Showing papers in "Polymer Degradation and Stability in 1988"

TL;DR: In this article, the role of metal compounds in the degradation of polyolefins has been investigated and some typical examples of degradation by metallic compounds, mostly commercial pigments and transition metal compounds of stearic acid and acetylacetone, in typical commercial polymers are discussed.

TL;DR: In this paper, the fundamental mechanisms by which fire retardant additives can interrupt the self-sustained combustion cycle of organic polymers are reviewed and a deeper understanding of fire retardance mechanisms acquired through detailed thermal degradation studies is the only way to answer the ever increasing demand for polymeric materials characterised by minimised overall fire hazard.

TL;DR: In this paper, the mechanism of action of hindered phenols was discussed using the results of the elucidation of the chemical transformations which occur during the stabilisation process, and the mechanisms responsible for co-operation phenomena, regenerative processes involved in homo- and heterosynergism, intramolecular cooperation in bifunctional phenolic antioxidants, and cooperation pathways between hindered compounds and HALS were shown.

TL;DR: In this article, the interaction of hindered amine stabilizers (2,2,6,6-tetramethylpiperidines) with simple hydroperoxides, peroxy radicals, and acylperoxy radicals was studied.

TL;DR: In this article, low density polyethylene (LDPE) samples were exposed to UV irradiation for 27 days and then they were added to an abiotic and a biotic environment.

TL;DR: The thermal and ablative properties of an insulator compound based on EPDM have been investigated by exposing the compound to the ablative environment produced by a plasma arc jet in the laboratory.

TL;DR: In this article, the etch rates for various polymer films exposed to O(3P) downstream from, and out of the glow of, the O2 plasma are compared with published values from the following sources: the Space Shuttle STS-8 flight experiment, and beam experiments.

TL;DR: In this paper, the degradation of polypropylene film was studied up to 2424 h of exposure and a continuous reduction of the mechanical properties began after about 700 h. The degradation mechanism was based mainly on the β-scission reaction.

TL;DR: It is proposed that the observed ageing process arises from the breakdown of metastable groups in the polymer, which are formed on irradiation, with consequent release of long inter-lamella tie chains, which removes an inhibition to crystal perfection processes, which can occur at room temperature in polyethylene.

TL;DR: In this paper, the relationship between changes in degree of polymerization and conversion was obtained experimentally for three anionically polymerized PMMA samples with different initial degrees of polymerisation (315, 1250 and 5690) Kinetic constants for random scission initiation and average zip length were determined by combined use of the experimental data and a theoretical model (Model 1) based on the same depropagation rate via β scission from both primary and tertiary radicals generated from random scissions of backbone CC bonds.

TL;DR: In this article, a unique bifunctional mechanism was proposed, which consists of polymer radical trapping by the acrylate group, followed by fast hydrogen transfer from intramolecular hydrogen-bonded phenolic hydroxyl groups to result in stable phenoxyl radicals.

TL;DR: In this paper, the effect of chain defects in PVC on the rate of thermo-dehydrochlorination (TDHC) has been investigated and it has been shown that allylic chlorine is a major initiation site during TDHC.

TL;DR: In this paper, the effect of 9,10-dibromoanthracene, an excited carbonyl sensitizer, and β-carotene, a singlet oxygen quencher, on the intensity and spectral distribution analysis of chemiluminescence emitted from the stored IPP was discussed.

TL;DR: In this article, the properties of blends of polypropylene and degraded polyethylene have been studied and the unusual behaviour of the elongation at break at break is correlated with crystalline phase segregation which appears with decreasing molecular weight of the degraded component.

TL;DR: In this article, the properties of 8-quinolyl acrylate with transition metal bromides and uranyl acetate have been characterized by elemental analyses, electronic and vibration spectroscopic studies and magnetic moments.

TL;DR: In this article, the photo-initiation rates of three acrylic-melamine coatings have been followed as a function of "QUV-light only" accelerated exposure, and no evidence is found for autoxidation in these coatings.

TL;DR: In this article, the chemical and physical properties of polypropylene samples by γ-irradiation in air have been measured for a range of potential stabilizers, including benzophenone derivatives.

TL;DR: In this article, the quantum yield for random chain scission during environmental photo-degradation of a stabilised low density polyethylene film was calculated on the basis of the reduction of Mw during exposure.

TL;DR: In this article, it was shown that the oxidation of nickel dialkyl dithiophosphates by hydroperoxides at room temperature, as measured by 31P NMR, yields thiophophosphoryl monosulphide and thionophosphoric acid as major products when the molar ratio of hydroperoxide to the nickel complex is high.

TL;DR: In this paper, the bulk and surface effects of UV-irradiation are compared in relation to oxidative degradation in blow-extruded films of low-density polyethylene.

TL;DR: In this article, Fourier transform infrared spectrometry (FTIR) was used to identify free and H-bonded hydroperoxide bands at 3540 and 3440 cm −1, on the basis of absorption frequency and a decrease in peak intensity upon exposure to reactive chemical vapors.

TL;DR: In this article, a kinetic model for the mechanism of inhibited autooxidation of polymers is presented, where the reaction of the peroxide radical RO2• with the radical In• (stage 8) and the molecule InH (stage 7) of the inhibitor is considered to be the kinetic chain termination step.

TL;DR: In this article, it has been shown that on rapid heating to 700°C, DBDPO volatilisation competes with debromination by antimony trioxide or bismuth carbonate leading to volatile SbBr3 or BiBr3 which are formed by different mechanisms.

TL;DR: In this paper, the authors evaluated consistent rate constants for the reaction of alkylperoxyl radicals with phosphites at 65°C depending on the structures of the phosphite and of the hydrocarbon substrate.

TL;DR: The thermal stability and the mechanism and kinetics of decomposition of polyphenylsilsilesquioxane (PPS) and some related polyorganosiloxanes were studied by means of thermal analysis, pyrolysis GC, GC-MS, and other methods as discussed by the authors.

TL;DR: In this paper, the thermal, hydrolytic and photochemical oxidation of blue water pipe material has been studied using Fourier Transform infra-red microscopy, differential scanning calorimetry (DSC) and hydroperoxide analysis.

TL;DR: In this article, p-Benzoquinone was polymerized either cationically using dilute sulfuric acid or borontrifluoride-acetic acid complex or anionically by the use of sodium ethoxide in ethanol as polymerization catalysts.

TL;DR: In this paper, the authors consider a complex of problems dealing with the kinetics of hydrolytic degradation and stabilization of a wide range of mono-and polyacetals as well as giving examples of the use of various hydrolysis mechanisms and methods of inhibition of acid acid degradation.

TL;DR: The effect of a thin coating of hydroxyterminated polybutadiene (HTPB) rubber on the stress relaxation of unaged and aged solid propellant insulator compound based on EPDM has been investigated in this paper.

TL;DR: In this paper, the effect of metal ions on the effectiveness of four commercial antioxidant systems, viz. Topanol, Santowhite, Hostanox 03 and Irganox 1425, in polypropylene (PP) films was examined using infra-red and second-order derivative uv spectroscopy.