Surface modification of polypropylene by plasmas

In spite of these disadvantages, plasma treatment of polymers is an attractive process to produce the required surface modification. By using different types of gas, various chemical functionalities can be introduced on the surface. In general, more uniform surfaces are produced by plasmas than by flame and corona treatments. The modification is typically confined to the surface without changing the bulk physical and chemical properties of the pol)uner. 

A typical system consists of a gas inlet, reactor vessel, vacuum pump, matching network and power source. Various reactors have been used in plasma processing. For EXT and low-frequency glow discharges, internal electrodes are necessary. As the frequency increases, electrodes may be placed outside the reactor vessel. 

Treatment (pressure=W Pa time=7 min current density =40 jtA cm ) Atomic ratio Surface energy (mj mr ) 

(1994) Polymer Surface Modification and Characterization, Hanser, New York. 

Keywords electron spectroscopy for chemical analysis (ESCA), functionality, lap shear strength, plasma treatment, secondary ion mass spectrometry (SIMS), surface modification, surface energy. X-ray photoelectron spectroscopy (XPS). 

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Better effects on complicated PP parts are produced by a low-pressure plasma treatment in oxidizing gases, such as oxygen. The disadvantage of the plasma process (pressure 0.01-1 mbar, lOMhz, 500 W) is that the plasma chamber after the positioning of the parts must be evacuated and filled with the plasma gas. This process is discontinuous and needs approximately 1.5 min or more for a filled chamber (see also the chapter Surface modification of polypropylene by plasma in this book). 

Kang, M.S., Chun, B. and Kim, S.S. 2001. Surface modification of polypropylene membrane by low-temperature plasma treatment. 

Q F Wei, R R Mather, X Q Wang and A F Fotheringham, Functional nanostructures generated by plasma enhanced modification of polypropylene fibre surfaces , J. Mat. Sci, 2005 40 5387-5392. 

Another interesting example of surface modification is represented by the modification of hydrophobic polypropylene surfaces by carbon dioxide plasma [23] and carbon tetrachloride plasma [24] treatment to convert them into hydrophilic surfaces. This technique has potential applications in coatings and adhesion to other materials such as polymers, metals, and ceramics [24]. Radiation-induced reactions for LDPE/PP blends have also been recently reported [25]. 

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. 

Modifications of polymer surfaces by exposure to electrical plasmas and discharges have also been subjected to XPS examination in several recent articles (4, , 7). An example is the plasma oxidation of polyethylene, polypropylene and polystyrene in a radiofrequency inductively coupled system ( ). Figure 14 shows the Cls and 01s spectra of a polyethylene film after... 

This modification could be made by plasma polymerization wherein a thin, highly cross-linked and pin hole free film of filler free silicone polymer could be added onto a variety of substrate materials in order to prepare improved blood compatible surfaces (1). Alternatively, gaseous plasma could be used to add new chemical groups to a material surface which could then be used for attaching a variety of biomolecules. By anhydrous ammonia plasma, amino groups can be added to the surface of polypropylene membranes or to the surface of polypropylene beads. These amino groups can then be employed to bind albumin to polypropylene as was done in our previous work in which a quantitative measure of bound protein was... 

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. 

Ghemically well-defined surface fimctionalization of polyethylene and polypropylene by pulsed plasma modification followed by grafting of molecules. In Polymer surface modification Relevance to adhesion, Vol. 2, pp. 45-64, Mittal, K L. Ed., VSP Utrecht, ISBN-10 9067643270. 

Abstract The use of two environmentally friendly technologies, the plasma and laser approaches, in treating the surface of textiles is discussed in this chapter. The surface of fibrous materials can be functionalized and structured on the nano- and micro-scales, and the results of the treatment of natural and synthetic fibres such as wool, cotton, polypropylene, polyester and polyamide which have been treated by different plasmas and lasers are detailed and are found to be similar to morphological modification of a textile surface using the ripple/roll-structure technique. 

Commercial APGD systems are offered, for example, by Dow Corning Plasma Solutions (Ireland) [34] and Enercon (USA) [35]. As a practical example, Enercon has developed an implementation of the APGD technology for large scale plasma treatment of polypropylene (PP) film. Fig. 20.7 shows an industrial APGD system for modification of polymer sheet surfaces. 

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

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