Showing papers in "Polymer Degradation and Stability in 1994"

TL;DR: In this article, the authors discuss the role of PAPERS of PURE CELLULOSE - MECHANISM of CELLULE DEGRADATION and PAPER EMBRITTLEMENT.

TL;DR: In this paper, the authors investigated the thermal degradation of poly(l-lactide) and developed a stabilizer to stabilize the polymer against thermal degradation by deactivating the catalyst residues.

TL;DR: In this article, the thermal degradation of a series of homopolymers and copolymers of chlorotrifluoroethylene and vinylidene fluoride was carried out using thermogravimetry and thermal volatilisation analysis (TVA).

TL;DR: In this paper, the authors examined the performance of commercial photodegradable polyethylenes with respect to rate and extent of oxidation as measured by carbonyl formation, molar mass reduction and ability to support microbial growth when used as the only source of carbon.

TL;DR: In this article, the degradation of poly(ethylene terephthalate) bottle and amorphous sheet materials are investigated under different environmental conditions (wet soil, 100 and 45% relative humidity and UV irradiation) by measuring the rate of chain scission, using viscometric analysis, endgroup analysis by FTIR and crystallinity via density measurements at different temperatures.

TL;DR: In this article, the authors applied the invariant kinetic parameter (IKP) method in order to describe the degradation of two epoxy resins using a non-isothermal thermogravimetric technique.

TL;DR: In this paper, it was shown that the rate of decrease of PET properties drops after three extrusions, and with further recycling steps no remarkable changes of the properties are observed.

TL;DR: In this article, the second-order kinetic model was applied to the amorphous phase, taking into account the increase in its hydrophilicity, leading to a relatively good representation of the polymer behaviour, the second order rate constant being k = 1·83 × 10−8 kg mol−1 s−1.

TL;DR: In this article, the activation energy of degradation of cellulose in the temperature range 100-200°C is 111 ± 6 kJ/mole and is independent of the reaction conditions.

TL;DR: Ten species of independent Gram-negative bacteria capable of degrading polyhydroxyalkanoates (PHA) were isolated from the fresh water of Lake Biwa and the rate of enzymic degradation of P[(R)-3HB] film was about twice as high as that due to the enzymes from other bacteria such as Alcaligenes faecalis, pseudomonas pickettii, Comamounas testosteroni, and Pseudomonas lemoignei.

TL;DR: The kinetics of the thermal degradation of solid powdered polyvinyl chloride (PVC) under nitrogen was studied by thermogravimetry, rate of hydrogen chloride evolution and rate of polyene sequence formation.

TL;DR: The photofading and photostability of dyed and pigmented polymers is a commercial problem involving a complex interplay of phenomena and mechanisms many of which remain unresolved as mentioned in this paper.

TL;DR: The importance of providing materials with low energy demands from renewable resources, which also offer biodegradability as an option in waste disposal not conflicting with recycling or incineration activities, has served to promote starch blends and alloys in polymer applications which have already achieved a significant position in world markets.

TL;DR: In this paper, the degradability of polycaprolactone (PCL) and conventional plastics (polyethylene, LDPE; polypropylene, PP; nylon 6, NY; polystyrene, PS; polyethylene terephthalate, PET; and poly-β-hydroxybutyrate, PHB) were prepared by mechanical blending.

TL;DR: The optimum activity of degrading P(3HB) by the depolymerase was observed at pH 8·5 and 70°C, and the rate of production of the monomer and dimer increased to a maximum value with the concentration of PHB depolyMERases, followed by a gradual decrease.

TL;DR: The rate of biodegradation of polycaprolactone samples, hydroxy- and methoxy- terminated, by mixed cultures of micro-organisms from a suspension of compost, and by a pure culture of an actinomycete isolated from compost, has been monitored by the measurement of oxygen consumption.

TL;DR: The enzymatic degradation processes of the poly(3-hydroxyalkanoates) (PHA) films were studied at 37°C in a phosphate buffer containing the PHA depolymerase from A. faecalis T1 and markedly decreased with an increase in the side-chain length of the 3-hydroalkanoate monomeric units.

TL;DR: In this article, the influence of temperature, atmosphere and drying conditions on pre-processing degradation of PET, which is known to give volatile aldehydic products, was investigated using thermogravimetric analysis, the formation of 2,4-dinitrophenylhydrazones and solid/gas headspace chromatography.

TL;DR: The use of carbon black in polyolefins is widespread as mentioned in this paper, and the role of reactive chemical groups on the carbon black surface, particle size and concentration has been reviewed.

TL;DR: In this article, the effect of tensile stress on the rate of photo-oxidation of polypropylene has been investigated and it was shown that the presence of glass-fibre-reinforcement reduced the sensitivity of the material to the application of Tensile stress during ultraviolet irradiation.

TL;DR: The thermal degradation of PVC consists of a slow initiation followed by a chain of fast reactions generating a series of active intermediates with an increasing number of double-bonded double bonds as mentioned in this paper.

TL;DR: In this paper, a thermogravimetric analysis of unmodified cotton fabrics and cotton fabrics finished with various flame retardant treatments at commercial levels of application were subjected to thermogram analysis in a continuous flow of nitrogen.

TL;DR: In this paper, a detailed oxidation mechanism based on FTIR and 13C-NMR analysis is proposed for isotactic polypropylene, showing the presence of vinylidene groups and the predominance of methyl ketones on in-chain ketones.

TL;DR: Hindered amine stabilizers (HAS) are promoted as long-term heat stabilizers as discussed by the authors, but their effectiveness at low temperatures (below 100°C) is more pronounced than at high temperatures (150°C).

TL;DR: In this paper, a comparative study of a number of intumescent systems for commercial ethylene-vinyl acetate polymers and based on ammonium polyphosphate and polyol is presented.

TL;DR: In this article, the burning behavior and influence of flame-retardant species on the flammability of fiber-forming homopolymer and copolymers of acrylonitrile are reported.

TL;DR: In this article, the principal degradative process induced by γ-ray irradiation involves Fries type free radical reactions leading to the destruction of the carbonate linkages and formation of a number of phenol coupling products and salicylate esters.

TL;DR: In this article, a 1:2 ratio mixture of calcium and zinc stearates was heated at different temperatures to form the CaSt[ZnSt3] complex reported in the literature.

TL;DR: In this article, two accelerated degradation systems for the marine and soil exposures of polymer films are described, which are designed to provide controlled environments in which rates of degradation could be accelerated.

TL;DR: In this paper, the performance of the Hindered Amine Light Stabilizer (HALS) was investigated in polyolefin fibers and its effect on UV stability and long-term heat aging.