INVESTIGADORES
SLAVUTSKY Anibal Marcelo
congresos y reuniones científicas
Título:
A thermodynamic study of water vapour sorption in hydrocolloids/MMT nanocomposite based films
Autor/es:
SLAVUTSKY, ANIBAL M.; BERTUZZI, MARÍA A.
Reunión:
Congreso; European Polymers Congress; 2013
Resumen:
Water transport in edible films based on hydrocolloids is a complex
phenomenon due to the strong interaction of sorbed water molecules
with polymeric structure of polysacharides. Edible films based on corn
starch (CS) and brea gum (BG) were obtained. In order to improve water
resistance, films based on nanocomposites of hydrocolloids and
nanoclay (montmorillonite, MMT) were prepared. Moisture sorption
isotherms of hydrocolloid based films and nanocomposites based films,
were obtained at 5, 25, 35 and 45¨¬C through the gravimetric method.
The entropy changes, ¥ÄS , Gibb¢¥s energy changes, ¥ÄG and isosteric
heat of sorption, Qs, were calculated.
Water vapour sorption experimental data showed an exothermic process
and were well described by GAB model in all samples. Isotherm curves
showed an exponential increase of water uptake above aw=0.6,
producing film structural changes which allow a facilitated water
transport phenomenon and deteriorate mechanical resistance. MMT
addition decreased water uptake of CS and BG films in all the studied
temperatures. The water content values of the monolayer calculated with
GAB equation reduced with MMT incorporation in both cases.
Entropy changes and net isosteric heat of sorption showed a well
defined peak at monolayer water content and in both cases indicated a
more stable and ordered structure when MMT was added. Gibb¡¯s energy
changes showed the process spontaneity and that final structure of
CS/MMT and BG/MMT films has less affinity with water than the CS and
BG films respectivelly.
The results indicated that nanoclay incorporation produce a decrease of
water uptake at all temperatures analyzed. Thermodynamic parameters
showed that sorption process is less favourable when MMT is
incorporated into the polysacharide matrix.
producing film structural changes which allow a facilitated water
transport phenomenon and deteriorate mechanical resistance. MMT
addition decreased water uptake of CS and BG films in all the studied
temperatures. The water content values of the monolayer calculated with
GAB equation reduced with MMT incorporation in both cases.
Entropy changes and net isosteric heat of sorption showed a well
defined peak at monolayer water content and in both cases indicated a
more stable and ordered structure when MMT was added. Gibb¡¯s energy
changes showed the process spontaneity and that final structure of
CS/MMT and BG/MMT films has less affinity with water than the CS and
BG films respectivelly.
The results indicated that nanoclay incorporation produce a decrease of
water uptake at all temperatures analyzed. Thermodynamic parameters
showed that sorption process is less favourable when MMT is
incorporated into the polysacharide matrix.
producing film structural changes which allow a facilitated water
transport phenomenon and deteriorate mechanical resistance. MMT
addition decreased water uptake of CS and BG films in all the studied
temperatures. The water content values of the monolayer calculated with
GAB equation reduced with MMT incorporation in both cases.
Entropy changes and net isosteric heat of sorption showed a well
defined peak at monolayer water content and in both cases indicated a
more stable and ordered structure when MMT was added. Gibb¡¯s energy
changes showed the process spontaneity and that final structure of
CS/MMT and BG/MMT films has less affinity with water than the CS and
BG films respectivelly.
The results indicated that nanoclay incorporation produce a decrease of
water uptake at all temperatures analyzed. Thermodynamic parameters
showed that sorption process is less favourable when MMT is
incorporated into the polysacharide matrix.
w=0.6,
producing film structural changes which allow a facilitated water
transport phenomenon and deteriorate mechanical resistance. MMT
addition decreased water uptake of CS and BG films in all the studied
temperatures. The water content values of the monolayer calculated with
GAB equation reduced with MMT incorporation in both cases.
Entropy changes and net isosteric heat of sorption showed a well
defined peak at monolayer water content and in both cases indicated a
more stable and ordered structure when MMT was added. Gibb¡¯s energy
changes showed the process spontaneity and that final structure of
CS/MMT and BG/MMT films has less affinity with water than the CS and
BG films respectivelly.
The results indicated that nanoclay incorporation produce a decrease of
water uptake at all temperatures analyzed. Thermodynamic parameters
showed that sorption process is less favourable when MMT is
incorporated into the polysacharide matrix.