{{Short description|Determination of the softening point for materials that have no definite melting point}} {{Refimprove|date=December 2009}} {{notability|date=August 2022}} thumb|200px|Vicat needle for cement paste solidification time measurement
'''Vicat softening temperature''' or '''Vicat hardness''' is the determination of the softening point for materials that have no definite melting point, such as plastics. It is taken as the temperature at which the specimen is penetrated to a depth of {{val|1|u=mm}} by a flat-ended needle with a {{val|1|u=mm2}} circular or square cross-section. For the Vicat A test, a load of {{val|10|ul=N}} is used. For the Vicat B test, the load is {{val|50|u=N}}. It is named after the French engineer Louis Vicat.
Standards to determine Vicat softening point include ASTM D 1525 and ISO 306, which are largely equivalent.<ref>[http://www.makeitfrom.com/info/?about=Vicat_Softening_Point Vicat Softening Point: Definition] {{webarchive |url=https://web.archive.org/web/20100424004026/http://www.makeitfrom.com/info/?about=Vicat_Softening_Point |date=April 24, 2010 }}</ref>
One advantage of measuring the softening point using the Vicat test rather than heat deflection temperature is that the Vicat is less sensitive to internal stresses introduced by processes like injection molding.<ref>{{cite book | chapter= The Vicat Softening Point Test Method: Correlations, Uses, and Variants | title= International Symposium on Plastics Testing and Standardization | author1= C. E. Stephenson | author2= A. H. Willbourn | volume = STP247-EB | orig-date = 1959 | isbn = 978-0-8031-6105-4 | doi = 10.1520/STP44205S }}</ref>
The Vicat softening temperature can be used to compare the heat-characteristics of different materials.
Four different methods may be used for testing. {| class="wikitable sortable" style="text-align:left" |- ! Method !! Load !! Heating rate |- ! !! {{nobold|(N)}} !! {{nobold|(°C/h)}} |- | A50 | style="text-align:right" | 10 | style="text-align:right" | 50 |- | B50 | style="text-align:right" | 50 | style="text-align:right" | 50 |- | A120 | style="text-align:right" | 10 | style="text-align:right" | 120 |- | B120 | style="text-align:right" | 50 | style="text-align:right" | 120 |}
ISO 10350 Note
ISO 10350 Vicat values are tested using the B50 method.
Similar Standards: ASTM D1525
==References== {{Reflist}}
{{ISO standards}}
{{DEFAULTSORT:Vicat Softening Point}} Category:Cement Category:Polymer chemistry