HDPE SPIRAL PIPE Information PP-B. part 3

Januari 11, 2020 by admin in Uncategorized

PP Impact copolymers for non-pressure sewage and drainage

A number of PP ethylrnr block co-polymers (PP-B) have been specially developed for the manufacture of non-pressure pipes and offer the best balance of properties for these applications. In modern heterophasic PP-B materials, rubber particles which contain ethylene-propylene co-polymer are dispersed in a homo-polymer PP-H matrix. The high crystalline PP-H matrix provides the polymer with superior stiffness, whereas the rubber particles contribute to its high impact resistance.

In the BorECO^TM range of materials supplied by Borealis and Borouge the stiffness of the PP-B material is maximized by nucleating the material during production using proprietary nucleation technology.

Thus nucleation leads to smaller, more evenly distributed crystal modification and a fine dispersion of comonomer/ethylene propylene rubber phase in the PP-H matrix, which significantly improves the stiffness-toughness balance of the material compared to non-nucleated PP-B grades and enabling materials with an E-modulus of larger than 1700 Mpa, even up to 2000 Mpa.

The mechanical properties for selected PP-B products are given in table 2 including PP-HM and other characteristic PP-B materials used for drainage and sewerage.

Products 1 to 3 are the preferred choice when the low temperature impact resistance is of key importance. The PP-HM materials, product 3 and 4, are the superior materials when a better balance of stiffness and impact is needed.

The increased E-modulus of the new generation PP-HM materials offers a higher resistance against creep. As an example, in figure 6 a creep curve of a PP-HM material following ATV127 procedure is shown.

Due to the significantly higher E-modulus of PP-B-HM materials there are considerable differences in the design of these pipes, consequently leading to a weight reduction per meter of pipe by keeping the mechanical and long term requirements according to the relevant product standards. Depending on the pipe design the weight reduction is achieved due to reduction of the wall thickness of a solid wall pipe, or due to optimised profile geometry.

article source:
Handbook on large plastic pipe
KRAH COMMUNITY
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