Kraft lignin/poly(ethylene oxide) blends: Effect of lignin structure on miscibility and hydrogen bonding

Abstract

Blends of poly(ethylene oxide) (PEO) with softwood kraft lignin (SKL) were prepared by thermal blending. The miscibility behavior and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The experimental results indicate that PEO was miscible with SKL, as shown by the existence of a single glass-transition temperature over the entire composition range by DSC. In addition, a negative polymer-polymer interaction energy density was calculated on the basis of the melting point depression of PEO. The formation of strong intermolecular hydrogen bonding was detected by FTIR analysis. A comparison of the results obtained for the SKL/ PEO blend system with those previously observed for a hardwood kraft lignin/PEO system revealed the existence of stronger hydrogen bonding within the SKL/PEO blends but weaker overall intermolecular interactions between components; this suggested that more than just hydrogen bonding was involved in the determination of the blend behavior in the kraft lignin/PEO blends.

Synthesis and Tribological Behavior of Ultra High Molecular Weight Polyethylene (UHMWPE)-Lignin Composites

“…Various fundamental studies have been done to understand the effect of unmodified lignin on the physical properties of thermoplastic [12][13][14][15][16][17][18][19], thermosets [20], and rubbers [21]. Based on these studies, lignin has been documented to be a promising additive for stabilizing against UV degradation or thermo-oxidation [9,13,15,16,21].…”

“…Based on these studies, lignin has been documented to be a promising additive for stabilizing against UV degradation or thermo-oxidation [9,13,15,16,21]. The mechanical behavior of these composites is dependent on the interaction between different constituents, for example whether blends can form miscible or can phase separate [9,18,19,22]. More particularly, as unmodified lignin contains numerous OH groups, the lignin molecule is thus relatively polar, and will show comparably better affinity toward polar polymer matrices [9,18,19,22].…”

“…The mechanical behavior of these composites is dependent on the interaction between different constituents, for example whether blends can form miscible or can phase separate [9,18,19,22]. More particularly, as unmodified lignin contains numerous OH groups, the lignin molecule is thus relatively polar, and will show comparably better affinity toward polar polymer matrices [9,18,19,22]. By chemical treatments, it is also possible to enhance the lignin compatibility with non-polar polymer matrices by derivatizing some or all of the OH groups, and exposing non-polar groups at the chain end [9,22,23].…”

Experiences of Kraft Lignin Functionalization by Enzymatic and Chemical Oxidation

“…The latter is partly due to crosslinking between the macromolecules via intermolecular hydrogen bonding. Polymer blending (Kadla and Kubo 2004;Kubo and Kadla 2005) or chemical modifications (Glasser and Jain 1993a, b;Lora and Glasser 2002) of lignin by linear substituents, e.g., alkylene, (poly)ethylene, propylene oxide, and butylene oxide have been studied as means to block this type of crosslinking. This internal plasticization of lignin is often measured as the reduced glass transition temperature (Tg), which indicates the ability of the material to undergo softening at reduced temperature.…”

Influence of the lignin on thermal degradation and melting behaviour of poly(ethylene terephthalate) based composites

“…The antioxidant properties of L were used to stabilize polymer matrix composites against photo-and thermo-oxidation [3][4][5]. The intermolecular interactions occurring in blends based on L and synthetic polymers were also investigated [6][7][8]. Previous papers reported about the nucleation effect of L during the crystallization of the polymeric matrix [9][10][11].…”