Z. Maňásek

Stabilising effect of monomers, homopolymers and copolymers of vinyl derivatives of sterically hindered amines on the photo-oxidation of polypropylene

Abstract Vinyl derivatives of sterically hindered amines, N-(2,2,6,6-tetramethyl-4-piperidyl)methacrylamide, 2,2,6,6-tetramethyl-4-piperidyl acrylate and methacrylate and 1,2,2,6,6-pentamethyl-4-piperidyl acrylate and methacrylate were prepared. Monomers, homopolymers and copolymers with dodecyl methacrylate (DMA) and octadecyl acrylate (ODA) were tested as stabilisers of the photo-oxidation of polypropylene film. The copolymers exhibited higher efficiency and lower extractability. The photostabilising efficiency increased in the order: homopolymer

E.S.R. study of alkaline, oxidative degradation of saccharides. Identification of 2,5-dihydroxy-p-benzosemiquinone

Abstract The formation of radical intermediates during alkaline, oxidative degradation of saccharides and α-hydroxycarbonyl compounds has been studied by e.s.r. spectroscopy. Quantum chemical calculation and experiments in alkaline D 2 O solution showed that the dominant component of the overall spectrum corresponds to 2,5-dihydro- p -benzosemiquinone. Formation of this radical was also observed in the alkaline-degradation products of cellulose, starch, and (4- O -methylglucurono)xylan in the presence of air.

Ultra-violet degradation of polymethyl methacrylate in solution in presence of free and bound photostabilizers

Abstract A study has been made of the photolysis of polymethyl methacrylate in the presence of photostabilizer of the 2-hydroxybenzophenone type added or incorporated by copolymerization. It was found that the efficiency of a stabilizer is unaffected by the way in which it was added to the polymer. The photostabilizer acts in this system mainly as light filter.