Obiettivo
UPGRADING OF BARK BY CRACKING THIS RAW MATERIAL INTO SEVERAL FRACTIONS AND FINDING A GOOD APPLICATION FOR EACH PRODUCT.
THIS PROGRAMME IS DIVIDED IN THREE PARTS :
1. ANALYSIS OF BARK : THIS PART IS VERY IMPORTANT AND THIS WORK HAS NOT BEEN COMPLETELY CARRIED OUT.
2. DEVELOPMENT OF THE CRACKING PROCESS, ESPECIALLY AN ALKALINE EXTRACTION. THE POLYPHENOLS SOLUBILIZED ARE MAINLY CONSTITUTED BY POLYFLAVONOIDS.
DURING THIS TREATMENT THE POLYSACCHARIDE LOSSES ACCOUNT FOR LESS THAN 10 % OF THE INITIAL POLYSACCHARIDES IN BARK. THE LOSSES ARE DUE TO HEMICELLULOSE REMOVAL AND CELLULOSE CONTENT DOES NOT VARY. EXTRACTION CONDITIONS WILL BE OPTIMIZED AND STANDARDIZED IN THIS PROGRAMME.
3. UPGRADING OF THE TWO FRACTIONS. ROUGHLY 85 % OF THE MATERIAL DISSOLVED IN ALKALINE EXTRACTION CORRESPONDS TO FORMALDEHYDE - CONDENSABLE POLYPHENOLS WHICH HAVE BEEN IDENTIFIED AS ACTIVE AGENTS FOR THE PRODUCTION OF ADHESIVES. EXTRACTION CONDITIONS WILL BE STUDIED FOR FINDING AN EQUILIBRIUM BETWEEN POLYPHENOLS EXTRACTION AND POLYSACCHARIDES LOSSES. PARAMETERS SUCH AS TEMPERATURE, TIME ALKALI CONCENTRATION, ALKALI WILL BE TAKEN INTO ACCOUNT. THE DIFFERENT FRACTIONS WILL BE CONCENTRATED AND THEIR REACTIVITY WITH FORMALDEHYDE STUDIED.