The first aim of this study was to prepare thermoplastic starch (TPS), namely blends of tapioca starch and hyperbranched polyester polyol and to evaluate the hyperbranched polyester polyol (HBP) as a plasticizing agent for tapioca starch. The second aim was to prepare blends of maleic-anhydride-grafted low-density polyethylene (LDPE-g-MA) and TPS, and to evaluate the effect of the mass ratio LDPE-g-MA/TPS on the structural, thermal, rheological, morphological, and mechanical properties of the blends. The melting and crystallization temperatures of the LDPE-g-MA/TPS blends did not correlate well with the ratio of LDPE-g-MA/TPS. The blends exhibited a reduction in the A-type crystallinity and a pseudoplastic rheological behavior. V-type crystallinity was not observed for neither TPS nor LDPE-g-MA/TPS blends. Scanning electronic microscophy provided an evidence for the presence of starch granules in all the blends and for low interaction degree between LDPE-g-MA and TPS. Young's modulus and tensile strength of the LDPE-g-MA/TPS blends decreased with the decreasing LDPE-g-MA/TPS ratio. POLYM. ENG. SCI., 55:2526-2533, 2015. (c) 2015 Society of Plastics Engineers