Multiphase Materials with Lignin. IV. Blends of Hydroxypropyl Cellulose with Lignin

Polymer blends of hydroXYpl"Opyl cenul~ (HPC) and organ~lv lignin (OSL) were prepared by mixing in solutions of both pyridine and dioxane, and casting 88 fibD8, and by mixing in the melt followed by extrusioo. All preparations exhibited partial miscibility 88 evidmced by a aingle T. up to a compositioo of 40 wt % lignin above which phase aeparatioo was detected. Dioxan~t and injectioo-molded bl_ds were distinguished from the pyridine-cast materiaJs by a positive T. deviatioo from additivity, an approximatioo which adequately dM<:ribed the latter. This ~tive deviatioo in T. is attributed to the formatioo of a liquid-cryatai mesophase with a nIIultant reduction of amOl'phous HPC available fOl' interactioo with the lignin componmt. This explanatioo is supported by a rapid rise in modulus ( IfKJ%) and tenaile 8trmgth with very low lignin contSlt, and by an aBSociated sharp decline in ultimate eloogatioo. The developmmt of morphological f~tur-. 88 obesved by scanning electron micr(S»PY provide further' substantiation of this hypothesis.