Polypropylene surfaces

Grafting of Acrylic Acid Derivatives onto Polyethylene and Polypropylene Surfaces... 

In our study we have found that UV-light greatly accelerates the rate of ozone attack at the polypropylene surface. Presented results were undertaken to determine mechanism of the photo-oxidation of polypropylene surface upon UV-irradiation of polymer films in ozone. 

It promotes adhesion of intaglio inks to the polypropylene surface. An acrylic based primer is a good choice because of its ability to effectively bond water-based inks. Dry powder form of acrylic primer is diluted with methyl ethyl ketone and xylene (each component is mixed in equal parts by weight). To create the opaque surface, 5wt% titanium dioxide pigment is added to the solution. 

I. Sutherland, D.M. Brewis, R.J. Heath, and E. Sheng. Modification of Polypropylene Surfaces by Flame Treatement. Surf. Inter/. Anal., 17 508-510,1991. 

Figure 7. FAB SIMS Spectra of Fluoropolymers and Plasma Treated Polypropylene Surfaces...

K.R. Czerwinski et al. [3] could not be reproduced by C.D. Kacher et al. [5] who reported that they observed that significant amounts of Hf (more than 50 % in some cases) stick to Teflon surfaces. (They actually conducted their subsequent experiments with polypropylene equipment because only negligible adsorption was observed with polypropylene surfaces.) The Hf results from the Czerwinski et al. experiments [3] were based on on-line data taken at the 88-Inch Cyclotron where the activity was collected on a teflon disc which according to [5] accounts for the seemingly low Hf extraction. Surprisingly, a similar loss of Rf due to adsorption in the Czerwinski et al. work [3] was not suspected by Kacher et al, and so the latter authors, based on their new Zr-, Hf-, and Ti-results and on the old [3] Rf results, suggested a revised, still questionable, sequence of extraction into TBP/benzene from around 8 M HC1 as Zr > Hf > Rf > Ti. In a parallel study of liquid-liquid extractions into TBP/benzene from HBr solutions, extraction of Rf was found to be low and was only increased for bromide concentrations beyond 9 M [5]. The extraction behavior of the group-4 elements into TBP from both HC1 and HBr solutions was primarily attributed to their different tendencies to hydrolyze [5]. 

Fig. 6 Reaction scheme of covalent alanine grafting onto polypropylene surfaces...

It can be seen that a-globulin removes more heparin than do any of the other plasma proteins. The reason for the loss of heparin from the polypropylene surface and not from the silicone rubber is not understood since the same chemical reactions are used to effect bonding to both polymers. 

Analysis of the Non Metallized. Pretreated Polypropylene. In a previous paper (1), we have shown that for very short treatment times (23 ms) in N2 or NH3 plasma, the first observed effect of the plasma was an increase of the dispersive component (y ) of the polypropylene surface tension. Since almost no nitrogen nor oxygen were detected by XPS for treatment times shorter than 0.7 s, it was concluded that the plasma had first a physical effect rather than a chemical one, although the efficiency of the treatment on the Al-PP adhesion was high (as proven by the use of a scotch-tape test). 

Previous static SIMS analyses have also shown (2) that the plasma treatment may induce fragmentation of the polymer backbone and some homogeneization of the polypropylene surface composition. Figure 6a shows static SIMS spectra obtained on a virgin polypropylene sample and Figure 6b on polypropylene which was treated in a N2 plasma for 7 seconds. 

In this work, we have shown how a plasma treatment, which enables us to improve the Al-PP adhesion, leads to both chemical and physical modifications (the latter being observed for treatment time as short as 23 ms) at the polypropylene surface. 

In this way the Multigrain model would take on a precise physical meaning. The microglobular polypropylene surface, obtained with both traditional and high yield catalysts is clearly shown out by electron scanning microscopy. 

Measurements of the hydrophobic attraction between solid polypropylene surfaces show that on degassing the water the force drops back to van der Waals forces predicted by Lifshitz theory - by one or two order of magnitude. 

Immobilization of Proteins and Enzymes onto Functionalized Polypropylene Surfaces by a Gaseous Plasma Modification Technique... 

The results of the present ammonia plasma treatment show that a polypropylene surface can be functionalized with NH2 groups by the ammonia plasma technique. The resultant polymer is fairly suitable... 

Figure 1. FT-IR absorption spectrum of an untreated polypropylene surface (control).

The effects of the reduced and modified mechanism (Table 22.1) on the functional groups found on the polypropylene surface are given in Figure 22.16. In comparison to the original plasma treatment mechanism [33], the reduced and modified reaction mechanism presented by Stroud and Branch [34] yields surface species functionalities that are more consistent with the data available from the most recent studies [31,32]. In comparing... 

Figure Bl.19.31. AFM image of a 2.7 nm x 2.7 nm area of a polypropylene surface, displaying methyl groups and right- and left-handed helices. (Taken from [143], figure 10.)... 

Figure 7. Scanning electron microscope photograph of polypropylene surface after 1-h exposure to flowing blood at 200 mL/min and rod rotation...

The principal aim of the present work was to study the modification of polymer surfaces by plasma treatment as well as the interaction of a metal film with these treated surfaces by surface analytical techniques. As shown above, the results indeed show increased interaction after surface treatment under certain conditions. However, ultimately, improved adhesion should also be observed. For this purpose preliminary expenments with aluminum films on plasma treated polypropylene were carried out. These films were not evaporated under in-situ conditions, but in a separate electron beam evaporator under identical conditions for the different polymer surfaces. A simple Scotch tape test was performed in order to characterize the adhesion qualitatively. In agreement with the surface analytical results, the as-received polypropylene surfaces show poor adhesion as the aluminum film and can be peeled off completely. A five second nitrogen plasma treatment however leads to a film which adheres well and cannot be lifted off by the same tape. Hnally, a 120 s ocatment in a nitrogen plaana leads to an oveitreatmcntof the surface characterized by a low adherion again. 

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