) was studied as functions of temperature and relative humidity. As the relative humidity rises at room temperature, the permeability first decreases and then increases. This behavior is attributed to the effects of pore filling and plasticization by water molecules. Linear correlations are obtained on the plots of logarithmic permeability versus reciprocal free volume hole size for EVOH at different temperatures and humidities as well as for different polymers including EVOH at room temperature, suggesting that the free volume hole size plays a crucial role in the oxygen permeation in EVOH and other polymers.

Optical detection of Cu 2+ ion using a SQ-dye containing polymeric thin-film on Au surface

In this study, we have fabricated Cu 2+ ion sensor using a squarylium dye (SQ-dye) containing polymeric thin-film. Surface Plasmon Resonance (SPR) was used as a signal amplifier to achieve high sensitivity and large linear dynamic range for detection of Cu 2+ ion. High selectivity to Cu 2+ ion was obtained by the effective electro-static interaction between SQ-dye and Cu 2+ ion in the polymeric film. The optimal analytical condition of high selectivity and sensitivity in the wider linear dynamic range obtained in this study may be a result of the cooperative ‘hard-soft’ metal ion-ligand interaction and effective detection of refractive index changes by the complexation of Cu 2+ ion and SQ-dye in SPR measurement. Among 10 different alkali metal, alkaline earth metal, and transition metal ions, SQ-dye in poly(vinylchloride)–poly(vinyl acetate)–poly(vinyl alcohol) (PVC–PVAc–PVA) copolymer film showed the highest selectivity to Cu 2+ ion. Although the interaction between SQ-dye and metal ions has not been well understood, both cooperative ‘hard-soft’ metal ion-ligand interaction and size-selective recognition of Cu 2+ ion to SQ-dye may contribute to high selectivity. Furthermore, additional sensitivity in the detection of Cu 2+ ion by SPR was obtained by matching the wavelength of probing radiation of SPR and absorption maximum of SQ-dye at 675 nm, which allow to detect small changes in the refractive index by complex formation on the sensing surface. This result may apply in development of the Cu 2+ ion selective sensor for medical, biochemical, and environmental applications.

On‐going solutions to environmental issues in plastic packaging

AbstractRecently, the consumption of polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) resins as packaging materials has been declining in the face of various environmental problems they pose. To replace PVC containers, the use of PET bottles and A‐PET containers is on the increase, but PVDC resins are still in wide use as gas‐barrier materials. For gas‐barrier purposes, however, ethylene vinyl alcohol co‐polymer (EVOH) films, polyvinyl alcohol (PVA)‐coated polypropylene films, and MX nylon or silica‐ or alumina‐coated PET films are becoming mainstream. The weight reduction of plastic bottles is considered to play an important role in tackling the waste disposal problem. Recently, a new type of stretch‐blow moulding system has been developed, which is effective in reducing the weight of PET bottles. This system is called COSMOS (complete stretch‐blow moulding system) or the two‐blow system. COSMOS PET bottles are now used to hold carbonated drinks containing fruit juice or lactic acid. Copyright © 2001 John Wiley & Sons, Ltd.

Water absorption in EVOH films and its influence on glass transition temperature

Moisture sorption kinetics of nonoriented ethylene vinyl alcohol copolymer (EVOH) film (EF-E15) were studied at 25, 35, and 45°C. Anomalous diffusion was observed for the polymeric film at high relative humidities (RH) and higher temperatures. Diffusion and solubility coefficients of water were found to be concentration dependent. The moisture sorption isotherms of three types of EVOH films (EF-E15, EF-F15, and EF-XL15) determined at 25, 35, and 45°C, were well described using the GAB equation. Glass transition temperatures (Tg) of the EVOH films, as influenced by RH, were measured using differential scanning calorimetry. Tg values decreased with increasing RH due to the plasticization effect of water, and were found to be dependent on ethylene content and orientation of the EVOH films. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 691–699, 1999

Surface modification of ethylene-vinyl alcohol (EVOH) copolymer films by the attachment of triethoxysilane functionality

Triethoxysilane groups were covalently attached onto the surface of ethylene-vinyl alcohol (EVOH) copolymer film via a urethane linkage through reaction between the hydroxyl groups in EVOH and 3-isocyanatopropyltriethoxysilane in the presence of dibutyltin dilaurate as catalyst. This reaction was confirmed by ATR-IR and XPS analysis. XPS results also indicated that this reaction was not surface sensitive and the modified layer was at least 40 A in depth. The modified film samples were further reacted with tetramethoxysilane (TMOS) for partial hydrolysis and condensation and XPS results showed a significant increase in the contents of oxygen and silicone on the surface which confirmed the above reaction.

Sorption Behavior of Flavors with Water Sensitive Ethylene-Vinyl Alcohol Copolymer Film in Aqueous Solution.

Water sorption into ethylene-vinyl alcohol copolymer (EVOH) film largely affected the sorption behavior of flavors in aqueous solution. For EVOH-F (vinyl alcohol content; 68 mol%), the sorptions of flavors increased with temperature up to 20°C (10°C for EVOH-E; vinyl alcohol content; 56 mol%), and afterwards decreased. On the basis of the behavior of the water sorption and the corresponding glass transition temperature (Tg) changes in EVOH films, the signbell-type sorption behavior was considered to result from the flexibility change due to water sorption. Namely, the increase in sorption up to 20°C-storage for EVOH-F (10°C for EVOH-E) would be caused by the increasing free volume in EVOH films with decreasing Tg due to water sorption. On the other hand, at >20°C (EVOH-F)- and 10°C (EVOH-E)-storage, because the EVOH would behave as a rubbery polymer and have a roughly constant Tg, the sorption decreased with temperature.

Optimization of the interaction between ethylenevinyl alcohol copolymers and human endothelial cells

To better understand and optimize the fine interactions that occur during adhesion events between human cells and synthetic materials, we seeded human umbilical vein endothelial cells (HUVEC) onto ethylene-vinyl alcohol (EVOH) copolymer films prepared by casting. Different adhesive proteins, e.g. fibronectin and gelatin, and the monoclonal antibody (MoAb) CLB-HEC19 specific for the endothelial cell membrane were used to coat the materials. We used atomic force microscopy (AFM) to analyse the EVOH film structure, to test its planarity and homogeneity, before seeding it with endothelial cells. The metabolic changes induced in the endothelial cells by interactions with the copolymer functional groups and the adhesive proteins were monitored by a micro-electronic pH sensor, positioned close to the HUVEC monolayer. We found that the adhesion of HUVEC onto various substrates was finely modulated by the MoAb CLB-HEC19 and that the endothelial cell metabolic rate was enhanced when cultured onto a CLB-HEC19 coating. Surface roughness seems also to play a role in the interaction with HUVEC. The AFM measurement analysis demonstrated that L6 surface is rougher than R20. These surface characteristics could favour cell adhesion; in fact HUVEC adhesion results on R20 were significantly lower than on L6.

Sorption Behavior of Flavor Compounds into Packaging Films from Ethanol Solution

The sorption of flavor compounds into low-density polyethylene (LDPE) and ethylene−vinyl alcohol copolymer (EVOH) films was greatly influenced by ethanol concentration, and maximal sorptions were observed at 5−10% (v/v) ethanol for LDPE and 10−20% (v/v) ethanol for EVOH. The sorptions of ethyl hexanoate, octanal, and octanol into LDPE film were ∼1.7, 16.5, and 2.5 times higher than those in the 0% (v/v) ethanol solution, respectively (for EVOH film, the sorption increments of these compounds were ∼6.2, 3.5, and 4.1 times, respectively). To better understand this phenomenon, the solvent properties of ethanol solutions were investigated. The dielectric constants were roughly unchanged in the range 5−15% (v/v) ethanol. According to the results obtained by 1H NMR measurement, in which the difference in proton chemical shift from water-d (HDO) and ethyl alcohol-d (EtOD) became maximum at 23% (v/v) ethanol solution, the structural change of water induced by the addition of ethanol would be great up to 23% (v/v) ethanol. These results accurately reflected the sorption behavior. Therefore, the specific sorption behavior of flavor compounds from an ethanol solution would be brought about by the heterogeneous water−ethanol structure. Keywords: Sorption; flavor; ethanol solution

Photografting of acrylamide on ethylene–vinyl alcohol copolymer film

AbstractPhotografting (λ > 300nm) of acrylamide on ethylene‐vinyl alcohol copolymer film (vinyl alcohol unit = 56 mol%, film thickness = 20μm) was investigated at 60°C in water medium, where photoinitiators were coated on the film earlier. The percent grafting decreased in the order of xanthone ≈ benzophenone > anthraquinone > benzoyl peroxide. The graft efficiencies in each sensitized system were less than 30%, showing a predominant formation of homopolymer. Grafting of acrylamide on the film was also initiated in systems with and without photoirradiation when ceric salt was used as an initiator. Based on electron probe microanalysis of the grafted films, the grafted chains of the sample prepared by photografting were distributed inside the film, while those of the sample prepared by ceric salt‐initiated grafting without photoirradiation were located mainly on the film surface. The grafted films prepared by the former system exhibited a higher moisture permeability than those prepared by the latter system.

Temperature‐responsive characteristics of N‐isopropylacrylamide‐grafted polymer films prepared by photografting

AbstractPhotografting of N‐isopropylacrylamide (NIPAAm) on ethylene–vinyl alcohol copolymer films (thickness = 15,20, and 25 μm) and low‐and high‐density polyethylene films (thickness = 30 μm) was carried out at 60°C in a water medium. Xanthone was used as a photoinitiator by coating it on the film samples. The resultant NIPAAm‐grafted films exhibited a temperature‐responsive character, which was evaluated by measuring a dimensional change of the grafted films. The grafted films swelled and shrank in water at temperatures lower and higher than around 30°C, respectively. The character was found to be reversible between 0 and 50°C. It was observed that the extent of the character is largely influenced by film thickness, location of NIPAAm‐grafted chains, and crystallinity of film substrate. © 1994 John Wiley & Sons, Inc.

Sorption of Volatile Compounds in Aqueous Solution by Ethylene‐Vinyl Alcohol Copolymer Films

ABSTRACTSorption of volatile compounds by ethylene‐vinyl alcohol copolymer (EVOH) films from an aqueous solution was investigated to evaluate the merit of their use for food packaging. With regard to EVOH, equilibrium swelling values gave rise to a bimodal solubility parameter distribution with maxima at δ values of 8.5 assigned to ethylene units and 14.5 to vinyl alcohol units. Comparing distribution ratios of EVOH with those of middle‐density polyethylene (MDPE), the ratios were 1:100 for terpene hydrocarbons, 1:10 for esters, 1:2 for alcohols, and almost 1:1 for aldehydes. By biaxial orientation of EVOH film, the sorption could be depressed below 60%. These results suggested EVOH films are more appropriate than MDPE for food container lining.

Irradiation grafted ion-exchange membranes from uniaxially and biaxially oriented copolymer films

Ion-exchange membranes were prepared by electron beam (EB) pre-irradiation grafting of styrenesulfonic acid K salt (SSKS) on uniaxially and biaxially oriented ethylene-vinyl alcohol copolymer (EVAL) films. A wide range of membranes with different ion capacities was characterized. The following features were determined: water uptake and the related change of area, pervaporation, evaporation, transport number, permselectivity, KOH diffusion, salt rejection (by reverse osmosis), specific electrical resistance, tensile strength, elongation, and enthalpy of fusion. The influence of the morphology of the precursor film on membrane characteristics is discussed.

Effect of trunk polymer orientation on ionic vinyl monomer grafting reaction

Mono- and bioriented ethylene-vinyl alcohol (EVAL) copolymer films were grafted by means of the electron beam pre-irradiation method with the potassium salt of styrenesulphonic acid (SSKS). The influences of pre-irradiation dose, reaction temperature and monomer concentration on grafting degree were determined for EVAL films with different drawing orientations. The dependence of the initial grafting rate on these parameters was found to be influenced by the morphology of the trunk polymer. The inhibitory effect of tert-butyl catechol, ferric chloride and Mohr salt on homopolymerization, as well as on the grafting reactions, was followed. Promotion of grafting by sodium acetate was established. Film dimension changes, induced by grafting, revealed a significant influence of EVAL morphology on the location of SSKS grafted chains.

Synthesis and Biomedical Properties of Poly-[(Ethylene-Vinylalcohol)-g-Acrylamide

Abstract This paper deals with the graft copolymerization of acrylamide (AM) onto ethylene-vinyl alcohol copolymer (EVAL) film initiated by cerium(IV) ion. It was found that both the chemical and diffusion factors had influences on the graft reaction. The reaction was initiated on the surface and then penetrated inward as the grafting percentage was increased. The permeability of urea through the grafted EVAL film was improved compared to that of the original film as was the blood compatibility.

Kinetics and equilibria associated with the absorption and desorption of water and lithium chloride in an ethylene—vinyl alcohol copolymer

Sorption and desorption equilibria and kinetics for LiCl and H 2O in an ethylene—vinyl alcohol copolymer film containing 70 mole percent vinyl alcohol were investigated at 25°C. The swelling behavior of water in the polymer was characterized by vapor and liquid sorption experiments over a range of water activities. p]The effects of LiCl content on the water sorption kinetics and equilibria in the films are presented and discussed. The kinetics and mechanism of LiCl sorption have also been studied. The amount of salt sorbed into the polymeric films increases linearly with the salt concentration in the external aqueous solutions. Both the rate and the amount of sorbed water increase significantly as the LiCl content increases. p]The desorption of LiCl, previously sorbed into the polymer, was characterized for different salt loadings. The rate of fractional salt release is independent of LiCl concentration in the film. Initially, the salt release is controlled by the nearly constant-rate absorption of water. The salt release, at long times, lags behind the swelling-controlled water uptake, indicating that the salt release is not completely controlled by the water sorption and that diffusion in the swollen polymer matrix contributes significantly to the long term elution of LiCl. Independent thermal analysis experiments suggest the formation of a metal salt—poly(ethylene—vinyl alcohol) complex.

Resistance of Polymer Films to Penetration by Lesser Grain Borer and Description of a Device for Measuring Resistance13

In tests with a newly developed laboratory device for determining the resistance to penetration of flexible packaging films by adults of Rhyzopertha dominica (F.), polyurethane and polyester films were the most resistant of 18 types tested. Polypropylene and fluorinated carbon polymer films varied in resistance to penetration. Plasticized polyvinyl chloride, ionomer, cellulose propionate, polyvinyl alcohol, saran, and polyethylene-ethylene vinyl acetate copolymer films were susceptible to penetration, as were 7 types of cellophanes.

Grafting of proteins onto polymer surfaces with the use of oxidized starch

A study has been carried out on the coupling of proteins onto crosslinked poly(vinyl alcohol) hydrogel membranes and ethylene-vinyl alcohol copolymer(EVA) films previously grafted with oxidized starches having many pendant aldehyde groups. The coupling reaction of proteins is based on the Schiff's base formation between the amino groups of proteins and the aldehyde groups of the oxidized starches which have been grafted onto the substrate membrane or film through acetalization of the aldehyde of starch with hydroxyl groups of the substrate polymers. The grafting of oxidized starches onto the EVA films seems to be restricted to the film surface, since no detectable change is observed in the weight and the attenuated total reflection infrared spectrum of the grafted films. The amount of grafted protein, determined by the ninhydrin method, reveals that, at least, plasma proteins such as serum albumin and fibrinogen are grafted to the film surface in a monomolecular layer without undergoing a marked denaturation. The alpha-amylase grafted onto the EVA film showed a distinct enzymatic activity in hydrolysis of amylose and starch, but the activity was very low compared with that of the ungrafted, soluble alpha-amylase.