Correlating different techniques in the thermooxidative degradation monitoring of high-density polyethylene containing pro-degradant and antioxidants (original) (raw)
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Polyolefins Journal, 2023
I n the present study, the thermal oxidation behaviour of high-density polyethylene (HDPE) containing each of two types of oxidized polyethylene (OPE), one prepared using 500 ppm of iron (III) stearate as pro-oxidant and the other without the pro-oxidant, was investigated. Fourier-transform infrared spectroscopy (FTIR) showed that the carbonyl index of the HDPE increased from 1.03 to 6.37 upon the addition of 5.0 wt.% of OPE containing the pro-oxidant after 100 h of thermo-oxidative aging at 90°C. Moreover, it was observed that the rate of changes in retained tensile strength and retained elongation-at-break of the HDPE during the thermal oxidation increased in the presence of 5.0 wt.% of each type of OPE, especially, the one containing iron (III) stearate, which was consistent with the obtained data from gel content measurements. Lastly, the evolution in crystallinity of the film samples was monitored by density measurements as well as differential scanning calorimetry (DSC). It was revealed that the crystallinity of the tested films during thermo-oxidative degradation grows faster in the presence of OPE. Overall, the findings indicated that the utilization of OPE containing trace amounts of iron (III) stearate can accelerate the thermal oxidation of HDPE films and facilitate entering the final biodegradation stage, while resolving the need to use high concentrations of harmful heavy metal salts.
Polymer Degradation and Stability, 2013
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Polymer Degradation and Stability, 1999
Thermo-oxidation of blown low density polyethylene (LDPE) films modified with different combination of biodegradable filler, prooxidant and photosensitizers was conducted in oven at 60 and 100°C for a period of 14 days. Volatile and semivolatile degradation products were extracted by solid phase micro extraction (SPME) technique and identified utilizing gas chromatography–mass spectrometry (GC–MS). Chemical and morphological changes were monitored and
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Polymer Degradation and Stability, 2003
Thermo-oxidative degradation of polyethylene films, containing pro-oxidant has been studied at three temperatures that normally occurs during composting conditions. Beside temperature, oxygen content was also varied. After various periods of time the effects of thermo-oxidation were evaluated by measurements of molecular mass of the materials. It is shown that the temperature is the most important factor influencing rate of thermo-oxidative degradation of the materials while oxygen content is of negligible importance. The investigation has also shown that when the material is degraded into low molecular mass products the material is bioassimilated. The degree of bioassimilation in our case was about 60 % and still increasing, after 180 days.
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Journal of Polymer Science Part A: Polymer Chemistry, 1988
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Evaluation of the Thermal and Natural Oxidation of Modified Polyethylene
The polymer polyethylene (PE) is a flexible, light, transparent and impermeable material, which it takes it more than a hundred years to be degraded. One of the possible solutions for this low rate of degradability is applying the biodegradable polymer, that is, polymers that present their chemical structure modified by the action of the microorganisms. The main of this work is to evaluate the (bio)degradation of low-density polyethylene (LDPE) modified by the incorporation of CESA-BIO PEA0420086-ZN addictive under natural and thermal ageing. The incorporation of the addictive to the LDPE didn't cause any effect on its degradable, but, after a period of either thermal or natural ageing, the functions of ox-degradation were activated and meaningful reductions of the properties analyzed were reached, which are directly proportional to the amount of addictive preset in the composition. The results on the mechanical properties showed that 1% of the addictive caused a reduction of 75% for the compositions exposed to a thermal treatment; meanwhile a 50% reduction was reached by those under a natural treatment.
Journal of Applied Polymer Science, 2008
This article reports the results of studies on the photooxidative and thermooxidative degradation of linear low-density polyethylene (LLDPE) in the presence of cobalt stearate. Various amounts of cobalt stearate (0.1-0.9% w/w) blended with LLDPE and films of 70 6 5 l thickness were prepared by a film-blowing technique. The films were subjected to xenon arc weathering and air-oven aging tests (at 708C) for extended time periods. We followed the chemical and physical changes induced as a result of aging by monitoring changes in the mechanical properties (tensile strength and elongation at break), carbonyl index, morphology (scanning electron microscopy), melt flow index, and differential scanning calorimetry crystallinity. Cobalt stearate was highly effective in accelerating the photodegradation of LLDPE films at concentrations greater than 0.2% w/w. The kinetic parameters of degradation, as determined by nonisothermal thermogravimetric analysis, were estimated with the Flynn-Wall-Ozawa isoconversion technique, which was subsequently used to determine the effect of cobalt stearate on the theoretical lifetime of LLDPE.
Materials Sciences and Applications, 2017
High density polyethylene (HDPE) samples, containing different concentrations of prodegradant additive d2w ® , were prepared. The properties of the samples were evaluated through differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheometry, and scanning electron microscopy (SEM). The work contributes to decreasing the products made of non-biodegradable polymeric materials derived from fossil sources which are have become a problem due to their increasingly inappropriate disposal and long degradation time in the environment. The obtained results indicated that there was no degradation of the samples due to processing. No significant changes in melting temperature, crystallinity, viscoelastic behavior, molecular weight and chemical composition were observed. Images from SEM analysis showed particles on HDPE surface, attributed to prodegradant additive d2w ®. Oxidation Onset Temperature (OOT) results showed that the additive d2w ® accelerated the degradation of HDPE. The activation energy (Ea) was determined by Ozawa-Wall-Flynn method. The obtained values were used for lifetime estimation of the samples. At 25˚C, HDPE with d2w ® showed a lifetime 50% higher than that of HDPE without this additive. This fact is attributed to the presence of stabilizers in masterbatch d2w ® and the absence of oxygen in thermogravimetric analysis.
Journal of Polymers …, 1998
The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products. The samples were thermooxidized for 6 days at 100°C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono-and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in M n from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.