As a homomorphic image of the hyperalgebra U q,R (m|n) associated with the quantum linear supergroup U υ (gl m|n ), we first give a presentation for the q-Schur superalgebra S q,R (m|n, r) over a commutative ring R. We then develop a criterion for polynomial supermodules of U q,F (m|n) over a filed F and use this to determine a classification of polynomial irreducible supermodules at roots of unity. This also gives classifications of irreducible S q,F (m|n, r)-supermodules for all r. As an application when m = n ≥ r and motivated by the beautiful work [3] in the classical (non-quantum) case, we provide a new proof for the Mullineux conjecture related to the irreducible modules over the Hecke algebra H q 2 ,F (S r ); see [2] for a proof without using the super theory.