PEBAX Tubing — Dispelling the Myths
27 May 21
Dispelling the Myths About PEBAX Tubing
PEBAX is a lightweight thermoplastic elastomer that ensures higher elastic memory. This elastomer provides greater kink resistance and torque transference. It also holds qualities, like impact resistance and consistent hardening at body and room temperatures. Another benefit of PEBAX is that it is resistant to various chemicals, making it a perfect choice for medical PEBAX tubing. This elastomer is known for its dielectric strength, thermal stability, chemical resistance, and mechanical strength. However, there are some myths about this type of tubing.
In this article, we will dispel the myths about this type of tubing. The information available in this article is for learning purposes.
About Medical PEBAX Tubing
PEBAX comes with exceptional processing versatility for various flexural moduli. It ensures greater mechanical, chemical, and physical properties with top biocompatibility for various commercial products.
The processing versatility of PEBAX makes it ideal for products with different levels of stiffness to provide a smooth transition and precise control. For these qualities, the PEBAX tubing is known as an ideal choice in the medical industry for tubing applications.
Customized tubing is also a possibility because of the versatility of the PEBAX. Here are the top beneficial qualities of customized PEBAX tubing:
- Greater torque transference
- Excellent impact resistance
- Exceptional kink resistance
- Resistant to many chemicals
- Flexibility and consistent hardness at body/room temperatures
The steady melt flow, even molecular weight, and narrow temperature processing range ensure excellent PEBAX processability. It also offers exceptional toughness and greater elastic memory. Now, let’s talk about the most common myths about medical PEBAX tubing.
1. It is Hard to Bond Polyimide Tubing
The construction of polyimide tubing involves several layers on the mandrel. This process is known as “dip dispersion” or “dipping”, applying and curing every layer until you achieve the required thickness.
Every single tube layer is very thin and goes through different temperature ranges. Thermal bonding methods, like solvent bonding and ultrasonic welding, do not ensure great results. However, two-part epoxies and cyanoacrylates are the adhesives with a high success rate.
A design engineer must consider a credible adhesive company to take guidance on choosing a suitable adhesive. It will be a useless effort if you try to UV treat with polyimide. Polyimide tends to absorb most of the employed UV which makes your adhesive uncured. However, polyimide bonding can be easy and successful if you pay attention to details right from the very first step.
2. The Kinking of Polyimide Tubing is Easy
Every single plastic tube would kink after a certain time. Polyimide comes with excellent mechanical properties, but not magical. In recent times, catheter designs have become complex.
Therefore, engineers try to avoid tubing with identical properties at both ends. However, you can avoid kinking while bending the tube to a slight diameter. With a decrease in wall thickness and an increase in the diameter of the tube, you can minimize the chances of tube kinking. A tube kinks when the tube cross-section in the tube bend becomes oval to a certain point.
A stronger plastic tends to kink easily at the larger radius at certain dimensions. Therefore, the material strength and dimensions are critical in this regard. A polyimide tube with 1.016mm diameter and 0.01905mm wall thickness will easily kink at the larger radius. However, the same size tube of a soft polymer, like PEBAX tubing, is hard to kink.
Material strength is critical when considering the kink radius. You can also add reinforcement, such as the coil reinforcement of stainless steel. Coil reinforcements are extremely helpful in improving kink results and maintaining tube dimensions and strength.
3. Polyimide Tubing Lacks Flexibility
Here, flexibility means the capabilities of being flexed or bent. You can bend and flex polyimide tubing. However, bending polyimide tubes needs additional force as compared to softer plastics. It is both against and in favor of polyimide as the material in the catheter design. Polyimide may not be the most ideal material for all types of applications, but it is perfect when you require superior strength.
In recent times, enhanced manufacturing techniques are helping the utilization of composite material. Several modern-day catheter designs accept polyimide as a strengthening component. Polyimide is the most recommended material to add strength, especially for tight areas.
4. Brittle Nature of Polyimide Tubing
It is extremely hard to snap, crack, or break polyimide if its cure is improper. In simple words, you cannot call polyimide PEBAX tubing brittle. However, you can puncture a kinked tube by placing a very thin polyimide layer over the braid.
However, you need to be extra cautious while employing very thin-walled polyimide tubes. You can regain over 85% properties of the tube material after it kinks by heating that tube at a temperature of 200-degree Celsius.
If you find out that the polyimide tube is brittle, it must not be cured properly and you have to discard it. Different layers comprise a polyimide tube. These layers are bonded molecularly to layers below and above.
But, excessive stress to the tube wall can cause delamination by overcoming the strength of the covalent bond. However, appropriate layers cross-linking is possible by implementing testing and controls in the operations to resist delamination.
5. It is hard to Drill, Form, and Machine Polyimide Tubing
Polyimide tubes are made of thermoset materials. But, you can perform some formation with methods, like tapering and/or flaring. Generally, forming is possible at a comparatively higher temperature using mandrels for supporting all aspects of a process.
Catheter surface holes are possible with punches. In recent times, laser ablation has emerged as an effective method for various features, such as holes, chamfers, diameter reduction, slots, printing, and cuts, etc. Laser ablation is a perfect alternative to old mechanical methods as it eliminates issues like excessive stress and burrs.
Polyimide PEBAX tubing is around for a long time and it has been the most reliable solution for medical tubing for many reasons. Although polyimide is known for strength, there are a few challenges with the material.
However, its strength along with other benefits is helping the medical industry by reducing health care costs and introducing top-quality medical devices. Design engineers can easily achieve specific device requirements by using it with ingenuity and little thought for a long time.
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