HCR Silicone for Medical Devices: How PEG Improves Processability, Extrusion Quality & Material Performance

PEG contributes several important benefits that improve both processing efficiency and final part performance.

Improved Flow and Controlled Viscosity

PEG reduces silicone viscosity, leading to smoother, more consistent extrusion behavior. Medical tubing and precision profile components depend on this improved flow to achieve uniform wall thickness and dimensional accuracy—key factors for device safety and functional reliability.

Cleaner, More Consistent Surface Finish

A refined surface finish reduces particulate generation, lowers the risk of microdefects, and supports downstream assembly. In many medical applications, surface quality is directly tied to regulatory acceptance and long-term device performance.

Lower Tack for Better Handling and Cleaner Processing

PEG decreases surface tack, which enhances release from tooling and reduces contamination risk. This contributes to cleaner manufacturing environments—critical for medical production under strict quality and cleanliness requirements.

PEG’s effects on silicone vary significantly depending on formulation and end use. For medical devices, precise customization is essential.

• Cure behavior must be preserved. PEG can influence cure kinetics in both peroxide and platinum-cured systems. Any shift must be controlled to maintain mechanical integrity and avoid unwanted byproducts.
• Regulatory compliance is nonnegotiable. Device requirements may involve ISO 10993, USP Class VI, or long-term implantation standards. PEG levels must align with these regulatory pathways.
• Mechanical properties must match clinical demands. PEG can modify medical-grade silicone hardness, flexibility, tear strength, kink resistance, and compression set—properties that differ widely between catheters, valves, and sealing components.

For these reasons, PEG is never added using a onesizefitsall formula. Each application requires careful tuning to meet exact performance specifications.

1. Molecular Weight Selection

Different PEG molecular weights influence lubricity, miscibility, and potential migration. Controlled migration is especially important in medical devices, where purity, surface quality, and long-term stability are critical.

2. Mechanical Property Evaluation

Because PEG can soften silicone, its effect on hardness, tensile strength, elongation, and tear resistance must be evaluated to ensure the final material meets device performance requirements.

3. Extrusion and Cure Optimization

Introducing PEG may require adjustments to:

• Die design
• Temperature and pressure profiles
• Line speed
• Cure time and temperature

These refinements help maintain precision, surface smoothness, and efficient throughput.

4. Long-term Stability and Aging

Medical devices often require long shelf life or extended stability within the body. Testing must confirm:

• PEG migration behavior
• Compatibility with fillers and additives
• Retention of mechanical properties over time

Incorporating PEG into HCR silicone can significantly enhance flow behavior, surface quality, and processing efficiency for medical device manufacturing. However, to achieve these benefits, while ensuring regulatory compliance and mechanical performance, material customization and process optimization are essential.

At Flexan, we collaborate with medical device manufacturers to develop tailored silicone formulations and refined processing strategies that meet demanding clinical, performance, and regulatory requirements. If your next device requires precise material behavior or enhanced manufacturing performance, our materials engineering team is ready to partner with you.