This study aimed to evaluate the thermal behavior of polyhydroxybutyrate (PHB)/polypropylene grafted with maleic anhydride (PP‐g‐MA) blends and PHB/PP‐g‐MA/vermiculite bionanocomposites submitted to the biodegradation test according to ASTM G 160‐03. The blends and bionanocomposites were prepared by melt intercalation method using a single screw extruder, and then, compression molded. The thermal analyzes were performed by thermogravimetry (TG) and differential scanning calorimetry. It was verified the decrease of onset degradation temperature and the melting temperature mainly after 86 days of exposure to the simulated soil. This behavior was more pronounced in bionanocomposites because of interactions between the maleic anhydride groups and the clay favoring biodegradation, making the systems more amorphous and propitious to the attack of microorganisms. POLYM. ENG. SCI., 56:555–560, 2016. © 2016 Society of Plastics Engineers

ResumoEste trabalho teve como objetivo preparar e avaliar filmes PHB/vermiculita natural e modificada nas quantidades em peso de 1%, 3% e 6% através dos métodos intercalação por fusão e intercalação por solução. Os bionanocompósitos obtidos pelo método intercalação por fusão foram preparados em uma extrusora monorosca e posteriormente os filmes foram moldados via compressão. Na preparação dos filmes por solução, os sistemas foram submetidos à agitação e aquecimento a 80 °C. Os sistemas foram avaliados por difração de raios-X e o comportamento de biodegradação foi avaliado de acordo com a norma ASTM G 160-03. O acompanhamento da biodegradação foi realizado por meio de inspeção visual e perda de massa. Observou-se que o percentual de argila e o método de obtenção dos filmes influenciaram na estrutura formada e na biodegradação dos sistemas. Palavras-chave: polímeros biodegradáveis, argila vermiculita, ensaio de biodegradação, bionanocompósitos. AbstractThis study aimed to prepare and to evaluate natural and modified PHB /vermiculite films in quantities of 1%, 3% and 6% by weight, through melt intercalation and solution intercalation methods. The bionanocomposites in the form of thin films, obtained by the melt intercalation method, were prepared in a single screw extruder and then molded via compression. In the preparation of the films by solution method, the systems were stirred and heated at 80 °C in the presence of the chloroform solvent. The systems were evaluated by X-ray diffraction and the degradation behavior was evaluated according to ASTM G 160-03, by visual inspection and through weight loss. It was observed that the percentage of clay and the method of obtaining of the films influenced in the structure and biodegradability of the systems.

In this study, the biodegradation process of PHB/PP-g-MA/clay bionanocomposites was evaluated. Films with compositions of 5% PP-g-MA and 3% clay (BIO5); and 2.5% PP-g-MA and 3% clay (BIO2,5) were prepared. The biodegradation test was performed according to ASTM G 160-03 for a period of 86 days. The evaluation of the degradation was carried out by optical microscopy (OM), weight loss, FTIR and XRD. The bionanocomposites showed change of color and appearance of cracks. As the mass loss, the BIO2,5 system presented loss of 22.5%, and the BIO5, of 25.9%, for 86 days of exposure in simulated soil. It was also observed by FTIR, a marked reduction in the intensity of the corresponding band to the C = O groups, indicating that microbial attack promoted cleavage of bonds of the ester group. By XRD, there was a decrease in the intensity of the peaks and enlargements thereof with increasing exposure time, demonstrating the biodegradation behavior of bionanocomposites.