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New peroxide-free redox initiator for radical polymerization. [Display omitted] • Saccharin/copper salt/amine works as radical initiating system. • p-toluene sulfonate accelerates the polymerization. • high final conversions are obtained. In this work, a peroxide-free redox initiating system for radical polymerization of acrylate is suggested, based on the combination of saccharin, aromatic amine and copper salt. Free radical redox polymerization was investigated through differential scanning calorimetry (DSC), highlighting the efficiency of the redox initiating system. The role of the different components was studied mainly through liquid chromatography-coupled mass spectrometry (LC-MS), evidencing the involvement of aminoalkyl radical as initiating species. When p-toluenesulfonate is added as accelerator, the corresponding radical, as well as the oxygenated derived one, were found to act also as initiating radical. The oxidation state of the copper catalyst during the reaction is studied by UV–visible spectroscopy experiments, using bathophenanthroline as a probe for the involvement of Cu(I). From these experiments, a mechanism is proposed to account for the initiation reaction. [ABSTRACT FROM AUTHOR]

Abstract: Free-radical grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) films has been studied using supercritical carbon dioxide (SC-CO2) as a solvent and a swelling agent. As the reaction temperature was below the melting point, PP was modified in the solid phase. The PP film was first soaked with the monomer GMA and benzoyl peroxide (BPO) as an initiator using SC-CO2 at different experimental conditions of pressure, temperature, and thermal treatment time. After releasing CO2, film GMA molecules were grafted onto PP in different times. Using this method, the degree of grafting and the morphology could be controlled through the combination of pressure, temperature, and soaking time. FTIR spectra confirmed that GMA had been grafted onto PP and that polypropylene-graft-glycidyl methacrylate (PP-g-GMA) presented a high surface reactivity for conductive polyaniline anchoring. DSC measurements and TG analyses showed that the thermal profiles of the graft copolymer and virgin PP are quite similar and that the graft PP does not exhibit changes in terms of thermal degradation profile and melting temperature, respectively. X-ray data showed that a high degree of grafting leads to a lower degree of crystallinity of polypropylene. [Copyright &y& Elsevier]