$($a$)$ A sample of linear polyethylene is dissolved in a large excess of xylene at $130C,$ 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 $170C,$ and cooled slowly to room

temperature, a different type of structure is obtained. Compare and contrast the two different

structures.

$(20$ points$)$