Environmental degradation of stabilized LDPE. Initial step

Severini, F.; Gallo, Raffaele; Ipsale, Salvatore; Fanti, Natalino Del

doi:10.1016/0141-3910(86)90038-8

Cited by 31 publications

(12 citation statements)

References 8 publications

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“…6 The rate of crosslinking is found to be higher at initial stages as compared to chain scission. However, chain scission is found to be dominate during the later stages.'…”

Section: Resultsmentioning

confidence: 97%

Lifetime prediction of polymers

Hamid

Amin

1995

J of Applied Polymer Sci

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SYNOPSISNatural and artificially accelerated weathering trials were carried out on low-density polyethylene samples used for agricultural and disposable purposes. Modifications in polymer characteristics were studied using Fourier transform infrared (FTIR) spectroscopy, different scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscopy (SEM), and mechanical properties testing. The natural exposure trials were conducted at five geographical locations representing varying ambient temperature and humidity conditions and receiving different doses of solar radiation. The artificially accelerated exposure trials were carried out in an Atlas weatherometer for 5,000 hours, whereas the natural exposure was for 24 months. Rates of photo-oxidative and thermal degradation have been determined by measuring the formation of non-volatile carbonyl oxidation products which absorb in the infrared region with a maximum absorbance level at 1710 cm-'. Thermal characteristics were noticed to vary in terms of the shape and size of melting peak for both the natural and artificial weathering. This implies a change in crystallinity, which has indicated an increasing trend with exposure time. The crystalline melting temperature (T,) remains almost steady for both exposure tests. The drop in mechanical properties and the modification in polymer chain length were also monitored. The GPC analysis indicated the change in molecular weight distribution (MWD), which shows the formation of lower molecular-weight species. Surface modifications were revealed in terms of abrasion effects apparent from SEM micrographs. A correlation between natural and artificial weathering was considered for lifetime prediction in a short exposure time. It was found that the confidence level of predicting lifetime on the basis of artificially accelerated exposure trials is dependent on many parameters, which include time, material, equipment, etc.

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“…6 The rate of crosslinking is found to be higher at initial stages as compared to chain scission. However, chain scission is found to be dominate during the later stages.'…”

Section: Resultsmentioning

confidence: 97%

Lifetime prediction of polymers

Hamid

Amin

1995

J of Applied Polymer Sci

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“…This unsaturated configuration, which does not correspond to the nominal microstructure of LDPE, appears during the high-pressure polymerization process. 1 Figure 5 shows that the population of the vinylidene species decreases during the ageing process.…”

Section: Ftir Characterizationmentioning

confidence: 99%

“…This is because this type of agriculture allows earlier production, higher yields, and sustainable water economy. However, in such regions where sun irradiation is very intensive, it was reported by several authors that the films undergo rapid degradation when exposed outdoor to climatic ageing 1–4. The effect of sun exposure was also investigated for other polyethylene grades, like linear LDPE4 and high‐density polyethylene 5…”

Section: Introductionmentioning

confidence: 99%

“…However, in such regions where sun irradiation is very intensive, it was reported by several authors that the films undergo rapid degradation when exposed outdoor to climatic ageing. [1][2][3][4] The effect of sun exposure was also investigated for other polyethylene grades, like linear LDPE 4 and high-density polyethylene. 5 Although the study of UV-irradiation ageing in accelerated tests with artificial sources requires less time due to constant photon flux and faster degradation kinetics, 6,7 it is important to study the climatic ageing phenomena in outdoor experiments as well.…”

Section: Introductionmentioning

confidence: 99%

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Influence of climatic ageing on the mechanical properties and the microstructure of low‐density polyethylene films

Chabira

Sebaa

G’Sell

2008

J of Applied Polymer Sci

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Blown extruded films of low-density polyethylene (LDPE) have been subjected to climatic ageing in a subSaharan facility at Laghouat (Algeria) with direct exposure to sun. Samples were characterized by complementary techniques after prescribed amounts of time up to 8 months. It was shown by tensile testing that the mechanical properties are quite sensitive to ageing: (i) the elastic modulus increases and saturates, (ii) the tensile stress increases slightly, and (iii) the rupture energy decreases dramatically after 4 months weathering. Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance ( 13 C NMR) were performed to identify the evolution of the polymer microstructure. The FTIR spectra reveal the initial presence of vinylidene groups that exhaust rapidly after 4 months ageing. Also, it detects the progressive multiplication of vinyl groups and oxidation products of many kinds. The NMR technique revealed specifically the carbon-carbon configurations in the polymer chains. By contrast to the original film that contained almost exclusively butyl chain branches, the aged specimens presented shorter ramifications, namely ethyl branches. Also, the presence of quaternary atoms was detected after long ageing times. The discussion of these complementary results in the light of current literature makes possible to identify the leading mechanisms that control the decay of LDPE film properties. Although these mechanisms are numerous and complex, they can be schematically summarized within three main classes: oxidation, scission, and crosslinking. Each class is discussed in details.

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“…Feboseverini et al [11,12] , studied the environmental degradation of stabilized LDPE film. They found that the polymer degradation had started in the first 2400 h of exposure, and there are irregular changes in tensile strength and elongation at break up to exposure time of 7080 h. Also there is a constant reduction of the mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

An Investigation into the UV-Photo-Oxidative Degradation of LDPE by Using Cobalt Naphthenate as Photosensitizer

Eltayeb

Barikani

Mahdavian

et al. 2010

Polymer-Plastics Technology and Engineering

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The effect of cobalt naphthenate on photo degradation of low density polyethylene was studied. The carbonyl index, tensile strength, elongation at break, density and relative crystallinity of the samples were measured. The samples were made of different concentrations of LDPE and cobalt naphthenate. Parts of uniform thickness were cut for testing before and after UV-irradiation at every 30-days interval for 90 days. From the results of FTIR, and other measurements, it was observed that the UV-irradiation affects on the LDPE films and the rate of degradation increased with increasing both the concentration of the photosensitizer and time of irradiation.

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Environmental degradation of stabilized LDPE. Initial step

Cited by 31 publications

References 8 publications

Lifetime prediction of polymers

Lifetime prediction of polymers

Influence of climatic ageing on the mechanical properties and the microstructure of low‐density polyethylene films

An Investigation into the UV-Photo-Oxidative Degradation of LDPE by Using Cobalt Naphthenate as Photosensitizer

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