Polyethylene contact angle

A zero or near-zero contact angle is necessary otherwise results will be low. This was found to be the case with surfactant solutions where adsorption on the ring changed its wetting characteristics, and where liquid-liquid interfacial tensions were measured. In such cases a Teflon or polyethylene ring may be used [47]. When used to study monolayers, it may be necessary to know the increase in area at detachment, and some calculations of this are available [48]. Finally, an alternative method obtains y from the slope of the plot of W versus z, the elevation of the ring above the liquid surface [49]. 

Fig. X-13. Advancing contact angles for methylene iodide-decalin mixtures on polyethylene. (From Ref. 172.)...

Table 4 Contact Angle and Contact Angle Hysteresis of Modified Polyethylene ...

The effect of thermal aging on polyethylene and isotactic polypropylene have been studied by Konar et al. [49]. They used contact angle, contact angle hysteresis, and XPS to characterize the modified surfaces of the polymers. Hysteresis increased with aging temperature. In the case of polyethylene, thermal aging led to a significant increase in adhesion strength of polyethylene with aluminium, but the increase in the case of polypropylene was much less marked. 

Better surface stability could be achieved if the surface components are less mobile. Some success has been achieved with polyethylene and perhalogenated polymer surfaces (8,11,12,29). Crosslinking the surface should also decrease its mobility, and this is how (TD)2DPM provides added stability, Figure 3. Some surface rearrangement does appear to occur initially, but samples have retained good hydrophilicity (contact angle 45-55°) for a year. 

These data show the surface characteristics as related to ycr. In many cases, the surface of a solid may not behave as desired, and therefore it treated accordingly, which results in a change of the contact angle of fluids. For instance, the low surface energy of polymers (polyethylene [PE]) is found to change when treated with flame or corona (as shown in the following table). 

Thin films of polyethylene, poly(ethylene-co-5-norbomen-2-yl acetate), and poly-(cthylene-co-5-norbomen-2-ol) were prepared on glass slides and contact angle measurements of water droplets determined. Testing results are provided in Table 2. 

On low energy surfaces such as polyethylene, polypropylene, or polytetrafluoroethylene many liquids have finite contact angles and Tre values are generally zero (3). On high energy surfaces such as most mineral oxides most liquids have no contact angle, tt6 values are quite appreciable and... 

The modification of the chemical composition of polymer surfaces, and thus their wettability with chemical substances, can be realized in different ways electric discharges more commonly called Corona effect, oxidation by a flame, plasma treatment, UV irradiation and also UV irradiation under ozone atmosphere. Numerous studies have been devoted to the effects of these different treatments. More recently, Strobel et al. [204] compared the effects of these treatments on polypropylene and polyethylene terephthalate using analytical methods such as E.S.C.A., F.T.I.R., and contact angle measurements. They demonstrated that a flame oxidizes polymers only superficially (2-3 nm) whereas treatment realized by plasma effect or Corona effect permits one to work deeply in the polymer (10 nm). The combination of UV irradiation with ozone flux modifies the chemical composition of the polymers to a depth much greater than 10 nm, introducing oxygenated functions into the core of the polymer. 

Some of the commonly used techniques for measuring contact angle [215, 216, 217] are the sessile drop method, captive bubble method and Wilhelmy plate method. These techniques have been extensively used and well documented for characterisation of modified PE surfaces [218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230] for various applications. Whitesides et al. [231 ] studied the wetting of flame-treated polyethylene film having ionisable organic acids and bases at the polymer-water interface. The effect of the size of substituted alkyl groups in amide and ester moieties on the surface hydrophilicity was also studied [232]. The biocompatibility of the polyethylene film surface modified with various water-soluble polymers was evaluated using the same technique [233]. The surface properties of hy-perbranched polymers have been very recently reported [234]. 

Polyethylene (PE) Contact angle 94° 4, RMS 45 nm Human insulin Nucleation faster than bulk. Elongation not different to the bulk Nayak et al. (2008)... 

Keywords Contact angle Cross-linked LDPE Photosulfonation Polyethylene Surface modification Zeta potential... 

The aim of the present study was a closer investigation of the properties of LDPE surfaces subjected to photosulfonation processes. Until today no zeta potential studies had been carried out on photosulfonated LDPE. In the present investigation such modified LDPE surfaces were characterized by FTIR spectra, contact angle testing and zeta potential measurements were carried out. To improve the stability of modified LDPE surfaces, polyethylene samples were crosslinked by e-beam irradiation and... 

The contact angle of water on non-crosslinked polyethylene decreased from 99.2° (unmodified LDPE) to... 

A crosslinking pre-treatment of LDPE prevents the extraction of sulfonated polyethylene chains during the postexposure extraction process with acetone/H20. This is caused by a radiation-induced network formation. As a result, a higher amount of sulfonic acid groups is maintained at the surface at a given period of sulfonation. This was evidenced both by zeta potential and contact angle measurements. 

Surface fluorination of several polymers other than polyethylene has been attempted to show the effectiveness of this technique in generating perfluorinated surfaces. Results of formamide contact angle experiments are summarized in Table (3). It appears from these results that under the conditions studied, polypropylene and nylon 6,6 can be perfluorinated but polymethylmethacrylate does not perfluorinate in the time scale shown. The C, XPS spectra and the respective chemical compositions are shown in Figure (7) and Table (3). Even though PMMA shows high... 

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