The molecular weight of HPMC can be expressed by its solution viscosity in the solvent used.
Unless otherwise stated, the molecular weight of HPMC is measured here with UBBELOHDE viscometer at 20 ℃ using an aqueous solution containing 2% (weight) of HPMC.
Its withering degree is generally about 5 to 200000 mpa. Sd uses hydroxypropyl methyl cellulose ether as a suspension agent for suspension polymerization of ethylene unsaturated monomers. The selected firmness is about 5 mpa. s, from about lOmpa. S. to about 400 mpa. s, which is about I00mPa. s.
S, 10100, and 400mpa S is respectively equivalent to the number average molecular weight of 1000013000,26000, and 410000 HPMC ether aqueous solution used as thickener according to the invention and viscosity at 20 ℃, at least about l, o ∞ mpa s. It is better to be about 15000 mpa. s, so the viscosity of the solution is usually up to about 200000 to iso, and it is better to be 120000 to 100000 m pa. s, and it is better to be 75000 mpa So number average molecular weight (M).
The average molecular weight (M) of the number a can be determined by osmometry from about 20000, better from about 55000, better from about 120000; About 280000, 250000 is better, and 2200000 is better.