Coming from a low pressure process based on special catalysts (Ti- or Cr-based), HDPE has a linear polymeric chain, combined with a higher density and melting point. To fit special applications, the molarmass distribution can be adjusted in a wide range by means of catalysts or polymerisation technology. New applications are opened for HDPE as well as other low pressure PEs by applying metallocene (single-site) catalysts, which allow the production of very narrow molar mass distributions and the better distribution of comonomers.
Based on the same technology as HDPE, but the density is reduced through the incorporation of longer a-olefins as comonomers. With this, another way of adapting the products to the final applications turns up. Single-site catalysts allow an expansion of the application range, mainly by allowing higher comonomer contents and a more even distribution of these.
A product from a high-pressure polymerisation process, LDPE is characterised by its highly branched chain structure. As a result of this, density and crystallinity are reduced while the processability in a variety of conversion technologies is greatly facilitated. The addition of special comonomers can further expand the property range of these grades.