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Melting of hydrogels containing ammonium nitrate
Author(s) -
Ahad Elie
Publication year - 1978
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1978.070220617
Subject(s) - self healing hydrogels , bound water , differential scanning calorimetry , polymer , crystallization , ammonium nitrate , polymer chemistry , water of crystallization , chemistry , polyacrylamide , chemical engineering , materials science , organic chemistry , molecule , thermodynamics , physics , engineering
The fusion of hydrogels containing ammonium nitrate (AN) has been investigated by differential scanning calorimetry (DSC). The polymers used were guar and xanthan gums as well as synthetic polyacrylamide polymers. Water in hydrogels could be classified into three types labeled as ordinary water (hump of the melting peak), intermediate water (broad component of the peak), and bound nonfreezing water (without any phase transition). The temperature of fusion of intermediate water was about 10° to 35°C lower than that of ordinary water. Intermediate and bound water was found in all the gels studied, whereas ordinary water existed mainly in mixtures with total water content higher than 62%. The presence, type, and concentration of a crosslinker had no effect on the amount of bound water in hydrogels containing AN. In such mixtures the amount of nonfreezing water increased with the polymer concentration as well with the AN proportion relative to water and represented in some cases up to 27% of the gel. Cold‐crystallization was observed in all cases (except xanthan) and was probably initiated by AN or the crosslinking agent.