We had experienced a similar problom a few years back in a section of the mold where the melt flow first passed through a thin-walled section, then a thick-walled section and at last through another thin-walled section. The bubbles formed in thick-walled section. We think the cause is air...
Try Wacker Silicones. They have some new grades two component Platinum catalyzed silicone rubber for injection molding on the market specially made for overmolding different thermoplastics.
To my knowledge, PEEK is currently being used for this kind of application. The medical grade type is called PEEK-Optima and manufactured by a Swiss (?) company called Invibio. It's strong, flexible, implant tested and most certainly withstands any type of sterilization and to my knowledge...
Most petroleum-based products (such as hydraulic oil used in injection molding machines) will cause EPDM rubber to swell or dissolve. Chloroprene Rubber (Neoprene) on the other hand is generally resistant to most oils, fats and greases.
Probably what you mean by a "flamed" surface is what is generally called surface splay. There are several causes of splay, all of which may lead to a weakening of the part and possible brittle fracture. Please note that even of you do not see any visible splay, the underlying effects might still...
I have a few points which might be of some help :
1. Black masterbatch
- if you are using a masterbatch with a Polycarbonate carrier, be sure to dry it along with the base material.
- if you are using a "universal" Masterbatch with a non-PC carrier, the problem might be due to incompatibility...
Apart from the RF-weld "standard", which is PVC, themoplastic Polyurethane (TPU) can also give a very good RF weld, although the welding equipment must be modified to accomodate this material. Also, TPU-film is rather expensive.
A few years ago, The Dow Chemical Company came out with a new...
One big supplier of ex stock tubes and profiles made of various engineering and high-temperature plastics is a company called Ensinger. Check them out at www.ensinger-online.com. I'm sure they have what you need.
If what you are talking about is a collapsible, high-pressure Balloon Catheder, these are mostly injection molded and either made of PET or PA. For more info see www.advpoly.com
I have also seen large, low-pressure Balloon Catheders made of thermoplastic Polyurethane (for example Bayer makes...
I would like to point out that, due to the short length of the capillary die used in the standard MFI measurements, the MFI value not only reflects the shear viscosity at a certain shear rate (single-point shear viscosity measurement), but also reflects to a certain degree the so-called normal...
