INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Changing essential characteristics of Poly(vinylalcohol) cryogels by thermal treatments.
Autor/es:
JIMENA SOLEDAD GONZALEZ; VERA ALEJANDRA ALVAREZ
Lugar:
granada
Reunión:
Congreso; XII Congress Of The Specialized Group Of Polymers; 2011
Resumen:
The crosslinking method, based on freeze and then thaw (F/T) solution of Poly vinyl alcohol (PVA) several times, results in the formation of crystallites that serve as physical crosslinks making a three-dimensional network [1-3] that become the material insoluble in water. PVA molecules are aggregated during ice formation and hydrogen bonding is established between molecular chains. By increase the number of F/T cycles, residual free molecular chains are successively included in linking zones [4]. On the other hand, the glass transition temperature (Tg) of these kind of materials sharply decreases with the water content [5]. Heat treatments above the Tg [2-3] as well as repeated F/T cycles, are also used to achieve the same results mainly by increasing the amount of crystals of the polymer, which act as a physical crosslinkers of the network. When PVA films are annealed at constant temperature (between Tg and the melting temperature; Tm), the macromolecular chains have enough mobility to align themselves and fold to form crystals [3]. It is well known that the increasing in the polymer crystallinity degree (Xcr), results in a more resistant material [6]. The aim of this work was to investigate the effect of the annealing temperature over the structural and swelling characteristics of the PVA hydrogels obtained by F/T technique.