Green Plasticizers from Liquefied Wood

Green plasticizers were designed from liquefied wood flour, a non-edible biobased waste product. Wood flour was liquefied to low molecular weight polyols by acid catalyzed reaction. The resulting polyol mixture, including the remaining liquefaction solvents glycerol and diethylene glycol, was further utilized for the synthesis of low molecular weight ester plasticizers. Monomeric (MLWP) and oligomeric (OLWP) plasticizers were prepared by esterification of the polyols by hexanoic acid or a mixture of hexanoic and adipic acid, respectively. Liquefied wood polyol mixture and the synthesized plasticizers were characterized by size exclusion chromatography, electrospray ionization-mass spectrometry and fourier transform infrared spectroscopy. MLWP, OLWP and traditional dioctyl phthalate (DIOP) plasticizer were blended with poly(vinyl chloride) (PVC) and tensile testing was performed to evaluate the plasticizing efficiency of the new plasticizers. In addition PVC blends containing model disaccharide ester, sucrose octaacetate (SOA), were prepared and tested. Highest strain at break was obtained after addition of SOA ester, which clearly shows the potential of sugar esters as PVC plasticizers. Addition of MLWP also resulted in slightly higher strain at break as compared to films plasticized with same amount of phthalate plasticizer, DIOP. Differential scanning calorimetry showed one concentration dependent glass transition temperature for all the studied blends indicating good miscibility. Our novel plasticizers are attractive environmentally friendly alternatives for phthalate plasticizers and could be prepared from biomass waste from agriculture and forest industry.