The effects of blend ratio and storage time on thermoplastic starch/poly(butylene adipate-co-terephthalate) films

Abstract

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.

Characterization and Biodegradability of Rice Husk-Filled Polymer Composites

“…This result was in agreement with the study of Hardinnawirda and Aisha [ 45 ], who claimed that when the rice husk loading exceeds 15 wt%, the tensile strength shows a remarkable decrement. Incorporation of 40% TPS or TPRH caused linear decrement in the tensile strength and elongation at break of PBS/PBAT matrix, which was same as the results of Garalde et al [ 46 ]. The decrement of tensile strength was due to the stiffness of TPS or TPRH, causing the steric hindrance effect ascribed to cross-linked aromatic structures of PBS and PBAT.…”

Nanocellulose Reinforced Thermoplastic Starch (TPS), Polylactic Acid (PLA), and Polybutylene Succinate (PBS) for Food Packaging Applications

“…Blending natural polymers withaliphatic polyesters can improve the overall mechanical and water resistance properties without negatively affecting their biodegradability (Garalde et al, 2019). The major problem is their compatibility due to hydrophilicity of starch and hydrophobicity of PBS, resulting in poor adhesion bonding between the two materials (Zeng et al, 2011).…”

Ecofriendly Preparation and Characterization of a Cassava Starch/Polybutylene Adipate Terephthalate Film

“…Many studies have been conducted on the potential advantages of blending TPS with poly (PBAT) [13][14][15]. Due to the difference in surface polarity between TPS and PBAT, the properties of TPS/PBAT composite materials largely depend on their compatibility.…”

“…Olivato et al explored the effects of the addition of citric acid and tartaric acid on the TPS/PBAT composite material and found that the addition of low content of organic acid could effectively increase the compatibility of TPS and PBAT and improve the uniformity of the membrane [6,16,20]. Meanwhile, blend ratio was the primary determinant of crystalline peak intensity for both TPS and polyester, and influences blend morphology [14,21]. Van Soest and Knooren found that V h -and B-type crystallinity increased in potato starch TPS sheets and that it can strengthen and harden materials [22] In addition, it has been found that the addition of nanoparticles can increase the compatibility of materials and improve the mechanical properties of composites.…”