Adhesion plasma pretreatment, effects

When each of the acrylate or methacrylate polymers was preincubated with whole plasma, the platelet reactivity of the surfaces upon subsequent exposure to whole blood decreased significantly (Fig. 3). On the other hand, with many other polymers this effect of plasma was not seen. Of 20 varieties of segmented polyurethanes examined, none showed this behavior (22), and platelet adhesion to polystyrene was also unaffected by plasma pretreatment ( ). The phenomenon of plasma-induced passivation of methacrylate and acrylate polymers presumably involves selective adsorption of specific plasma proteins by the surfaces and/or a particular alteration of the adsorbed protein once bound. 

In a stucfy of fiber/matrix adhesion, the effect of surface pretreatment of carbon fibers in gas plasmas on adhesion have been described (39). The atomic concentrations of Hercules IM7 carbon fiber as determined by XPS before and after plasma exposure are listed in Table V. The nitrogen content of carbon fibers is increased in an ammonia plasma whereas the o gen content is increased in an air plasma. No effect of the air plasma treatment of carbon fibers on adhesion to polyethersulfone is seen as noted in... 

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). 

Pretreated (enzymatic and enzymatic-I-hydrogen peroxide) knitted wool fabrics were treated with argon and atmospheric air plasma to improve adsorption capacity (Demir et al., 2010). After plasma treatment, a chitosan solution was appUed for antimicrobial effect. The treated fabrics were evaluated in terms of washing stabiUty as well as antimicrobial activity. The surface morphology was characterized by SEM images and Fourier transform infrared (FilR) analysis. The results indicate that the atmospheric plasma treatment had an etching effect and increased the fiinctionahty of wool surface. Atmospheric plasma treatment also enhanced the adhesion of chitosan to the surface and improved the antimicrobial activity. 

Depending on their chemical composition, they wUl require mechanical, chemical, and physical pretreatment or priming to enhance coating adhesion. Since mechanical pretreatment consists of abrasion, its effect on the substrate must be considered. Chemical pretreatments involve corrosive materials which etch the substrates and can be hazardous. Therefore, handhng and disposal must be considered. Physical pretreatments consist of plasma, corona discharge, and flame impingement. Process control must be considered. 

The chemical pretreatment methods mentioned are mostly used for TPOs, but in some cases can also be effective when used on polyamide (PA), polybutylene terephthalate (PBT), or other crystalline polymers, as well as some blends like poly(phenylene oxide)/polyamide (PPO/PA), are flamed. As a possible future trend, research is currently underway (plasma polymerization) attempting to combine a pretreatment for adhesion and to provide the surface conductivity on necessary on plastic parts for acceptable electrostatic application (15). 

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