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  • Author or Editor: J. Šívarová x
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Abstract  

Hydrolysates from chromed leather waste obtained in powdered form on an industrial scale by using biotechnical methods were analysed by TG an DSC techniques. Besides about 9% (mass/mass) of moisture, around 1% (mass/mass) of cyclohexylamine was found in the pulverized hydrolysates. Calorimetric measurement of the reaction heats of the reactions of the hydrolysates with commercially available aldehydes indicates that their reactivity decreases in the sequenceglutardialdehyde>>methylglyoxal≈acetaldehyde>>glyoxal>formaldehyde.

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Abstract  

Condensation of dimethylol-urea (DMU) mixed with urea (U) and collagen hydrolysate (H), obtained through enzymatic hydrolysis of chrome-tanned leather waste, without added acid curing agents in the solid phase was studied through DSC and TG techniques in a temperature interval up to 220°C. Among both techniques TG proved be more useful.While the DMU+U mix produced methylene-oxide (-CH2-O-CH2-) and methylene (-CH2-) bridges at a ratio of approx. 1:1, urea substituted for collagen hydrolysate increased the proportion of more stable methylene bridges to methylene-oxide bridges to a ratio of approx. 2:1. Methylene-oxide bridges are considered to be the main potential sources of formaldehyde emissions from cured urea-formaldehyde type adhesives, and thus the use of collagen hydrolysate in preparation of urea-formaldehyde adhesive types is a suitable way how to make such adhesives more environmental friendly.

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