Showing papers in "Polymer Degradation and Stability in 1993"

TL;DR: In this article, the primary thermal degradation mechanisms of polyethyleneterephthalate (PET) and polybutylenetrephthalate(PBT) have been studied by direct pyrolysis mass spectrometry using negative chemical ionization (NCI).

TL;DR: In this article, the thermal degradation behavior of chitosan and N -(2-hydroxy-3-mercaptopropyl)-chitosans (HMPC) has been studied by means of dynamic thermogravimetric analysis (TGA) in the range 30-600°C.

TL;DR: In this article, a series of resorbable polyhydroxyacids were studied by size exclusion chromatography (SEC), viscosity measurements, and differential scanning calorimetry (DSC) for the effect of the injection molding process on the molecular weight and thermal properties of the polymers.

TL;DR: The peroxides formed by the oxidation of polypropylene (PP) between 50 and 90°C consist of two types: fast-decomposing and slow-decomposed as mentioned in this paper.

TL;DR: In practical stabilization of polymers, phenols are mostly applied in combination with secondary antioxidants and light stabilizers as mentioned in this paper, as well as specific features of the reactivity of phenolic moieties creating a part of UV absorbers and bifunctional stabilizers.

TL;DR: A bacterium capable of degrading poly(hydroxyalkanoates) (PHA) was isolated from sea water and identified as Comamonas testosteroni, which had a very high hydrophobicity to adhere to the surface of the polyesters.

TL;DR: In this article, the role of the oxidation products of HALS in polyolefin stabilization is discussed in detail, and new stabilization mechanisms are proposed to explain the experimental facts, which are based on modified photooxidation mechanisms of unstabilized polymers.

TL;DR: In this paper, it was shown that the sigmoidal increase in apparent oxidation rate with time is inappropriate and should be considered instead as a statistical accumulation of rapidly oxidizing centres.

TL;DR: In this paper, high sensitive chemiluminescence equipment was applied to study the oxidative behavior at 125-150°C of individual polypropylene powder particles (10-500 μm) and film sections pressed from the powder.

TL;DR: In this article, the thermal properties of poly(vinyl chloride)/poly(ethylene-co-vinyl acetate) (PVC/EVA), poly(vyl chloride/poly(styreneco-acrylonitrile) (pVC/SAN) and poly(methylene-colonized polyvinyl alcohol) (PCA) blends were investigated by thermogravimetric methods.

TL;DR: In this paper, the degradation of a copolymer is attributed to the formation of polyenic chromophores of various lengths and appears to be closely related to the loss of Cyasorb UV 531.

TL;DR: In this paper, the degradation of an unstabilized and two HALS-stabilized polyethylene (PE) films is described by measuring: the oxygen uptake, the formation of CO and CO2, the FT-IR spectra, the stabilizer concentration and the oxygen content.

TL;DR: Weight-loss data have been obtained for the degradation in air of tetrafluoro-ethylene (TFE) homopolymer, its copolymers with hexafluoropropylene (HFP) and perfluorsopropylvinyl ether (PPVE), and for TFE/ethylene/perfluorobutylethylene terpolymer as discussed by the authors.

TL;DR: In this paper, the influence of temperature and residues of a TiCl 3 -based polymerization catalyst on the oxidation rate of polypropylene was determined, and the plots of the logarithm of the induction period versus the reciprocal temperature (Arrhenius plot) are curved.

TL;DR: In this article, the thermal decomposition of divalent metal alginate gel compounds has been studied using thermogravimetry (TG) and differential thermal analysis (DTA).

TL;DR: In this article, the authors re-examined the mechanisms of stabilization of polymers by UV absorbers, Ni stabilizers and hydroxybenzoates and found that only part of these light stabilizers is efficiently inhibiting formation of trans-vinylene groups in the initiation reaction in polyethylene.

TL;DR: In this article, a simple computer program has been devised to model the photodegradation process of UV screeners, which is highly dependent on the matrix since hydrogen bonding effects and free radicals can lead to decomposition of the screeners.

TL;DR: In this article, the authors studied the thermodegradation of the tetraglycidyl diamino diphenyl methane/diaminodiphenylsulfone system (TGDDM/DDS) defining the differents steps of the carbonization process.

TL;DR: In this article, the photolysis of poly(butyleneterephthalate) was carried out under radiation of long wavelength (λ ≥ 300 nm) and short wavelength(λ = 254 nm) in vacuum atmosphere.

TL;DR: In this paper, Ramaman spectroscopy has been used to study the in situ degradation of PVC in nitrogen and in air at different temperatures, and the results are interpreted using a "steady-state" approach.

TL;DR: In this paper, measurements of the molecular weights and molecular weight distributions of polymers using GPC were performed to investigate the photodegradation of polyethersulfone (PESF) and polysulfones (PSF).

TL;DR: In this article, the thermal decomposition behavior of polycarbonates has been investigated and conflicting explanations have been provided in relation to the differences in degradation conditions and methods of determining the nature of the reaction products.

TL;DR: In this article, the thermal degradation of two network copolymers of methyl methacrylate was studied as a function of the chemical nature of the cross-linking agent and the frequency of cross-links.

TL;DR: In this article, the behavior of oriented and non-oriented film samples irradiated under load has been investigated, as well as the effect of UV-irradiation on samples being mechanically tested, and the existence of photo-tribo-chemical effects have been detected by stress relaxation and stress-strain measurements, and by carbonyl index determinations.

TL;DR: The thermal degradation of lignins separated from black liquor waste from pulping of bagasse and cotton stalks has been investigated in this article, where the use of anthraquinone (AQ) as an additive for accelerating the pulping process raises the activation energy of the lignin in the black liquors waste.

TL;DR: In this paper, the thermal degradation of poly(furfuryl methacrylate) was studied by means of dynamic thermogravimetric analysis (TGA) in the temperature range 100-600°C under nitrogen and oxygen atmospheres at various heating rates, and the apparent activation energy for the interval 230-340°C corresponding to the first degradation step was determined.

TL;DR: Zinc hydroxystannate and zinc stannate (ZS) have been found to be effective flame retardants and smoke suppressants in unsaturated polyester resins when used in conjunction with additive-type halogenated compounds such as chlorinated paraffin wax and decabromodiphenyl oxide as mentioned in this paper.

TL;DR: In this paper, the structural changes of LLDPE have been studied using infrared spectroscopy combined with chemical derivatization and some stoichiometry differences under the two modes of exposure have been found.

TL;DR: In this paper, the thermal degradation of three different PVC samples has been studied at temperatures ranging from 110 to 200°C, and it was shown that the GTTG − isotactic triad conformation is the instability-determining structure in PVC.

TL;DR: In this paper, the thermooxidative aging of extruded ribbons of linear polyethylene cross-linked by irradiation was studied in the temperature interval 110 − 180°C.