Peroxide cross-linking and its role on the rheological, mechanical and thermal properties of poly(butylene adipate-co-butylene terephthalate)

The effects of two different peroxides [di(tert-butylperoxyisopropyl) benzene (DTBP) and bis(tert-butyl dioxy isopropyl) benzene (BIBP)] and a co-agent such as [triallyl isocyanurate (TAIC)], singly and together, were studied through the rheological, mechanical and thermal properties of poly(butylene adipate-co-butylene terephthalate) (PBAT). It was found that a cross-linked PBAT with different gel fractions were obtained by adding small amounts of peroxides and a co-agent. Addition of the peroxides and the co-agent similarly induced bond breakage of PBAT chain during the melting extrusion, which produced high carboxyl end-groups contents. Moreover, cross-linked PBAT exhibited a remarkable improvement in modulus and complex viscosity due to the formation of a gel network. Furthermore, the elongation-at-break decreased with an increase in gel fraction, but the tensile strength was slightly affected. It was interesting that the cross-linked structures could act as nucleating agents which enhanced the crystallization of PBAT. In addition, the thermal stability of PBAT was improved due to the cross-linked structures in PBAT which retarded degradation. According to the above results, cross-linking could extend processing methods of PBAT, like foaming and film blowing. Therefore, the practical applications of PBAT could be widely expanded.