Water retention capacity and working mechanism of methyl hydroxypropyl cellulose (MHPC) in gypsum plaster — Which impact has sulfate?

摘要

The water retention effectiveness of a commercial methyl hydroxypropyl cellulose (MHPC) sample (DS_(methyl)~1.6, MS_(hydroxypropyl) ~ 0.2, M_w=419,000 g/mol) in cement paste and in a gypsum plaster was compared utilizing the filter paper test It was found that the water retention capacity decreased significantly in the calcium sulfate system. Thus, higher dosages of MHPC were required in the gypsum plaster to attain water retention values comparable to those in cement This effect is well known from practical application