The objective of this work was to investigate blend ratio and storage time effects on the morphological, mechanical, and thermal properties of thermoplastic starch/poly(butylene adipate- co -terephthalate) (TPS/PBAT) films. TPS was prepared from plasticized cassava starch using a twin-screw extruder. TPS was subsequently melt-blended with PBAT with varied weight ratios (i.e., 20/80, 40/60 and 60/40) and blown to form TPS/PBAT films. It was found that increasing the TPS/PBAT ratio to 40/60 led to improved distributions of polymeric components and increased PBAT crystallization temperatures while reducing TPS melting transitions and tensile properties of TPS/PBAT films. After three months of storage at 30 °C, the tensile strength and secant modulus at 2% strain of TPS/PBAT films increased due to recrystallization of both TPS and PBAT. Blend ratios were the primary determinant for changes in TPS/PBAT film elongation at break with this storage time. Elongation at break decreased at low TPS:PBAT ratios (i.e., 20/80) and increased at high blend ratios (i.e., 60/40). The recrystallization of both TPS and PBAT components were observed from XRD and DSC analyses. Results obtained from both techniques confirmed the formation of additional crystalline structures of individual components during storage. The recrystallization phenomena also affected thermal transition temperatures of blend components. The crystallization temperature of PBAT-rich phase increased as starch could act as nucleating sites for PBAT. Using DMA, the tan δ curve of TPS/PBAT film exhibited two sharp individual peaks corresponding to the glass transitions of PBAT-rich and starch-rich phases. The tan δ of TPS-rich phase shifted to higher temperature due to recrystallization of TPS-rich phase.

Polymer composites consisting of linear low-density polyethylene (LLDPE), thermoplastic starch (TPS), and zeolite 5A (Z), with a constant PE to TPS weight ratio of 70 : 30 and zeolite 5A contents of 1-5 wt % were prepared in the forms of pellets and films by using a co-rotating intermeshing twin-screw extruder and a blown film extrusion line, respectively. The objective of this work was to investigate the effect of zeolite 5A on compatibility between PE and TPS, as well as morphological, thermal, and tensile properties of PE/TPS/Z composites. The presence of zeolite 5A increased the miscibility and tensile properties of the PE/TPS blend. Tensile properties of the blend considerably improved after compounding with zeo-lite 5A, as the tensile strength, modulus, and elongation at break increased significantly (P 0.05) by up to $ 60, 30, and 70%, respectively. Increasing the zeolite 5A content from 1-5 wt % significantly increased (P 0.05) the tensile strength, modulus, and elongation at break of PE/TPS/Z composites from $ 12 to 16 MPa, 133 to 154 MPa, and 305 to 390%, respectively. However, the addition of zeolite 5A slightly decreased the thermal stability of the PE/TPS blend by $ 5-15 C.

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The aim of this work was to explore the effect of zeolite ZSM-5 (ZSM5) incorporation sequence on the phase morphology, microstructure, and performance of polyethylene/thermoplastic starch (PE/TPS) films. Two processing sequences were used for preparing PE/TPS/ZSM5 composites at a weight ratio of PE to TPS of 70:30 and ZSM5 concentrations of 1-5 wt%: (i) melt compounding of PE with ZSM5 prior to melt blending with TPS (SI); and (ii) TPS was compounded with ZSM5 prior to blending with PE (SII). Distributive mixing and mechanical properties of PE/TPS blend were greatly enhanced when ZSM5 was incorporated via SII. These were caused by both the higher affinity between PE and ZSM5, compared to that of TPS and ZSM5, and the reduction of TPS viscosity after compounding with ZSM5, leading to migration of ZSM5 from TPS dispersed phase toward PE matrix and increase in breakup of TPS droplets during SII sequence.