Chitosan Bioplastic Breakdown in Soil and Water

ISEF Category: Environmental Engineering

Subcategory: Recycling and Waste Management  ·  Difficulty: Intermediate  ·  Setup: Home Setup  ·  Time: Full Year

The Hook

Plastic waste hangs around for years, but some bio-based films fall apart much faster. Your job is to measure how fast that happens, and where. A film that breaks down in compost may behave very differently in salty water. That gap makes a strong science fair project.

What Is It?

This project asks how a bioplastic film changes over time in two different environments. The film uses chitosan, a material made from shrimp shells, and eggshell powder, which adds calcium carbonate. Think of the film like a thin snack wrapper made from recycled biological ingredients. You are not just asking, 'Does it disappear?' You are asking, 'How fast does it lose mass, strength, and structure?'

That matters because materials do not break down the same way everywhere. Compost has microbes, moisture, and oxygen. Seawater has salt, waves, and a different set of microbes. A film that looks eco-friendly on paper may still last too long in the ocean, or fall apart too quickly in storage. By tracking visible changes, mass loss, and simple strength checks, you can turn biodegradation into data.

Why This Is a Good Topic

This is a strong science fair topic because you can measure real change over time, compare two environments, and build a clear claim from your data. It connects to plastic waste, packaging design, and marine pollution. You can start with simple materials and still ask a serious research question. If you plan your controls well, you can learn how to run a time-series experiment, analyze kinetics, and explain why one environment speeds breakdown more than another.

Research Questions

• How does compost proxy affect the mass loss of chitosan-eggshell films over time?
• How does seawater proxy affect the tensile strength of chitosan-eggshell films over time?
• What is the effect of eggshell powder loading on the biodegradation rate of chitosan films?
• To what extent does film thickness change the breakdown rate in compost and seawater proxies?
• Which environment causes a larger change in surface appearance, compost proxy or seawater proxy?
• How does pH shift during degradation of chitosan-eggshell films in each proxy?
• What is the effect of crosslinking level on the stability of chitosan-eggshell films?

Basic Materials

• Chitosan powder or flakes from a reliable supplier.
• Clean, dried eggshells.
• White vinegar or dilute acetic acid for film preparation.
• Digital kitchen scale with 0.1 g accuracy.
• Measuring spoons or graduated cylinder.
• Flat casting trays or petri dishes.
• Wax paper or silicone baking mats.
• Ruler or digital caliper.
• Sealable containers for compost proxy and seawater proxy.
• Compost proxy materials such as potting soil and kitchen scraps, or finished compost.
• Salt, distilled water, and a container for seawater proxy.
• Gloves, safety glasses, and a mask for handling dry powders.
• Notebook or spreadsheet for daily observations.
• Smartphone camera for photo records.

Advanced Materials

• Precision balance with 0.001 g accuracy.
• Universal testing machine or texture analyzer for strength testing.
• Digital caliper for thickness mapping.
• pH meter with calibration buffers.
• Fourier-transform infrared spectroscopy access for chemical change checks.
• Scanning electron microscopy access for surface imaging.
• Differential scanning calorimetry access for thermal property changes.
• Controlled composting chambers or incubators.
• Salinity meter or refractometer.
• Image analysis target card for standardized photography.

Software & Tools

• Google Sheets: Organizes mass loss, strength data, and time-series plots.
• ImageJ: Measures surface area change, cracks, and color shifts from standardized photos.
• Python: Fits decay curves and compares degradation rates between treatments.
• R: Runs statistical tests and visualizes group differences cleanly.
• GeoGebra: Helps you inspect trend lines and simple kinetic models.

Experiment Steps

1. Define the exact film recipe, then decide which factor you will change first, such as environment, eggshell loading, or thickness.
2. Set up a control film with no eggshell powder so you can separate the effect of the filler from the base polymer.
3. Choose simple outcome measures, such as mass loss, visible cracking, thickness change, and strength, then decide how you will score them the same way each week.
4. Build a sampling plan that keeps one group in compost proxy and one group in seawater proxy, while holding light, container type, and film size as constant as possible.
5. Plan a standard photo method and a standard drying method so your measurements stay comparable across all 12 weeks.
6. Preselect the graph and statistical test you will use to compare breakdown curves, not just end-point values.

Common Pitfalls

• Letting films dry unevenly before weighing, which makes mass loss look larger or smaller than it really is.
• Using a compost proxy with too little microbial activity, which can make the biodegradation curve look flat.
• Photographing samples under changing room light, which makes visual scoring and image analysis drift between sessions.
• Confusing swelling with degradation, which can happen when films absorb water before they actually break down.
• Comparing samples with different starting thicknesses, which can hide the real effect of environment on breakdown rate.

What Makes This Competitive

A stronger project will compare more than one measurement, not just final mass loss. You can stand out by modeling the breakdown curve, testing whether the two environments follow different kinetics, and controlling film thickness and composition carefully. Strong entries also separate physical swelling from true degradation. If you add image analysis or mechanical testing, your project becomes much more convincing.

Project Variations

• Compare shrimp-shell chitosan films with starch-based films to see which one breaks down faster in each proxy.
• Test how different eggshell powder amounts change film stability, cracking, and mass loss over time.
• Swap compost proxy for freshwater proxy to see whether salinity changes the degradation curve.

Learn More

• PubMed: Search review articles on chitosan biopolymers, biodegradation, and film properties.
• NIH National Library of Medicine Bookshelf: Look for free textbook chapters on polymers and biomaterials.
• NOAA Marine Debris Program: Find background on plastic pollution in marine environments and breakdown concerns.
• USGS Water Science School: Review basic information on salinity, water chemistry, and environmental conditions.
• NASA Earth Observatory: Read free articles on materials, waste, and environmental impacts from a systems view.
• MIT OpenCourseWare: Search for free materials science, environmental engineering, or polymer-related lecture notes.