Plasticization of cellulose ethers used in the film coating of tablets.
Plasticizer/polymer interactions have been studied by measuring the intrinsic viscosities of both ethyl cellulose and hydroxypropyl methylcellulose in a series of dialkyl phthalates and in a series of liquid glycols respectively. A correlation was found between the intrinsic viscosity of the polymer/plasticizer solutions and the tensile strength, elongation at rupture and work done in stressing to failure of cast films--the mechanical properties being at a minimum when the intrinsic viscosity was at a maximum. This correlation held only within a homologous series of plasticizers and none was found for plasticizers of different structures. A relationship was found between the lowering of a calculated glass transition temperature of hydroxypropyl methylcellulose in the presence of the plasticizers propylene glycol, polyethylene glycol 200 and glycerol and the intrinsic viscosity of the corresponding solutions--the higher the viscosity the greater the lowering of the transition temperature.
D002482:Cellulose / Q000031:analogs & derivatives*; D002626:Chemistry, Pharmaceutical; D004987:Ethers; D010968:Plasticizers; D011108:Polymers; D013607:Tablets; D013696:Temperature; D014783:Viscosity
D004987:Ethers; D010968:Plasticizers; D011108:Polymers; D013607:Tablets; D002482:Cellulose