This product can also be obtain by co-polymerisation by ethylene-propylene
$\underset{\text{(Propylene)}}{CH_2= \overset{\underset{|}{C}H_3}{C}H} + \underset{\text{(ethylene)}}{CH_2=CH_2} \to -\left[CH_2-\overset{\underset{|}{C}H_3}{C}H-CH_2 - CH_2\right]_n-$