EFFECT OF TEMPERATURE ON THE GRAFTING OF STYRENE ON FILMS OF POLYTETRAFLUORETHYLENE AND POLYVINYL CHLORIDE BY A DIRECT RADIOCHEMICAL METHOD

Journal Article · Thu Mar 01 04:00:00 EST 1962 · J. Polymer Sci.

DOI:https://doi.org/10.1002/pol.1962.1205716559· OSTI ID:4818321

Chapiro, A; Matsumoto, A

Direct radiochemical grafting of styrene on films of tetrafluoroethylene was studied at 40 and 60 deg C. At 40 deg the reaction shows kinetic characteristics similar to those observed at 19 deg . Above a given critical intensity, the grafting no longer proceeds in the mass, but is limited to the surface of the film. The value of this critical intensity is 6-8 rads/sec at.40 deg , while at 19 deg it is 1.0 rad/sec. At 60 deg the critical intensity is higher for the highest intensity examined, namely 35.1 rads/sec. The conversion curves obtained for intensities lower than the critical value indicate an autoacceleration. By representing these curves on a logarithmic scale, straight lines are obtained with a slope of 1.5-1.6 at40 deg and 1.0-1.3 at 60 deg . At 19 deg the slopes of the corresponding straight lines varied from 2.5 to 3.2; this slope, which indicates the exponent of the time in the equation C = Kt/sup B/ is called autoacceleration coefficient. The shift of the critical intensity to higher values, when the temperature increases, is interpreted as an increase of diffusion rate of the monomer; at 60 deg this last no longer deter mines the reaction kinetics in the experimental conditions. On the other hand, it is suggested that the decrease is due to a decrease of the contribution of the gel effect, on account of the increased mobility of the growing chains. Nevertheless, the exponent alpha of the intensity in the relation V = KI/sup alpha / which is equal to 0.5-0.55 at 19 deg , varies from 0.68 at40 deg to form of the conversion curves at 60 deg C, the reaction does not become stationary. The radiochemical grafting of styrene on polyvinyl chloride was studied at 60 deg C. Contrarily to the reaction examined previously at 20 deg this reaction is not controlled by the monomer diffusion rate, and the kinetics of grafting are normal. The conversion curves are practically linear and the reaction rate is proportional to the square root of the intensity. Some curvature in the direction of the abcissa axis nevertheless exists for the conversion curves at low intensities. It may result either from a nonhomogeneous monomer diffusion or from a radiochemical protection of polyvinyl chloride by the phenyl rings of the grafted styrene. (auth)

• Research Organization: C.N.R.S., Bellevue, France
• NSA Number: NSA-16-018966
• OSTI ID: 4818321
• Journal Information: J. Polymer Sci., Journal Name: J. Polymer Sci. Vol. Vol: 57
• Country of Publication: Country unknown/Code not available
• Language: French

Related Subjects

CHEMISTRY
CHLORIDES
COLLOIDS
DIAGRAMS
DIFFUSION
EQUATIONS
EXPANSION
FLUORINATED HYDROCARBONS
GRAFT POLYMERS
LAYERS
ORGANIC FLUORINE COMPOUNDS
PHENYL RADICALS
POLYETHYLENES
POLYMERIZATION
POLYMERS
POLYVINYLS
RADIOCHEMISTRY
REACTION KINETICS
SPECTRAL SHIFT
STYRENE
SURFACES
TEFLON
TEMPERATURE