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Weathering and accelerated aging of high density polyethylene mixtures with regranulate
Bruzl, Dominik ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
This master thesis deals with the effect of multiple extrusion (1, 2, 3) and the addition of 30, 60 and 90 % of this recycled material on the weathering and accelerated ageing of high density polyethylene (HDPE) copolymer. The weathering lasted 9 months and the accelerated ageing 1000 h at 65 °C. The degree of material degradation was assessed from changes in mechanical and physical properties and compositional changes using dynamic mechanical analysis and tensile testing, differential compensation calorimetry, thermogravimetric analysis and infrared spectrometry in the full attenuated reflection mode. The measurements showed that repeated extrusion as well as the addition of recycle material to the original one (R0) slightly slows down the photo-oxidative degradation during first month, but after that it does not have a negative or significant positive effect on the progress and rate of overall material degradation. A certain exception was the recycled material after the 3rd extrusion (R3), where the original properties comparable to R0 did not change much during ageing. The mechanical properties of the blends were better or comparable to R0 during ageing, but after months 6 and 9 the breaking strength of most of them decreased substantially as a result of the shortening of the chains. Accelerated ageing caused significant embrittlement in all samples, resulting in a reduction in yield strength by about half and almost immediate failure.
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Controlled life-time polypropylene
Demková, Eva ; Petruš, Josef (referee) ; Tocháček, Jiří (advisor)
The master´s thesis is focused on the characterization of degradation process of polypropylene and polypropylene with statistic copolymer into which manganese (II) stearate and cobalt (II) stearates were added at 0.05, 0.10 and 0.20 wt.% loadings. The aim of the thesis was to prepare the controlled life-time polypropylene. The degradation was studied at varying temperatures and prodegradant loadings. The prodegradants were synthetized and characterized using the FTIR and DSC techniques. Thermooxidation of the tested samples induced the changes in crystallinity, melting points and melt-flow indexes. Tensile strength and other mechanical properties were determined by means of the tensile test. The carbonyl index was determined using FTIR, the thermooxidation stability test was used to determine the activation energies of reactions. The changes in morphology of degraded samples were observed by SEM analysis.
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Weathering and accelerated aging of high density polyethylene mixtures with regranulate
Bruzl, Dominik ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
This master thesis deals with the effect of multiple extrusion (1, 2, 3) and the addition of 30, 60 and 90 % of this recycled material on the weathering and accelerated ageing of high density polyethylene (HDPE) copolymer. The weathering lasted 9 months and the accelerated ageing 1000 h at 65 °C. The degree of material degradation was assessed from changes in mechanical and physical properties and compositional changes using dynamic mechanical analysis and tensile testing, differential compensation calorimetry, thermogravimetric analysis and infrared spectrometry in the full attenuated reflection mode. The measurements showed that repeated extrusion as well as the addition of recycle material to the original one (R0) slightly slows down the photo-oxidative degradation during first month, but after that it does not have a negative or significant positive effect on the progress and rate of overall material degradation. A certain exception was the recycled material after the 3rd extrusion (R3), where the original properties comparable to R0 did not change much during ageing. The mechanical properties of the blends were better or comparable to R0 during ageing, but after months 6 and 9 the breaking strength of most of them decreased substantially as a result of the shortening of the chains. Accelerated ageing caused significant embrittlement in all samples, resulting in a reduction in yield strength by about half and almost immediate failure.
|
|
|
Controlled life-time polypropylene
Demková, Eva ; Petruš, Josef (referee) ; Tocháček, Jiří (advisor)
The master´s thesis is focused on the characterization of degradation process of polypropylene and polypropylene with statistic copolymer into which manganese (II) stearate and cobalt (II) stearates were added at 0.05, 0.10 and 0.20 wt.% loadings. The aim of the thesis was to prepare the controlled life-time polypropylene. The degradation was studied at varying temperatures and prodegradant loadings. The prodegradants were synthetized and characterized using the FTIR and DSC techniques. Thermooxidation of the tested samples induced the changes in crystallinity, melting points and melt-flow indexes. Tensile strength and other mechanical properties were determined by means of the tensile test. The carbonyl index was determined using FTIR, the thermooxidation stability test was used to determine the activation energies of reactions. The changes in morphology of degraded samples were observed by SEM analysis.
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