INDUSTRIAL AND ENGINEERING CHEMISTRY
1384
Vol. 39, No. 11
may lie due to thtx further rnt~c~lianical entnnyl~~mcnt of u - ~ i u t y l Table I-, CHAXGEIS CONCESTRATIOS OF WATERIS TYPICAL alcohol s:olveiit within the, growing polysilicic w t c r molcc*ulnr SAMPLES units. IIr. Heated 0 10
20 30 40 50 65 iG
Degree of Esterification, BuO/Si = 0.48 Viscosity. CP. HzO, % 1 21 0.07 ... 0.16 ... 0.25 1.21 0.24
...
1.21 , . I
1.23
n . 18
O,l4 0.22 0.26
Degree of Esterifiration, RuO/Bi = 0.31 Viscosity, CP. H20, % 1.23 0.14 ... 0.25 1.23 0.33 1,233 0.20 . , , 0.23 1.25 0.30 ... 0.31 1.28 0.34
I t i, postulated that, the unestei,ified hydroxyl groups ivitliin the polysilicic acid molecule slowl>-undergo intramolecular condensation; thus they liberated water and account for the initial rise in the n-ater content of the solution. This water may then be consumed in the hydrol! of butoxy groups, liberat iiig ributyl alcohol and forniing nelv hydrosj-1 groups, al~iioughthis second increase in hydroxyl groups has not bccn checked by actual analysis. This process r o u l d lead t o a decrease in the water content of the system. Finally, the nen-ly formcd hyclrosyl groups may then permit intermolecular condensation anti the growth of larger molecular units, water again being liberatetl in the process, and the viscosity increasing. This increase in viscosity
ACKNOWLEDG3IENT
Thc authors tliank those n h o have cmtrikiutcd t o : h i 3 I W ~ ~ ~ L ~ with sptLci:tl acknowledgmt~nt t o J. S. Iiii,k, II. 13. I~t~rriaId, I
