Fotodegradação do polipropileno: Um processo essencialmente heterogêneo

Rabello, Marcelo S.; White, James R.

doi:10.1590/s0104-14281997000200007

Cited by 20 publications

(22 citation statements)

References 38 publications

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“…The property of tensile at break is more closely related to damages in the amorphous region of the material 39 . However, scissions in the linked molecules are the ones that cause the highest losses in mechanical properties to a crystalline polymer 40 . The properties of tensile at break and impact resistance Izod in P(3-HB) test specimens were the most affected by radiation at sterilization dose (25 kGy), as is shown in Table 5, while elongation at break and modulus of elasticity suffered negligible decreasing.…”

Section: Discussionmentioning

confidence: 99%

The effect of gamma radiation on mechanical properties of biodegradable polymers poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Oliveira

Araújo

2012

Mat. Res.

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B r a z i l i a n p o l y ( 3 -h y d r o x y b u t y r a t e ) , P ( 3 -H B ) , a n d i t s c o p o l y m e r, p o l y (3-hydroxybutyrate-co-3-hydroxyvalerate), P(3-HB-co-3-HV) were irradiated with gamma radiation ( 60 Co) at room temperature and in the presence of oxygen. The viscosity-average molar mass (Mv) was analyzed by viscometry using an Ostwald-type capillary viscometer. Both polymers showed a decrease in molar mass with the increase in dose, reflecting that random main chain scissions occurred. The value G (scissions/100 eV of energy transferred to the system) and the parameter α (scissions per original molecule) were also determined. Mechanical properties decrease with the increase in dose, revealing that P(3-HB) underwent significant changes, especially at doses higher than 50 kGy. Tensile at break and impact resistance properties were the most affected by radiation, while the elastic modulus remained virtually unaltered up to 100 kGy dose.

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Section: Discussionmentioning

confidence: 99%

The effect of gamma radiation on mechanical properties of biodegradable polymers poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Oliveira

Araújo

2012

Mat. Res.

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“…A Figura 4 mostra os resultados da temperatura de fusão e da cristalinidade do PPrep e do PPv, quando expostos à radiação sob diferentes tempos de exposição. Pode ser visto que para ambas resinas a temperatura de fusão diminui com o tempo de exposição devido às cisões de cadeias ocorridas na superfície lamelar dos cristais [27] . Os resultados apresentados na Figura 4 também mostram que a cristalinidade do material aumenta com o tempo de exposição devido ao fenômeno bem conhecido e chamado de quemicristalização.…”

Section: Materiais E Métodosunclassified

Estudo do efeito do tipo de polipropileno na fotodegradação da blenda polipropileno/poliestireno de alto impacto

et al. 2012

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Resumo: Este trabalho visa avaliar a influência do tipo de polipropileno no comportamento da blenda polipropileno/poliestireno de alto impacto (PP/HIPS) quando exposta à radiação UV. Foram usados uma resina virgem de PP (PPv) e outra reprocessada (PPrep). Inicialmente, avaliou-se o comportamento individual dos componentes da blenda, HIPS, PPv e PPrep, quando submetidos à radiação UV por até 15 semanas de exposição. As técnicas de caracterização utilizadas para monitorar o desempenho tanto das resinas individualmente quanto das blendas submetidas à radiação UV foram: propriedades mecânicas (tração e impacto), medidas de índice de fluidez (MFI), análise térmica (DSC), espectroscopia no infravermelho (FTIR) e microscopia eletrônica de varredura (MEV). A partir dos resultados com essas técnicas verificou-se que o PPv foi a resina mais afetada pela radiação e consequentemente as blendas preparadas com esse PP também foram mais sensíveis à fotodegradação do que as demais. Em termos de fotoestabilização este resultado mostra-se interessante, já que as blendas PP/HIPS preparadas com uma resina previamente degradada necessitariam de menores teores de aditivos do que esse mesmo tipo de blenda preparada com resina virgem. Palavras-chave: Polipropileno, poliestireno de alto impacto, blenda, fotodegradação. Influence of the Type of Polypropylene on the Photodegradation of Blends of Polypropylene/High Impact PolystyreneAbstract: The influence from the type of polypropylene on the photodegradation resistance of blends of polypropylene/high impact polystyrene (PP/HIPS) was studied. A virgin polypropylene (PPv) and another sample that suffered prior thermo-mechanical degradation (PPrep) were used. All materials, components of the blends and blends were exposed to UV radiation for up to 15 weeks. They were characterized as a function of time of UV exposure using differential scanning calorimetry (DSC), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical (tensile and impact) properties and melt flow indexes of the materials were also evaluated. The experimental results revealed that PPv resin and its blends were more sensitive to UV radiation than PPrep and its blends. In terms of photostabilization this finding is very interesting, since PP/HIPS blends prepared with a previously degraded polyolefin would require smaller amounts of additives than the same kind of blends prepared with virgin resin. Keywords: Polypropylene, high impact polystyrene, blend, photodegradation. IntroduçãoO interesse no estudo das blendas poliméricas tem aumentado a cada ano. Um dos grandes motivos para esse crescimento se dá pela vantagem: 1) tecnológica: as blendas possuem a capacidade de combinar as propriedades de diferentes componentes de modo a obter excelentes propriedades mecânicas, térmicas e químicas, e 2) financeira: o custo de desenvolvimento de uma blenda é menor que o custo de desenvolvimento de um novo polímero. Porém o desenvolvimento de um novo material não se restringe apenas a sua obtenção, é preciso tamb...

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“…At the same time, the value of polydispersity has increased. These results indicated that the process involved in the thermodegradation of PBAT is governed by the scission chain reactions [11,12] . This hypothesis is confirmed by the rheometric data since the values of torque at 10 min has decreased significantly at 200 °C.…”

Section: Methodsmentioning

confidence: 86%

Thermo stabilisation of poly (butylene adipate-co-terephthalate)

Chaves

Fechine

2016

Polímeros

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SbstractPoly (butylene adipate-co-terephthalate) -PBAT is a synthetic biodegradable polymer commonly used for plastic film production from neat polymer or nanocomposites. The PBAT is submitted to high temperatures and shear rate during its processing. In the present study, the thermo stabilisation of PBAT by the addition of two types of stabilisers was studied using a torque rheometer at 60 rpm and two levels of temperature. The stabilisers were used as master batches with a percentage of 10% by weight of additive in the PBAT. Molecular weight, torque values after 10 minutes of mixing, and absorbance at 400 nm were used to evaluate the process of stabilisation. The primary and secondary antioxidant used here had a positive effect on both processing temperatures, 180 and 200 °C. The best results indicate that the primary antioxidant could be used alone to protect PBAT against thermodegradation reactions.

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Fotodegradação do polipropileno: Um processo essencialmente heterogêneo

Cited by 20 publications

References 38 publications

The effect of gamma radiation on mechanical properties of biodegradable polymers poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

The effect of gamma radiation on mechanical properties of biodegradable polymers poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Estudo do efeito do tipo de polipropileno na fotodegradação da blenda polipropileno/poliestireno de alto impacto

Thermo stabilisation of poly (butylene adipate-co-terephthalate)

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