1-butyne and 1, 3-butadiene are :

Explanation

Butadiene is a conjugated diene and its free radical polymerisation can occur in two ways:
(i) When the polymerisation takes place at `C_(1)` and `C_(4)` of butadiene, an unbranched polymer results. It can exist either as trans-polybutadiene or as cis isomer or as the mixture of both

(ii) 1, 3 butadiene can also undergo polymerisation at `C_(1)` and `C_(2)` to give polyvinyl polyethene as the product.
`2n CH_(2) = CH - CH = CH_(2) overset(.)overset(R)rarr R - underset("Polyvinyl polythene")((CH_(2) - overset(CH_(2))overset(||)overset(CH)overset(|)(CH)- CH_(2) - overset(CH_(2))overset(||)overset(CH)overset(|)(CH) -)_(n))`