Polyethylene greenhouse cover aged under simulated sub-Saharan climatic conditions

Hassini, Noureddine; Guenachi, K; Hamou, A.; Saiter, Jean‐Marc; Marais, Stéphane; Beucher, E.

doi:10.1016/s0141-3910(01)00225-7

Cited by 31 publications

(21 citation statements)

References 16 publications

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“…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. This is because natural weathering represents a complex combination of factors including sun radiation periodicity, temperature, humidity, sand wind stresses, and atmospheric gases permeation (oxygen and pollutants) 8. The effect of these factors intervening altogether cannot be predicted simply by the combination of results from standard laboratory tests for which environmental constraints are imposed separately 9, 10…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…The most facile alternative for chemical resistance improvement is the addition of a suitable antioxidant. Several classes of antioxidants were intensively studied for various purposes: prevention of thermal degradation [6][7][8] or weather aging [9][10][11][12] , and radiation stability. [13][14][15] The majority of products reach high performances due to protective action of antioxidants, which confer excellent protection against the action of permanent Summary: The thermal stability of gamma irradiated low density polyethylene (LDPE) films in presence of various structures of hindered amine stabilizers (HAS) was investigated by the oxygen uptake method under constant temperature of 180 8C and normal pressure conditions.…”

Section: Introductionmentioning

confidence: 99%

Thermal Stability of Gamma Irradiated Low Density Polyethylene Films Containing Hindered Amine Stabilizers

Zaharescu¹,

Kaci

Hebal

et al. 2004

Macro Materials & Eng

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Summary: The thermal stability of gamma irradiated low density polyethylene (LDPE) films in presence of various structures of hindered amine stabilizers (HAS) was investigated by the oxygen uptake method under constant temperature of 180 °C and normal pressure conditions. The thermo‐oxidation was run using air environment. The sigmoidal dependency of oxygen uptake allows the calculation of the main kinetic parameters: oxidation induction time and oxidation rate on the propagation step. The various steps involved in the thermal degradation process were detected by the derivative procedure applied to the dependencies of oxygen uptake on time. It was found that the kinetic parameters of the thermal degradation process, determined by oxygen uptake, revealed the antioxidant role of HAS in γ‐irradiated LDPE films by providing better stability, when compared with the unstabilized samples. Moreover, the results indicated that the dependencies of oxygen uptake on thermal degradation time involved two degradation stages: the former occurring in the ungrafted moiety and the latter taking place after the antioxidant depletion is achieved. The stabilization efficiency of these oxidation inhibitors provides satisfactory thermal resistance to LDPE films, especially those based on an alkoxyamine structure.Dependencies of oxygen uptake on time at the thermal degradation of LDPE irradiated at 812 kGy. (‐□‐) free of additive; (‐○‐) Tinuvin 123; (‐▵‐) Sanduvor PR 31; (‐⋄‐) Uvasil 299.magnified imageDependencies of oxygen uptake on time at the thermal degradation of LDPE irradiated at 812 kGy. (‐□‐) free of additive; (‐○‐) Tinuvin 123; (‐▵‐) Sanduvor PR 31; (‐⋄‐) Uvasil 299.

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“…After natural weather ageing, the PVA surface becomes increasingly rough, and holes can be seen due to the erosion of the polymer ( Figure 6B). The sand wind also contributes to the erosion of the polymer [27] . With an increase in exposure time, the surface showed brittleness and lack of physical integrity.…”

Section: Resultsmentioning

confidence: 99%

Natural weather ageing of starch/polyvinyl alcohol blend: effect of glycerol content

Appu¹,

Khan

et al. 2013

Journal of Polymer Engineering

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Starch plasticized with glycerol and blended with polyvinyl alcohol (PVA) is recommended for use as a biodegradable material. The present article reports the results of studies of the natural weather ageing of starch/PVA blends having various amounts of glycerol in natural weather conditions of Saudi Arabia, with special reference to morphology and thermal behavior. Neat PVA has been used as a control to understand its behavior in its blend with starch. Differential scanning calorimeter studies indicated that an increase in the exposure time of samples to natural environment increases the crystallinity of PVA due to the breakage of intermolecular hydrogen bonding, thus facilitating the removal of the amorphous portion of the polymers in the blend. Thermogravimetric analysis revealed that an increase in glycerol content enhanced the degradation of the polymer, which is corroborated with the findings from the surface morphology using scanning electron microscopy and Fourier transfer infrared spectroscopy analyses.

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Polyethylene greenhouse cover aged under simulated sub-Saharan climatic conditions

Cited by 31 publications

References 16 publications

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

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

Thermal Stability of Gamma Irradiated Low Density Polyethylene Films Containing Hindered Amine Stabilizers

Natural weather ageing of starch/polyvinyl alcohol blend: effect of glycerol content

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