“I want to find an epoxy that can bond two pieces of polycarbonate materials and be sterilized using autoclave. We tried using epoxy 353ND from Epoxy Technology but it is very difficult to cure completely, and after the sterilization process, the epoxy failed.”
Similar to light-curable adhesives, polycarbonate is usually not suitable for repeated autoclaving cycles. If a strong bond between the two pieces of polycarbonate is achieved, 1-5 cycles may be possible without damaging the adhesive and the polycarbonate.
There are several light-curable adhesives for polycarbonate available that are also approved for medical applications. One example is Dymax 1161-M, which I recommend for further testing with your application.
“We are observing a cracking problem in the bonding of a PVC tube and component of PC-144R with a 50% Cyclohexanone + 50% Tetrahydrofuran solvent mixture. Please suggest an alternative solvent for bonding the above component. Also describe why the polycarbonate is showing cracks when used with aforementioned solvents.”
There are cases where the PC tends to crack upon contact to attacking chemicals like ketones (Cyclohexanone, MEK) , ethers, and esters (Tetrahydrofuran):
- Applied stress due to joint design: when both parts are pushed into each other putting them into tension. To resolve, we recommend changing the design.
- Residual stress due to the molding process: when the molded PC does not cool down consistently. An annealing step (time and temperature to be determined) will relieve residual stress.
I would recommend looking at the possibility of stress within the Polycarbonate and make changes to design and/or process accordingly.
You can also look into switching to a light-curable adhesive, which is typically less harsh to Polycarbonate. For bonding PVC to PC, Dymax has a variety of products if you are interested exploring this path further.
“What bonding agent would you recommend for bonding soft PVC tubing to a polycarbonate connector? This is a sterile disposable tubing set.”
For this type of application I would recommend a light-curable adhesive. Dymax 1161-M could be a good candidate due to its ability to bond dissimilar substrates like PVC and polycarbonate together. This adhesive is solvent free, resistant to EtO, Gamma or Beta sterilization, and passes ISO 10993 biocompatibility testing. Via UV and visible light, the adhesive cures on demand within seconds using Dymax UV light-curing equipment.