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. 2025 Jan 8;17(2):138.
doi: 10.3390/polym17020138.

Enhancing Thermal Insulation Property and Flexibility of Starch/Poly(butylene adipate terephthalate) (PBAT) Blend Foam by Improving Rheological Properties

JunGi Hong  1   2 , Junhyuk Lee  1 , Sung Kyu Kim  1   3 , Dasom Son  1   3 , DongHo Kang  1 , Jin Kie Shim  1
Affiliations

Enhancing Thermal Insulation Property and Flexibility of Starch/Poly(butylene adipate terephthalate) (PBAT) Blend Foam by Improving Rheological Properties

JunGi Hong et al. Polymers (Basel). .

Abstract

Starch foam has attracted significant attention as an alternative to expanded styrene (EPS) foam owing to its abundance and biodegradability. Despite these merits, its limited thermal insulation and flexibility compared to EPS have hindered its utilization in packaging. Herein, we report the effect of blending with starch/PBAT on foaming behavior and physical properties during foaming processing. We fabricated a starch/PBAT blend with systematically controlled blending ratios (0, 10, 15, 20, and 25 wt%) to analyze their effect on the interaction and characteristics of blended foam. The blending of starch and PBAT significantly reduced complex viscosity, enhancing resin flow during the foaming process. This improvement in resin flow led to increases in expansion ratio while reducing density and cell wall thickness. The thermo-insulation performance improved to 0.043 W/mK with 20 wt% of PBAT due to the enhanced expansion ratio and cell morphology. Additionally, the flexural strain at break improved significantly from 2.8 ± 0.6% to 9.6 ± 1.0% with increasing PBAT content. Enhanced water resistance was also observed, demonstrated by a reduction in water absorption and an extension of dissolution time. Overall, these findings underscore the potential of starch/PBAT foam to improve the thermal-insulating property, flexibility, and water resistance while maintaining their biodegradability and sustainability.

Keywords: PBAT; foaming behavior; rheology; starch-based foam; thermal insulating.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Schematic of extruding the starch blend foams and the comparison of neat starch and blend foams foaming process.
Figure 2
Figure 2
Complex viscosity of starch pre-foam with different PBAT contents at 140 °C.
Figure 3
Figure 3
(a) Cross-sectional SEM images, (b) expansion ratio and (c) density of starch foam with various blending ratios.
Figure 4
Figure 4
(a) Compressive stress, (b) resilience, and (c) flexural strain at the break of starch blend foams conditioned at 25 °C, RH 50%.
Figure 5
Figure 5
(a) Thermal conductivities of starch blend foams of various blending ratios, (b) comparison of thermal conductivities with commercial and other reported thermo-insulators with starch blend foams in this work.
Figure 6
Figure 6
(a) Water absorption at 70%RH and (b) degree of dissolving at 60 °C water with different PBAT contents.
See this image and copyright information in PMC

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