%0 Journal Article
%T Dispersiones acuosas de poliuretano bloqueado: una alternativa como agente curtiente
%A Mata-Mata
%A Jos¨¦ Luis
%A Mendoza Olivares
%A Diana
%A Alvarado Castro
%A Diego Ismael
%A Am¨¦zquita L¨®pez
%A Fernando de Jes¨²s
%J Pol¨ªmeros
%D 2008
%I Associa??o Brasileira de Pol¨ªmeros
%R 10.1590/S0104-14282008000200011
%X two types of crosslinking agents blocked polyurethanes were synthesized and evaluated as tanning agents of bovine skins. the results of the synthesis of aqueous dispersions of blocked polyurethane (dpu£¿s) are presented. they were based on prepolymers from the reaction of the aliphatic diisocyanates h12mdi 4,4£¿-methylenebis(cyclohexyl isocyanate) and hdi (hexamethylene diisocyanate) with ho-polyols such as polyethylene oxide of molecular weight 1 and 2 kda. the molar nco/oh ratio was fixed in 4:1 or 6:1, at 100 ¡ãc and 2 or 4 hours for the reaction time. in a second reaction, the prepolymer containing terminal nco groups were blocked by reaction with an aqueous nahso3 or na2s2o5 solution to 40% w/w. the obtained prepolymers were characterized by ir and 1h nmr. the % of free isocyanate (nco) in the prepolymer as well as the blockade of these groups were determined by ir. the evaluation of the tanning capacity of the dpu£¿s was determined according to the thermal stability of the skin (thermal denaturalization), through the differential scanning calorimetry analysis (dsc). the index of crosslinking of the dpu£¿s with the collagen of the skin was determined with the nynhidrin essay.
%K aqueous dispersions of blocked polyurethane (dpu£¿s)
%K tanning agents
%K crosslinking.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S0104-14282008000200011&lng=en&nrm=iso&tlng=en