Graft copolymers of lignin with electron poor alkenes

Abstract

ABSTRACT:The synthesis of copolymers between lignin and electron poor alkenes is described. Lignin from steamexploded pine, from steam-exploded straw, and organosolv were used as starting materials. Beforehand, lignins were fully characterized by using elemental analysis, ultraviolet spectroscopy, gel permeation chromatography (GPC), Fourier transform infrared (FTIR), and both 1 H and 13 C nuclear magnetic resonance (NMR) spectroscopy. The synthesis of copolymers was performed using a previously described procedure utilizing calcium chloride and hydrogen peroxide as reagents. FTIR of copolymers showed absorptions due to the presence of both lignin and the electron withdrawing group on the alkene. GPC analysis showed the presence of fractions with high molecular weights: the M z of lignin from pine was 3729 while the copolymer with methyl acrylate showed M z ϭ 383790. Differential calorimetry showed the presence of glass transitions in the range of Ϫ9 to 4.5°C due to the presence of grafted polyalkene chains. When acrylonitrile was used as starting material DSC analysis of the product showed a glass transition at 119°C, which can be attributed to grafted polyacrylonitrile chain. Lignin from steam explosion could be a good raw material in the preparation of graft copolymers. Furthermore, lignin from pine gave better results than that from straw. Finally, lignin from steam explosion gave better results than organosolv lignin. These results can be explained on the basis of the structural properties of used lignins. Both UV and 13 C NMR spectra showed that lignin from pine contained a consistent amount of double bonds.

Simultaneous enhancement in strength and elongation of waterborne polyurethane and role of star‐like network with lignin core

“…Usually, a three-dimensional network structure of lignin, 3 which is built on CÀ ÀC and CÀ ÀO linkages of phenylpropane units, is shown as a dense and rigid sphere, 16 and acts as core to derivate star-like 7 or hyperbranched structures. 17 The stretching grafted chains of star-like hydropropyl lignin can be tightly associated with soy protein matrix, and hence facilitate the reinforcing of the lignin core. 10 At the same time, spherical nitro-lignin (NL) was blended into polyurethane to form a great star-like networks with the NL core, resulting in the remarkably enhancement in strength and elongation at one time.…”

Role of Star‐Like Hydroxylpropyl Lignin in Soy‐Protein Plastics

“…[5,6] Lignin is a kind of biopolymer with polyfunctional active groups and has been evaluated as a good filler for modifying polymeric materials, [7] such as rubber, polyolefin and starch. [8] Lignin, a sphere-like molecules, [9] can further form star-like [10] or hyperbranched structures [11] via graft copolymerization and chemical derivation, which are very effective for enhancing the reactivity of the groups or changing their functions. Additionally, the polar groups in Summary: Star-like hydroxypropyl lignin (HL) was compounded into soy protein isolated (SPI) to develop a potential biodegradable plastic with better mechanical performance than pure sheet-SPI.…”

Synthesis and characterization of kraft lignin-graft-polylactide copolymers

“…For the production of lignin-based biomaterials, the grafting method is considered one of the most effective ways of altering the physical properties (e.g., tensile strength, thermal stability, etc.) of lignin (Bonini et al 2003;Bhattacharya and Misra 2004). Thus, as part of ongoing research into ways to utilize lignin effectively, the graft copolymerization of PLA onto lignin was investigated in depth.…”