PREPARATION OF GRAFTED COPOLYMERS OF POLYTETRAFLUOROETHYLENE (TEFLON) BY RADIATION CHEMISTRY

Journal Article · Thu Jan 01 04:00:00 EST 1959 · J. Polymer Sci.

DOI:https://doi.org/10.1002/pol.1959.1203412735· OSTI ID:4288570

Chapiro, A

It was previously found that different polymers maybe grafted onto polytetrafluoroethylene by irradiating this polymer in the presence of vinyl monomers. However, because of the high chemical stability of Teflon, no monomer is able to penetrate inside this polymer in the usual way, and therefore the grafting remains limited to the surface. It was found that if the grafting of Teflon proceeds with a monomer under well-defined experimental conditions in which the graft copolymer swells, the grafting can propagate progressively into the material, and finally a graft copolymer is obtained which is entirely homogeneous. This reaction was studied by grafting on films of Teflon, styrene, and methyl methacrylate monomers. During grafting the monomeric films swell regularly in three dimensions without modification of their over-all shape. However, if the styrene content in the films exceeds 90 wt.%, the films crack because of the strains caused by the swelling of the grafted film in styrene. The kinetics of this reaction is controlled by the diffusion of the monomer in the partially grafted films. The plots of the degree of conversion versus time show an acceleration of the reaction with time. These may be represented by the empirical equation C% = At/sup a/ + B, in which t is the time and alpha has a value generally between 2 and 3. If the rate of monomer diffusion is lower than the rate of polymerization, the grafting is limited on the surface of the film; if the rate of polymerization is diminished while the rate of diffusion is maintained constant, grafting becomes possible through all the material. The influence of several parameters on the kinetics of the reaction has been studied. Thus, the intensity of irradiation, the monomer concentration, and the temperature are most important. Teflon films of different thicknesses were grafted in these conditions. Intermittent irradiation also enhances the grafting through the material. Some properties of Teflon films grafted homogeneously with polystyrene were studied. These films swell only weakly in benzene, even at high styrene content (70%). The weakening point is about 150 C, without melting, and they remain chemical inert. These results have been discussed. (auth)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-13-009825
• OSTI ID: 4288570
• Journal Information: J. Polymer Sci., Journal Name: J. Polymer Sci. Vol. Vol: 34
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BENZENE
CHEMICAL REACTIONS
CHEMISTRY
DIFFUSION
EQUATIONS
ORGANIC FLUORINE COMPOUNDS
POLYETHYLENES
POLYMERIZATION
POLYMERS
PRODUCTION
QUANTITY RATIO
RADIATION CHEMISTRY
RADIATION EFFECTS
REACTION KINETICS
STABILITY
STYRENE
SURFACES
TEMPERATURE
THICKNESS
VINYL RADICALS