Recently, polymeric materials composed entirely of methylated ball-milled softwood lignin have been found to possess tensile properties (50 MPa strength, 8% elongation-at-break) that surpass those of polystyrene (46 MPa strength, 2% elongation-at-break).  The intermolecular forces between methylated ball-milled lignin components arise pre-eminently from electron correlation.  The question naturally arises as to how hydrogen bonding might affect the tensile behavior of materials containing the highest attainable ball-milled lignin levels.  Interestingly, 100% ball-milled softwood lignin-based polymeric materials are weaker in tensile behavior (34 MPa strength, 6% elongation-at-break) than polystyrene, but their properties may be substantially improved by blending with small quantities of selected blend components.  Thus, incorporating just 5% w/w tetrabromobisphenol A (a flame retardant) can result in a blend with 53 MPa tensile strength and 7% elongation-at-break.  Generally, however, unmethylated ball-milled lignin-based materials are less ductile than their methylated counterparts.  For example, a 10% w/w blend of tetrabromobisphenol A with methylated ball-milled softwood lignin can exhibit a 65 MPa tensile strength as elongation-at-break reaches 9%.  Ultimately, whether or not polymeric materials with the highest attainable lignin contents should be methylated will be dictated by a balance between mechanical properties, blend composition, and production cost. <br/>

To methylate or not to methylate polymeric materials with the highest attainable lignin contents

251st National Meeting (2016)

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