Apparatus for mixing polymer, the apparatus comprising (i) a mixer housing including an internal chamber, said internal chamber having first and second sections in fluid communication with each other through a passageway; (ii) a first ram received in said first section; and (iii) a second ram received in said second section, where the apparatus is adapted to receive a composition including polymer within said internal chamber and move said composition between said first and second chambers through said passageway by operation of said first and second rams.