Why are tempered samples not tempered

The change in density and heat of fusion when tempering 6.6 polyamide

Polymer Aspects pp 61-76 | Cite as

Conference paper
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Part of the Progress in Colloid & Polymer Science book series (PROGCOLLOID, volume 58)

Summary

The dependence of the density (20 ° C) and the heat of fusion on the tempering temperature (50–260 ° C) and the tempering time (2–10 ° C) is shown on sharply quenched and slowly crystallized 6.6-polyamide in the form of press plates and unstretched or stretched wires4 min) examined. When determining the heat of fusion from the DSC curves, a premelting range between 100 and 200 ° C must also be taken into account, the proportion of which increases sharply with tempering above 200 ° C. In the case of dry samples, the relationship between the heat of fusion and spec. Volume as with 6-polyamide, two straight lines. The quenched and tempered samples with a “pseudo-hexagonal” structure are located on straight line II. All samples with a well-developed triclinic structure are located on straight line I (quenched and tempered plate above 180 ° C., all slowly crystallized spherulitic samples, stretched and undrawn wires). The transition between straight lines I and II is formed by the quenched samples tempered between 100 and 180 ° C. The post-condensation and decomposition phenomena that occur at higher tempering temperatures and longer tempering periods have no influence on the dependence of the heat of fusion on the spec. Volume.

Contrary to that of Hinrichsen The opinion expressed is the density of humid samples around 0.005–0.007 g / cm3 larger than when dry. The heat of desorption of the water, which occurs at the same time when warming moist samples in the temperature range of the premelting, causes an apparent increase in the heat of fusion. The from Hinrichsen The approximate constancy of the heat of fusion found during tempering with a simultaneous strong increase in density is very likely due to the use of moist samples, and above all to not taking into account the premelting area.

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CCl4 Veri Zinn Rhein Darge
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literature

  1. Illers, K. H. and H. Haberkorn, Makromol. Chem. 142, 31 (1971). CrossRefGoogle Scholar
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Copyright information

© Dr. Dietrich Steinkopff Verlag GmbH & Co. KG 1975

Authors and Affiliations

  1. 1st measuring and testing laboratory of BASF Aktiengesellschaft Ludwigshafen / Rhein