0000000000749200
AUTHOR
Maurizio Paci
Influence of small amounts of polyvinylchloride on the recycling of polyethyleneterephthalate
Abstract Polyethylene terephthalate (PET), and polyvinyl chloride (PVC), are commonly encountered in plastics stream coming from separate collections of plastic bottles. The presence of PVC in the recycled PET is very dangerous because of the chain scission provoked by the hydrogen chloride evolved from the macromolecules during degradation of PVC. Recycled PET must be free of PVC; contents of PVC as little as 100 ppm can induce degradation and discoloration of the polyester. PET, in its turn, is degraded when the processing is carried out in the presence of water. In previous work, however, the degradation of PET was eliminated and rather an increase of the molecular weight has been measur…
Competition between degradation and chain extension during processing of reclaimed poly(ethylene terephthalate)
During processing of poly(ethylene terephthalate) (PET) hydrolytic chain scission, induced by the presence of small amounts of water, is the main cause of degradation. During repeated reprocessing chain scission can also occur because of the presence of other polymeric contaminants like PVC. In order to avoid or to limit hydrolytic chain cleavage adequate drying of PET before melt processing is necessary. Of course this practice is even more recommended when repeated processing steps are used, as for PET recycling. The behavior of recycling PET obtained from post-consumer water bottles when treated in a melt mixer under different conditions has been investigated in order to better understan…
Coordination properties of imino(2-pyridyl)methylpalladium(II) compounds. Reactions with the chloride-bridged allyl dimers [MCl(η3-2-MeC3H4)]2 (MPd, Pt)
Abstract The imino(2-pyridyl)methylpalladium(II) compounds py-2-CR 1 NR [R 1 = trans -PdCl(PPh 3 ) 2 , R = C 6 H 4 OMe- p ( Ia ), Me ( Ib ), CMe 3 ( Ic ); R 1 = Pd(dmtc)(PPh 3 ), R = C 6 H 4 OMe- p ( Id )] react with [MCl(η 3 - 2-MeC 3 H 4 )] 2 (M = Pd, Pt) in a molar ratio 1/0.5 and in the presence of NaClO 4 to yield the binuclear cationic complexes II , [M(η 3 -2-MeC 3 H 4 )(py-2-CR 1 NR)]ClO 4 , where the α-diimino group acts as σ,σ N , N ′ chelating ligand. In the absence of NaClO 4 and with a molar ratio 1/1, the reaction leads initially to formation of a ionic intermediate A , [M(η 3 - 2-MeC 3 H 4 )(py-2-CR 1 NR)] [MCl 2 (η 3 -2-MeC 3 H 4 )], which subsequently undergoes exchange …
Liquid crystal polymers (LCP) as processing aids and reinforcing agents. A study of nylon 6/LCP blends
Influence de petites quantites d'un copolyesteramide thermotropique sur les proprietes mecaniques et la mise en œuvre du polyamide 6
Isomer Distribution and Interconversion in Cationic Allylpalladium(II) Complexes with 2-(Iminomethyl)pyridine Ligands
The complexes [Pd(η3-allyl)(N-N‘)]ClO4 [allyl = 2-butenyl or 3-methyl-2-butenyl, N-N‘ = C5H3(6-R)N-2-CHNR‘ (R = H, R‘ = Me, CMe3, C6H4OMe-4; R = Me, R‘ = C6H4OMe-4) and C5H4N-2-CH2NMe2] are present in solution with different isomers, the structures of which may be assigned by an 1H NMR criterion based on chemical shift changes of the pyridine H(6) and/or of the allylic methyl protons, as confirmed also by 2D 1H NMR spectra. The isomer distribution depends mainly on the steric requirements of both the allyl and N-N‘ ligands: for [Pd(η3-3-methyl-2-butenyl)(N-N‘)]ClO4 the predominant isomer (ca. 100%) has a structure with the allylic methyl groups cis to the coordinated pyridine nitrogen when…