Avaliação da estabilidade termica de embalagem de polietileno tereftalato (PET) : estudo dos oligomeros e substancias volateis

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

The thermal stability of PET food packaging materiais was evaluated under severe heating conditions at several exposure times, by means of the determination of PET oligomers and volatile substances released under heating. The first step for determination of thermal stability of the polymer was carried out heating PET films at 150°C for 30 and 60 minutes, 260°C, for 5 minutes and 260 °C and 270°C for 30 and 60 minutes. The main changes occurred at 260°C and 270°C, with an increase in concentration for second seires opened chain oligomers identified, in relation to their concentration determined prior to heating. Volatile substances identified at 260 and 270°C, included toluene, benzaldehyde, p-xylene, derivatives of benzoic acid and esters of terephthalic acid, and were released at 260°C and 270°C. The second step of the present study was to verify the suitability of PET as a food packaging material intended to conventional and microwave ovens, as well as the suitability of the polymerfor future recycling procedures, where PET is exposed to high temperature. For the experiments, different samples were (bottles, multi-layer films and roasting bags) were exposed at temperatures of 120, 150 and 230°C, for 50 minutes. PET showed good stability at tempertures below 150°C, with few volatile substances released in very low concentrations. Although PET had shown good stability under heating in relation to oligomer and volatiles composition, degradation compounds of other materiais in PET laminates, like printing ink and adhesive components, as well as degradation products of antioxidantsand paper were identified. The results suggest that PET is stable at temperatures up to 230°C for 50 minutes, indicating that PET is suitableas food packaging materials intended to conventional and microwave ovens. In addition, the good stability of PET, in realtion to oligomer composition, when heated to high temperatures, suggest that the polymeris also suitable for further recycling procedures

ASSUNTO(S)

fornos de microondas degradação embalagens plasticas migração

ACESSO AO ARTIGO

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