Both polyurethane and silicone gastrostomy buttons are designed to provide safe enteral feeding access. However, these two materials behave differently and can influence device performance, durability, and patient experience.
Material Comparison
| Feature | Polyurethane Gastrostomy Button | Silicone Gastrostomy Button |
|---|---|---|
| Material strength | Strong, durable polymer | Very soft elastomer |
| Wall thickness | Thinner possible due to strength | Typically thicker |
| Internal diameter | Larger lumen for same size device | Smaller lumen |
| Biofilm adhesion | Lower surface tackiness | Higher tendency for biofilm |
| Structural stability | Maintains shape under load | Highly flexible |
First, what is polycarbonate?
Polycarbonate is a very strong, rigid plastic commonly used in technical devices because it is tough and durable.
Because it is a smooth and dense material, the adhesive used to bond to it needs to:
- Grip the surface well
- Be strong enough to carry mechanical load
- Stay stable when force is applied
Polyurethane vs Silicone: the simple difference
A simple way to understand the difference is to compare polyurethane to a construction adhesive and silicone to a sealant.
| Property | Polyurethane (PU) | Silicone |
|---|---|---|
| Strength | High | Moderate |
| Resistance to pulling or load | High | Lower |
| Flexibility | Balanced | Very flexible |
| Adhesion to plastics | Very good | Moderate |
| Typical use | Structural bonding | Sealing / waterproofing |
In simple terms:
- Polyurethane = strong structural bonding
- Silicone = flexible sealing material
Why polyurethane holds better
Stronger under load
When parts are bonded together, the joint is usually under shear force, meaning sideways force.
Typical strength:
- Polyurethane: about 1.5–3 MPa
- Silicone: about 0.3–0.8 MPa
This means polyurethane can handle roughly 3 to 5 times more force before failing.
Better force distribution
Silicone is very soft and elastic. When force is applied:
- Silicone stretches significantly
- Stress concentrates in one area
- The joint can eventually peel away
Polyurethane is firmer, so it:
- Spreads the load more evenly
- Holds parts together more securely
- Reduces the risk of detachment
Better grip on the plastic surface
Polyurethane adhesives can:
- Form strong chemical bonds
- Slightly penetrate micro-roughness in the plastic
- Provide stronger anchoring
Silicone usually relies more on surface contact and often requires special primers to bond well to polycarbonate.
A real-world example customers understand
A good example is automotive windshields.
In cars:
- The windshield is bonded with polyurethane
- Silicone is used for sealing, not structural bonding
Why? Because polyurethane provides the strength needed to hold structural components in place.
Simple strength example
Imagine a bonded area of 10 cm², about the size of a postage stamp.
Approximate maximum load:
| Adhesive | Load it can hold |
|---|---|
| Polyurethane | ~200 kg |
| Silicone | ~50 kg |
So polyurethane can hold about four times more weight on the same surface.
Simple conclusion for customers
Polyurethane bonding on polycarbonate is stronger because it offers:
- Higher mechanical strength
- Much better resistance to load
- Better force distribution
- Stronger grip to the plastic surface
Why polyurethane can provide clinical performance benefits
1. Larger feeding lumen
Polyurethane is stronger than silicone, which allows the device wall to be thinner while maintaining strength. This means:
- Larger internal diameter
- Improved flow rates over silicone buttons of the same Fr size
- Reduced risk of clogging
For clinicians, this can make feeding and medication administration easier.
2. Greater structural stability
Polyurethane maintains its shape better under pressure. Benefits include:
- Consistent flow performance
- Improved durability during daily handling
3. Lower surface tackiness
Silicone is naturally more “sticky” at a microscopic level, which can encourage:
- Biofilm formation
- Residue build-up
- Feeding tube occlusion
Polyurethane surfaces tend to be smoother and less tacky, helping maintain device function.
4. Durable but still comfortable
Polyurethane provides structural strength while remaining flexible enough for patient comfort, allowing the button to maintain integrity during daily movement. Once in place, it softens at body temperature.
A simple way to explain it
A useful analogy for clinicians:
- Silicone behaves like soft rubber: very flexible but less structurally strong.
- Polyurethane behaves more like a strong, flexible plastic: it keeps its shape and allows more efficient device design.
What this means for patients
Potential benefits may include:
- Improved feeding flow
- Reduced clogging risk
- Durable device performance
- Reliable structural stability
Evidence and Technical References
- Petrie, E. M. – Handbook of Adhesives and Sealants, McGraw-Hill.
- Ratner et al. – Biomaterials Science: An Introduction to Materials in Medicine, Academic Press.
- Fisher & Paykel Healthcare clinical materials science guidance on polymer selection in medical tubing.
- Enteral device material reviews in the journal Nutrition in Clinical Practice.
- Kinloch, A.J. – Adhesion and Adhesives: Science and Technology, Springer.
