LIGNINA CA AGENT DE MODIFICARE PENTRU CRESTEREA DURABILITATII LEMNULUI

Jelena CHIRKOVA
Dr. Chem., Researcher - Latvian State Institute of Wood Chemistry
Adresa: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: cirkel@edi.lv

Ingeborga ANDERSONE
Dr. Chem., Senior Researcher - Latvian State Institure of Wood Chemistr
Adresa: 27 Dzerbenes str., LV-1006, Riga, Latvia
E-mail: brunoan@edi.lv

Bruno ANDERSONS
Dr. Chem., Senior Researcher - Latvian State Institute of Wood Chemistry
Adresa: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: brunoandersons@edi.lv

Nina KURNOSOVA
Dr. Chem., Researcher - Latvian State Institute of Wood Chemistry
Adresa: 27 Dzerbenes Str., LV-1006 Riga, Latvia
E-mail: kurnosova@edi.lv

Rezumat:
Pentru inlocuirea produselor clasice de protectie a lemnului cu continut de metale grele, sunt propuse diferite metode de modificare a lemnului (termice si chimice, utilizarea biocidelor organice etc.) in vederea imbunatatirii rezistentei la biodegradare. Consumul mare de energie, costul ridicat al agentilor de modificare si impactul lor nefavorabil asupra mediului constituie elemente ce franeaza dezvoltarea acestor tehnologii. In studiul de fata se propune pentru imbunatatirea durabilitatii lemnului introducerea ligninei - o substanta prietenoasa atat fata de lemn cat si de mediu - in golurile lemnului (canale, lumen celular si spatii intercelulare). Probe de lemn de pin au fost impregnate sub vid cu solutii apoase de lignina alcalina. In ciuda caracterului pronuntat hidrofil al lemnului modificat expunerea sa la atacul ciupercilor de putregai brun si alb pe medii de cultura timp de 6 saptamani a aratat eficienta ridicata a ligninei in cresterea durabilitatii lemnului fata de ambele tipuri de putregai. Studii privind absorbtia de apa si densitatea au demonstrat o slabire a legaturilor interstructurale in urma modificarii, volumul porilor ingusti (micro- si mezo-) crescand aproape de doua ori, in timp ce volumul porilor largi (macro-pori) a scazut cu o treime. S-a ajuns la concluzia ca lignina umple partial (pana la 13%) canalele, blocand intrarile in acestea, impiedicand astfel difuzia enzimelor ciupercilor spre suprafata peretelui celular.

Cuvinte cheie: lemn, biodegradare, lignina, sorbtie de apa, densitate, modificare.

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