The effects of chemical structure and synthesis method on photodegradation of polypropylene

Tang, Longxiang; Wu, Qianghua; Qu, Baihua

doi:10.1002/app.21272

Cited by 42 publications

(27 citation statements)

References 20 publications

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“…It was found that photo-oxidation only leads to slight changes in the DSC thermogram of pure PP. The DSC curve shape is qualitatively not modified, however it is slightly shifted towards lower temperatures [37,[57][58][59][60]. In consequence, the melting temperature and the maximum lamellar thickness of pure PP tend to slightly decrease during photo-oxidation (Table 1).…”

Section: Morphological Changesmentioning

confidence: 95%

“…Furthermore, a slight increase of the original crystalline content is also observed for pure PP during exposure to UV radiation (Table 1). It is well evidenced that the crystalline content of polypropylene increases at the beginning of oxidation [35][36][37]57,59,60,[63][64][65]. This phenomenon has been explained as due to chain scission, which initially is the major driving force of the oxidative process, and leads to increasing segment mobility and chain arrangements, favouring further crystallisation [58].…”

Section: Morphological Changesmentioning

confidence: 97%

“…limits the secondary crystallization of polypropylene by reducing its molecular regularity. Thus, at high UV exposure times, the large number of chemical defects in the polymeric chain becomes the major driving force that prevents further crystallization [57,58,60,66].…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Thermal characterization of the oxo-degradation of polypropylene containing a pro-oxidant/pro-degradant additive

Contat‐Rodrigo

2013

Polymer Degradation and Stability

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The oxo-degradation process of polypropylene (PP) samples containing different concentrations (4% and 10% w/w) of pro-oxidant/pro-degradant additive Envirocare TM AG1000C was investigated under accelerated test conditions. Samples were initially exposed to UV radiation for 300 hours. The tendency to biodegradation in soil medium of these UV-aged samples was then indirectly assessed by an indirect method for a period of 6 months. The entire degradation process of these materials was first examined by monitoring changes in their morphological properties (melting temperature, maximum lamellar thickness and crystallinity) with the aging time, by Differential Scanning Calorimetry (DSC). Then, changes in the thermal properties (onset temperature and maximum decomposition temperature) of these materials with the aging time were analysed by Thermogravimetric Analysis (TGA). Furthermore, the kinetics of the thermal decomposition of these PP samples with pro-oxidant/prodegradant was also studied during the oxo-degradation process, by means of the Chang differential method. During exposure to UV radiation, the more significant changes in the morphological and thermal properties that were detected in PP samples containing M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPTpro-oxidant/pro-degradant additive compared to pure PP, clearly suggest a higher level of oxidation in these samples, confirming the effectiveness of this pro-oxidant/prodegradant additive in promoting the abiotic oxidation of polypropylene during UVirradiation. Moreover, the level of oxidation observed in UV-aged samples seems to be dependent on the additive load.On the other hand, during incubation in soil medium, changes in the morphological and thermal properties of previously photo-oxidized PP samples with pro-oxidant/prodegradant were detected that indirectly support a certain progress of oxidation, indicating that previous abiotic oxidation can promote further degradation of the polypropylene matrix by soil microorganisms. In general, both morphological and thermal properties exhibit a non-linear dependency with the incubation time in soil, supporting the idea that biodegradation is a complex process that occurs in different stages. Furthermore, the extent of the changes in these properties during soil incubation was found to be proportional to the pro-oxidant/pro-degradant load and the previous photo-oxidation level.

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Section: Morphological Changesmentioning

confidence: 95%

Section: Morphological Changesmentioning

confidence: 97%

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Thermal characterization of the oxo-degradation of polypropylene containing a pro-oxidant/pro-degradant additive

Contat‐Rodrigo

2013

Polymer Degradation and Stability

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“…Devido ao alto número de cisão de cadeias, o valor do MFI das amostras expostas natural e artificialmente aumentou bastante, chegando a valores que não puderam ser medidos, uma vez que o fluxo da massa polimérica pela matriz era muito rápido e descontínuo. De acordo com vários autores 1,34,35 , este tipo de comportamento é conseqüência do mecanismo de degradação do PP, que envolve reações de quebra de cadeias, que ocorrem através da cisão β de radicais alcoxi (PPO•) gerados pela auto-oxidação do PP (reação 3 do Esquema 1) ou pela foto-clivagem de hidroperóxidos (reação 5). Como subproduto dessas reações temse a formação de grupos carbonila, que é o principal grupo quími-co característico da degradação oxidativa do PP.…”

Section: Medidas De íNdice De Fluidez E De Infravermelhounclassified

Avaliação da fotodegradação de poliolefinas através de exposição natural e artificial

Fechine¹,

Santos²,

Rabello³

2006

Quím. Nova

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Recebido em 23/3/05; aceito em 13/9/05; publicado na web em 14/3/06 THE EVALUATION OF POLYOLEFIN PHOTODEGRADATION WITH NATURAL AND ARTIFICIAL EXPOSURE. Samples of polypropylene (PP) and low-density polyethylene (LDPE) were submitted to ultraviolet radiation, in the natural environment and also in the laboratory. Chemical modifications were quantified by the carbonyl index (CI), mechanical properties and melt flow index. The degradation in the laboratory was comparatively faster than in the environment for both types of polymers. The accelerating factor was determined for the various properties investigated. This parameter, however, showed a large variation with the degradation criteria and the type of polymer. The existence of a "universal accelerating factor", therefore, was not observed in the current study.Keywords: polypropylene; low-density polyethylene; photodegradation. INTRODUÇÃOTodos os polímeros orgânicos não estabilizados são degradados sob exposição à luz solar na presença de oxigênio. Entretanto, as taxas de degradação fotooxidativa dependem fortemente da natureza química do polímero, com a vida útil variando desde poucos meses para o polipropileno, até alguns anos para o politereftalato de etileno (PET), poli(metacrilato de metila) (PMMA) e o politetrafluoretileno 1,2 . Os problemas da fotodegradação têm aumentado com o crescente uso de polímeros em aplicações exteriores aliado à necessidade da redução de custos com aditivos fotoestabilizantes. Durante o processo degradativo ocorrem mudanças físicas e químicas no polímero que levam à descoloração, fissuramento, perda de brilho e queda de resistência mecânica. Tais fenômenos estão quase sempre associados a processos de cisão de cadeia e, em alguns casos, ocorrem também reticulações 2 . A investigação da degradação foto-oxidativa de polímeros é um dos principais elementos que subsidiam o desenvolvimento do produto e sua expectativa de vida útil. Ao se expor o material às intempéries e avaliar os efeitos nas suas propriedades busca-se obter uma fotografia do que aconteceria durante a aplicação desse produto. Nesse tipo de investigação utilizam-se a exposição no ambiente natural e a exposição simulada, realizada em laboratório. Nas exposições em laboratório, as variáveis mais importantes são tipo de fonte geradora de radiação ultravioleta, intensidade de radiação, temperatura, umidade e ciclos térmicos [3][4][5][6][7][8] . A resposta do material à exposição depende, portanto, da intensidade dessas variá-veis. É comum a intensificação desses fatores para aceleração da fotodegradação e, assim, se obter resultados mais rápidos. Outra maneira de se investigar a resistência fotoquímica dos polímeros é a exposição ambiental, onde os diversos constituintes do ambiente, como radiação ultravioleta, luz visível, temperatura, intempé-ries, umidade, etc, afetam a estrutura química do polímero provocando degradação. A intensidade desses elementos do ambiente natural varia significativamente com o local de exposição, a época do ano e o período do dia, de tal modo qu...

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“…Many of those parts, having been exposed to UV light for long periods of time are heavily photo-oxidized because of the relative high photosensitivity, especially if they were made of PP; hence changes are expected in the thermal behavior, mechanical properties, and surface morphology of the products. [1][2][3][4][5] Photo-degradation of LDPE/PP blend, 6 PC/PP blend, 7 blends of PP with recycled PP 8 has been studied. PP/LDPE blends compatibilized with rubber-PP-graft copolymers or ethylene-propylene-dienemonomer rubber (EPDM) copolymer have been reported more susceptible to be photo-oxidized than incompatible blends.…”

Section: Introductionmentioning

confidence: 99%

Studies on the photo‐oxidation of PP and PP/mLLDPE blend systems: Thermal, physicochemical, and mechanical behavior

Gupta

Saroop

Gupta

2007

J of Applied Polymer Sci

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The photo-oxidative degradation of the blends of polypropylene (PP) with metallocene linear low density polyethylene (mLLDPE) were studied. The blend samples were exposed to the ultraviolet radiation (UV) for a period of 6 weeks. Tensile mechanical characteristics were derived from stress-strain curves. The changes in crystallinity during exposure were followed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), whereas the chemical degradation of the blend samples was evaluated by FTIR-ATR. In case of PP, tremendous decrease is observed in tensile strength, elongation at break, and increase is observed in tensile modulus with exposure time. However, with the addition of mLLDPE, UV stability of PP has significantly improved. A significant increase in crystallinity during UV exposure was noted for PP, whereas for PP/mLLDPE (80/20) blend system the crystallinity did not change much. Therefore low level of stabilizers may be required for PP/mLLDPE blend systems.2007 Wiley Periodicals, Inc. J Appl Polym Sci 106: [917][918][919][920][921][922][923][924][925] 2007

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The effects of chemical structure and synthesis method on photodegradation of polypropylene

Cited by 42 publications

References 20 publications

Thermal characterization of the oxo-degradation of polypropylene containing a pro-oxidant/pro-degradant additive

Thermal characterization of the oxo-degradation of polypropylene containing a pro-oxidant/pro-degradant additive

Avaliação da fotodegradação de poliolefinas através de exposição natural e artificial

Studies on the photo‐oxidation of PP and PP/mLLDPE blend systems: Thermal, physicochemical, and mechanical behavior

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