Showing papers in "Polymer Degradation and Stability in 1982"

TL;DR: In this article, the influence of oxygen diffusion on the rate of photo-oxidation of polyethylene plaques was investigated and the results showed a relatively weak distance dependence to a depth of 1 mm, beyond which they are diffusion controlled.

TL;DR: In this article, the photo-oxidation of an ethylene-propylene copolymer has been studied at 310 and 365 nm, and the results indicate that the Norrish type II reaction occurs but that another chain scission mechanism is also operative.

TL;DR: In this paper, it was shown that a commercial hindered piperidine (I(A)) is not an effective melt stabiliser for polypropylene whereas related nitroxyl radicals (II(A)), and related hydroxylamine (III(B)) are highly effective.

TL;DR: In this article, the oxidative main chain degradation of polyacrylamide was studied and it was shown that only a small fraction (about 1%) of the attacking radicals initiated main chain scission.

TL;DR: In this article, the thermal degradation reactions of poly(1,3-phenylene isophthalamide) or Nomex (I) or Kevlar (II) aramids have been investigated in the temperature range 300-700°C by pyrolysis/gas chromatography/mass spectrometry.

TL;DR: In this paper, the changes in the surface chemistry of Bisphenol A polycarbonate initiated by irradiation with ultraviolet light (λ > 290 nm) in controlled atmospheres were monitored.

TL;DR: In this article, the initiating role played in the thermal degradation of anionic polystyrene by chain ends, either present originally or formed during the degradation, has been investigated and a constant ratio is found between rates of weight loss and of α-methyl styrene evolution throughout the degradation.

TL;DR: In this article, the photo-stabilising action of three metal chelates (nickel (II) 2,2′ thiobis (4-tert-octylphenylato) n -butylamine and the nickel and calcium derivatives of bis (ethyl-3,5-di-TERt-butyl-4-hydroxybenzyl) phosphonate, in polypropylene) was examined using normal and second order derivative ultraviolet, infra-red and phosphorescence spectroscopic techniques and hydroperoxide analysis.

TL;DR: In this paper, Nitrile rubbers containing three thiol antioxidants ((I) to (III)) in bound form have been evaluated as masterbatch concentrates by dilution in unstabilised nitrile rubber both at the latex stage and in the polymer melt.

TL;DR: In this paper, the rate of volatilisation of polystyrene with a fire retardant chloroparaffin is investigated and the mechanisms of the reactions which occur in the mixture are discussed and related to the fire retardants action of the chloroparaaffin.

TL;DR: The catalysis of the E2 dehydrochlorination of a model compound for the allylic chlorine atoms in PVC involves the co-ordination of this chlorine to the tin atom as discussed by the authors.

TL;DR: In this paper, it was shown that when polypropylene is thermally degraded in mixtures with a highly chlorinated fire retardant chloroparaffin, a smaller amount of the lighter hydrocarbon fraction, which is also modified in composition, is evolved compared with that evolved from pure polypropylon.

TL;DR: In this paper, the thermal stabilities of N-methylsubstituted polymers are sensibly higher than those of the corresponding N-H polymers based on a knowledge of the primary thermal fragmentation processes in these polymers, an attempt was made to correlate chemical structure, mechanism of thermal decomposition and thermal stability

TL;DR: In this article, a simple method of measuring the radiation output of artificial weathering devices below 320 nm, based on the use of polysulphone film, is described and compared with the level of radiation above 320 nm found outdoors.

TL;DR: In this paper, the photo-degradation of cellulose nitrates of differing degrees of substitution and double-based propellants from the surface point of view was studied. But the results were limited to the case of double-base propellants.

TL;DR: In this article, a technological study of the performance of concentrates (master-batches) of two thiol-based bound antioxidants (I and II) under conditions of solvent extraction is presented.

TL;DR: A phenolic thiol antioxidant and two thiol amides have been reacted with nitrile-butadiene rubber both in the latex and during melt processing to give masterbatch concentrates as discussed by the authors.

TL;DR: A number of phenolic antioxidants containing a sulphide linkage have been found to react with natural rubber latex in the presence of a redox radical generator, but the extent of adduct formation is only about 50% as discussed by the authors.

TL;DR: In this paper, the thermal degradation reactions of seven aromatic amides which are structurally related to the commercial aramids Kevlar (poly(1,4-phenylene terephthalamide)) and Nomex (poly (1,3-phenylon isophthalamide) have been investigated in the temperature range 450 to 700°C by pyrolysis/gas chromatography/mass spectrometry.

TL;DR: In this article, it was shown that antioxidants containing a thiol group can be mechanochemically reacted with both natural rubber (NR) and styrene-butadiene-rubber (SBR).

TL;DR: In this paper, the thermal and photochemical stability of PVC samples stabilised by a combination of dibutyl tin bis iso-octyl thioglycollate (DOTG) and DIBUTYL tin maleate (DBM) has been studied.

TL;DR: In this paper, the same carbocation intermediate is believed to be involved in these reactions and its formation can be catalysed by the Lewis acid, in the same way as the dehydrochlorination of the chlorohexenes and their isomerisation.

TL;DR: From oxygen and nitrous oxide indices of polypropylene-chlorinated paraffin mixtures, it can be deduced that, in addition to the flame poisoning effect of HCl eliminated by the chloroparaffin, the lower flammability of the volatile products formed by thermal degradation, heated in the presence of this additive seems to contribute to its fire retardance activity.

TL;DR: In this paper, a study was made, using thermogravimetry, of the thermal stability of some of the most recently produced fluorine-containing elastomers, and the evolution of hydrogen fluoride (HF) as a function of time and temperature was also monitored by a fluoride ion selective electrode.

TL;DR: In this article, the irradiation of nylon 6,6 film with light of wavelengths greater than 250 nm and 300 nm has been studied using uv derivative absorption spectroscopy, and the polymer showed a strong absorption at 290 nm which is associated with an α,β-unsaturated carbonyl species.

TL;DR: In this article, a 119m Mossbauer spectroscopy has been used to study chemical changes undergone by two commonly used stabilisers, dibutyltinbis( iso -octylthioglycollate) and dibdutyltinbi( iso-octylmaleate), during irradiation of stabilised PVC in artificial sunlight.

TL;DR: In this article, the influence of bromination, treatment with sulphur dioxide and light filtration on the rate of photo-oxidation of unstabilised polypropylene film has been examined using infra-red and derivative ultraviolet-visible absorption spectroscopic techniques.

TL;DR: In this article, the rate of oxygen absorption by unstabilised PE and PP, as well as by the same polymers stabilised with bis-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770), has been determined during photo-oxidation at several temperatures and uv light intensities.

TL;DR: In this paper, evidence is presented to show that there is a correlation between the amount of unsaturation in polypropylene and its induction period during photo-oxidation, while doping the polymer with hexane extracts causes an increase in stability.