$($a$)$ A sample of linear polyethylene is dissolved in a large excess of xylene at $130$

C$,$ and dilute solution is then slowly cooled. After a while, a fine white suspension is obtained. What does this suspension consist of$?$

$($b$)$ If the suspension is filtered and dried, then heated to $170$C$,$ and cooled slowly to room temperature, a different type of structure is obtained. Compare and contrast the two different

structures.