Showing papers in "Polymer Degradation and Stability in 1991"

TL;DR: In this paper, the authors studied the thermo-oxidative and thermodynamic stability of polypropylene and high density polyethylene (Cr-catalyst technology) using multiple extrusions.

TL;DR: In this paper, a review of recent mechanistic studies of intumescent and halogen-based fire retardants is presented, where the parameters which affect the thermal behavior of polymeric materials, such as oxygen concentration, pressure and heating rate, are examined in relation to combustion conditions.

TL;DR: The most relevant experimental observations for the understanding of the mechanism of thermal decomposition of PVC were obtained by the method of direct pyrolysis in the mass spectrometer as mentioned in this paper.

TL;DR: The decomposition products from pre-oxidized, linear low-density polyethylene have been identified and quantified for films exposed in the absence of oxygen to ultra-violet irradiation, heat or γ-irradiation as mentioned in this paper.

TL;DR: The degradation of poly(ethylene terephthalate) (PET) as substrate for audio-visual materials, amorphous sheet and bottles has been studied by both accelerated thermal and photo-ageing methods as mentioned in this paper.

TL;DR: The weak chemiluminescence observed when partially oxidised samples of polypropylene are heated in an inert atmosphere has been studied as a function of oxidation as discussed by the authors, and the integrated luminescence is shown to be proportional to titratable peroxides in the early stages of oxidation but the relation is curved at higher oxidation levels.

TL;DR: In this paper, thermogravimetry (TG) and thermal volatilisation analysis (TVA) were used to study the properties of poly(ethylene terephthalate) (PET), poly(butylene terephate), PBT and poly(decamethylene-terephthalates) (PDMT) and their thermal stabilities have been studied.

TL;DR: Several quinoidal oxidation products of 2,6-di-t-butyl-phenol-based antioxidants have been evaluated for UV/visible absorption characteristics in methylene chloride solutions and for contributions to Yellowness Index (YI) values in polyolefins.

TL;DR: In this paper, the traditional iodometric method appears to be highly reliable within certain constraints of reaction time imposed by sample crosslinking and the Fe2+ reaction was found to give values consistently one order of magnitude below the true level because of failure of the reagents to penetrate into the oxidized polymers even after a prior swelling step.

TL;DR: It is concluded that proper characterization of the implant surface before and after degradation studies is important for the understanding of degradation, in particular to exclude effects caused not by the polyurethane itself, but by surface contaminants which appear to have been present on the majority of materials subjected to detailed characterization so far.

TL;DR: In this paper, the mechanisms of photochemical and thermal oxidations of polyvinyl chloride (PVC) are investigated by UV-visible and FTIR spectroscopies associated to specific derivatization reactions or physical treatments.

TL;DR: In this article, the ageing of thin PET films in an oxygen plasma was investigated and a large decrease in mechanical strength was observed after several hours exposure, and the chemical reactions leading to the ageing process were identified.

TL;DR: In this paper, the degradation of glass-reinforced epoxy resin was studied under the following conditions: atmospheric pressure, and temperatures 145, 160, 180 and 190°C.

TL;DR: In this article, a study of low temperature degradation was carried out on hydrogenated (HNBR), highly saturated (HSN) nitrile rubber and NBR in the temperature range 75°C to 150°C and high-temperature degradation in the presence of nitrogen from room temperature to 800°C, respectively, and it was observed from thermogravimetric analysis that the temperature at which the degradation was maximum (T max ) was much higher in the case of HNBR than of NBR.

TL;DR: In this paper, the thermal degradation of bisphenol A polycarbonate has been studied using thermal volatilisation analysis (TVA), thermogravimetry and differential scanning calorimetry.

TL;DR: In this article, the photo-oxidation of polyisoprenes with different compositions (i.e. with different relative concentrations of 1,4 cis, 3,4 and 1,2 groups) have been compared.

TL;DR: In this paper, the influence of temperature, in the range 300-1000°C, and flame retardant type, on the yields of volatile products and char from flame-retardant treated cotton fabrics was investigated.

TL;DR: An analytical study of the thermo-oxidation of poly(vinyl chloride), carried out at moderate temperatures, is presented in this paper, where the authors consider the case of polyvinyl acid.

TL;DR: In this article, the presence of peracids among the peroxy species formed during photo-oxidation of isotactic polypropylene (PP) has been proven both chemically and spectroscopically.

TL;DR: In this paper, the properties of transformation products formed from thiocompounds, phenols and amines are interpreted from the point of view of their exploitation in complementary or supporting stabilization mechanisms in polymers.

TL;DR: In this article, it was shown that in the autoxidation of aralkyl hydrocarbons (tetralin and a normal paraffin blend) inhibited by aryl phosphites and phosphonites at 150-180°C, the phosphorus acid esters are hydrolysed to give phenols and hydrogen phosphites, respectively.

TL;DR: In this paper, the application of mechanistic knowledge of antioxidant action to address some of the problems of green issues and health hazards are exemplified in the discussion of time-controlled stabilisation, bound antioxidants and polymer modification by reactive processing.

TL;DR: Zinc hydroxystannate (ZHS) has been found to exhibit exceptional flame-, smoke and toxic gas-retardant properties in unsaturated polyester resins based on the reactive halogenated compounds, chlorendic anhydride (CA) or dibromoneopentylglycol (DBNPG) as discussed by the authors.

TL;DR: In this paper, the authors used titration to measure hydroperoxide concentrations in a series of unstabilized acrylic melamine and acrylic urethane coatings as a function of laboratory weathering time.

TL;DR: In this article, the authors investigated the thermal decomposition mechanisms of poly(trimethylene carbonate), poly(neopentylene carbonate, poly(2-phenyltrimmethylene carbonates) and poly(p-xylylene carbonate) and showed that all four polycarbonates decompose by an intramolecular exchange, an ionic process that produces cyclic carbonates as pyrolysis products.

TL;DR: The solubility of stabilizing additive is dependent upon intrinsic properties (melting point and heat of fusion) and upon interactions with the polymer and both may be equally important as mentioned in this paper.

TL;DR: In this article, the effect of photo-catalytic pigments (zinc oxide and two rutile forms of titanium dioxide) has been studied from the changes in the UV-visible and IR spectra of irradiated samples.

TL;DR: In this paper, a new cyclic chain termination mechanism for photo-oxidation of polymers was proposed, in which both hydrogen peroxide and acid are the necessary components of the inhibiting system.

TL;DR: The chemical reactions which occur in the thermal treatment of polycarbonate/poly(ethyleneterephthalate) (PC/PET) blends have been investigated by gradual heating (10°C/min) using thermogravimetry and direct pyrolysis into the mass spectrometer.

TL;DR: The structural changes in PVC chains brought about by photo-degradation are discussed in this article, where the lengths of the conjugated polyenes are n = 2-4 and do not change with reaction temperature or irradiation time either in air or in nitrogen.