Effect of surface oxyfluorination on the dyeability of polyethylene film

The effect of surface oxyfluorination on low-density polyethylene (LDPE) film was studied in terms of surface functionality and surface energetics of the film surfaces, which can be attributed to improvement of the dyeability. The growth of functional groups and surface free energy was confirmed by FTIR-ATR, XPS, and contact angle methods. As a result, the total surface free energy was increased with oxyfluorination time, as a progressive increase of the polar component together with a small decrease of the dispersive component of surface free energy. From the dyeability test using the Kubelka-Munk equation, it was found that the oxyfluorination treatment plays an important role in the growth of oxygen-containing functional groups of LDPE film, resulting in improving the dyeability with a basic dyeing agent. A direct linear relationship is shown between the specific component of surface free energy and the K/S value for this work.     

Surface changes brought about by corona discharge treatment of polyethylene film and the effect on subsequent microbial colonisation

Microbial colonisation of synthetic plastic films is normally slow, which affects the total period of biodegradation. Correlation between the modified surface condition and the ability for microorganisms to colonise low-density polyethylene (LDPE) film was studied. Corona discharge treatment was applied to obtain enriched and activated surface condition of LDPE film. It was found from water contact angle and FTIR spectrum evaluations that surface energy was significantly increased due to production of free radicals. Stabilised oxidised LDPE surface was also obtained by further exposure to the corona which gave more suitable condition for subsequent colonisation. Results were compared with UV irradiated (photo-oxidised) LDPE films. Colonisation of corona discharged and UV treated LDPE films were tested in the laboratory environment using known fungal isolates and in a natural compost environment. More active microbial colonisation was observed in all cases for corona discharged and UV treated LDPE films. Far longer UV exposure was required to have the same physicochemical and biological effect as the corona discharge treatment.     

Oxidation of polyethylene surface by corona discharge and the subsequent graft polymerization

Oxidation of a polyethylene (PE) surface by corona discharge and the subsequent graft polymerization of acrylamide (AAm) were studied. The maximum amount of peroxides introduced by corona treatment at a voltage of 15 kV was about 2.3 × 10^?9 mol cm^?2. The decomposition rate of peroxide and the dependence of graft amount on the storage period of the corona-treated PE films showed that there were several kinds of peroxides, the labile one being mainly responsible for the initiation of graft polymerization. When the corona-treated film was brought into contact with a deaerated aqueous solution of AAm, graft polymerization took place more strongly with the treatment time, but was reduced after passing a maximum. Although the x-ray photoelectron spectroscopic analyses of the corona-treated PE films showed homogeneous oxidation of the outer polymer surface by corona discharge, optical microscopy on the cross section of the grafted film revealed the graft polymerization to be limited to a very thin surface region.     

Pretreatments of wood to enhance the performance of outdoor coatings

The wet adhesion of water borne acrylic dispersions is a crucial factor on the performance of outdoor coatings on wood. Pine sapwood was treated with several methods for surface activation to increase the wet adhesion of water borne acrylic dispersions. The wet adhesion was measured by pull-off tests as well as with a modified cross-cut test. Atmospheric plasma, corona treatment and fluorination increased the wet adhesion of the coating which is attributed to the increasing polar portion of the surface free energy. Other ways of improving the wet adhesion are the addition of promotors, the use of primers and organisational improvements.     

Effect of Fiber-Polymer Interactions on Fracture Toughness Behavior of Carbon Fiber-Reinforced Epoxy Matrix Composites

The effect of anodic oxidation on high-strength polyacrylonitrile-based carbon fibers has been studied in terms of fiber surface energetics and fracture toughness of the composites. According to contact angle measurements based on the wicking rate of a test liquid, anodic oxidation leads to an increase in surface free energy, mainly due to the increase of its specific (or polar) component. For the carbon-fiber-reinforced epoxy resin matrix system, a direct linear relationship is shown between the specific component and the critical stress intensity factor measured by the single edge notched beam fracture toughness test. From a surface-energetic point of view, the anodic treatment may be suitable for carbon fibers incorporated in a polar organic matrix, resulting in an increased specific component of the surface free energy. Good wetting plays an important role in improving the degree of adhesion at interfaces between fibers and matrices of the resulting composites. Copyright 2000 Academic Press.     

Effect of the corona treatment and of the 1,4-cyclohexanedimethanol on the surface characteristics of the poly(ethylene terephthalate) film

Several techniques have been applied for the characterization of three PET films surfaces: homopolymer PET film, corona treated PET film and a poly(ethylene terephthalate-co-1,4-cyclohexanedimethanol) film. The objective of this work is to investigate and to apply precise and mutually complementary techniques which give detailled information about theses surfaces, as there are few papers with global and conclusive results. The film surfaces were investigated to support the development of new products and envisage new apllications to the existent films. Scanning electron micrographs, attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR) and multiple internal reflection Fourier transform infrared spectroscopy (FTIR-MIR) spectra show that the chemical composition, topography and surface roughness of the films are different. The corona-treated PET film shows high surface tension value due to the major contribution on the polar groups and oxidation level acquired. The copolyester film is much less crystalline than the other films analyzed, as demonstrated by refractive index measurements and X-ray photoelectron spectroscopy (XPS). The amorphous structures obtained and the high tension level of the corona-treated films provide a better understanding of the adhesion phenomena. In view of results obtained, one can assume that corona treated films owing to its higher surface tension and films with CHDM owing to its surface amorphization should provide manufacturing industries better processing conditions than films without surface treatment and also higher levels of adhesion to paints and coatings.     

A Comparison of Corona-Treated and Flame-Treated Polypropylene Films

The comparison of corona-treated and flame-treated polypropylene (PP) films provides insight into the mechanism of these surface-oxidation processes. Atomic force microscopy (AFM), contact-angle measurements, and X-ray photoelectron spectroscopy (XPS or ESCA) were used to characterize surface-treated biaxially oriented PP. While both processes oxidize the PP surface, corona treatment leads to the formation of water-soluble low-molecular-weight oxidized materials (LMWOM), while flame treatment does not. Computational modeling of the gas-phase chemistry in an air corona was performed using a zero-dimensional plasma-chemistry model. The modeling results indicate that the ratio of O to OH is much higher in a corona discharge than in a flame. Chain scission and the formation of LMWOM are associated with reactions involving O atoms. The higher ratios of O to OH in a corona are more conducive to LMWOM production. Surface-oxidized PP exhibits considerable thermodynamic contact-angle hysteresis that is primarily caused by microscopic chemical heterogeneity.     

Influence of the Particle Size of CaCO3 on the Adhesion of Filled EVA Materials

A surface treatment with corona discharge was used to improve the adhesion properties of ethylene vinyl acetate copolymer (EVA) containing small amounts of four CaCO₃ with different particle size. The nature of the surface modifications produced by the corona discharge treatment and the adhesion to a polychloroprene adhesive were assessed. Treatment of CaCO₃ filled EVA with corona discharge produced a decrease in water contact angle value, irrelevant to the different particle size of the calcium carbonates. The corona discharge treatment created C-O and C=O moieties on the EVA surface and also increased the peel strength, more markedly as the CaCO₃ particle size increased. In general, a mixed (adhesion + cohesive in the EVA) failure in the filled EVA material was produced (assessed by IR-ATR spectroscopy and SEM micrographs of the failed surfaces), but the failure was more cohesive in the EVA containing higher particle size CaCO₃. The durability of the joints was also studied.     

空气电晕辐照对聚酯薄膜表面组成及形貌的影响

分析了聚酯薄膜经空气电晕等离子体辐照处理后,其表面组成和形貌的变化。 结果表明,聚酯薄膜表面的活性基团在亲水环境中更倾向于迁移至表面,而不是向次表面或者基材本体内迁移。 薄膜表面C=O和O-H的引入量随电晕辐照强度的增加而增大,XPS结果表明,C-O、C=O和O-C=O的总含量增大,O1s谱图中新峰的结合能为532.49 eV,对应于聚酯薄膜表面过氧化物的-O-O-键。 原子力显微镜研究表明,聚酯薄膜经电晕辐照后,表面形成离散的球状颗粒,表面粗糙度变化范围在10 nm左右。     

电火花引发丙烯酰胺接枝BOPP薄膜的研究

采用FT-IR,ESCA,试样与水接触角和接枝率的测定探索了电火花用于引发丙烯酰胺(AAM)在BOPP薄膜表面接枝聚合反应的方法,研究了接枝BOPP薄膜的表面结构和亲水性能。结果表明,电火花能有效地引发AAM在BOPP薄膜表面的接枝聚合反应,随着电火花处理时间和接枝反应时间的延长,AAM在BOPP薄膜表面的接枝率增大。电火花处理10min,BOPP薄膜在70℃,20%(质量分数)的AAM水溶液中反应1h,接枝率高达2.06%。接枝后BOPP薄膜与水的接触角显著下降,亲水性能得到明显改善。     

THE SURFACE PROPERTIES OF A HYDROPHOBIC TRANSPOSON (Tn-5) MUTANT OF RHIZOBIUM ETLI

The physicochemical surface characteristics of a Tn-5 induced hydrophobic mutant (CE3003) of Rhizobium etli CE3 were investigated. The wild type CE3 was very hydrophilic with low contact angles for polar liquids, while the Tn-5 induced mutant had a surface that was moderately hydrophobic, with polar liquid contact angles in the 50–60° range. As a result, the polar surface free energy components (γ ⁺ and γ ^-) that constitute the acid-base component (γ ^AB) of surface tension, were greatly reduced on THE surface of the hydrophobic mutant. This decreased electron donicity of the mutant' surface caused an almost five fold increase in the magnitude of the acid-base component of the interfacial interaction free energy between the mutant and hexadecane. The increased adhesion to hexadecane reported earlier is probably attributable to this interaction free energy change and not to any alteration in zeta potential, which was similar for CE3 and CE3003 at pH 7. X-ray photoelectron spectroscopy showed CE3OO3 to have less surface carbon and nitrogen and more surface oxygen than CE3 with alterations in the (C-C,H) and (C-O,N) components being observed.     

Surface modification of low density polyethylene (LDPE) film by low pressure O2 plasma treatment

In this work, low pressure glow discharge O₂ plasma has been used to increase wettability in a LDPE film in order to improve adhesion properties and make it useful for technical applications. Surface energy values have been estimated using contact angle measurements for different exposure times and different test liquids. In addition, plasma-treated samples have been subjected to an aging process to determine the durability of the plasma treatment. Characterization of the surface changes due to the plasma treatment has been carried out by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups. In addition to this, atomic force microscopy (AFM) analysis has been used to evaluate changes in surface morphology and roughness. Furthermore, and considering the semicrystalline nature of the LDPE film, a calorimetric study using differential scanning calorimetry (DSC) has been carried out to determine changes in crystallinity and degradation temperatures induced by the plasma treatment. The results show that low pressure O₂ plasma improves wettability in LDPE films and no significant changes can be observed at longer exposure times. Nevertheless, we can observe that short exposure times to low pressure O₂ plasma promote the formation of some polar species on the exposed surface and longer exposure times cause slight abrasion on LDPE films as observed by the little increase in surface roughness.     

Application of the chromatographic step profile method for determination of water film pressure and surface free energy of quartz

Summary Investigation of water adsorption by the step profile method (Glueckauf method) was carried out with the help of a modified gas chromatography equipped with thermal-conductivity detector. On the basis of the adsorption isotherm obtained, the water film pressure and the polar component of the surface free energy of quartz were calculated. The calculated value of the polar component of the surface free energy of quartz agrees with analogous values obtained by other methods.     

热解条件对LiFePO4/C表面自由能的影响

以葡萄糖为碳前驱体对水热合成的磷酸铁锂粉末进行碳包覆. 测定磷酸铁锂粉末与三种探测液的接触角, 并据此通过Young方程采用Wu方法计算了粉末的表面自由能. 研究了表面自由能与电导率、放电比容量的关系及对工业化涂布性能的影响. 结果表明, 在电导率相同的前提下, 粉末表面自由能中色散分量与极性分量的比值(γd/γp)对低倍率放电性能没有影响, 但对高倍率放电性能影响较大. 提高热解温度和延长热解时间可使γd/γp值增加, 这有利于粉体与聚偏氟乙烯(PVdF)的粘合和高倍率放电容量的提高.     

Determination of the acid/base properties of MgY and NH4Y molecular sieves by inverse gas chromatography

The surface characterization of MgY and NH(4)Y zeolites was performed using inverse gas chromatography (IGC). The adsorption thermodynamic parameters (the standard enthalpy (DeltaH degrees ), standard entropy change (DeltaS degrees ), and free energy change of adsorption (DeltaG degrees ), the dispersive component of the surface free energies (gamma(S)(d)), and the acid-base character of the surface of MgY and NH(4)Y zeolites were estimated using the retention time of different non-polar and polar probes at infinite dilution region. The specific free energy of adsorption (DeltaG(sp)), the specific enthalpy of adsorption (DeltaH(sp)), and the specific entropy of adsorption (DeltaS(sp)) of polar probes on MgY and NH(4)Y zeolites were determined. The values of the DeltaH(sp) were correlated with both the donor and acceptor numbers of the probes to quantify the acidic K(A) and the basic K(D) parameters of the zeolite surfaces. The values obtained for the K(A) and K(D) parameters indicated a basic character for the surface of MgY and NH(4)Y zeolites.     

Effect of atmospheric-pressure plasma on adhesion characteristics of polyimide film

In this work, the effect of atmospheric-pressure plasma treatments on surface properties of polyimide film are investigated in terms of X-ray photoelectron spectroscopy (XPS), contact angles, and atomic force microscopy (AFM). The adhesion characteristics of the film are also studied in the peel strengths of polyimide/copper film. As experimental results, the polyimide surfaces treated by plasma lead to an increase of oxygen-containing functional groups or the polar component of the surface free energy, resulting in improving the adhesion characteristics of the polyimide/copper foil. Also, the roughness of the film surfaces, confirmed by AFM observation, is largely increased. These results can be explained by the fact that the atmospheric-pressure plasma treatment of polyimide surface yields several oxygen complexes in hydrophobic surfaces, which can play an important role in increasing the surface polarity, wettability, and the adhesion characteristics of the polyimide/copper system.     

Acrylic polymer/silica hybrids prepared by emulsifier‐free emulsion polymerization and the sol–gel process

Acrylic polymer/silica hybrids were prepared by emulsifier‐free emulsion polymerization and the sol–gel process. Acrylic polymer emulsions containing triethoxysilyl groups were synthesized by emulsifier‐free batch emulsion polymerization. The acrylic polymer/silica hybrid films prepared from the acrylic polymer emulsions and tetraethoxysilane (TEOS) were transparent and solvent‐resistant. Atomic force microscopy studies of the hybrid film surface suggested that the hybrid films did not contain large (e.g., micrometer‐size) silica particles, which could be formed because of the organic–inorganic phase separation. The Si? O? Si bond formed by the cocondensation of TEOS and the triethoxysilyl groups on the acrylic polymer increased the miscibility between the acrylic polymer component and the silica component in the hybrid films, in which the nanometer‐size silica domains (particles) were dispersed homogeneously in the acrylic polymer component. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 273–280, 2006     

Biaxially Oriented Polypropylene (BOPP) Surface Modification by Nitrogen Atmospheric Pressure Glow Discharge (APGD) and by Air Corona

We compare two surface treatments of biaxially-oriented polypropylene (BOPP), which are carried out in the same dielectric barrier discharge (DBD) apparatus, namely air corona, and N₂ atmospheric pressure glow discharge (APGD). Changes in the surface energy and chemistry are investigated by contact angle measurements, by X-ray photoelectron spectroscopy (XPS) and by attenuated total reflectance infrared spectroscopy (ATR-FTIR). It is shown that N₂ APGD treatment leads to a higher surface energy than air corona treatment, and to the formation of mostly amine, amide, and hydroxyl functional groups at the polypropylene surface. Finally, hydrophobic recovery of the treated film is studied; for both treatment types, the increased surface energy is found to decay in a similar manner with increasing storage time after treatment.     

反相气相色谱法研究1,3,5-三氨基-2,4,6-三硝基苯的表面特性

采用反相气相色谱技术(IGC)研究了4种不同粒度的1,3,5-三氨基-2,4,6-三硝基苯(TATB)的表面性质。4种不同粒度的TATB表面自由能的色散分量（γds）随着温度的升高而增加;粒度越大的粒子,其色散自由能上升越快;在较高温度下,粗颗粒TATB显示了更强的色散作用(γds=193.2 mJ/m2,353 K),粒度最小的亚微米TATB显示了最弱的色散作用(γds=64.0 mJ/m2,353 K)。由于制备方法不同和粒子大小的差异,4种TATB的表面酸碱性质显示了明显的差别,细颗粒TATB表面有较强的亲电子特性;而其他3种TATB在极性探针分子的作用下的吸附均表现为吸热吸附,表现出在分子内和分子间具有强烈的相互作用,其Ka和Kb值均为负。     

Comparison of the surface characteristics of polypropylene films treated by Ar and mixed gas (Ar/O2) atmospheric pressure plasma

In an attempt to modify the hydrophobic surface properties of polypropylene (PP) films, this study examined the optimum process parameters of atmospheric pressure plasma (APP) using Ar gas. Under optimized conditions, the effects of a mixed gas (Ar/O2) plasma treatment on the surface-free energy of a PP film were investigated as a function of the O2 content. The polar contribution of the surface-free energy of the PP film increased with increasing O2 content in the gas mixture. However, slightly more oxygen-containing polar functional groups such as CO, CO, and COO were introduced on the PP film surface by the Ar gas only rather than by the Ar/O2 gas mixture. In addition, AFM analysis showed that the Ar plasma treatment of the PP film produced the smoothest surface as a result of the relatively homogeneous etching process.