International Journal of Engineering

International Journal of Engineering

Investigation of the Biodegradability of Bio-Plastics Based on Polypropylene and Starch

Document Type : Original Article

Authors
A. Ganji 1
Z. Ghobadi Nejad 2
S. Yaghmaei 1, 2
R. Amini 3
1 Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
2 Biochemical and Bioenvironmental Research Center, Sharif University of Technology, Tehran, Iran
3 Kimia Samaneh Sabz Co., Qom, Iran
10.5829/ije.2026.39.10a.17
Abstract
To address the environmental crisis caused by plastic accumulation, this study investigated the biodegradation potential of bio-based containers using indigenous microorganisms isolated and purified from plastic-contaminated sources. Two types of polymers were tested: pure polypropylene granules and starch-polypropylene based bioplastic. The biodegradation process was evaluated through visual observation, gravimetric analysis, field emission scanning electron microscope, Fourier transform infrared analysis, and thermogravimetric analysis. Results showed the indigenous bacterial strain Bacillus sp. achieved weight reductions of 4.73% for the granules and 7.1% for the bio-based product after 150 days of incubation. Fourier transform infrared analysis revealed significant surface oxidation, evidenced by the appearance of hydroxyl groups. The disappearance of methyl stretching and methylene asymmetrical stretching peaks indicated microbial carbon consumption. For the bio-based product, starch-related peaks at 713, 871, and 998 cm-1 disappeared, confirming the successful degradation of starch components. Thermogravimetric analysis results demonstrated a decrease in thermal stability for both polymer types, with weight loss beginning at 120°C for the granules and 150°C for the bio-based product. These findings highlight the effectiveness of indigenous microorganisms in biodegrading bioplastics, offering a targeted bioremediation approach to reduce persistent plastic waste.

Graphical Abstract

Investigation of the Biodegradability of Bio-Plastics Based on Polypropylene and Starch
Keywords
Bacillus sp
Bacteria
Biodegradability
Bioplastic
Polypropylene
Starch

Subjects

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International Journal of Engineering
Volume 39, Issue 10
TRANSACTIONS A: Basics
October 2026
Pages 2559-2570