can i stay 24 hrs visa free? if im not in transit but have 2 different flights form different airlin

Am i gonna be able to come back to china to fly back home if i leave without another entry??
Is there any problem if I leave shanghai, and then fly to thailand, come back to shanghai in AIR Aisia, and then take another flight the next day through UNITED to Mexico? I already bought my way back to mexico, but i dont know that if I go to thailand i would be able to take it!!