Thermo and photo-oxidation of functionalized metallocene high density polyethylene: Effect of hydrophilic groups

Abstract

Many of the applications (packaging, bottles, films and pipes manufacture, among others) of high density polyethylene, HDPE (the most crystalline of the commercially available PEs) are based on its chemical inertness. Although this is an advantage along the shelf life for a specific product, inertness becomes an enormous shortcoming after its useful service when proper recycling processes are not viable, since the natural decomposition process can span over many decades [1-4]. Therefore, the need for degradable polyolefins has become a hot topic in research to manage those environmental problems. An ideal solution would be the obtainment of degradable polyolefins capable of retaining functionality as Thermo and photo-oxidation of functionalized metallocene high density polyethylene: Effect of hydrophilic groups M.U. de la Orden a, b, *

Degradation of Conventional and Oxodegradable High Density Polyethylene in Tropical Aqueous and Outdoor Environments

“…The degradation of each material caused the appearance of bands between 1800 and 1600 cm -1 , which can be assigned to ketones. This results agrees with those published by other researchs (Chiellini et al 2006, Huang et al 2011, Krehula et al 2014, de la Orden et al 2015. Figure 7 shows the average results of measurements of the absorbance of the carbonyl index during the experiment.…”

Applicability of Polymeric Materials as Phase Change Materials

“…This was in good agreement with the loss of Δ H M as shown in Figure where Δ H M was decreased to 27% after 360 h of exposure to static thermal load at 160 °C. However, an increase in Δ H M is typically observed at the beginning of the thermo‐oxidation due to higher chain mobility caused by chain scission . In the present study, however, this step in thermo‐oxidation could not be detected probably due to the comparably high exposure temperatures above T Mpeak and/or the long exposure times (minimum exposure time of 120 h) and the accompanied fast degradation of the HDPE.…”

“…According to refs. , the absorption bands correspond to unsaturated compounds (the presence of these unsaturated compounds was further proved by the increase of the absorption bands in the wavenumber range from ≈970 to 880 cm −1 , which represent the deformation vibrations of the unsaturated compounds). However, these compounds proved to be thermally less stable than the simultaneously formed carbonyl groups (lactones, esters, aldehydes, and carboxylic acids) as this broad absorption band decreased after 120 h of exposure at 160 °C.…”

“…The spectrum recorded from the unexposed granule and representative spectra recorded from the surface of specimens exposed to static thermal load of 160 °C at various times are displayed in Figure . Compared to the unexposed granule, an increase of the absorption band at 3404 cm −1 , which represents the stretching vibration of hydroperoxides, an increase of the absorption bands in the wavenumber range from ≈1780 to 1700 cm −1 , which represents the stretching vibrations of carbonyl groups, an increase of the absorption band at 1171 cm −1 , which represents the CO stretching vibration of the ester, and an increase in the absorption bands in the wavenumber range from ≈970 cm to 880 cm −1 , which represent the deformation vibrations of unsaturated compounds, a decrease of the absorption bands at 2915 and 2850 cm −1 , which represent the CH 2  stretching vibrations and changes in the absorption bands in the wavenumber range from ≈1480 cm to 1200 cm −1 , which represent the CH 2  deformation vibrations, were ascertained at the specimen surface. These findings were in good agreement with the thermo‐oxidative degradation mechanism and the resulting oxidation products for PE given in ref.…”

“…As described in refs. , the thermo‐oxidative degradation of PE yields, inter alia, lactones (1777 cm −1 ), esters/aldehydes (1734/1731 cm −1 ), which are rather difficult to distinguish with a spectral resolution of 4 cm −1 , and carboxylic acids (1712 cm −1 ) as oxidation products. Most likely, the broad absorption band between 1780 and 1700 cm −1 represents an overlap of these oxidation products.…”