PubMed Health⌕ Search

Biomedical subjects

T W Herfort

Publications and source records attributed to T W Herfort.

2 recordsLinked to original sources
PubMed1978

Tear strength of elastomeric impression materials.

1. Under simulated clinical conditions the maximum tear strength of those materials tested was reached in 10 to 15 minutes. 2. The polysulfide materials showed three to six times the tear strength of the silicones. 3. The polyether material displayed a tear resistance slightly higher than that of the silicones but one third to one fifth as high as that of the polysulfides. 4. The clinical significance of the differences in tear strength was undetermined since other factors (such as adhesion) were not considered.

Chemical Phenomena↗
PubMed1977

Viscosity of elastomeric impression materials.

(1) Some elastomeric impression materials (Omniflex and Impregum) exhibited extreme shear thinning properties. This property was considered useful and these materials can be considered all-purpose. (2) The use of impression materials in syringing applications should not be precluded simply because the substances are thick or heavy during spatulation. A tenfold reduction in viscosity with increasing shear rate was found for three of the materials tested. (3) Viscosity characteristics of the impression rubbers were linked to filler content. (4) The viscosity rise during cross-linking was monitored for various impression products. It was found that each manufacturer's specifications of the length of time for syringing were relatively accurate.

Chemical Phenomena↗