What is C6?

C6 is shorthand for the hexene co-monomer used in the Linear Low Density Polyethylene (LLDPE) plastic from which the water tank is made.

In LLDPE, the branching in the molecule is achieved through copolymerisation with monomers such as butene (C4), hexene (C6) or octene (C8).  The toughness of the LLDPE is highly dependent on the short chain branch length, which is determined by the co-monomer used. A C6 co-monomer has a longer short chain branch length than a C4 co-monomer, and so on.

The degree of branching increases as the proportion of co-monomer in the polymer is increased. The branching structure will hence depend on the type and proportion of co-monomer, and also the distribution of co-monomer along the molecule (ie. whether the branches are evenly distributed or clumped together). This means that the LLDPE’s supplied by different manufacturers can have noticeably different properties.

In Alkatuff LLDPE, which is a hexene copolymer, the branch points occur every 50 to 100 carbon atoms.