Effects of melt reprocessing on volatile emissions and structural/rheological changes of unstabilized polypropylene

Qin, Xiang; Xanthos, M.; Mitra, Somenath; Patel, Saumya; Guo, Junyi

doi:10.1016/s0141-3910(02)00083-6

Cited by 46 publications

(22 citation statements)

References 9 publications

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“…Xiang et al [4] estudaram a emissão de compostos orgâni-cos voláteis (VOC) de um PP comercial sem estabilizantes, multiprocessado em uma injetora. Após cada ciclo de injeção o PP foi aquecido dinamicamente em um reator e os VOC foram monitorados através de um detector de ionização de chama.…”

Section: Extrusãounclassified

“…Para reduzir ao máximo a degradação durante a preparação dos filmes foi utilizado o melhor par tempo-temperatura, sendo este de aproximada- que a degradação apresenta um outro processo concorrente à cisão de cadeia, provavelmente um mecanismo de ramificação e/ou reticulação, similar ao processo de degradação termo-mecânico do HDPE [4] , mas de baixa intensidade. Este último comportamento pode ter sido favorecido pela presença de meros de etileno no copolímero propileno-etileno utilizado.…”

Section: Espectrometria No Infravermelhounclassified

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Degradação do polipropileno durante a extrusão e a geração de compostos orgânicos voláteis

Cáceres

Canevarolo

2009

Polímeros

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Resumo: Estudou-se a degradação de um polipropileno copolímero não estabilizado durante a extrusão a diferentes temperaturas (de 180 a 240 °C) e a conseqüente geração de compostos orgânicos voláteis (VOC). Os VOC foram coletados por meio de um condensador de gases, conectado na zona de desgaseificação da extrusora, e analisados por espectrometria no infravermelho (FTIR-ATR). A degradação do polímero foi acompanhada através da cromatografia de exclusão por tamanho e FTIR. À temperatura de 180 °C a degradação do polipropileno não gerou quantidades coletáveis de compostos orgânicos voláteis. Por outro lado, a partir de 200 °C houve geração de compostos olefínicos, não voláteis à temperatura ambiente, que aumentaram em quantidade com o aumento da temperatura de extrusão. A Função de Distribuição de Cisão de Cadeia (CSDF) mostrou que a baixas temperaturas, 180 e 200 °C, o mecanismo de degradação do polipropileno é preferencialmente por cisão de cadeia com alguma ramificação e/ou reticulação. Entretanto, nas temperaturas de extrusão mais altas, 220 e 240 °C, o mecanismo de degradação envolve exclusivamente cisão de cadeia e do tipo preferencial, ou seja, o número de cisões aumenta com o aumento da massa molar inicial da cadeia polimérica original. Palavras-chave: Polipropileno, degradação termo-mecânica, distribuição de massa molar, cisão de cadeia, FTIR, CSDF. Polypropylene Degradation during Extrusion and the Formation of Volatile Organic CompoundsAbstract: The thermo-mechanical degradation of an unstabilized polypropylene copolymer during extrusion at different temperatures (from 180 to 240 °C) and the production of volatile organic compounds (VOC) were studied. VOC's were collected via a volatile condenser, fitted at the degassing exit of the extruder and analyzed via infrared spectroscopy ( FTIR-ATR). The polymer degradation was followed via size exclusion chromatography and FTIR. At low extrusion temperatures (180 °C) the PP degradation produces undetectable quantities of VOC's. On the other hand, starting from 200 °C, there is the formation of olefinic compounds of molecular weight not volatile at room temperature, which increase in quantity with the rise of the extrusion temperature. The Chain Scission Distribution Function (CSDF) shows that at low temperatures (180 and 200 °C) the PP degradation mechanism is preferentially via chain scission with some branching and/or crosslinking in the lower molecular weight. At higher extrusion temperatures (220 and 240 °C) the degradation mechanism is exclusively via chain scission and it is preferential, i.e., the number of chain scission increases with the increase in the initial molecular weight of the original polymeric chain.

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Section: Extrusãounclassified

Section: Espectrometria No Infravermelhounclassified

Degradação do polipropileno durante a extrusão e a geração de compostos orgânicos voláteis

Cáceres

Canevarolo

2009

Polímeros

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“…Volatile organic compounds are products formed during the thermo-mechanical degradation of a polymer, which particularly in the case of polypropylene can be chain fragments, impurities and fragments of different classes of additives 8,9 . Adams et al 10 collected particulates and volatile organic compounds emissions during the PP extrusion.…”

Section: Introductionmentioning

confidence: 99%

Thermo-mechanical degradation and VOC emission of unstabilized and stabilized polypropylene copolymer during multiple Extrusions

2011

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The thermo-mechanical degradation during the multi-extrusion of unstabilized and stabilized polypropylene copolymer (cPP) was analyzed using the Chain Scission Distribution Function (CSDF) method. During the first extrusion of unstabilized cPP almost 60% of the initial polymeric chains were submitted to chain scission. The calculations using CSDF show a random chain scission process of chains with molecular weight below 100 kg.mol -1 , and above that a preferential chain scission process. When stabilized the cPP molecular weight is kept constant, even after four extrusions, independently of the stabilizers concentration used. Its chain scission is greatly reduced, only being noteworthy at high values of molecular weight, presenting in this case a preferential chain scission process. During extrusion the unstabilized cPP evolves Volatile Organic Compounds (VOC) due to the volatilization of low molecular weight oxidized chain segments. VOC's emissions are greatly reduced during the melt processing of stabilized cPP, even after multiple extrusions.

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“…3 This thermal degradation can result on one hand in both cross-linking and chain scission of the polymer matrix and on the other hand in structural and chemical attrition of wood flour. [4][5][6][7][8][9][10][11][12][13] The literature review indicates that PP is significantly less stable than PE.…”

Section: Introductionmentioning

confidence: 99%

Effects of Multiple Extrusions on Structure-property Performance of Natural Fiber High-density Polyethylene Biocomposites

et al. 2018

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Detailed analysis of the effects of multiple extrusions on physical, mechanical, micro-structural as well as dynamic mechanical thermal properties of natural fiber high-density polyethylene (HDPE) composites is reported. Composite materials containing HDPE, wood flour, and Maleic Anhydride polyethylene (MAPE) were manufactured and subjected to a recycling process consisting of up to four times grinding and reprocessing under industrial conditions. A wide range of analytical methods including bending tests, modulus of elasticity, impact strength, Scanning electron microscopy (SEM), fiber length measurement, water absorption tests, and dynamic mechanical thermal analysis (DMTA) were employed to understand the effects of recycling on natural fiber-HDPE composites. The results revealed that the recycled composites had lower bending strength and modulus of elasticity values, as compared to the reference counterparts. Also, the once recycled composites showed higher impact strength. Results, as well, indicated that generally the recycled composites had lower water absorption values as compared to the reference ones. The results obtained from DMTA exhibited a decrease in storage modulus and an increase in mechanical loss factor (tan δ) for all composites subjected to recycling. Alterations in phase transition temperatures and intensities were also monitored and the possible reasons were analyzed.

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Effects of melt reprocessing on volatile emissions and structural/rheological changes of unstabilized polypropylene

Cited by 46 publications

References 9 publications

Degradação do polipropileno durante a extrusão e a geração de compostos orgânicos voláteis

Degradação do polipropileno durante a extrusão e a geração de compostos orgânicos voláteis

Thermo-mechanical degradation and VOC emission of unstabilized and stabilized polypropylene copolymer during multiple Extrusions

Effects of Multiple Extrusions on Structure-property Performance of Natural Fiber High-density Polyethylene Biocomposites

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