Abstract There is considerable concern about the impact plastic materials have on the environment due to their durability and resistance to degradation. The use of pro-oxidant additives in the polymer films could be a viable way to decrease the harmful effects of these discarded materials. In this study, films of PHBV/PP-co-PE (80/20 w/w) and PHBV/PP-co-PE/add (80/19/1 w/w/w) (with pro-oxidant additive) were employed to verify the influence of the additive on the biodegradation of these films in the soil. These films were obtained by melting the pellets in a press at 180 °C which were buried in soil columns for 3 and 6 months. Some samples were also heated before being buried in soil. The biodegradation is higher for the additive blend buried for 3 months than for the pre-heated blend. After 6 months the blend buried and heated/buried was completely degraded in soil. The effect of the additive, on chain oxidation, is more time-dependant than heat-dependant.

O propósito deste estudo é investigar a biodegradação de filmes de PHB, PP e blenda de PP/PHB (1:1) por microrganismos de águas de rio poluído que recebeu vários tipos de descartes, inclusive de refinaria de petróleo. Os filmes poliméricos foram obtidos por fusão do pó do material a 175 ºC, prensados a 71,3 kgf.cm-2 e resfriados a 25 ºC. Estes filmes foram mantidos em amostras de águas do rio poluído, coletadas antes e após o descarte do efluente da refinaria de petróleo e mantidas em estufa bacteriológica a 28 ºC, durante 120 dias. As mudanças, causadas pela ação microbiana nos filmes, foram analisadas por medidas de perda de massa, infravermelho com transformada de Fourier (FTIR) e microscopia eletrônica de varredura (MEV). Os resultados provaram que a degradação do PHB ocorre tanto na sua fase amorfa como na cristalina, sendo mais significativa na água do rio que recebeu o efluente da refinaria de petróleo, contendo microrganismos reconhecidos como potencialmente capazes de degradar substâncias persistentes no meio ambiente.

The purpose of this study is to investigate the biodegradation of films made with PP, PHB and PP/PHB (1:1) blend caused by microorganisms from polluted river which received several types of waste, including an oil refinery effluent. The films were obtained by melting the powder from the material at 175 ºC, pressed at 71.3 kgf.cm-2 and cooled at 25 ºC. These films were kept in polluted river water samples, collected before and after the discarding of oil refinery waste, and they were kept in the bacteriological incubator at 28 ºC for 120 days. The changes caused by microbial action on the films were analyzed by measurements of weight loss, Fourier transform infrared (FTIR) and scanning electronic microscopy (SEM). The results proved that PHB degradation occurs in amorphous and crystalline phases, being more significant in the river water which received refinery oil waste, containing microorganisms recognized as potentially capable to degrade recalcitrant substances in the environment.