Sintering and modification of porous structure caused by binders added to whiteware body composition

The behavior of 2 viscosity-grade polyvinyl alcohols. was studied at 2 different percentages added to the slurry used for the preparation of tableware by isostatic pressing. The modification of the porous structure, the apparent d., and the elimination of the binder were examined. Results obtained show that binders do not modify the reactions during the firing process. More evident differences are verifiable in the porosity of the green and fired bodies, according to their mol. wt. and concn. Porosity decreased until 350°C (200°C for the binder with high mol. wt.), while from 450°C (350°C high wt. binder) to 700°C it increased quickly. At higher temps., as an effect of sintering, porosity fell dramatically to <3% and residual porosity is concd. in large pores. Effect of mol. wt. is to det. a higher porosity using the binder with longer chain while the bulk d. is lower. The green body with higher percentage of adhesive presents a lower open porosity and bulk d.