Abstract
The growing interest in biodegradable materials has led to extensive research on polylactic acid (PLA)-based biocomposites reinforced with natural fillers such as coconut shell powder (CSP). This study investigates the enzymatic degradation behavior of CSP-reinforced PLA biocomposites, providing insights into their biodegradability and material performance. The results demonstrate that enzymatic degradation significantly influences the mechanical properties and microstructural integrity of the biocomposites, highlighting their potential as sustainable alternatives to conventional plastics.
Introduction
Biodegradable polymers have gained attention as an eco-friendly alternative to synthetic plastics. PLA, a well-known biodegradable polymer, exhibits promising mechanical properties but suffers from brittleness. Reinforcing PLA with natural fillers such as CSP enhances its strength and biodegradability, making it suitable for various applications. This study focuses on the enzymatic degradation of PLA-CSP biocomposites, analyzing their structural, thermal, and mechanical changes during degradation.
Materials and Methods
1. Materials
- PLA (commercial grade)
- Coconut shell powder (sieved to <100 µm)
- Enzymes (Proteinase K)
- Phosphate-buffered saline (PBS) solution
2. Sample Preparation
- CSP was mixed with PLA at different weight percentages (5%, 10%, 15%).
- The mixture was processed via melt blending and compression molding.
- Specimens were prepared according to ASTM standards for mechanical testing.
3. Enzymatic Degradation Test
- Samples were immersed in PBS solution containing Proteinase K at 37°C.
- Weight loss was measured periodically.
- Morphological changes were observed using scanning electron microscopy (SEM).
Results and Discussion
1. Biodegradability Analysis
- Increased CSP content accelerated enzymatic degradation due to the hydrophilic nature of lignocellulosic fillers.
- Weight loss was more significant in 15% CSP-PLA biocomposites compared to pure PLA.
2. Mechanical Properties
- Initial reinforcement improved tensile strength, but degradation reduced mechanical integrity over time.
- Flexural modulus decreased gradually with increased degradation duration.
3. Microstructural Changes
- SEM analysis revealed surface erosion and microcrack formation due to enzymatic activity.
- CSP acted as a nucleation site for enzymatic attack, enhancing the overall degradation process.
