Evaluation of the thermal decomposition of blends prepared with poly(3-hydroxybutyrate) (PHB) and recyclable ethylene poly-terephthalate (RPET)

Abstract

In this work, the thermal behavior of polymeric blends was prepared with the combination of post-consumer bottles of ethylene poly-terephthalate (recyclable RPET) and PHB (poly(3-hydroxybutyrate)), under several proportions. The PHB, RPET and PHB/RPET films were prepared from individual PHB and RPET solutions, obtained from controlled heating. X-ray diffractions, the absorption spectra in the infrared region (FTIR), thermogravimetry (TG), differential thermal analysis (DTA) techniques were used to examine the crystallinity, chemical interactions, thermal stability and melting point, respectively. In addition, the derivative thermogravimetry (DTG) curves under non-isothermal condition were also used to evaluate the behavior kinetics of the blends to see the possible alterations in thermal decomposition. The results of the X-ray analysis showed that the crystallinity in PHB/RPET had signals intense and also the lack of the diffraction related to PHB, while the FTIR analysis showed individual bands of the two polymers, indicating that there was little interaction between them. The TG/DTG and DTA curves had several reactions, shown that the blends are strongly dependent on the heating rates used. The thermal reactions also showed different events, which correspond to the decomposition of different components, of the blends. The kinetic parameters, such as activation energy (E) and the factor of Arrhenius (A), showed that two blends had a similar behavior in the initial development of the kinetic behavior, while the third sample had behavior differently of the others. Additionally, the kinetic compensation effect was determined and showed the probable direction of the thermal decomposition for individual PHB and RPET as for its respective blends.