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. © 2015 Society of Plastics Engineers