Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Polyethylene surface oxidation

Surface oxidation reactions have been carried out on a number of polymers, particularly polyethylene. Surface oxidation techniques include the use of corona discharge, ozone, hydrogen peroxide, nitrous acid, alkaline hypochloride, UV irradiation, oxidizing flame, and chromic acid The reactions lead initially to the formation of hydroperoxides, which catalyze the formation of aldehydes and ketones and finally, acids and esters. Surface oxidation treatment has been used to increase the printabdity of polyethylene and poly(ethylene terephthalate) and to improve the adhesion of polyethylene and polypropylene to polar polymers and that of polytetrafluoroethylene to pressure-sensitive tapes. Surface-oxidized polyethylene, when coated with a thin film of vinylidene chloride, acrylonitrile, and acryhc acid terpolymers becomes impermeable to oxygen and more resistant to grease, oil, abrasion, and high temperatures. The greasy feel of polyethylene has also been removed by surface oxidation. [Pg.150]

Corrosion. Ammonium bifluoride dissolves in aqueous solutions to yield the acidic bifluoride ion the pH of a 5% solution is 3.5. In most cases, NH4HF2 solutions react readily with surface oxide coatings on metals thus NH4HF2 is used in pickling solutions (see Metal surface treatments). Many plastics, such as polyethylene, polypropylene, unplasticized PVC, and carbon brick, are resistant to attack by ammonium bifluoride. [Pg.148]

If corona, plasma, or flame treatment is chosen as the surface treatment, it is important to bond quickly after the treatment. Waiting several hours will reduce the effectiveness of the treatment. In some cases, attempts to bond 24 h after the treatment can give the same poor bonding results as if the plastic had never been surface treated. If surface oxidation is not possible, priming the surface with a chlorinated polyethylene primer is a second choice [95]. [Pg.809]

Thermal aging is another simple pretreatment process that can effectively improve adhesion properties of polymers. Polyethylene becomes wettable and bondable by exposing to a blast of hot ( 500°C) air [47]. Melt-extruded polyethylene gets oxidized and as a result, carbonyl, carboxyl, and hydroperoxide groups are introduced onto the surface [48]. [Pg.527]

For a ToF-SIMS investigation of the surface oxidative degradation of low-density polyethylene (LDPE), the polymer was exposed to 1802 rather than 1602 in order to be able to readily discriminate oxygen introduced by the ageing process from that in the polymer prior to ageing [102], Figure 36 shows an example series of ToF-SIMS spectra from this investigation, which shows the clear separation of the lsO species from the lsO species. In the study, close correlation was observed between the intensity of the lsO carbonyl species determined by mid-infrared spectroscopy with the ToF-SIMS 180- peak intensity as a function of 1802 exposure time. ToF-SIMS spectra obtained from microtomed cross-sections showed no... [Pg.435]

In PE/aluminium laminates, which are used for packaging, the bond strength can be improved by surface oxidation of the polymer. An alternative to surface oxidation is to use copolymers of ethylene and monomers containing polar groups that can provide stronger bonds to metal thus increasing adhesion [24,25]. The effects of three functional groups in ethylene copolymers, namely EVS [polyethylene-co-vinyl trimethoxy silane], EBA [polyethylene-co-butyl acrylate], EAA [polyethylene-co-acrylic acid) on the adhesion was studied [25]. The interface in polymer/metal laminates has been analysed by FT-IR... [Pg.178]

Strong joints with epoxy adhesives can be made to polyethylene surfaces which have been oxidized by a variety of techniques (4, 5). The general belief has been that the presence of polar groups on the polymer surface creates an affinity for the polar epoxy adhesive which improves wettability and results in a strong adhesive joint. [Pg.154]

Hydrocarbon polymers that were exposed in the LEO environment invariably showed an increase in surface oxide content. For example, the oxygen atomic concentration on a polyethylene surface increased by roughly 10 percent during exposure in LEO. And similar exposures of polystyrene and Kapton led to an increase in surface oxygen atomic concentration of approximately 20 percent and three percent, respectively. 67... [Pg.447]

Outdoor exposure of these hlgh-denslty samples for the last 18 years caused no substantial change due to surface oxidation. Bulk changes similar to those found In low-density polyethylene were also found In these high density materials. The melt Index slowly decreases and the overall thermal stability measured at high temperature by thermal analysis decreases. However, the secondary crystallization seen In low-density polyethylene was not detected In these high density compounds. [Pg.68]

Nordhage and Backstrom (12) found the charging of polyethylene film in rubbing contact against aluminum, plat inum or gold electrodes to have a 1 inear dependence on the applied potential. Hays (19) investigated the effects of surface oxidation and applied electric field on mercury-polyethylene contact charging and discussed the results in terms of a model based on polymer surface states. [Pg.184]

Polyethylene, as LDPE, LLDPE or a mixture or blend involving combinations of LDPE, MDPE, HDPE, EVA, etc., finds a wide usage in bags, sacks, sachets, overwraps, shrink wraps, stretch wraps, etc. Most deep freeze packs, for example, use LDPE or an LDPE mixture which is produced from a reel on a form fill seal type machine. However, as many of these packs are up to 100% printed, even ink of 2-5 Pm could be considered as a separate layer which modifies some of the physical and chemical properties. As all polyolefins need a surface (oxidative) treatment to ensure a good print key, this or any other surface treatment process may further modify the film properties. [Pg.258]

The present generally accepted procedure for structurally bonding polyethylene with an adhesive is to oxidize the polyethylene surface this raises its surface free energy and improves the wettability of the polyethylene by the adhesive [2]. An improvement in bond strength is thus obtained. We are not, however, aware of any previous work in which the strength levels reported were comparable to those which we have obtained. [Pg.198]

However, in spite of these similarities, the adsorbed amounts and the structure of the adsorbed mucin and collagen layers on the surfaces studied are entirely different. The behavior of these proteins is analyzed here on the hydrophobic polyethylene surface (water contact angle 0 20 95°), on the surface modified polyethy-lenes oxidized polyethylene (0h q 74°) and poly(maleic acid) grafted polyethylene ( Ho0 74°) a d on the hydrophilic mica surface ( H2 0 0°) Acidic pH = 2.75 (for collagen) and slightly alkaline pH = 7.2 (for mucin) were chosen in order to minimize the association of these proteins in solution and to make possible the analysis of their adsorbabilities in comparable conditions. [Pg.459]

The surface density/solution concentration isotherms, not shown in this paper, reflect also the differences in the behavior of mucin and collagen upon their adsorption at solid interfaces. While the collagen isotherms on polyethylene and surface-grafted polyethylene show a plateau of adsorption at solution concentrations higher than 0.05 mg/ml, no plateau values for mucin adsorption are observed on polyethylene and surface oxidized polyethylene. [Pg.461]

Finally, Figure 9 presents the desorption-adsorption relationship for mucin and collagen on polyethylene and surface-modified polyethylene. The adsorption of mucin on untreated polyethylene is typically irreversible and the maximum adsorbed quantity is equal to 2.2 mg/m2. In contrast, low but continuous desorption of mucin with increasing adsorbed concentrations is observed on surface oxidized polyethylene. [Pg.461]

Figure 9. Desorption-adsorption relationships (a) polyethylene-collagen (a) poly(maleic acid) grafted polyethylene-collagen (o) polyethylene-mucin ) surface oxidized polyethylene-mucin. Adsorption time 20 hrs temp. 20°C. Adsorption conditions as indicated in Figure 7. Figure 9. Desorption-adsorption relationships (a) polyethylene-collagen (a) poly(maleic acid) grafted polyethylene-collagen (o) polyethylene-mucin ) surface oxidized polyethylene-mucin. Adsorption time 20 hrs temp. 20°C. Adsorption conditions as indicated in Figure 7.
E. Kiss, J. Samu, A. Toth, I. Bertoti, Novel ways of covalent attachment of poly (ethylene oxide) onto polyethylene surface modification and characterization by XPS and contact angle measurements. Langmuir 12, 1651—1657 (19%)... [Pg.228]

The effects of air or oxygen plasma on polymer films have been reported. In a comparative study with polypropylene (PP) and polyethylene (PE), higher levels of oxygen incorporation were achieved in PP than with PE. In this method, the initial step involves formation of radicals on the top of the layer of the polymer surface. These can react with each other to initiate cross linking or branching or result in surface oxidation. The use of nonthermal plasma treatment to polymer surfaces to enhance wettability and adhesion has been reported. The use of Corona discharge and dielectric discharge has also been reported for polymer modification [78]. [Pg.383]


See other pages where Polyethylene surface oxidation is mentioned: [Pg.225]    [Pg.427]    [Pg.520]    [Pg.190]    [Pg.192]    [Pg.669]    [Pg.76]    [Pg.322]    [Pg.728]    [Pg.5]    [Pg.232]    [Pg.237]    [Pg.239]    [Pg.258]    [Pg.264]    [Pg.264]    [Pg.270]    [Pg.153]    [Pg.583]    [Pg.5]    [Pg.66]    [Pg.225]    [Pg.19]    [Pg.657]    [Pg.372]    [Pg.233]    [Pg.264]    [Pg.392]    [Pg.1316]    [Pg.39]    [Pg.129]   
See also in sourсe #XX -- [ Pg.68 ]




SEARCH



Polyethylene , surface

Polyethylene oxide

Polyethylene oxide surfaces

© 2024 chempedia.info