Changes on surface morphology of corn starch blend films

Area of Science:

• Materials Science
• Biomaterials Engineering
• Polymer Chemistry

Background:

• Poly(ethylene-vinyl alcohol) copolymer-corn starch thermoplastic blend (SEVA-C) is a promising material for various applications.
• Understanding the biodegradation behavior of SEVA-C is crucial for its sustainable use and disposal.
• Enzymatic degradation can significantly alter the properties of starch-based blends.

Purpose of the Study:

• To evaluate the impact of enzymatic degradation on the surface morphology and thermal properties of SEVA-C.
• To investigate the influence of immersion time on SEVA-C degradation.
• To elucidate the mechanisms driving SEVA-C biodegradation.

Main Methods:

• Samples of SEVA-C with varying thicknesses were immersed in an alpha-amylase solution (50 u/L) for up to 90 days at 37°C.
• Techniques employed include Thermogravimetric Analysis (TGA), contact angle measurements, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM).
• Analysis focused on mass loss, surface changes, and thermal property alterations.

Main Results:

• Enzymatic hydrolysis of the starch component led to increased surface porosity, pore size, and roughness.
• SEM and AFM revealed the development of small pits on the SEVA-C surface.
• Degradation mechanisms include plasticizer leaching, starch enzymatic cleavage, and synthetic polymer fraction degradation.

Conclusions:

• Enzymatic degradation significantly modifies the surface morphology of SEVA-C.
• The observed changes are attributed to the combined effects of starch hydrolysis and leaching.
• This study provides a detailed understanding of SEVA-C biodegradation pathways.