Melting interval
The temperature interval between the solidus and liquidus temperature of a substance is referred to as the melting interval , melting range or solidification interval .
Materials science
In materials science, the mixture of alloys between the solidus and liquidus temperature is mushy, solid and liquid phases coexist.
In contrast, pure metals and eutectic alloys melt or solidify at a constant temperature, the so-called melting point .
In order to determine the start and end point of a melting interval for any alloys, these are subjected to a thermal analysis and the results are then transferred to a phase diagram .
| material | Θ [ ° C ] |
|---|---|
| Low pressure polyethylene ( LDPE ) | 105-120 |
| High pressure polyethylene ( HDPE ) | 125-135 |
| isotactic polypropylene | 176 |
| Polymethyl methacrylate (PMMA) | 120-160 |
| Polyoxymethylene | 165-185 |
| tactical polystyrene | 235-250 |
| Polytetrafluoroethylene (PTFE) | |
| Polyamide 6 | 215-225 |
| Polyamide 11 | 180-190 |
| Polyamide 66 | 250-260 |
| Polyamide 610 | 210-220 |
| Polyethylene terephthalate (PET) | 250-260 |
Plastics
Only some crystalline polymers have a relatively sharp melting point. However, since crystalline plastics still contain amorphous areas, the melting takes place over a certain temperature range when heated, the melting interval. The melting interval can be determined with a hot-stage microscope or in a melting point tube (using the CF Linström apparatus (often incorrectly written as Lindström ); the sample is heated in a copper block and the behavior of the sample in the melting point tube is observed through a built-in magnifying glass ) respectively.
Organic chemistry
Most organic chemical compounds have a certain melting point or a narrow melting range, usually below 300 ° C, and are a purity criterion for these substances. Most organochemical compounds decompose above 300 ° C. H. thermolytically , decomposition products (new, different substances) arise.
Salt-like compounds (example: amino acids ) have higher melting temperatures, but these are often not very characteristic.
See also
literature
- Dieter Kohtz: Introduction to materials science for metal welders . In: Der Praktiker: the magazine for welding technology and more . 9/1982 to 1/1985. DVS-Verlag, ISSN 0554-9965 .
- Roland Strietzel: The material science of metal-ceramic systems . Verlag Neuer Merkur, Munich 2005, ISBN 3-937346-14-7 , p. 13 (available via Google book search ).
Individual evidence
- ^ MD Lechner, K. Gehrke, EH Nordmeier: Makromolekulare Chemie . 4th edition. Birkhäuser Verlag, 2010, ISBN 978-3-7643-8890-4 , p. 475.
- ^ MD Lechner, K. Gehrke, EH Nordmeier: Makromolekulare Chemie . 4th edition. Birkhäuser Verlag, 2010, ISBN 978-3-7643-8890-4 , pp. 474-475.
- ↑ CF Linström: A new melting point determination apparatus made of copper. In: Chem. Fabrik , 7, 270, 1934; Note: Carl Friedrich Linström was assistant at the Phys.-Chemisches Institut in Erlangen under G. Scheibe.