# Investigations on the Performances of Corn Starch/PBAT Blends

## TL;DR

This paper studies blends of corn starch and PBAT to evaluate their performance in terms of flow, strength, thermal stability, and degradation.

## Contribution

The study reveals how varying corn starch content affects the mechanical and degradation properties of PBAT blends.

## Key findings

- Adding corn starch initially improves mechanical properties but reduces thermal stability.
- 50%CS/PBAT degrades more rapidly in water and air compared to pure PBAT.
- Corn starch lowers production costs and enhances degradability, making the blend suitable for packaging and agriculture.

## Abstract

Corn starch (CS)/poly (butylene adipate-co-terephthalate) (PBAT) blends were prepared by extrusion and injection molding processes. The CS content in the blends changed between 0 and 50 wt.% in 10 wt.% steps. Melt flow rates, mechanical properties, thermal stability, melting and crystallization behavior, as well as hydrophilicity of the blends were investigated. Based on these, the degradation properties of PBAT and the blend containing 50 wt.% CS (50%CS/PBAT) in water and open-air storage were comparatively studied via visual appearance observation, Shore hardness testing, and water absorption measurement. The results showed that the melt flow rates and the mechanical properties of the blends, including the tensile strength, tensile modulus, impact strength, and elongation at break, initially increased before decreasing as CS content in the blends increased, while the flexural strength and flexural modulus of the samples increased monotonously. The sample would become more thermal unstable when more CS was used. Besides these, the crystallinity and water contact angle became smaller. Immersion in water would blacken the visual appearances of PBAT and 50%CS/PBAT samples, but cracks could be found much more obviously in the blend than in neat PBAT; both the hardness and the mass of PBAT rose slightly while those of 50%CS/PBAT dropped significantly. An open-air storage would also blacken the visual appearances of PBAT and 50%CS/PBAT, and the hardness of the two samples would be decreased to almost the same extent. The results showed that the incorporation of CS in PBAT had much greater effects on the flow ability, mechanical properties, thermal stability, melt and crystallization behavior, as well as hydrophilicity of the blends. Immersion in water or being placed in air could accelerate the degradation of 50%CS/PBAT much more seriously than PBAT. Compared with PBAT, 50%CS/PBAT was of much lower cost and easier to be degraded, especially in water; it should be an ideal degradable blend for applications in packaging, agricultural mulch, and some other areas.