Synthesis of graft -copolymers from palm cellulose and solketal acrylate and their characterization
Résumé
he use of partially biobased monomers to functionalize palm cellulose via graft-copolymerization was explored. The aim of this work is to recycle a waste, the leaves of palm trees, which are abundant in North African countries in order to obtain novel cellulose derivatives having interesting physico-chemical properties. Furthermore, the monomer that was used for the graft-copolymerization was synthesized from a biobased synthon, glycerol. The synthesis of graft-copolymers from cellulose and (2,2-dimethyl-1,3-dioxolan-4-yl)methyl acrylate (solketal acrylate, DMDMA) was studied to determine the optimal conditions for grafting. The maximum grafting weight gain was 27% obtained after 72min of reaction at 65°C with 6.4mmol KPS/eq OH and 1.51mol DMDMA/eq OH. THF, used as dispersion solvent, hinders the homopolymerization side-reaction by creation of terminating radicals. FTIR spectroscopy confirmed the grafting of monomers to cellulose and X-ray diffraction revealed an organized structure of the side-chains. Thermogravimetry showed that the grafting could not confer a higher thermal stability to cellulose (loss of 35°C in the decomposition temperature). Even though partial melting was observed when thermopressed, DSC analysis could not show a neat glass transition temperature but rather multiple exothermal peaks attributed to side-chains reorganization. Thermopressed grafted samples showed improved mechanical properties compared to palm cellulose.
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