Spider-Silk Mimic Fibers and Tensile Scaling

ISEF Category: Materials Science

Subcategory: Composite Materials  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

Spider silk is tougher than many materials people use every day, yet it comes from a tiny animal. You can try to copy some of that behavior with polymer fibers you spin yourself. The tricky part is not just making fibers. It is figuring out whether their strength follows a real scaling law or just random luck.

What Is It?

This project looks at electrospinning, a method that uses high voltage to pull very thin fibers from a liquid polymer solution. Think of it like stretching warm sugar into a thread, but with an electric field doing the pulling. You start with gelatin and PVA, two common polymers, then turn them into fibers that can be tested like a tiny fabric.

The big science question is how the fiber strength changes when you change the recipe or the spinning conditions. That matters because real materials rarely act like simple one-piece solids. Their strength depends on chain alignment, fiber thickness, and how the molecules pack together. Flory theory helps explain how polymer chains behave, so your job is to see whether your data matches that kind of scaling or breaks away from it.

Why This Is a Good Topic

This is a strong science fair topic because you can change one variable at a time, measure a clear outcome, and compare your results with a real theory. It connects to lightweight fabrics, biomedical fibers, and sustainable materials design. You can learn how to build controls, collect mechanical data, fit trends, and ask whether a theory actually predicts what your samples do.

Research Questions

• How does the gelatin to PVA ratio affect tensile strength in electrospun fibers?
• How does the fiber diameter affect tensile strength and elongation before break?
• Does changing the collector distance alter the scaling relation between diameter and strength?
• To what extent does humidity during spinning change fiber uniformity and mechanical performance?
• Which post-treatment condition produces the biggest increase in tensile strength without reducing stretch too much?
• How does the measured strength scaling compare with the trend predicted by Flory theory?

Basic Materials

• Gelatin powder or food-grade gelatin.
• PVA powder or solution.
• DIY electrospinner components with insulated housing and safety interlocks.
• High-voltage power supply rated for electrospinning.
• Syringes or small solution reservoirs.
• Collection surface or rotating drum collector.
• Digital microscope or USB microscope.
• Digital calipers or image analysis for fiber diameter.
• Small tensile test setup or force gauge.
• Digital kitchen scale with 0.01 g or better resolution.
• Nitrile gloves and safety goggles.
• Humidity and temperature meter.

Advanced Materials

• Analytical balance.
• Rheometer or viscometer.
• Scanning electron microscope access.
• Universal testing machine with fiber grips.
• Differential scanning calorimeter.
• Fourier transform infrared spectroscopy access.
• Environmental chamber for humidity control.
• Surface profilometer or atomic force microscope.
• Precision syringe pump.
• Data logger for voltage, current, and environmental conditions.

Software & Tools

• ImageJ: Measures fiber diameter from microscope images and helps build size distributions.
• Python: Fits scaling laws, runs regression tests, and plots tensile data cleanly.
• Google Sheets: Organizes samples, labels controls, and tracks measurement metadata.
• R: Compares models, checks uncertainty, and tests whether theory fits better than a straight line.
• Origin: Creates publication-style graphs if your school has access to it.

Experiment Steps

1. Define the one structural variable you will change first, such as polymer ratio, spinning distance, or humidity.
2. Plan how you will make fibers that are similar enough to compare, then list the controls that stay fixed.
3. Build a measurement plan for fiber diameter, alignment, and tensile response so every sample gets the same checks.
4. Decide how you will turn raw force data into a real comparison, such as stress, strain, or strength per cross-sectional area.
5. Build a standard curve or scaling model that lets you compare your results with Flory theory instead of just ranking samples.
6. Plan one follow-up test that explains any surprising result, such as poor uniformity, bead formation, or weak fiber bundles.

Common Pitfalls

• Making fibers with uneven diameter, which makes strength data noisy and hard to compare.
• Mixing the polymer solution inconsistently, which changes viscosity from batch to batch.
• Ignoring humidity, which can change how the jet stretches and dries.
• Testing bundles that slip in the grips, which gives fake low tensile strength values.
• Comparing samples with different alignment or thickness and then blaming the recipe instead of the structure.

What Makes This Competitive

A stronger project does more than report which fiber is strongest. It tests a clear model, checks uncertainty, and explains why the data follow or reject the expected scaling law. You can raise the level by using better diameter measurements, tighter controls on spinning conditions, and statistics that compare competing fits. A thoughtful link between structure, mechanics, and theory makes the work feel like real materials research.

Project Variations

• Try chitosan-PVA or silk fibroin blends to compare whether a different polymer system follows the same scaling trend.
• Compare aligned fibers with random mats to test how orientation changes tensile strength and failure strain.
• Add a post-spinning crosslinking step and analyze whether the strength gain depends on fiber diameter or composition.

Learn More

• NASA NTRS: Search for review articles on electrospun polymer fibers and mechanical properties in the NASA Technical Reports Server.
• PubMed: Search review articles on gelatin, PVA, and electrospun biomaterials.
• NIH PubChem: Look up polymer properties, structure, and safety data for common lab chemicals.
• MIT OpenCourseWare: Find materials science and polymer engineering lecture notes for mechanical behavior and scaling concepts.
• Materials Today and Polymer: Search peer-reviewed review articles on electrospinning and polymer fiber mechanics.