From UHMWPE Powder to Consolidated Form

Conversion From UHMWPE Powder to Consolidated Form 

UHMWPE is produced as powder and must be consolidated under elevated temperatures and pressures because of its high melt viscosity. As already discussed in Chapter 1, UHMWPE does not flow like lower molecular weight polyethylenes when raised above its melt temperature. For this reason, many thermoplastic processing techniques, such as injection molding, screw extrusion, or blow molding, are not practical for UHMWPE. Insfead, semifinished UHMWPE is typically produced by compression molding and ram extrusion. 

compression-molded sheets of GUR 1020 and 1050 are produced commercially by two companies (Perplas Medical and Poly Hi Solidur Meditech). Ticona stopped producing compression-molded UHMWPE in 1994. Perplas s molding facility is in England, whereas Poly Hi Solidur produces medical grade UHMWPE sheets in the United States and in Germany. 

Depending on tire size of a press, the UHMWPE sheet may range in size between 1 m x 2 m (shown in the photo) to 2 m x 4 m, witir thicknesses of 30 mm to 80 mm. However, the facilities necessary to mold a 2 m x 4 m sheet of UHMWPE are considerably larger than that shown in the photo. The press 

Compression molding press (along with the author, for scale) for production of I m X 2 m sheets of UHMWPE. This press is located at Poly Hi Solidur Meditech in Vreden, Germany, and was originally used by Ticona in the production of Chirulen sheets of UHMWPE. The press is still used today in the production of medical grade UHMWPE. 

---

CONVERSION FROM UHMWPE POWDER TO CONSOLIDATED FORM... 

---