HPMC, on the other hand, is Hydroxypropyl Methylcellulose. It is produced by alkali treatment of refined cotton and further etherified using epichlorohydrin and chloromethane as etherifying agents, resulting in a nonionic mixed ether of cellulose. The degree of substitution is typically between 1.2 and 2.0, and its properties vary based on the ratio of methoxy and hydroxypropoxy groups.