So having built Polyethylene and Polyethene from molymods I am left with 2 free Carbon bonds which I an use to chain them together.  Just tried to build PolyPropene and  just have 1 free carbon bond,  so I can attach to a 2nd polypropene   (included the info graphic for reference above)

Am I doing something wrong or does polymerisation work differently for different types of monomers.

I am kinda learning as I go along and making blog posts,  the end game is to gain a basic understanding of this, enough to help in schools, it just seems interesting what I am finding.

After posting an initial video to Peertube ( like you tube but decentralised ) it was suggested I use Molview,  this works but I think I am discovering far more about this above with the actual physical building. 

So am I doing something wrong.  I need to look in to this further as putting two polypropene molecules together just looks like there is an Alkane chain of 6 Carbon and  14 Hydrogen C6H14

 

Polyethylene is essentially a long chain alkane.

Polypropylene is a long chain alkane with a lot of methyl groups attached to it. 

Polystyrene is similar, but with a lot of benzene rings stuck to the chain.