Partially carbamate reaction of cellulose with urea

Partially Carbamate Reaction of Cellulose with UreaThe reaction of cellulose with urea and substituted ureas has been studied by Segal' and Nuessle.2Some cellulose carbamate derivatives of aromatic amines3 were investigated to prepare in relation to facts that the treated cotton cellulose with urea a t 120°C in alkaline condition was favorable toThe treatments of cellulose with urea are believed to be significant in the sense of improving fiber and cotton cloth, and so a precise curing condition should be considered to get an optimum on the cellulose carbamate reactions.The conventional curing procedures on heating to an elevated temperature had been applied to the cellulose materials, which were pretreated to soak in an aqueous padding solution of urea and dried a t 116°C.The effects of the curing conditions such as temperature, time, and weight ratio of urea to cellulose on the carbamate reactions are not able to examine adequately in the curing manner since the reaction may occur a t the drying stage of the samples padded.Therefore, the carbamate reactions of microcrystalline cellulose curing with urea in the state of a dry solid mixture were discussed with reference to the relation between a nitrogen content and an intensity ratio of absorption band in infrared spectra. EXPERIMENTALVarious samples were prepared by the following procedures.Dried mixture of solid both predetermined weight ratio of microcrystalline cellulose (Avicel, Asahi Kasei Co.) and urea (Wako Pure Chemical Co.) were heated to cure in a glass vessel immersed in a silicone oil bath at a controlled temperature of 110,135,160, or 185°C for 1-15 h without catalyst.These samples were thoroughly washed with boiling water more than five times until the washings were no longer colored, then finally washed with methyl alcohol, and dried under reduced pressure.The samples' color turned slightly grayish brown.Nitrogen contents of the samples prepared were determined by the apparatus of Nitrogen-Nalyzer Coleman model 29.Infrared spectra were recorded in potassium bromide disk technique by JASCO AP-2 spectrometer.The intensity of maxima in infrated absorption band was determined by the baseline method.