Kinetic study of hindered amine light stabilizer photografting in low density polyethylene films under natural weathering conditions

Kaci, Mustapha; Hebal, Ghania; Benhamida, Aida; Boukerrou, Amar; Djidjelli, Hocine; Sadoun, Tahar

doi:10.1002/app.10492

Cited by 9 publications

References 18 publications

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Chemiluminescence of isotactic polypropylene induced by photo‐oxidative degradation and natural weathering

Jipa

Setnescu

Zaharescu³

et al. 2006

J of Applied Polymer Sci

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The analysis of the chemiluminescence (CL) kinetic parameters (induction time, oxidation rate, and activation energy) after the UV irradiation and outdoor exposure of isotactic polypropylene (i-PP) films have been studied. The initial CL emission intensity increased with increasing photodegradation time of i-PP films. On photodegradation, the activation energies were found to decrease linearly with time of UV-irradiation and outdoor exposure.The slopes of these linear dependences were used to indicate the degree of photodegradation of the polymer and also for the characterization of the stabilizing effect of the additive.

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Chemiluminescence of isotactic polypropylene induced by photo‐oxidative degradation and natural weathering

Jipa

Setnescu

Zaharescu³

et al. 2006

J of Applied Polymer Sci

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Kinetic Study of Hindered Amine Light Stabilizer Photografting in Poly(propylene) Films under Natural Weathering and Accelerated UV Conditions: Effect of Additive Concentration

Kaci

Hebal

Touati

et al. 2004

Macro Materials & Eng

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Full Paper: The objective of this work is aimed at determining the kinetics of HALS photografting in PP films as a function of the additive concentration under both natural weathering and accelerated UV conditions. The stabilizer studied had a single structure that combined HALS and a UV absorbing unit detectable at 308 nm in the UV spectrum of PP, capable of inducing a photoreaction with the polymer matrix. The kinetics of HALS photografting on PP films at various additive concentrations was determined by direct spectroscopic measurements on film samples through the absorption band of the stabilizer positioned at 308 nm in the UV spectra, which was attributed to the highly conjugated methylenic double bond. The content of free HALS was determined as a function of exposure time by UV spectroscopy for all the additive concentration ratios used. It is shown that the kinetics of HALS photografting increase with a decrease in the additive concentration ratio. The whole grafting process under conditions of natural weathering occurred in the PP film after almost 350 h of exposure, while approximately 20 h were necessary under accelerated UV conditions. Moreover, these kinetics are well described by a third order polynomial model, validated by a maximum value of the coefficient of correlation close to unity. This was also confirmed by a comparison of the time values measured at 50% of the total grafting calculated from the model with those observed experimentally. This finding was consistent with the data obtained on the free HALS content determined by UV spectroscopy.

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Grafting of Hindered Amine Stabilizer in Poly(propylene) Films under γ‐Irradiation

Kaci

Touati

Setnescu

et al. 2005

Macro Materials & Eng

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Summary: In this paper, the grafting of a hindered amine stabilizer (HAS) is studied in isotactic poly(propylene) (PP) films under γ‐irradiation. The HAS used has a definite structure that combines a hindered amine functionality and a UV‐absorbing unit (benzylidene malonate ester group) detectable at 308 nm in the UV spectrum of PP film and 314 nm in chloroform. The stabilizer is added to the polymer at various concentration ratios: 0.1, 0.2, and 0.3 wt.‐%. The percentage of HAS grafting in the PP film at various additive concentrations is determined as a function of γ‐radiation dose in the range of 0–100 kGy by direct spectroscopic measurements through the absorption band of the stabilizer in the UV spectra of the PP film. The percentage of free HAS extracted with chloroform from the PP film versus the radiation dose is determined by UV spectroscopy for all the additive concentrations used. This study reveals that only 80% of the HAS is grafted on the 100 kGy irradiated PP matrix independent of the additive concentration used. However, the percentage of HAS grafted on PP films displays an exponential dependence on γ‐radiation dose. These results are consistent with the data obtained on the free HAS content. γ‐Irradiation grafting of HAS in the PP is accompanied by the oxidative degradation of the polymer substrate that is evaluated by increasing the carbonyl index and reducing significantly the oxidation induction time of the PP films.

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Kinetic study of hindered amine light stabilizer photografting in low density polyethylene films under natural weathering conditions

Cited by 9 publications

References 18 publications

Chemiluminescence of isotactic polypropylene induced by photo‐oxidative degradation and natural weathering

Chemiluminescence of isotactic polypropylene induced by photo‐oxidative degradation and natural weathering

Kinetic Study of Hindered Amine Light Stabilizer Photografting in Poly(propylene) Films under Natural Weathering and Accelerated UV Conditions: Effect of Additive Concentration

Grafting of Hindered Amine Stabilizer in Poly(propylene) Films under γ‐Irradiation

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