Action of water in the degradation of low-density polyethylene studied by X-ray photoelectron spectroscopy

Abstract

Industrial low-density polyethylene (LDPE) was aged in stagnant distilled water during one year. Two types of this material were studied. The first one was without additives and the second type was doped with 4% of hindered-amine light stabilizers (HALS). Using X-ray photoelectron spectroscopy (XPS), the evidence that an oxidation occurs was demonstrated for the two types of LDPE (with and without HALS). One objective was to observe the chemical groups resulting of the ageing and to propose a mechanism of hydrolytic degradation for LDPE. The analysis of C1s spectra shows that the main oxidation products are C–O and C=O groups. Unlike the hydrolytic degradation of polypropylene, there is no presence of O=C–O groups, which suggests that there is no oxidative chain scission during hydrolytic ageing of the LDPE. The other objective of the study was to observe if the HALS can have an influence in the hydrolytic ageing of the LDPE. The values of the atomic concentration of the oxygen for the two types of samples show that the HALS could slightly slow down the oxidation of the LDPE

Chemical alteration of LDPE hollow fibers exposed to monoethanolamine solutions used as absorbent for CO2 capture process

“…This confirms that the rinsing procedure was effective. It is worth noting that the position of the above mentioned peaks (1643, 1577, 1543, 1261 and 1017 cm À1 ), do not correspond to those reported in previous works concerning PE auto-oxidation products, which were located at 1760, 1692, 1675 and 1410 cm À1 for HDPE oxidation in air at room temperature [21], at 1699, 1714 and 1740 for HDPE oxidation in air at 120°C [21,22] and at 1710-1720 cm À1 for LDPE oxidation in water [15]. Therefore, the newly observed peaks in Fig.…”

“…It is well known that oxidation can induce -COOH groups in PE, but this vibration, if present in the form of the COO À salts, would appear at a frequency between 1730-1700 cm À1 or around 1580 cm À1 [15]. Therefore, these newly observed bands cannot be attributed to acid groups.…”

“…In this mechanism, acetic acid, formic acid and acetone were reported to be the main polyethylene oxidation products. Messey et al [15] showed that, at room temperature, LDPE oxidation is accelerated in the presence of water due to a ''hydrolytic degradation'' mechanism, leading to the generation of ketone and alcohol groups. In addition, the impact of carbonyl group (main polyolefin oxidation product) concentration on oxidation rate of polyolefins in aqueous media was monitored by Henry et al [16].…”

“…Porcheron and Drozds [11] attributed the partial wetting of membrane pores to a possible plasticizing effect of CO 2 in membranes inside the contactors. Chemical degradation of polyolefin materials was investigated by different groups [12][13][14][15][16]. It was shown to be mainly due to the wellknown auto-oxidation phenomenon in air [12][13][14].…”

Flavonoids as Natural Stabilizers and Color Indicators of Ageing for Polymeric Materials

“…The division is determined by the types of environmental factors against which the material should be protected [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. One of the most important groups of stabilizers are, undoubtedly, antioxidants.…”